125-485: The eastern hog-nosed snake ( Heterodon platirhinos ), is a species of mildly venomous rear-fanged snake in the family Colubridae . The venom is specifically adapted to amphibian prey and is harmless to humans. However, some people may have an allergic reaction, and experience local swelling and other symptoms. The species is endemic to North America. There are no subspecies that are recognized as being valid. This species prefers habitats with sandy soils and
250-455: A mutation (the deletion of two nucleotides ) that inactives it. These changes are explained by the fact that its prey does not need to be subdued. Several groups of predatory fish have the ability to detect, track, and sometimes, as in the electric ray , to incapacitate their prey by sensing and generating electric fields . The electric organ is derived from modified nerve or muscle tissue. Physiological adaptations to predation include
375-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles
500-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed
625-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this
750-418: A better choice. If it chooses pursuit, its physical capabilities determine the mode of pursuit (e.g., ambush or chase). Having captured the prey, it may also need to expend energy handling it (e.g., killing it, removing any shell or spines, and ingesting it). Predators have a choice of search modes ranging from sit-and-wait to active or widely foraging . The sit-and-wait method is most suitable if
875-851: A broad range of taxa including arthropods. They are common among insects, including mantids, dragonflies , lacewings and scorpionflies . In some species such as the alderfly , only the larvae are predatory (the adults do not eat). Spiders are predatory, as well as other terrestrial invertebrates such as scorpions ; centipedes ; some mites , snails and slugs ; nematodes ; and planarian worms . In marine environments, most cnidarians (e.g., jellyfish , hydroids ), ctenophora (comb jellies), echinoderms (e.g., sea stars , sea urchins , sand dollars , and sea cucumbers ) and flatworms are predatory. Among crustaceans , lobsters , crabs , shrimps and barnacles are predators, and in turn crustaceans are preyed on by nearly all cephalopods (including octopuses , squid and cuttlefish ). Seed predation
1000-422: A combination of grass fields and forest edges. They come in many different colorations and have the identifiable upturned "snout". They can be found in captivity but are a relatively difficult species to keep due to a specialized diet of toads. As with other Heterodon species, they have a distinctive threat reaction of first bluffing by striking with a closed mouth and then pretending to die if this fails to deter
1125-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing
1250-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by
1375-582: A food trap, mechanical stimulation, and electrical impulses to eventually catch and consume its prey. Some carnivorous fungi catch nematodes using either active traps in the form of constricting rings, or passive traps with adhesive structures. Many species of protozoa ( eukaryotes ) and bacteria ( prokaryotes ) prey on other microorganisms; the feeding mode is evidently ancient, and evolved many times in both groups. Among freshwater and marine zooplankton , whether single-celled or multi-cellular, predatory grazing on phytoplankton and smaller zooplankton
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#17328546512281500-416: A foul musk from its cloaca and let its tongue hang out of its mouth . One individual was observed playing dead for 45 minutes before reanimating and moving away. This death-feigning behavior was also observed often in water habitats. The eastern hognose snake feeds extensively on amphibians , and has a particular fondness for toads . This snake has resistance to the toxins toads secrete. This immunity
1625-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider
1750-471: A huge gulp of water and filtering it through their feathery baleen plates. Pursuit predators may be social , like the lion and wolf that hunt in groups, or solitary. Once the predator has captured the prey, it has to handle it: very carefully if the prey is dangerous to eat, such as if it possesses sharp or poisonous spines, as in many prey fish. Some catfish such as the Ictaluridae have spines on
1875-725: A kill, and the coyote can be either solitary or social. Other solitary predators include the northern pike, wolf spiders and all the thousands of species of solitary wasps among arthropods, and many microorganisms and zooplankton . Under the pressure of natural selection , predators have evolved a variety of physical adaptations for detecting, catching, killing, and digesting prey. These include speed, agility, stealth, sharp senses, claws, teeth, filters, and suitable digestive systems. For detecting prey , predators have well-developed vision , smell , or hearing . Predators as diverse as owls and jumping spiders have forward-facing eyes, providing accurate binocular vision over
2000-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On
2125-539: A long distance, sometimes for hours at a time. The method is used by human hunter-gatherers and by canids such as African wild dogs and domestic hounds. The African wild dog is an extreme persistence predator, tiring out individual prey by following them for many miles at relatively low speed. A specialised form of pursuit predation is the lunge feeding of baleen whales . These very large marine predators feed on plankton , especially krill , diving and actively swimming into concentrations of plankton, and then taking
2250-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides
2375-412: A new egg clutch at this time, females will instead store sperm until the spring months for use. Males will follow the pheromone trails left behind by females on the move. Some females have been observed traveling past viable nesting conditions in order to reach communal nesting sites. Eggs might be laid in small soil depressions, mammal burrows, or under rocks depending on the region. The female may even dig
2500-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as
2625-445: A patch and decide whether to spend time searching for prey in it. This may involve some knowledge of the preferences of the prey; for example, ladybirds can choose a patch of vegetation suitable for their aphid prey. To capture prey, predators have a spectrum of pursuit modes that range from overt chase ( pursuit predation ) to a sudden strike on nearby prey ( ambush predation ). Another strategy in between ambush and pursuit
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#17328546512282750-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that
2875-425: A powerful selective effect on prey, and the prey develop antipredator adaptations such as warning coloration , alarm calls and other signals , camouflage , mimicry of well-defended species, and defensive spines and chemicals. Sometimes predator and prey find themselves in an evolutionary arms race , a cycle of adaptations and counter-adaptations. Predation has been a major driver of evolution since at least
3000-785: A predator, while small prey might prove hard to find and in any case provide less of a reward. This has led to a correlation between the size of predators and their prey. Size may also act as a refuge for large prey. For example, adult elephants are relatively safe from predation by lions, but juveniles are vulnerable. Members of the cat family such as the snow leopard (treeless highlands), tiger (grassy plains, reed swamps), ocelot (forest), fishing cat (waterside thickets), and lion (open plains) are camouflaged with coloration and disruptive patterns suiting their habitats. In aggressive mimicry , certain predators, including insects and fishes, make use of coloration and behaviour to attract prey. Female Photuris fireflies , for example, copy
3125-421: A preferred target is scarce. When prey have a clumped (uneven) distribution, the optimal strategy for the predator is predicted to be more specialized as the prey are more conspicuous and can be found more quickly; this appears to be correct for predators of immobile prey, but is doubtful with mobile prey. In size-selective predation, predators select prey of a certain size. Large prey may prove troublesome for
3250-820: A relatively narrow field of view, whereas prey animals often have less acute all-round vision. Animals such as foxes can smell their prey even when it is concealed under 2 feet (60 cm) of snow or earth. Many predators have acute hearing, and some such as echolocating bats hunt exclusively by active or passive use of sound. Predators including big cats , birds of prey , and ants share powerful jaws, sharp teeth, or claws which they use to seize and kill their prey. Some predators such as snakes and fish-eating birds like herons and cormorants swallow their prey whole; some snakes can unhinge their jaws to allow them to swallow large prey, while fish-eating birds have long spear-like beaks that they use to stab and grip fast-moving and slippery prey. Fish and other predators have developed
3375-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,
3500-478: A significant amount of energy, to locate each food patch. For example, the black-browed albatross regularly makes foraging flights to a range of around 700 kilometres (430 miles), up to a maximum foraging range of 3,000 kilometres (1,860 miles) for breeding birds gathering food for their young. With static prey, some predators can learn suitable patch locations and return to them at intervals to feed. The optimal foraging strategy for search has been modelled using
3625-406: A small animal, gulping the prey in an extremely rapid movement when it is within range. Many smaller predators such as the box jellyfish use venom to subdue their prey, and venom can also aid in digestion (as is the case for rattlesnakes and some spiders ). The marbled sea snake that has adapted to egg predation has atrophied venom glands, and the gene for its three finger toxin contains
3750-523: A smaller area. For example, when mixed flocks of birds forage, the birds in front flush out insects that are caught by the birds behind. Spinner dolphins form a circle around a school of fish and move inwards, concentrating the fish by a factor of 200. By hunting socially chimpanzees can catch colobus monkeys that would readily escape an individual hunter, while cooperating Harris hawks can trap rabbits. Predators of different species sometimes cooperate to catch prey. In coral reefs , when fish such as
3875-421: A solid gray, yellow, or cream-colored. In this species the underside of the tail is lighter than the belly. The most distinguishing feature is the upturned snout, used for digging in sandy soils. The average adult H. platirhinos measures 71 cm (28 in) in total length (including tail), with females being larger than males. The maximum recorded total length is 116 cm (46 in). The Eastern hognose
Eastern hognose snake - Misplaced Pages Continue
4000-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of
4125-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in
4250-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as
4375-488: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there
4500-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define
4625-519: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including
4750-415: A toad specialist species, it can be tricky to get them to eat frozen thawed mice. Scenting the food with toad or lizard is a trick used amongst hobbyists to entice the snake. Being a solitary species, snakes are kept individually unless it is for intentional breeding. Due to their burrowing nature, hognose snakes require suitable substrate depth to retain this natural instinct. This species, H. platirhinos ,
4875-506: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines
5000-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species
5125-440: A variety of defences including the ability to hear the echolocation calls. Many pursuit predators that run on land, such as wolves, have evolved long limbs in response to the increased speed of their prey. Their adaptations have been characterized as an evolutionary arms race , an example of the coevolution of two species. In a gene centered view of evolution , the genes of predator and prey can be thought of as competing for
Eastern hognose snake - Misplaced Pages Continue
5250-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,
5375-477: Is ballistic interception , where a predator observes and predicts a prey's motion and then launches its attack accordingly. Ambush or sit-and-wait predators are carnivorous animals that capture prey by stealth or surprise. In animals, ambush predation is characterized by the predator's scanning the environment from a concealed position until a prey is spotted, and then rapidly executing a fixed surprise attack. Vertebrate ambush predators include frogs, fish such as
5500-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that
5625-561: Is a diurnal species. It is typically most active during April–September after coming out of hibernation. Because there is such a wide range the snake is found there is variation in the population's climates which can cause the period of activity to change. In northern climates, hibernation comes earlier and begins late September–October whereas in southern climates, the snake might not retreat until November. There have been some recorded to still be active between December–February in Florida and along
5750-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if
5875-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This
6000-416: Is a toad feeding specialist, its venom is adapted to be effective against toads and has not been found to be harmful to humans. Eastern hognose snakes mate in early April and May. Both the male and female snakes are known to have multiple mates during this season. The act of copulation can last for up to 3 days. Occasionally, a second breeding period occurs around September and October. Rather than fertilizing
6125-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation
6250-412: Is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,
6375-498: Is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (Year assessed: 2007). However, it is a species of increasing conservation concern, especially in the northeastern part of its range. Of the five states in the northeast U.S. where the eastern hognose snake occurs, it currently has "listed" conservation status in four (Connecticut, New Hampshire, New York, and Rhode Island). Noted declines are believed to be
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#17328546512286500-494: Is common, and found in many species of nanoflagellates , dinoflagellates , ciliates , rotifers , a diverse range of meroplankton animal larvae, and two groups of crustaceans, namely copepods and cladocerans . To feed, a predator must search for, pursue and kill its prey. These actions form a foraging cycle. The predator must decide where to look for prey based on its geographical distribution; and once it has located prey, it must assess whether to pursue it or to wait for
6625-569: Is derived from the Greek words heteros meaning "different" and odon meaning "tooth". The specific name platirhinos is derived from the Greek words platys meaning "broad or flat" and rhinos meaning "snout". This species of snake is described as being quite stout-bodied. The color pattern of this snake is extremely variable. It can be red, green, orange, brown, gray to black, or any combination thereof depending on locality. Dorsally , it can be blotched, checkered, or patternless. The belly tends to be
6750-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when
6875-629: Is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation , sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision , hearing , or smell . Many predatory animals , both vertebrate and invertebrate , have sharp claws or jaws to grip, kill, and cut up their prey. Other adaptations include stealth and aggressive mimicry that improve hunting efficiency. Predation has
7000-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as
7125-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,
7250-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept
7375-468: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with
7500-514: Is restricted to mammals, birds, and insects but is found in almost all terrestrial ecosystems. Egg predation includes both specialist egg predators such as some colubrid snakes and generalists such as foxes and badgers that opportunistically take eggs when they find them. Some plants, like the pitcher plant , the Venus fly trap and the sundew , are carnivorous and consume insects . Methods of predation by plants varies greatly but often involves
7625-436: Is shown by the female such as nest and young guarding through hissing and chasing. Typically, males reach maturity at about 40 cm (16 in) SVL which can take up to 18-24 months. Females, however, reach maturity at about 45 cm (18 in) SVL, taking up to 21 months. Heterodon platirhinos is a mildly venomous species where the effects are not deadly to humans. Heterodon means "different tooth", which refers to
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#17328546512287750-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,
7875-430: Is size. Prey that is too small may not be worth the trouble for the amount of energy it provides. Too large, and it may be too difficult to capture. For example, a mantid captures prey with its forelegs and they are optimized for grabbing prey of a certain size. Mantids are reluctant to attack prey that is far from that size. There is a positive correlation between the size of a predator and its prey. A predator may assess
8000-434: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. Predation Predation is a biological interaction where one organism,
8125-447: Is thought to come from enlarged adrenal glands which secrete large amounts of hormones to counteract the toads' powerful skin poisons . At the rear of each upper jaw, it has enlarged teeth, which are neither hollow nor grooved, with which it punctures and deflates toads to be able to swallow them whole. It will also consume other amphibians, such as frogs and salamanders . Like all other snakes, they eat their prey whole. Because it
8250-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,
8375-426: Is threatened, the neck is flattened and the head is raised off the ground, like a cobra . It also hisses and will strike with its mouth closed, but it does not attempt to bite— a behavior known as "bluffing". The result can be likened to a high speed head-butt. If this threat display does not work to deter a would-be predator , an eastern hognose snake will often roll onto its back and play dead, going so far as to emit
8500-451: The Cambrian period. At the most basic level, predators kill and eat other organisms. However, the concept of predation is broad, defined differently in different contexts, and includes a wide variety of feeding methods; moreover, some relationships that result in the prey's death are not necessarily called predation. A parasitoid , such as an ichneumon wasp , lays its eggs in or on its host;
8625-523: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as
8750-465: The angel shark , the northern pike and the eastern frogfish . Among the many invertebrate ambush predators are trapdoor spiders and Australian Crab spiders on land and mantis shrimps in the sea. Ambush predators often construct a burrow in which to hide, improving concealment at the cost of reducing their field of vision. Some ambush predators also use lures to attract prey within striking range. The capturing movement has to be rapid to trap
8875-455: The common garter snake has developed a resistance to the toxin in the skin of the rough-skinned newt . Predators affect their ecosystems not only directly by eating their own prey, but by indirect means such as reducing predation by other species, or altering the foraging behaviour of a herbivore, as with the biodiversity effect of wolves on riverside vegetation or sea otters on kelp forests. This may explain population dynamics effects such as
9000-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is
9125-475: The grouper and coral trout spot prey that is inaccessible to them, they signal to giant moray eels , Napoleon wrasses or octopuses . These predators are able to access small crevices and flush out the prey. Killer whales have been known to help whalers hunt baleen whales . Social hunting allows predators to tackle a wider range of prey, but at the risk of competition for the captured food. Solitary predators have more chance of eating what they catch, at
9250-498: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen
9375-461: The marginal value theorem . Search patterns often appear random. One such is the Lévy walk , that tends to involve clusters of short steps with occasional long steps. It is a good fit to the behaviour of a wide variety of organisms including bacteria, honeybees, sharks and human hunter-gatherers. Having found prey, a predator must decide whether to pursue it or keep searching. The decision depends on
9500-527: The predator , kills and eats another organism, its prey . It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host ) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge ; it overlaps with herbivory , as seed predators and destructive frugivores are predators. Predators may actively search for or pursue prey or wait for it, often concealed. When prey
9625-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept
9750-473: The Gulf Coast. If the temperature reaches or drops below 19 degrees Celsius, hibernation will begin for the snake. This hibernation period takes place alone in burrows either dug by the snake or already made mammal burrows. To burrow, a snake forces its head into the soil then moves its head back and forth. For hibernation, these burrows will reach depths of 25 centimeters or more. When the eastern hognose snake
9875-622: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for
10000-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as
10125-709: The ability of predatory bacteria to digest the complex peptidoglycan polymer from the cell walls of the bacteria that they prey upon. Carnivorous vertebrates of all five major classes (fishes, amphibians, reptiles, birds, and mammals) have lower relative rates of sugar to amino acid transport than either herbivores or omnivores, presumably because they acquire plenty of amino acids from the animal proteins in their diet. To counter predation, prey have evolved defences for use at each stage of an attack. They can try to avoid detection, such as by using camouflage and mimicry . They can detect predators and warn others of their presence. If detected, they can try to avoid being
10250-728: The ability to crush or open the armoured shells of molluscs. Many predators are powerfully built and can catch and kill animals larger than themselves; this applies as much to small predators such as ants and shrews as to big and visibly muscular carnivores like the cougar and lion . Predators are often highly specialized in their diet and hunting behaviour; for example, the Eurasian lynx only hunts small ungulates . Others such as leopards are more opportunistic generalists, preying on at least 100 species. The specialists may be highly adapted to capturing their preferred prey, whereas generalists may be better able to switch to other prey when
10375-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to
10500-584: The assault. When animals eat seeds ( seed predation or granivory ) or eggs ( egg predation ), they are consuming entire living organisms, which by definition makes them predators. Scavengers , organisms that only eat organisms found already dead, are not predators, but many predators such as the jackal and the hyena scavenge when the opportunity arises. Among invertebrates, social wasps such as yellowjackets are both hunters and scavengers of other insects. While examples of predators among mammals and birds are well known, predators can be found in
10625-684: The back (dorsal) and belly (pectoral) which lock in the erect position; as the catfish thrashes about when captured, these could pierce the predator's mouth, possibly fatally. Some fish-eating birds like the osprey avoid the danger of spines by tearing up their prey before eating it. In social predation, a group of predators cooperates to kill prey. This makes it possible to kill creatures larger than those they could overpower singly; for example, hyenas , and wolves collaborate to catch and kill herbivores as large as buffalo, and lions even hunt elephants. It can also make prey more readily available through strategies like flushing of prey and herding it into
10750-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species
10875-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,
11000-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be
11125-734: The burrow herself, often choosing open and grassy areas with few herbs or shrubs because these areas get more sunlight, because the warm temperatures it provides are needed for the proper development of the eggs. The females, which lay 8–40 eggs (average about 25) in June or early July, do not take care of the eggs or young. The eggs, which measure about 33 mm × 23 mm ( 1 + 1 ⁄ 3 in × 1 in), hatch after about 60 days, from late July to September. The hatchlings are about 16.5–21 cm (6.5–8.3 in) long. They have an average nest temperature of 23–26 °C (73–79 °F) incubating for an average of 49–63 days. Some parental care
11250-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered
11375-416: The concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses ) are given a two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part
11500-416: The costs and benefits involved. A bird foraging for insects spends a lot of time searching but capturing and eating them is quick and easy, so the efficient strategy for the bird is to eat every palatable insect it finds. By contrast, a predator such as a lion or falcon finds its prey easily but capturing it requires a lot of effort. In that case, the predator is more selective. One of the factors to consider
11625-530: The eastern hognose snake. Species A species ( pl. : species) is a population of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use
11750-993: The eggs hatch into larvae, which eat the host, and it inevitably dies. Zoologists generally call this a form of parasitism , though conventionally parasites are thought not to kill their hosts. A predator can be defined to differ from a parasitoid in that it has many prey, captured over its lifetime, where a parasitoid's larva has just one, or at least has its food supply provisioned for it on just one occasion. There are other difficult and borderline cases. Micropredators are small animals that, like predators, feed entirely on other organisms; they include fleas and mosquitoes that consume blood from living animals, and aphids that consume sap from living plants. However, since they typically do not kill their hosts, they are now often thought of as parasites. Animals that graze on phytoplankton or mats of microbes are predators, as they consume and kill their food organisms, while herbivores that browse leaves are not, as their food plants usually survive
11875-710: The enlarged teeth at the rear of the upper jaw. These teeth inject a mild amphibian-specific venom into prey. The fangs receive the venom from the snake's Duvernoy's gland . Bitten humans who are allergic to the saliva have been known to experience local swelling, burning, discoloration, and bleeding from the wounds, but no human deaths have been documented. There are many predators of the Eastern hognose snake. These include: tarantulas, other snakes, crows, red-tailed hawks, barred owls, raccoons, Virginia opossums, foxes, and humans. Humans cause pollution and pesticide poisoning, habitat destruction, vehicular deaths, and intentionally hunt
12000-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising
12125-404: The evolution of mimicry. Avoidance is not necessarily an evolutionary response as it is generally learned from bad experiences with prey. However, when the prey is capable of killing the predator (as can a coral snake with its venom), there is no opportunity for learning and avoidance must be inherited. Predators can also respond to dangerous prey with counter-adaptations. In western North America,
12250-551: The genera Anaxyrus ). At the northern end of their range, they have been found to prefer developed lands as their desired habitat followed by mixed forests dominated by hemlock trees. Based on a study in Canada, the average home range size is about 40 hectares. Their habitats include southeastern and midwestern woodlands, tall-grassland prairies, and grassy or cultivated fields along woodland edges. Their habitat range tends to increase with grass and leaf litter. The generic name Heterodon
12375-431: The larvae of coccinellid beetles (ladybirds) , alternate between actively searching and scanning the environment. Prey distributions are often clumped, and predators respond by looking for patches where prey is dense and then searching within patches. Where food is found in patches, such as rare shoals of fish in a nearly empty ocean, the search stage requires the predator to travel for a substantial time, and to expend
12500-429: The light signals of other species, thereby attracting male fireflies, which they capture and eat. Flower mantises are ambush predators; camouflaged as flowers, such as orchids , they attract prey and seize it when it is close enough. Frogfishes are extremely well camouflaged, and actively lure their prey to approach using an esca , a bait on the end of a rod-like appendage on the head, which they wave gently to mimic
12625-553: The northern range. Studies have shown that H. platirhinos prefers upland sandy pine-forests, old-fields and forest edges. Like most of the genus Heterodon , the Eastern Hognose Snake prefers dry conditions with loose soil for burrowing purposes. These loose soils are preferable habitat components for nesting and egg laying. Barrier beach and dune ecosystems appear to contain some of the highest densities of Heterodon platirhinos because of abundant prey (primarily anurans from
12750-478: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting
12875-434: The other hand, the fitness cost of a given lost dinner is unpredictable, as the predator may quickly find better prey. In addition, most predators are generalists, which reduces the impact of a given prey adaption on a predator. Since specialization is caused by predator-prey coevolution, the rarity of specialists may imply that predator-prey arms races are rare. It is difficult to determine whether given adaptations are truly
13000-585: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using
13125-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species
13250-538: The prey an opportunity to escape. Some frogs wait until snakes have begun their strike before jumping, reducing the time available to the snake to recalibrate its attack, and maximising the angular adjustment that the snake would need to make to intercept the frog in real time. Ballistic predators include insects such as dragonflies, and vertebrates such as archerfish (attacking with a jet of water), chameleons (attacking with their tongues), and some colubrid snakes . In pursuit predation, predators chase fleeing prey. If
13375-549: The prey are dense and mobile, and the predator has low energy requirements. Wide foraging expends more energy, and is used when prey is sedentary or sparsely distributed. There is a continuum of search modes with intervals between periods of movement ranging from seconds to months. Sharks, sunfish , Insectivorous birds and shrews are almost always moving while web-building spiders, aquatic invertebrates, praying mantises and kestrels rarely move. In between, plovers and other shorebirds , freshwater fish including crappies , and
13500-413: The prey flees in a straight line, capture depends only on the predator's being faster than the prey. If the prey manoeuvres by turning as it flees, the predator must react in real time to calculate and follow a new intercept path, such as by parallel navigation , as it closes on the prey. Many pursuit predators use camouflage to approach the prey as close as possible unobserved ( stalking ) before starting
13625-428: The prey's body. However, the "life-dinner" principle of Dawkins and Krebs predicts that this arms race is asymmetric: if a predator fails to catch its prey, it loses its dinner, while if it succeeds, the prey loses its life. The metaphor of an arms race implies ever-escalating advances in attack and defence. However, these adaptations come with a cost; for instance, longer legs have an increased risk of breaking, while
13750-433: The prey, given that the attack is not modifiable once launched. Ballistic interception is the strategy where a predator observes the movement of a prey, predicts its motion, works out an interception path, and then attacks the prey on that path. This differs from ambush predation in that the predator adjusts its attack according to how the prey is moving. Ballistic interception involves a brief period for planning, giving
13875-504: The price of increased expenditure of energy to catch it, and increased risk that the prey will escape. Ambush predators are often solitary to reduce the risk of becoming prey themselves. Of 245 terrestrial members of the Carnivora (the group that includes the cats, dogs, and bears), 177 are solitary; and 35 of the 37 wild cats are solitary, including the cougar and cheetah. However, the solitary cougar does allow other cougars to share in
14000-414: The pursuit. Pursuit predators include terrestrial mammals such as humans, African wild dogs, spotted hyenas and wolves; marine predators such as dolphins, orcas and many predatory fishes, such as tuna; predatory birds (raptors) such as falcons; and insects such as dragonflies . An extreme form of pursuit is endurance or persistence hunting , in which the predator tires out the prey by following it over
14125-470: The result of coevolution, where a prey adaptation gives rise to a predator adaptation that is countered by further adaptation in the prey. An alternative explanation is escalation , where predators are adapting to competitors, their own predators or dangerous prey. Apparent adaptations to predation may also have arisen for other reasons and then been co-opted for attack or defence. In some of the insects preyed on by bats, hearing evolved before bats appeared and
14250-535: The result of direct anthropogenic pressures including habitat loss and fragmentation, road mortality, environmental degradation , and intentional killing. Some of this habitat fragmentation may be due to eastern hognose snakes having a reluctance to cross paved roads. In the Eastern United States, pitch pine-scrub oak barrens are an imperiled disturbance-dependent community that has declined substantially due to wildfires that have threatened vertebrates such as
14375-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean
14500-573: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be
14625-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that
14750-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered
14875-570: The snake. Further studies have shown that other effects humans have on the mortality of H. platirhinos come from roads. Laura E. Robson and Gabriel Blouin-Demers conducted a study and found that the Eastern hognose snake avoids crossing paved roads, increasing the isolation of populations. The snakes will cross unpaved roads but face higher mortality from vehicle collisions. The hognose snake is an intermediate level reptile to keep and lives between 10-15 years in captivity. Typically, mice and rats are used to feed most snakes in captivity. With hognose being
15000-417: The specialized tongue of the chameleon, with its ability to act like a projectile, is useless for lapping water, so the chameleon must drink dew off vegetation. The "life-dinner" principle has been criticized on multiple grounds. The extent of the asymmetry in natural selection depends in part on the heritability of the adaptive traits. Also, if a predator loses enough dinners, it too will lose its life. On
15125-502: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike
15250-684: The target of an attack, for example, by signalling that they are toxic or unpalatable , by signalling that a chase would be unprofitable, or by forming groups. If they become a target, they can try to fend off the attack with defences such as armour, quills , unpalatability, or mobbing; and they can often escape an attack in progress by startling the predator, playing dead , shedding body parts such as tails, or simply fleeing. Predators and prey are natural enemies, and many of their adaptations seem designed to counter each other. For example, bats have sophisticated echolocation systems to detect insects and other prey, and insects have developed
15375-457: The threat. H. platirhinos has a wide geographical range from the central United States to the east coast. In the northern parts of the range, it can be found in southern Ontario, southern New Hampshire, Minnesota, and Wisconsin. Going west the snake can be found in Texas and Kansas. The southern part of the range then goes down into southern Florida. Populations start to dwindle as the species reaches
15500-537: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of
15625-401: Was used to hear signals used for territorial defence and mating. Their hearing evolved in response to bat predation, but the only clear example of reciprocal adaptation in bats is stealth echolocation. A more symmetric arms race may occur when the prey are dangerous, having spines, quills, toxins or venom that can harm the predator. The predator can respond with avoidance, which in turn drives
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