91-433: The caddisflies (order Trichoptera ) are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis of the adult mouthparts. Integripalpian larvae construct a portable casing to protect themselves as they move around looking for food, while annulipalpian larvae make themselves
182-444: A Brownian motion model of trait evolution along a phylogeny. More recent methods also quantify the strength of convergence. One drawback to keep in mind is that these methods can confuse long-term stasis with convergence due to phenotypic similarities. Stasis occurs when there is little evolutionary change among taxa. Distance-based measures assess the degree of similarity between lineages over time. Frequency-based measures assess
273-500: A brain and a ventral nerve cord . Most insects reproduce by laying eggs . Insects breathe air through a system of paired openings along their sides, connected to small tubes that take air directly to the tissues. The blood therefore does not carry oxygen; it is only partly contained in vessels, and some circulates in an open hemocoel . Insect vision is mainly through their compound eyes , with additional small ocelli . Many insects can hear, using tympanal organs , which may be on
364-428: A nucleophile . In order to activate that nucleophile, they orient an acidic and a basic residue in a catalytic triad . The chemical and physical constraints on enzyme catalysis have caused identical triad arrangements to evolve independently more than 20 times in different enzyme superfamilies . Threonine proteases use the amino acid threonine as their catalytic nucleophile . Unlike cysteine and serine, threonine
455-412: A dispersal device. The larvae may drift in great numbers either close to the bottom, in mid-water or just below the surface. The fish swallow them whole, case and all. Caddisflies are best known for the portable cases created by their larvae. About thirty families of caddisfly, members of the suborder Integripalpia, adopt this stratagem. These larvae eat detritus , largely decaying vegetable material, and
546-417: A few in the genus Triplectides are ovoviviparous. Some species lay eggs on land and although most are associated with freshwater, a few like Symphitoneuria are found in coastal saline water. Philanisus plebeius females lay their eggs into the coelomic cavity of intertidal starfish. The larvae are long and roughly cylindrical, very similar to those of lepidoptera but lacking prolegs. In case-bearing species,
637-490: A fixed retreat in which they remain, waiting for food to come to them. The affinities of the small third suborder Spicipalpia are unclear, and molecular analysis suggests it may not be monophyletic . Also called sedge-flies or rail-flies , the adults are small moth -like insects with two pairs of hairy membranous wings . They are closely related to the Lepidoptera (moths and butterflies) which have scales on their wings;
728-575: A high concentration of cerebrosides in the skin of their wings. This improves skin flexibility, a trait useful for flying animals; other mammals have a far lower concentration. The extinct pterosaurs independently evolved wings from their fore- and hindlimbs, while insects have wings that evolved separately from different organs. Flying squirrels and sugar gliders are much alike in their mammalian body plans, with gliding wings stretched between their limbs, but flying squirrels are placentals while sugar gliders are marsupials, widely separated within
819-552: A hundred species, are marine. Insects such as snow scorpionflies flourish in cold habitats including the Arctic and at high altitude. Insects such as desert locusts , ants, beetles, and termites are adapted to some of the hottest and driest environments on earth, such as the Sonoran Desert . Insects form a clade , a natural group with a common ancestor, among the arthropods . A phylogenetic analysis by Kjer et al. (2016) places
910-635: A molecular level to toxins. One well-characterized example is the evolution of resistance to cardiotonic steroids (CTSs) via amino acid substitutions at well-defined positions of the α-subunit of Na ,K -ATPase (ATPalpha). Variation in ATPalpha has been surveyed in various CTS-adapted species spanning six insect orders. Among 21 CTS-adapted species, 58 (76%) of 76 amino acid substitutions at sites implicated in CTS resistance occur in parallel in at least two lineages. 30 of these substitutions (40%) occur at just two sites in
1001-618: A nearly immobile pupa . Insects that undergo three-stage metamorphosis lack a pupa, developing through a series of increasingly adult-like nymphal stages. The higher level relationship of the insects is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonfly-like insects with wingspans of 55 to 70 cm (22 to 28 in). The most diverse insect groups appear to have coevolved with flowering plants . Adult insects typically move about by walking and flying; some can swim. Insects are
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#17328593917771092-568: A phylogenetic reconstruction, and are sometimes explicitly sought by investigators. The methods applied to infer convergent evolution depend on whether pattern-based or process-based convergence is expected. Pattern-based convergence is the broader term, for when two or more lineages independently evolve patterns of similar traits. Process-based convergence is when the convergence is due to similar forces of natural selection . Earlier methods for measuring convergence incorporate ratios of phenotypic and phylogenetic distance by simulating evolution with
1183-480: A somewhat lesser extent, caddisflies are an indicator of good water quality; they die out of streams with polluted waters. They are an important part of the food web , both larvae and adults being eaten by many fish. The newly hatched adult is particularly vulnerable as it struggles to the surface after emerging from the submerged pupa, and as it dries its wings. The fish find these new adults easy pickings, and fishing flies resembling them can be successful for anglers at
1274-484: A special pair of mandibles, swim up to the water surface, moult using the exuviae as a floating platform, and emerge as fully formed adults. They can often fly immediately after breaking from their pupal cuticle. Emergence is mainly univoltine (once per year) with all the adults of a species emerging at the same time. Development is within a year in warm places, but takes over a year in high latitudes and at high elevation in mountain lakes and streams. The adult caddisfly
1365-501: A steadily decreasing probability of retaining potential functionality over time. The time scale of this process varies greatly in different phylogenies; in mammals and birds, there is a reasonable probability of remaining in the genome in a potentially functional state for around 6 million years. When two species are similar in a particular character, evolution is defined as parallel if the ancestors were also similar, and convergent if they were not. Some scientists have argued that there
1456-438: A trait presently identified with at least primates , corvids , and cetaceans . In cladistics, a homoplasy is a trait shared by two or more taxa for any reason other than that they share a common ancestry. Taxa which do share ancestry are part of the same clade ; cladistics seeks to arrange them according to their degree of relatedness to describe their phylogeny . Homoplastic traits caused by convergence are therefore, from
1547-544: A unique form of artwork. The resulting works are sold across the world. In Japan the larvae of Stenopsyche marmorata are eaten as a delicacy called Zazamushi . There are roughly 16,266 extant species in 618 genera and 51 families worldwide. A useful reference to the larvae of the British Trichoptera is "Caddis Larvae" Norman E. Hickin (1967) Hutchinson & Co. Ltd. London. Insect Insects (from Latin insectum ) are hexapod invertebrates of
1638-525: A variety of ways. Male moths can sense the pheromones of female moths over great distances. Other species communicate with sounds: crickets stridulate , or rub their wings together, to attract a mate and repel other males. Lampyrid beetles communicate with light. Humans regard many insects as pests , especially those that damage crops, and attempt to control them using insecticides and other techniques. Others are parasitic , and may act as vectors of diseases . Insect pollinators are essential to
1729-415: Is Gumaga nigricula (family: Sericostomatidae ) which has been observed scavenging fish carcasses and even bits of deer flesh. This particular family of caddisflies is typically classified among the shredders, suggesting caution when classifying macroinvertebrates into strict ecological functional groups , as some may shift their diets opportunistically. Like mayflies, stoneflies and dragonflies, but to
1820-421: Is divergent evolution , where related species evolve different traits. Convergent evolution is similar to parallel evolution , which occurs when two independent species evolve in the same direction and thus independently acquire similar characteristics; for instance, gliding frogs have evolved in parallel from multiple types of tree frog . Many instances of convergent evolution are known in plants , including
1911-427: Is a secondary alcohol (i.e. has a methyl group). The methyl group of threonine greatly restricts the possible orientations of triad and substrate, as the methyl clashes with either the enzyme backbone or the histidine base. Consequently, most threonine proteases use an N-terminal threonine in order to avoid such steric clashes . Several evolutionarily independent enzyme superfamilies with different protein folds use
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#17328593917772002-443: Is a continuum between parallel and convergent evolution, while others maintain that despite some overlap, there are still important distinctions between the two. When the ancestral forms are unspecified or unknown, or the range of traits considered is not clearly specified, the distinction between parallel and convergent evolution becomes more subjective. For instance, the striking example of similar placental and marsupial forms
2093-488: Is a medium-sized insect with membranous, hairy wings, which are held in a tent-wise fashion when the insect is at rest. The antennae are fairly long and threadlike, the mouthparts are reduced in size and the legs have five tarsi (lower leg joints). Adults are nocturnal and are attracted to light. Some species are strong fliers and can disperse to new localities, but many fly only weakly. Adults are usually short-lived, most being non-feeders and equipped only to breed. Once mated,
2184-463: Is a membrane stretched across four extremely elongated fingers and the legs. The airfoil of the bird wing is made of feathers , strongly attached to the forearm (the ulna) and the highly fused bones of the wrist and hand (the carpometacarpus ), with only tiny remnants of two fingers remaining, each anchoring a single feather. So, while the wings of bats and birds are functionally convergent, they are not anatomically convergent. Birds and bats also share
2275-415: Is added at the front, and the larva can turn round in the tube and trim the rear end so that it does not drag along the substrate. Caddisfly cases are open at both ends, the larvae drawing oxygenated water through the posterior end, over their gills, and pumping it out of the wider, anterior end. The larvae move around inside the tubes and this helps maintain the water current; the lower the oxygen content of
2366-664: Is described by Richard Dawkins in The Blind Watchmaker as a case of convergent evolution, because mammals on each continent had a long evolutionary history prior to the extinction of the dinosaurs under which to accumulate relevant differences. The enzymology of proteases provides some of the clearest examples of convergent evolution. These examples reflect the intrinsic chemical constraints on enzymes, leading evolution to converge on equivalent solutions independently and repeatedly. Serine and cysteine proteases use different amino acid functional groups (alcohol or thiol) as
2457-513: Is known as a hatch. Each type has its own angling name, so for example Mystacides is the dancer; Sericostoma the caperer; Leptocerus the silverhorn; Phryganea the murragh or great red sedge; Brachycentrus subnubilis the grannom; Lepidostoma the silver sedge; Oecetis the longhorn sedge; Cheumatopsyche the little sister sedge; Helicopsyche the speckled Peter, an important fishing fly in North America; and Hydropsyche
2548-542: Is responsible, say with brown dominant to blue eye colour . However, a single locus is responsible for about 80% of the variation. In lemurs, the differences between blue and brown eyes are not completely known, but the same gene locus is not involved. While most plant species are perennial , about 6% follow an annual life cycle, living for only one growing season. The annual life cycle independently emerged in over 120 plant families of angiosperms. The prevalence of annual species increases under hot-dry summer conditions in
2639-409: Is the camera eye of cephalopods (such as squid and octopus), vertebrates (including mammals) and cnidarians (such as jellyfish). Their last common ancestor had at most a simple photoreceptive spot, but a range of processes led to the progressive refinement of camera eyes —with one sharp difference: the cephalopod eye is "wired" in the opposite direction, with blood and nerve vessels entering from
2730-457: Is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy . The recurrent evolution of flight is a classic example, as flying insects , birds , pterosaurs , and bats have independently evolved
2821-522: The Chenopodiaceae and the Amaranthaceae . Fruits with a wide variety of structural origins have converged to become edible. Apples are pomes with five carpels ; their accessory tissues form the apple's core, surrounded by structures from outside the botanical fruit, the receptacle or hypanthium . Other edible fruits include other plant tissues; the fleshy part of a tomato is the walls of
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2912-457: The Greek : θρίξ ( thrix , "hair"), genitive trichos + πτερόν ( pteron , "wing"), and refers to the fact that the wings of these insects are bristly. The origin of the word "caddis" is unclear, but it dates back to at least as far as Izaak Walton 's 1653 book The Compleat Angler , where "cod-worms or caddis" were mentioned as being used as bait. The term cadyss was being used in
3003-830: The Latin word insectum from in , "cut up", as insects appear to be cut into three parts. The Latin word was introduced by Pliny the Elder who calqued the Ancient Greek word ἔντομον éntomon "insect" (as in entomology ) from ἔντομος éntomos "cut in pieces"; this was Aristotle 's term for this class of life in his biology , also in reference to their notched bodies. The English word insect first appears in 1601 in Philemon Holland 's translation of Pliny. In common speech, insects and other terrestrial arthropods are often called bugs . Entomologists to some extent reserve
3094-2226: The Paraneoptera , and Kjer et al. 2016 for the Holometabola . The numbers of described extant species (boldface for groups with over 100,000 species) are from Stork 2018. Archaeognatha (hump-backed/jumping bristletails, 513 spp) [REDACTED] Zygentoma (silverfish, firebrats, fishmoths, 560 spp) [REDACTED] Odonata (dragonflies and damselflies, 5,899 spp) [REDACTED] Ephemeroptera (mayflies, 3,240 spp) [REDACTED] Zoraptera (angel insects, 37 spp) [REDACTED] Dermaptera (earwigs, 1,978 spp) [REDACTED] Plecoptera (stoneflies, 3,743 spp) [REDACTED] Orthoptera (grasshoppers, crickets, katydids, 23,855 spp) [REDACTED] Grylloblattodea (ice crawlers, 34 spp) [REDACTED] Mantophasmatodea (gladiators, 15 spp) [REDACTED] Phasmatodea (stick insects, 3,014 spp) [REDACTED] Embioptera (webspinners, 463 spp) [REDACTED] Mantodea (mantises, 2,400 spp) [REDACTED] Blattodea (cockroaches and termites, 7,314 spp) [REDACTED] Psocodea (book lice, barklice and sucking lice, 11,000 spp) [REDACTED] [REDACTED] Hemiptera (true bugs, 103,590 spp) [REDACTED] Thysanoptera (thrips, 5,864 spp) [REDACTED] Hymenoptera (sawflies, wasps, bees, ants, 116,861 spp) [REDACTED] Strepsiptera (twisted-wing flies, 609 spp) [REDACTED] Coleoptera (beetles, 386,500 spp) [REDACTED] Raphidioptera (snakeflies, 254 spp) [REDACTED] Neuroptera (lacewings, 5,868 spp) [REDACTED] Megaloptera (alderflies and dobsonflies, 354 spp) [REDACTED] Lepidoptera (butterflies and moths, 157,338 spp) [REDACTED] Trichoptera (caddisflies, 14,391 spp) [REDACTED] Diptera (true flies, 155,477 spp) [REDACTED] Mecoptera (scorpionflies, 757 spp) [REDACTED] Siphonaptera (fleas, 2,075 spp) [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Convergent evolution Convergent evolution
3185-485: The benthos . Other species are collector-filterers, sieving organic particles from the water using silken nets, or hairs on their legs. Some species are scrapers, feeding on the film of algae and other periphyton that grows on underwater objects in sunlight. Others are shredder-herbivores, chewing fragments off living plant material while others are shredder-detritivores, gnawing at rotting wood or chewing dead leaves that have been pre-processed by bacteria and fungi; most of
3276-439: The class Insecta . They are the largest group within the arthropod phylum . Insects have a chitinous exoskeleton , a three-part body ( head , thorax and abdomen ), three pairs of jointed legs , compound eyes , and a pair of antennae . Insects are the most diverse group of animals, with more than a million described species ; they represent more than half of all animal species. The insect nervous system consists of
3367-433: The dragonflies , mayflies , stoneflies , alderflies and lacewings . The ancestors of all these groups were terrestrial, with open tracheal systems, convergently evolving different types of gills for their aquatic larvae as they took to the water to avoid predation. Caddisflies was the only group of these insects to use silk as part of their lifestyle, which has been a contributing factor to their success and why they are
3458-410: The microflora that get trapped in the net as water flows through. The larvae of other species of caddisfly make nets rather than cases. These are silken webs stretching between aquatic vegetation and over stones. These net-making larvae usually live in running water, different species occupying different habitats with varying water speeds. There is a constant drift of invertebrates washed downstream by
3549-619: The pericarp . This implies convergent evolution under selective pressure, in this case the competition for seed dispersal by animals through consumption of fleshy fruits. Seed dispersal by ants ( myrmecochory ) has evolved independently more than 100 times, and is present in more than 11,000 plant species. It is one of the most dramatic examples of convergent evolution in biology. Carnivory has evolved multiple times independently in plants in widely separated groups. In three species studied, Cephalotus follicularis , Nepenthes alata and Sarracenia purpurea , there has been convergence at
3640-446: The proboscis of flower-visiting insects such as bees and flower beetles , or the biting-sucking mouthparts of blood-sucking insects such as fleas and mosquitos . Opposable thumbs allowing the grasping of objects are most often associated with primates , like humans and other apes, monkeys, and lemurs. Opposable thumbs also evolved in giant pandas , but these are completely different in structure, having six fingers including
3731-618: The Hemiptera (true bugs), Lepidoptera (butterflies and moths), Diptera (true flies), Hymenoptera (wasps, ants, and bees), and Coleoptera (beetles), each with more than 100,000 described species. Insects are distributed over every continent and almost every terrestrial habitat. There are many more species in the tropics , especially in rainforests , than in temperate zones. The world's regions have received widely differing amounts of attention from entomologists. The British Isles have been thoroughly surveyed, so that Gullan and Cranston 2014 state that
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3822-570: The Mesozoic ) all converged on the same streamlined shape. A similar shape and swimming adaptations are even present in molluscs, such as Phylliroe . The fusiform bodyshape (a tube tapered at both ends) adopted by many aquatic animals is an adaptation to enable them to travel at high speed in a high drag environment. Similar body shapes are found in the earless seals and the eared seals : they still have four legs, but these are strongly modified for swimming. The marsupial fauna of Australia and
3913-517: The N-terminal residue as a nucleophile. This commonality of active site but difference of protein fold indicates that the active site evolved convergently in those families. Conus geographus produces a distinct form of insulin that is more similar to fish insulin protein sequences than to insulin from more closely related molluscs, suggesting convergent evolution, though with the possibility of horizontal gene transfer . Distant homologues of
4004-471: The back of the retina, rather than the front as in vertebrates. As a result, vertebrates have a blind spot . Birds and bats have homologous limbs because they are both ultimately derived from terrestrial tetrapods , but their flight mechanisms are only analogous, so their wings are examples of functional convergence. The two groups have independently evolved their own means of powered flight. Their wings differ substantially in construction. The bat wing
4095-523: The bottom, and feed on the accumulations of silt formed when suspended material is deposited. The tube can be lengthened when the growing larva needs to feed in new areas. More complex tubes, short and flattened, are built by Polycentropodidae larvae in hollows in rocks or other submerged objects, sometimes with strands of silk suspended across the nearby surface. These larvae are carnivorous, resembling spiders in their feeding habits and rushing out of their retreat to attack any unwary small prey crawling across
4186-416: The case), gills, and swimming legs. The pupal cocoon is spun from silk, but like the larval case, often has other materials attached. When pupating, species that build portable cases attach them to some underwater object, seal the front and back apertures against predators while still allowing water to flow through, and pupate within it. Once fully developed, most pupal caddisflies cut through their cases with
4277-400: The current, and these animals, and bits of debris, accumulate in the nets which serve both as food traps and as retreats. Caddisfly larvae are aquatic, with six pairs of tracheal gills on the underside of the abdomen. The eggs are laid above water on emergent twigs or vegetation or on the water surface although females of some species enter water to choose sites. Although most species lay eggs,
4368-448: The dead leaf fragments on which they feed tend to accumulate in hollows, in slow-moving sections of streams and behind stones and tree roots. The cases provide protection to the larvae as they make their way between these resources. The case is a tubular structure made of silk , secreted from salivary glands near the mouth of the larva, and is started soon after the egg hatches. Various reinforcements may be incorporated into its structure,
4459-448: The different superfamilies that the differences between the suborders is not clear-cut. The larvae of Annulipalpians are campodeiform (free-living, well sclerotized, long legged predators with dorso-ventrally flattened bodies and protruding mouthparts). The larvae of Integripalpians are polypod (poorly sclerotized detritivores, with abdominal prolegs in addition to thoracic legs, living permanently in tight-fitting cases). The affinities of
4550-437: The dolphin; among marine mammals; between giant and red pandas; and between the thylacine and canids. Convergence has also been detected in a type of non-coding DNA , cis-regulatory elements , such as in their rates of evolution; this could indicate either positive selection or relaxed purifying selection . Swimming animals including fish such as herrings , marine mammals such as dolphins , and ichthyosaurs ( of
4641-410: The environment. They form an important part of the diet of fish such as the trout . The fish acquire them by two means, either plucking them off vegetation or the stream-bed as the larvae move about, or during the daily behavioural drift; this drift happens during the night for many species of aquatic larvae, or around midday for some cased caddisfly species, and may result from population pressures or be
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#17328593917774732-617: The exposed surfaces of the proteins, where they might interact with other components of the cell or the digestive fluid. The authors also found that homologous genes in the non-carnivorous plant Arabidopsis thaliana tend to have their expression increased when the plant is stressed, leading the authors to suggest that stress-responsive proteins have often been co-opted in the repeated evolution of carnivory. Phylogenetic reconstruction and ancestral state reconstruction proceed by assuming that evolution has occurred without convergence. Convergent patterns may, however, appear at higher levels in
4823-429: The female caddisfly lays eggs in a gelatinous mass, attaching them above or below the water surface depending on species. The eggs hatch in a few weeks. Adult caddisflies are called sedges by anglers . Individual species emerge en masse at different times, and are used one after the other, often for only a few days each year, as models for artificial fishing flies for fly fishing in trout streams. A mass emergence
4914-487: The fifteenth century for silk or cotton cloth, and "cadice-men" were itinerant vendors of such materials, but a connection between these words and the insects has not been established. Fossil caddisflies have been found in rocks dating back to the Triassic . The largest numbers of fossilised remains are those of larval cases, which are made of durable materials that preserve well. Body fossils of caddisflies are extremely rare,
5005-480: The four species-rich families of annuals ( Asteraceae , Brassicaceae , Fabaceae , and Poaceae ), indicating that the annual life cycle is adaptive. C 4 photosynthesis , one of the three major carbon-fixing biochemical processes, has arisen independently up to 40 times . About 7,600 plant species of angiosperms use C 4 carbon fixation, with many monocots including 46% of grasses such as maize and sugar cane , and dicots including several species in
5096-634: The greater diversity being in warmer regions. They are associated with bodies of freshwater, the larvae being found in lakes, ponds, rivers, streams and other water bodies. The land caddis, Enoicyla pusilla (family: Limnephilidae ), lives in the damp litter of the woodland floor. In the United Kingdom it is found in and around the county of Worcestershire in oakwoods . Caddisfly larvae can be found in all feeding guilds in freshwater habitats. Most early stage larvae and some late stage ones are collector-gatherers, picking up fragments of organic matter from
5187-537: The heads are heavily sclerotised while the abdomen is soft; the antennae are short and the mouthparts adapted for biting. Each of the usually ten abdominal segments bears a pair of legs with a single tarsal joint. In case-bearing species, the first segment bears three papillae, one above and two at the sides, which anchor the larva centrally in the tube. The posterior segment bears a pair of hooks for grappling. There are five to seven larval instars , followed by an aquatic pupa which has functional mandibles (to cut through
5278-592: The insects among the Hexapoda , six-legged animals with segmented bodies; their closest relatives are the Diplura (bristletails). Collembola (springtails) [REDACTED] Protura (coneheads) [REDACTED] Diplura (two-pronged bristletails) [REDACTED] Insecta (=Ectognatha) [REDACTED] The internal phylogeny is based on the works of Wipfler et al. 2019 for the Polyneoptera , Johnson et al. 2018 for
5369-406: The legs or other parts of the body. Their sense of smell is via receptors, usually on the antennae and the mouthparts. Nearly all insects hatch from eggs . Insect growth is constrained by the inelastic exoskeleton, so development involves a series of molts . The immature stages often differ from the adults in structure, habit and habitat. Groups that undergo four-stage metamorphosis often have
5460-407: The lineages diverged and became genetically isolated, the skin of both groups lightened more, and that additional lightening was due to different genetic changes. Lemurs and humans are both primates. Ancestral primates had brown eyes, as most primates do today. The genetic basis of blue eyes in humans has been studied in detail and much is known about it. It is not the case that one gene locus
5551-516: The mammal lineage from the placentals. Hummingbird hawk-moths and hummingbirds have evolved similar flight and feeding patterns. Insect mouthparts show many examples of convergent evolution. The mouthparts of different insect groups consist of a set of homologous organs, specialised for the dietary intake of that insect group. Convergent evolution of many groups of insects led from original biting-chewing mouthparts to different, more specialised, derived function types. These include, for example,
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#17328593917775642-454: The metal ion transporters ZIP in land plants and chlorophytes have converged in structure, likely to take up Fe efficiently. The IRT1 proteins from Arabidopsis thaliana and rice have extremely different amino acid sequences from Chlamydomonas ' s IRT1, but their three-dimensional structures are similar, suggesting convergent evolution. Many examples of convergent evolution exist in insects in terms of developing resistance at
5733-405: The molecular level. Carnivorous plants secrete enzymes into the digestive fluid they produce. By studying phosphatase , glycoside hydrolase , glucanase , RNAse and chitinase enzymes as well as a pathogenesis-related protein and a thaumatin -related protein, the authors found many convergent amino acid substitutions. These changes were not at the enzymes' catalytic sites, but rather on
5824-466: The most species-rich order of aquatic insects. About 14,500 species of caddisfly in 45 families have been recognised worldwide, but many more species remain to be described. Most can be divided into the suborders Integripalpia and Annulipalpia on the basis of the adult mouthparts. The characteristics of adults depend on the palps , wing venation and genitalia of both sexes. The latter two characters have undergone such extensive differentiation among
5915-402: The name "bugs" for a narrow category of " true bugs ", insects of the order Hemiptera , such as cicadas and shield bugs . Other terrestrial arthropods, such as centipedes , millipedes , woodlice , spiders , mites and scorpions , are sometimes confused with insects, since they have a jointed exoskeleton. Adult insects are the only arthropods that ever have wings, with up to two pairs on
6006-413: The nature of the materials and design depending on the larva's genetic makeup; this means that caddisfly larvae can be recognised by their cases down to family, and even genus level. The materials used include grains of sand, larger fragments of rock, bark, sticks, leaves, seeds and mollusc shells. These are neatly arranged and stuck onto the outer surface of the silken tube. As the larva grows, more material
6097-404: The nutrients of the latter group come from consumption of the bacteria and fungi. The predatory species either actively hunt their prey, typically other insects, tiny crustaceans and worms, or lie in wait for unwary invertebrates to come too close. A few species feed opportunistically on dead animals or fish, and some Leptoceridae larvae feed on freshwater sponges. One such opportunistic species
6188-761: The oldest being from the Early and Middle Triassic, some 230 million years ago, and wings are another source of fossils. The evolution of the group to one with fully aquatic larvae seems to have taken place sometime during the Triassic. The finding of fossils resembling caddisfly larval cases in marine deposits in Brazil may push back the origins of the order to the Early Permian period. Nearly all adult caddisflies are terrestrial, but their larvae and pupae are aquatic. They share this characteristic with several distantly-related groups, namely
6279-554: The only invertebrates that can achieve sustained powered flight; insect flight evolved just once. Many insects are at least partly aquatic , and have larvae with gills; in some species, the adults too are aquatic. Some species, such as water striders , can walk on the surface of water. Insects are mostly solitary, but some, such as bees , ants and termites , are social and live in large, well-organized colonies . Others, such as earwigs , provide maternal care, guarding their eggs and young. Insects can communicate with each other in
6370-459: The order is based on a 2002 molecular phylogeny using ribosomal RNA, a nuclear elongation factor gene, and mitochondrial cytochrome oxidase. The Annulipalpia and Integripalpia are clades, but the relationships within the Spicipalpia are unclear. Annulipalpia (fixed-retreat makers) Integripalpia (portable-case makers) " Spicipalpia " ( paraphyletic ? ) Caddisflies are found worldwide, with
6461-474: The placental mammals of the Old World have several strikingly similar forms, developed in two clades, isolated from each other. The body, and especially the skull shape, of the thylacine (Tasmanian tiger or Tasmanian wolf) converged with those of Canidae such as the red fox, Vulpes vulpes . As a sensory adaptation, echolocation has evolved separately in cetaceans (dolphins and whales) and bats, but from
6552-401: The point of view of cladistics, confounding factors which could lead to an incorrect analysis. In some cases, it is difficult to tell whether a trait has been lost and then re-evolved convergently, or whether a gene has simply been switched off and then re-enabled later. Such a re-emerged trait is called an atavism . From a mathematical standpoint, an unused gene ( selectively neutral ) has
6643-404: The protein (positions 111 and 122). CTS-adapted species have also recurrently evolved neo-functionalized duplications of ATPalpha, with convergent tissue-specific expression patterns. Convergence occurs at the level of DNA and the amino acid sequences produced by translating structural genes into proteins . Studies have found convergence in amino acid sequences in echolocating bats and
6734-462: The repeated development of C 4 photosynthesis , seed dispersal by fleshy fruits adapted to be eaten by animals, and carnivory . In morphology, analogous traits arise when different species live in similar ways and/or a similar environment, and so face the same environmental factors. When occupying similar ecological niches (that is, a distinctive way of life) similar problems can lead to similar solutions. The British anatomist Richard Owen
6825-535: The reproduction of many flowering plants and so to their ecosystems. Many insects are ecologically beneficial as predators of pest insects, while a few provide direct economic benefit. Two species in particular are economically important and were domesticated many centuries ago: silkworms for silk and honey bees for honey . Insects are consumed as food in 80% of the world's nations, by people in roughly 3000 ethnic groups. Human activities are having serious effects on insect biodiversity . The word insect comes from
6916-414: The right time of year. The adult stage of a caddisfly may only survive for a few weeks; many species do not feed as adults and die soon after breeding, but some species are known to feed on nectar. The winged insects are nocturnal and provide food for night-flying birds, bats, small mammals, amphibians and arthropods. The larval stage lasts much longer, often for one or more years, and has a bigger impact on
7007-401: The same conditions were encountered again, evolution could take a very different course." Simon Conway Morris disputes this conclusion, arguing that convergence is a dominant force in evolution, and given that the same environmental and physical constraints are at work, life will inevitably evolve toward an "optimum" body plan, and at some point, evolution is bound to stumble upon intelligence,
7098-467: The same genetic mutations. The Gymnotiformes of South America and the Mormyridae of Africa independently evolved passive electroreception (around 119 and 110 million years ago, respectively). Around 20 million years after acquiring that ability, both groups evolved active electrogenesis , producing weak electric fields to help them detect prey. One of the best-known examples of convergent evolution
7189-720: The specked sedge, perhaps the most important caddisfly genus for anglers with over 50 species of net-makers. Caddisflies are useful as bioindicators (of good water quality), since they are sensitive to water pollution , and are large enough to be assessed conveniently in the field. Some species indicate undisturbed habitat, and some indicate degraded habitat. Although caddisflies may be found in waterbodies of varying qualities, species-rich caddisfly assemblages are generally thought to indicate clean water bodies, such as lakes, ponds, and marshes . Together with stoneflies and mayflies, caddisflies feature importantly in bioassessment surveys of streams and other water bodies. While caddisflies in
7280-461: The sport, where caddisflies are known as "sedges". Caddisflies are useful as bioindicators , as they are sensitive to water pollution and are large enough to be assessed in the field. In art, the French artist Hubert Duprat has created works by providing caddis larvae with small grains of gold and precious stones for them to build into decorative cases. The name of the order "Trichoptera" derives from
7371-437: The surface. Larvae of members of the family Glossosomatidae in the suborder Spicipalpia create dome-shaped enclosures of silk which enables them to graze on the periphyton, the biological film that grows on stones and other objects, while carrying their enclosure around like turtles . In the family Philopotamidae , the nets are sac-like, with intricate structure and tiny mesh. The larvae have specialised mouthparts to scrape off
7462-1030: The third suborder, Spicipalpia , are unclear; the larvae are free-living with no cases, instead creating net-like traps from silk. The cladogram of external relationships, based on molecular analysis, shows the order as a clade , sister to the Lepidoptera, and more distantly related to the Diptera (true flies) and Mecoptera (scorpionflies). Hymenoptera (sawflies, wasps) [REDACTED] Coleoptera (beetles) [REDACTED] Strepsiptera (twisted-wing parasites) [REDACTED] Raphidioptera (snakeflies) [REDACTED] Megaloptera (alderflies and allies) [REDACTED] Neuroptera (Lacewings and allies) [REDACTED] Lepidoptera (butterflies, moths) [REDACTED] Trichoptera (caddisflies) [REDACTED] Diptera [REDACTED] Mecoptera (scorpionflies) [REDACTED] Siphonaptera (fleas) [REDACTED] The cladogram of relationships within
7553-527: The thorax. Whether winged or not, adult insects can be distinguished by their three-part body plan, with head, thorax, and abdomen; they have three pairs of legs on the thorax. Estimates of the total number of insect species vary considerably, suggesting that there are perhaps some 5.5 million insect species in existence, of which about one million have been described and named. These constitute around half of all eukaryote species, including animals , plants , and fungi . The most diverse insect orders are
7644-554: The thumb, which develops from a wrist bone entirely separately from other fingers. Convergent evolution in humans includes blue eye colour and light skin colour. When humans migrated out of Africa , they moved to more northern latitudes with less intense sunlight. It was beneficial to them to reduce their skin pigmentation . It appears certain that there was some lightening of skin colour before European and East Asian lineages diverged, as there are some skin-lightening genetic differences that are common to both groups. However, after
7735-518: The total of around 22,500 species is probably within 5% of the actual number there; they comment that Canada's list of 30,000 described species is surely over half of the actual total. They add that the 3000 species of the American Arctic must be broadly accurate. In contrast, a large majority of the insect species of the tropics and the southern hemisphere are probably undescribed. Some 30–40,000 species inhabit freshwater ; very few insects, perhaps
7826-552: The two orders together form the superorder Amphiesmenoptera . The aquatic larvae are found in a wide variety of habitats such as streams, rivers, lakes, ponds, spring seeps and temporary waters ( vernal pools ), and even the ocean. The larvae of many species use silk to make protective cases, which are often strengthened with gravel, sand, twigs, bitten-off pieces of plants, or other debris. The larvae exhibit various feeding strategies, with different species being predators, leaf shredders, algal grazers, or collectors of particles from
7917-413: The useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous , whereas homologous structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence
8008-470: The water column and benthos . Most adults have short lives during which they do not feed. In fly fishing , artificial flies called dry flies are tied to imitate adults, while larvae and pupae are imitated with artificial flies called wet flies or nymphs. It is also possible to use them as bait, though this is not as common as artificial flies and is known as bait fishing. Common and widespread genera such as Helicopsyche and Hydropsyche are important in
8099-662: The water, the more active the larvae need to be. This mechanism enable caddisfly larvae to live in waters too low in oxygen content to support stonefly and mayfly larvae. In contrast to larvae that have portable cases, members of the Annulipalpia have a completely different feeding strategy. They make fixed retreats in which they remain stationary, waiting for food to come to them. Members of the Psychomyiidae , Ecnomidae and Xiphocentronidae families construct simple tubes of sand and other particles held together by silk and anchored to
8190-471: The wild construct their cases out of twigs, sand, aquatic plants, and rocks, the French artist Hubert Duprat makes art by providing wild caddisflies with precious stones and other materials. He collected caddisfly larvae from the wild and put them in climate-controlled tanks. He removes the larvae from their original cases and adds precious and semi-precious items such as grains of gold into the tank. The larvae then build new cases out of precious items, creating
8281-408: Was the first to identify the fundamental difference between analogies and homologies . In biochemistry, physical and chemical constraints on mechanisms have caused some active site arrangements such as the catalytic triad to evolve independently in separate enzyme superfamilies . In his 1989 book Wonderful Life , Stephen Jay Gould argued that if one could "rewind the tape of life [and]
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