56-519: Porpentine is an archaic term for a porcupine . Porpentine may also refer to: Porcupine Porcupines are large rodents with coats of sharp spines , or quills, that protect them against predation . The term covers two families of animals: the Old World porcupines of the family Hystricidae , and the New World porcupines of the family Erethizontidae . Both families belong to
112-444: 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
168-428: 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
224-442: A 20–25 cm (8–10 in) long tail. Weighing 5–16 kg (12–35 lb), they are rounded, large, and slow, and use an aposematic strategy of defence. Porcupines' colouration consists of various shades of brown, grey and white. Porcupines' spiny protection resembles that of the only distantly related erinaceomorph hedgehogs and Australian monotreme echidnas as well as tenrecid tenrecs . The word porcupine comes from
280-422: 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 is divergent evolution , where related species evolve different traits. Convergent evolution is similar to parallel evolution , which occurs when two independent species evolve in
336-413: 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 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
392-575: 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
448-468: 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
504-643: 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
560-568: 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
616-413: A porcupine: (in order from least to most aggressive) quill erection, teeth clattering, odour emission, and attack. A porcupine's colouring aids in part of its defence as most of the predators are nocturnal and colour-blind. A porcupine's markings are black and white. The dark body and coarse hair of the porcupine are dark brown/black and when quills are raised, present a white strip down its back mimicking
SECTION 10
#1732783471094672-416: A quill that has pierced the skin. The shape of the barbs makes the quills effective for penetrating the skin and for remaining in place. The quills have inspired research for such applications as the design of hypodermic needles and surgical staples. In contrast to the current design for surgical staples, the porcupine quill and barb design would allow easy and painless insertion, as the staple would stay in
728-636: A rocky environment. Porcupines can be found on rocky areas up to 3,700 m (12,100 ft) high. They are generally nocturnal but are occasionally active during daylight. Porcupines are distributed into two evolutionarily independent groups within the suborder Hystricomorpha of the Rodentia. Convergent evolution Convergent evolution 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
784-445: 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 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
840-427: 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
896-463: 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
952-401: Is aided by the hollow quills at the back end of the porcupine. The use of odour is when the sight and sound have failed. An unpleasant scent is produced from the skin above the tail in times of stress and is often seen with a quill erection. If these processes fail, the porcupine will attack by running sideways or backwards into predators. A porcupine's tail can also be swung in the direction of
1008-542: 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
1064-409: 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
1120-536: 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
1176-803: The Hystricognathi branch of the vast order Rodentia , they are not closely related. The 11 Old World porcupines tend to be fairly large and have spines grouped in clusters. The two subfamilies of New World porcupines are mostly smaller (although the North American porcupine reaches about 85 cm or 33 in in length and 18 kg or 40 lb), have their quills attached singly rather than grouped in clusters, and are excellent climbers, spending much of their time in trees. The New World porcupines evolved their spines independently (through convergent evolution ) and are more closely related to several other families of rodents than they are to
SECTION 20
#17327834710941232-467: The Latin porcus ' pig ' + spina ' spine, quill ' , from Old Italian porcospino , ' thorn-pig ' . A regional American name for the animal is quill-pig . A baby porcupine is a porcupette. When born, a porcupette's quills are soft hair; they harden within a few days, forming the sharp quills of adults. Fossils belonging to the genus Hystrix date back to the late Miocene of
1288-489: The Native American "porky roach" headdress. The main quills may be dyed and then applied in combination with thread to embellish leather accessories, such as knife sheaths and leather bags. Lakota women would harvest the quills for quillwork by throwing a blanket over a porcupine and retrieving the quills left stuck in the blanket. The presence of barbs, acting like anchors, causes increased pain when removing
1344-603: The capybara and beaver . The Old World porcupines (Hystricidae) live in Italy , Asia (western and southern), and most of Africa . They are large, terrestrial, and strictly nocturnal. The New World porcupines (Erethizontidae) are indigenous to North America and northern South America . They live in wooded areas and can climb trees, where some species spend their entire lives. They are less strictly nocturnal than their Old World counterparts and generally smaller. Most porcupines are about 60–90 cm (25–36 in) long, with
1400-411: 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] 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
1456-417: 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 the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous , whereas homologous structures or traits have
1512-619: 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
1568-446: 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
1624-575: 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
1680-523: 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
1736-484: The Old World porcupines. Porcupines have a relatively high longevity and hold the record for being the longest-living rodent, with one individual named Cooper living over 32 years. The North American porcupine is a herbivore and often climbs trees for food; it eats leaves, herbs, twigs, and green plants such as clover . In the winter, it may eat bark. The African porcupine is not a climber; instead, it forages on
Porpentine - Misplaced Pages Continue
1792-471: 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
1848-572: The continent of Africa. A porcupine is any of 30 species of rodents belonging to the families Erethizontidae (genera: Coendou , Erethizon , and Chaetomys ) or Hystricidae (genera: Atherurus , Hystrix , and Trichys ). Porcupines vary in size considerably: Rothschild's porcupine of South America weighs less than a kilogram (2.2 lb); the crested porcupine found in Italy , North Africa , and sub-Saharan Africa can grow to well over 27 kg (60 lb). The two families of porcupines are quite different, and although both belong to
1904-437: 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
1960-617: 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
2016-480: 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
2072-431: 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 is a continuum between parallel and convergent evolution, while others maintain that despite some overlap, there are still important distinctions between
2128-460: The ground. It is mostly nocturnal but will sometimes forage for food during the day, eating bark, roots, fruits, berries, and farm crops. Porcupines have become a pest in Kenya and are eaten as a delicacy. Defensive behaviour displays in a porcupine depend on sight, scent, and sound. Often, these displays are shown when a porcupine becomes agitated or annoyed. There are four main displays seen in
2184-475: The infraorder Hystricognathi within the profoundly diverse order Rodentia and display superficially similar coats of rigid or semi-rigid quills, which are modified hairs composed of keratin. Despite this, the two groups are distinct from one another and are not closely related to each other within the Hystricognathi. The largest species of porcupine is the third-largest living rodent in the world, after
2240-407: 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
2296-422: The look of a skunk. This, along with the raising of the sharp quills, deters predators. Along with the raising of the quills, porcupines clatter their teeth to warn predators not to approach. The incisors vibrate against each other, the strike zone shifts back, and the cheek teeth clatter. This behaviour is often paired with body shivering, which is used to further display the dangerous quills. The rattling of quills
Porpentine - Misplaced Pages Continue
2352-516: 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,
2408-454: 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
2464-405: 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
2520-422: 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
2576-628: The porcupine shakes its body. New quills grow to replace lost ones. Despite what is commonly believed, porcupines cannot launch their quills at range. There are some possible antibiotic properties within the quills, specifically associated with the free fatty acids coating the quills. The antibiotic properties are believed to aid a porcupine that has suffered from self-injury. Porcupines are seldom eaten in Western culture but are eaten often in Southeast Asia , particularly Vietnam , where
2632-562: The predator; if contact is made, the quills could be impaled into the predator causing injury or death. Porcupines' quills, or spines , take on various forms, depending on the species, but all are modified hairs coated with thick plates of keratin , and embedded in the skin musculature. Old World porcupines have quills embedded in clusters, whereas in New World porcupines, single quills are interspersed with bristles, underfur, and hair. Quills are released by contact or may drop out when
2688-474: The prominent use of them as a food source has contributed to declines in porcupine populations. Naturalist William J. Long reported the taste of the North American porcupine as "vile" and "malodorous" and delightful only to a lover of strong cheese. More commonly, their quills and guard hairs are used for traditional decorative clothing; for example, their guard hairs are used in the creation of
2744-404: 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
2800-399: 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 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
2856-468: 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 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
SECTION 50
#17327834710942912-442: 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, 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
2968-473: 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
3024-439: The skin using the anchored barb design rather than being bent under the skin like traditional staples. Porcupines are also sometimes kept as exotic pets . Porcupines occupy a small range of habitats in tropical and temperate parts of Asia, Southern Europe, Africa, and North and South America. They live in forests and deserts, rocky outcrops, and hillsides. Some New World porcupines live in trees, but Old World porcupines prefer
3080-554: 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
3136-490: 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 is described by Richard Dawkins in The Blind Watchmaker as a case of convergent evolution, because mammals on each continent had
#93906