Poison dart frog

From Wikipedia for FEVERv2
Jump to navigation Jump to search

"Poison frog" redirects here. Poison dart frog_sentence_0

For other frogs that are poisonous to humans, see Poisonous frog. Poison dart frog_sentence_1

Poison dart frog_table_infobox_0

Poison dart frogs (Dendrobatidae)Poison dart frog_header_cell_0_0_0
Scientific classification DendrobatidaePoison dart frog_header_cell_0_1_0
Kingdom:Poison dart frog_cell_0_2_0 AnimaliaPoison dart frog_cell_0_2_1
Phylum:Poison dart frog_cell_0_3_0 ChordataPoison dart frog_cell_0_3_1
Class:Poison dart frog_cell_0_4_0 AmphibiaPoison dart frog_cell_0_4_1
Order:Poison dart frog_cell_0_5_0 AnuraPoison dart frog_cell_0_5_1
Clade:Poison dart frog_cell_0_6_0 HyloideaPoison dart frog_cell_0_6_1
Superfamily:Poison dart frog_cell_0_7_0 DendrobatoideaPoison dart frog_cell_0_7_1
Family:Poison dart frog_cell_0_8_0 Dendrobatidae

Cope, 1865Poison dart frog_cell_0_8_1

Subfamilies and generaPoison dart frog_header_cell_0_9_0

Poison dart frog (also known as dart-poison frog, poison frog or formerly known as poison arrow frog) is the common name of a group of frogs in the family Dendrobatidae which are native to tropical Central and South America. Poison dart frog_sentence_2

These species are diurnal and often have brightly colored bodies. Poison dart frog_sentence_3

This bright coloration is correlated with the toxicity of the species, making them aposematic. Poison dart frog_sentence_4

Some species of the family Dendrobatidae exhibit extremely bright coloration along with high toxicity, while others have cryptic coloration with minimal to no amount of observed toxicity. Poison dart frog_sentence_5

The species that have great toxicity derive this from their diet of ants, mites and termites. Poison dart frog_sentence_6

Other species however, that exhibit cryptic coloration and low to no amounts of toxicity, eat a much larger variety of prey. Poison dart frog_sentence_7

Many species of this family are threatened due to human infrastructure encroaching on their habitats. Poison dart frog_sentence_8

These amphibians are often called "dart frogs" due to the Native Americans' use of their toxic secretions to poison the tips of blowdarts. Poison dart frog_sentence_9

However, of over 170 species, only four have been documented as being used for this purpose (curare plants are more commonly used), all of which come from the genus Phyllobates, which is characterized by the relatively large size and high levels of toxicity of its members. Poison dart frog_sentence_10

Characteristics Poison dart frog_section_0

Most species of poison dart frogs are small, sometimes less than 1.5 cm (0.59 in) in adult length, although a few grow up to 6 cm (2.4 in) in length. Poison dart frog_sentence_11

They weigh 1 oz. Poison dart frog_sentence_12

on average. Poison dart frog_sentence_13

Most poison dart frogs are brightly colored, displaying aposematic patterns to warn potential predators. Poison dart frog_sentence_14

Their bright coloration is associated with their toxicity and levels of alkaloids. Poison dart frog_sentence_15

For example, frogs of the genus Dendrobates have high levels of alkaloids, whereas Colostethus species are cryptically colored and are not toxic. Poison dart frog_sentence_16

Poison dart frogs are an example of an aposematic organism. Poison dart frog_sentence_17

Their bright coloration advertises unpalatability to potential predators. Poison dart frog_sentence_18

Aposematism is currently thought to have originated at least four times within the poison dart family according to phylogenetic trees, and dendrobatid frogs have since undergone dramatic divergences – both interspecific and intraspecific – in their aposematic coloration. Poison dart frog_sentence_19

This is surprising given the frequency-dependent nature of this type of defense mechanism. Poison dart frog_sentence_20

Adult frogs lay their eggs in moist places, including on leaves, in plants, among exposed roots, and elsewhere. Poison dart frog_sentence_21

Once the eggs hatch, the adult piggybacks the tadpoles, one at a time, to suitable water, either a pool, or the water gathered in the throat of bromeliads or other plants. Poison dart frog_sentence_22

The tadpoles remain there until they metamorphose, in some species fed by unfertilized eggs laid at regular intervals by the mother. Poison dart frog_sentence_23

Habitat Poison dart frog_section_1

Poison dart frogs are endemic to humid, tropical environments of Central and South America. Poison dart frog_sentence_24

These frogs are generally found in tropical rainforests, including in Bolivia, Costa Rica, Brazil, Colombia, Ecuador, Venezuela, Suriname, French Guiana, Peru, Panama, Guyana, Nicaragua, and Hawaii (introduced). Poison dart frog_sentence_25

Natural habitats include subtropical and tropical, moist, lowland forests, subtropical or tropical high-altitude shrubland, subtropical or tropical, moist, montanes and rivers, freshwater marshes, intermittent freshwater marshes, lakes and swamps. Poison dart frog_sentence_26

Other species can be found in seasonally wet or flooded lowland grassland, arable land, pastureland, rural gardens, plantations, moist savanna and heavily degraded former forest. Poison dart frog_sentence_27

Premontane forests and rocky areas have also been known to hold frogs. Poison dart frog_sentence_28

Dendrobatids tend to live on or close to the ground, but also in trees as much as 10 m (33 ft) from the ground. Poison dart frog_sentence_29

Reproduction Poison dart frog_section_2

Many species of poison dart frogs are dedicated parents. Poison dart frog_sentence_30

Many poison dart frogs in the genera Oophaga and Ranitomeya carry their newly hatched tadpoles into the canopy; the tadpoles stick to the mucus on the backs of their parents. Poison dart frog_sentence_31

Once in the upper reaches of the rainforest trees, the parents deposit their young in the pools of water that accumulate in epiphytic plants, such as bromeliads. Poison dart frog_sentence_32

The tadpoles feed on invertebrates in their nursery, and their mother will even supplement their diet by depositing eggs into the water. Poison dart frog_sentence_33

Other poison frogs lay their eggs on the forest floor, hidden beneath the leaf litter. Poison dart frog_sentence_34

Poison frogs fertilize their eggs externally; the female lays a cluster of eggs and a male fertilizes them afterward, in the same manner as most fish. Poison dart frog_sentence_35

Poison frogs can often be observed clutching each other, similar to the manner most frogs copulate. Poison dart frog_sentence_36

However, these demonstrations are actually territorial wrestling matches. Poison dart frog_sentence_37

Both males and females frequently engage in disputes over territory. Poison dart frog_sentence_38

A male will fight for the most prominent roosts from which to broadcast his mating call; females fight over desirable nests, and even invade the nests of other females to devour competitor's eggs. Poison dart frog_sentence_39

The operational sex ratio in the poison dart frog family is mostly female biased. Poison dart frog_sentence_40

This leads to a few characteristic behaviors and traits found in organisms with an uneven sex ratio. Poison dart frog_sentence_41

In general, females have a choice of mate. Poison dart frog_sentence_42

In turn, males show brighter coloration, are territorial, and are aggressive toward other males. Poison dart frog_sentence_43

Females select mates based on coloration (mainly dorsal), calling perch location, and territory. Poison dart frog_sentence_44

Taxonomy Poison dart frog_section_3

Dart frogs are the focus of major phylogenetic studies, and undergo taxonomic changes frequently. Poison dart frog_sentence_45

The family Dendrobatidae currently contains 16 genera, with about 200 species. Poison dart frog_sentence_46

Color morphs Poison dart frog_section_4

Some poison dart frogs species include a number of conspecific color morphs that emerged as recently as 6,000 years ago. Poison dart frog_sentence_47

Therefore, species such as Dendrobates tinctorius, Oophaga pumilio, and Oophaga granulifera can include color pattern morphs that can be interbred (colors are under polygenic control, while the actual patterns are probably controlled by a single locus). Poison dart frog_sentence_48

Differing coloration has historically misidentified single species as separate, and there is still controversy among taxonomists over classification. Poison dart frog_sentence_49

Variation in predation regimens may have influenced the evolution of polymorphism in Oophaga granulifera, while sexual selection appears to have contributed to differentiation among the Bocas del Toro populations of Oophaga pumilio. Poison dart frog_sentence_50

Toxicity and medicine Poison dart frog_section_5

Many poison dart frogs secrete lipophilic alkaloid toxins such as allopumiliotoxin 267A, batrachotoxin, epibatidine, histrionicotoxin, and pumiliotoxin 251D through their skin. Poison dart frog_sentence_51

Alkaloids in the skin glands of poison frogs serve as a chemical defense against predation, and they are therefore able to be active alongside potential predators during the day. Poison dart frog_sentence_52

About 28 structural classes of alkaloids are known in poison frogs. Poison dart frog_sentence_53

The most toxic of poison dart frog species is Phyllobates terribilis. Poison dart frog_sentence_54

It is argued that dart frogs do not synthesize their poisons, but sequester the chemicals from arthropod prey items, such as ants, centipedes and mites – the diet-toxicity hypothesis. Poison dart frog_sentence_55

Because of this, captive-bred animals do not possess significant levels of toxins as they are reared on diets that do not contain the alkaloids sequestered by wild populations. Poison dart frog_sentence_56

In fact, new studies suggest that the maternal frogs of some species lay unfertilized eggs, which are laced with trace amounts of alkaloids, to feed the tadpoles. Poison dart frog_sentence_57

This behavior shows that the poisons are introduced from a very young age. Poison dart frog_sentence_58

Nonetheless, the captive-bred frogs retain the ability to accumulate alkaloids when they are once again provided an alkaloid-containing diet. Poison dart frog_sentence_59

Despite the toxins used by some poison dart frogs, some predators have developed the ability to withstand them. Poison dart frog_sentence_60

One is the snake Erythrolamprus epinephalus, which has developed immunity to the poison. Poison dart frog_sentence_61

Chemicals extracted from the skin of Epipedobates tricolor may be shown to have medicinal value. Poison dart frog_sentence_62

Scientists use this poison to make a painkiller. Poison dart frog_sentence_63

One such chemical is a painkiller 200 times as potent as morphine, called epibatidine; however, the therapeutic dose is very close to the fatal dose. Poison dart frog_sentence_64

A derivative ABT-594 developed by Abbott Laboratories, called Tebanicline got as far as Phase II trials in humans, but was dropped from further development due to unacceptable incidence of gastrointestinal side effects. Poison dart frog_sentence_65

Secretions from dendrobatids are also showing promise as muscle relaxants, heart stimulants and appetite suppressants. Poison dart frog_sentence_66

The most poisonous of these frogs, the golden poison frog (Phyllobates terribilis), has enough toxin on average to kill ten to twenty men or about ten thousand mice. Poison dart frog_sentence_67

Most other dendrobatids, while colorful and toxic enough to discourage predation, pose far less risk to humans or other large animals. Poison dart frog_sentence_68

Evolution of skin coloration and toxicity Poison dart frog_section_6

Skin toxicity evolved alongside bright coloration, perhaps preceding it. Poison dart frog_sentence_69

Toxicity may have relied on a shift in diet to alkaloid-rich arthropods, which likely occurred at least four times among the dendrobatids. Poison dart frog_sentence_70

Conspicuous coloration in these frogs is further associated with diet specialization, body mass, aerobic capacity, and chemical defense. Poison dart frog_sentence_71

Either aposematism and aerobic capacity preceded greater resource gathering, making it easier for frogs to go out and gather the ants and mites required for diet specialization, contrary to classical aposematic theory, which assumes that toxicity from diet arises before signaling. Poison dart frog_sentence_72

Alternatively, diet specialization preceded higher aerobic capacity, and aposematism evolved to allow dendrobatids to gather resources without predation. Poison dart frog_sentence_73

Conspicuousness and toxicity may be inversely related, as polymorphic poison dart frogs that are less conspicuous are more toxic than the brightest and most conspicuous species. Poison dart frog_sentence_74

Energetic costs of producing toxins and bright color pigments lead to potential trade-offs between toxicity and bright coloration, and prey with strong secondary defenses have less to gain from costly signaling. Poison dart frog_sentence_75

Therefore, prey populations that are more toxic are predicted to manifest less bright signals, opposing the classical view that increased conspicuousness always evolves with increased toxicity. Poison dart frog_sentence_76

Prey mobility could also explain the initial development of aposematic signaling. Poison dart frog_sentence_77

If prey have characteristics that make them more exposed to predators, such as when some dendrobatids shifted from nocturnal to diurnal behavior, then they have more reason to develop aposematism. Poison dart frog_sentence_78

After the switch, the frogs had greater ecological opportunities, causing dietary specialization to arise. Poison dart frog_sentence_79

Thus, aposematism is not merely a signaling system, but a way for organisms to gain greater access to resources and increase their reproductive success. Poison dart frog_sentence_80

Dietary conservatism (long-term neophobia) in predators could facilitate the evolution of warning coloration, if predators avoid novel morphs for a long enough period of time. Poison dart frog_sentence_81

Another possibility is genetic drift, the so-called gradual-change hypothesis, which could strengthen weak pre-existing aposematism. Poison dart frog_sentence_82

Sexual selection may have played a role in the diversification of skin color and pattern in poison frogs. Poison dart frog_sentence_83

With female preferences in play, male coloration could evolve rapidly. Poison dart frog_sentence_84

Sexual selection is influenced by many things. Poison dart frog_sentence_85

The parental investment may shed some light on the evolution of coloration in relation to female choice. Poison dart frog_sentence_86

In Oophaga pumilio, the female provides care for the offspring for several weeks whereas the males provides care for a few days, implying a strong female preference. Poison dart frog_sentence_87

Sexual selection increases phenotypic variation drastically. Poison dart frog_sentence_88

In populations of O. pumilio that participated in sexual selection, the phenotypic polymorphism was evident. Poison dart frog_sentence_89

The lack of sexual dimorphism in some dendrobatid populations however suggests that sexual selection is not a valid explanation. Poison dart frog_sentence_90

Functional trade-offs are seen in poison frog defense mechanisms relating to toxin resistance. Poison dart frog_sentence_91

Poison dart frogs containing epibatidine have undergone a 3 amino acid mutation on receptors of the body, allowing the frog to be resistant to its own poison. Poison dart frog_sentence_92

Epibatidine-producing frogs have evolved poison resistance of body receptors independently three times. Poison dart frog_sentence_93

This target-site insensitivity to the potent toxin epibatidine on nicotinic acetylcholine receptors provides a toxin resistance while reducing the affinity of acetylcholine binding. Poison dart frog_sentence_94

Captive care Poison dart frog_section_7

See also: History of dendrobatid frogkeeping Poison dart frog_sentence_95

All species of poison dart frogs are Neotropical in origin. Poison dart frog_sentence_96

Wild-caught specimens can maintain toxicity for some time (this can be obtained through a form of bio accumulation), so appropriate care should be taken when handling such animals. Poison dart frog_sentence_97

While scientific study on the lifespan of poison dart frogs is scant, retagging frequencies indicate it can range from one to three years in the wild. Poison dart frog_sentence_98

However, these frogs typically live for much longer than that in captivity, having been reported to live as long as 25 years. Poison dart frog_sentence_99

These claims also seem to be questionable, since many of the larger species take a year or more to mature, and Phyllobates species can take more than two years. Poison dart frog_sentence_100

In captivity, most species thrive where the humidity is kept constant at 80 to 100% and where the temperature is around 72 °F (22 °C) to 80 °F (27 °C) during the day and no lower than 60 °F (16 °C) to 65 °F (18 °C) at night. Poison dart frog_sentence_101

Some species tolerate lower temperatures better than others. Poison dart frog_sentence_102

Conservation status Poison dart frog_section_8

Many species of poison dart frogs have recently experienced habitat loss, chytrid diseases, and collection for the pet trade. Poison dart frog_sentence_103

Some are listed as threatened or endangered as a result. Poison dart frog_sentence_104

Zoos have tried to counteract this disease by treating captive frogs with an antifungal agent that is used to cure athlete's foot in humans. Poison dart frog_sentence_105

See also Poison dart frog_section_9

Poison dart frog_unordered_list_0


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Poison dart frog.