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.[2] These species are diurnal and often have brightly colored bodies. This bright coloration is correlated with the toxicity of the species, making them aposematic. Some species of the family Dendrobatidae exhibit extremely bright coloration along with high toxicity — a feature derived from their diet of ants, mites and termites[3][4]— while species which eat a much larger variety of prey have cryptic coloration with minimal to no amount of observed toxicity.[3][4] Many species of this family are threatened due to human infrastructure encroaching on their habitats.
Subfamilies and genera
- Colostethinae (Cope, 1867)
- Dendrobatinae (Cope, 1865)
- Hyloxalinae (Grant et al., 2006)[1]
These amphibians are often called “dart frogs” due to the aboriginal South Americans’ use of their toxic secretions to poison the tips of blowdarts. However, out of over 170 species, only four have been documented as being used for this purpose (curare plants are more commonly used for aboriginal South American darts) all of which come from the genus Phyllobates , which is characterized by the relatively large size and high levels of toxicity of its members.[5][6]
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. They weigh 1 oz. on average.[7] Most poison dart frogs are brightly colored, displaying aposematic patterns to warn potential predators. Their bright coloration is associated with their toxicity and levels of alkaloids. For example, frogs of the genus Dendrobates have high levels of alkaloids, whereas Colostethus species are cryptically colored and are not toxic.[4]
Poison dart frogs are an example of an aposematic organism. Their bright coloration advertises unpalatability to potential predators. 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. This is surprising given the frequency-dependent nature of this type of defense mechanism.[3][8]
Adult frogs lay their eggs in moist places, including on leaves, in plants, among exposed roots, and elsewhere. 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. The tadpoles remain there until they metamorphose, in some species fed by unfertilized eggs laid at regular intervals by the mother.[9]
Poison dart frogs are endemic to humid, tropical environments of Central and South America.[5] 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).
Color morphs
Some poison dart frogs species include a number of conspecific color morphs that emerged as recently as 6,000 years ago.[14] 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).[15] Differing coloration has historically misidentified single species as separate, and there is still controversy among taxonomists over classification.[16]
Variation in predation regimens may have influenced the evolution of polymorphism in Oophaga granulifera,[17] while sexual selection appears to have contributed to differentiation among the Bocas del Toro populations of Oophaga pumilio.