Strawberry poison-dart frog

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Oophaga pumilio
Oophaga.pumilio.zoo.jpg
Conservation status
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Dendrobatidae
Genus: Oophaga
Species: O. pumilio
Binomial name
Oophaga pumilio
(Schmidt, 1857)
Synonyms

Dendrobates pumilio Schmidt, 1857

The strawberry poison frog or strawberry poison-dart frog (Oophaga pumilio, formerly Dendrobates pumilio) is a species of small poison dart frog found in Central America.[2] It is common throughout its range, which extends from eastern central Nicaragua through Costa Rica and northwestern Panama. The species is often found in humid lowlands and premontane forest, but large populations are also found in disturbed areas such as plantations.[3] The strawberry poison frog is perhaps most famous for its widespread variation in coloration, comprising approximately 15–30 color morphs, most of which are presumed to be true-breeding.[4] O. pumilio, while not the most poisonous of the dendrobatids, is the most toxic member of its genus.[citation needed]

Diet[edit]

The diet of O. pumilio causes the skin of the amphibian to become toxic in nature when certain subspecies of mites and ants are ingested. Alkaloid toxins are organic in nature and contain nitrogenous bases that react with carbon and hydrogen groups.[5] Pumiliotoxin 251D is the specialized toxin that is sequestered by this species of frog. This toxin has a negative stimulating effect on cardiac function and is a severe disruptor of the sodium potassium ion channels within cells. Upon ingestion of Pumiliotoxin 251D, organisms preying on O. pumilio experience convulsions, paralysis, and death.[5]

Oribatida mites belonging to the glandulate suborder Brachypylina are an important origin of pumiliotoxins in O. pumilio. Hexane-extraction techniques indicate presence of alkaloid toxins in Brachypylina.[6] Toxins appear to be biosynthesized in adult mites, as nymph and larval stages of the insect do not carry the toxins. Experimental analysis of this species of mite show alkaloid toxins are found almost exclusively in the opisthonotal glands of mites of the Scheloribatidae.[7] Oil glands of the mite contain the toxins and are then released internally as the amphibian digests the insect.

O. pumilio

O. pumilio also attributes its cutaneous toxicity from its rich diet of the formicine ants. Species of the formicine genus Brachymyrmex contain pumiliotoxins which the frogs incorporate and accumulate poison from.[8] There is a variability of alkaloid profiles among populations and individuals of O. pumilio, which is indicative of varying levels of available prey within their intraspecific habitats.[9] Research and physical analysis reveal that maternally derived alkaloids exist in young tadpoles.[10] During tadpole-rearing, mother frogs feed their young an unfertilized egg from their ovaries after dropping each individual tadpole into a repository of water usually found in a bromeliad.[11] Tadpoles lacking the obligate nutritive egg diet do not contain the alkaloid.[10] This step is crucial for the tadpoles to sequester the alkaloid from their mother; without such, young tadpoles become susceptible to predation by arthropods and other frogs.

Behavior[edit]

Oophaga pumilio is diurnal and primarily terrestrial, and can often be found in leaf litter in both forested and disturbed areas. Though brightly colored and toxic, these frogs are relatively small, growing to approximately 17.5–22 mm in standard length.[3] Males are extremely territorial, guarding small territories;[12] females and juveniles are far more sociable.

Male advertisement call

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Reproduction and parental care[edit]

Oophaga pumilio is an external breeder, and other species of the genus Oophaga are notable in the amphibian world for exhibiting a high degree of parental care.[13] The strawberry poison frog has dual parental care.[14] The males defend and water the nests, and the females feed the oophagous tadpoles their unfertilized eggs. Although both sexes contribute to parental care, females invest more heavily in terms of energy expenditure, time investment, and loss of potential reproduction.[14] Females provide energetically costly eggs to the tadpoles for 6–8 weeks (until metamorphosis), remain sexually inactive during tadpole rearing, and care for only one clutch of four to six tadpoles at a time.[14] The males, though, contribute the relatively "cheap" (in terms of energy) act of watering and protecting the eggs for a relatively short period (10–12 days), and can care for multiple nests at one time.[14] The extreme maternal investment in their offspring is believed to be the result of high egg mortality. Only 5–12% of the clutch develops into tadpoles, so the female's fitness may be best increased by making sure those few eggs that form tadpoles survive.[15]

The la gruta morph from Colón Province, Panama

After mating, the female lays three to five eggs on a leaf or bromeliad axil. The male then ensures the eggs are kept hydrated by transporting water in his cloaca. After about 10 days, the eggs hatch and the female transports the tadpoles on her back to some water-filled location.[16] In captivity, on rare occasions, the male is observed transporting the tadpoles, though whether this is intentional, or the tadpoles simply hitch a ride, is unknown. Bromeliad axils are frequently used tadpole deposition sites, but anything suitable can be used, such as knots in trees, small puddles, or human trash such as aluminum cans.

Tadpoles are deposited singly at each location. Once this has been done, the female will come to each tadpole every few days and deposit several unfertilized food eggs.[3] In captivity, tadpoles have been raised on a variety of diets, ranging from algae to the eggs of other dart frogs, but with minimal success. O. pumilio tadpoles are considered obligate egg feeders, as they are unable to accept any other form of nutrition.

After about a month, the tadpole will metamorphose into a small froglet. Generally, it stays near its water source for a few days for protection as it absorbs the rest of its tail.

Taxonomy[edit]

Oophaga pumilio belongs to the genus Oophaga,[13] although the name Dendrobates pumilio is still sometimes used. There is evidence that the species of the Oophaga genus (previously classified as the "female parental care group" of Dendrobates[17]) are a monophyletic evolutionary group. Due to the low level of genetic divergence between the species analyzed in this genus, it is estimated that they speciated relatively recently, after the formation of the current Panamanian land bridge in the Pliocene (3–5 million years ago).[18] Oophaga pumilio is believed to be most closely related to Oophaga arborea.[19]

Captivity[edit]

Oophaga pumilio is a popular frog in captivity, due to its striking colors and unique life cycle. They have been imported in vast quantities to the United States and Europe since the early 1990s, when they would typically be available for around US$30 each. However, these shipments have since stopped, and O. pumilio is much less common and available in reduced diversity. In Europe, O. pumilio is much more diverse and available due to an increased frequency of smuggling and the resulting offspring of smuggled animals. Smuggling of dart frogs is less common elsewhere, but still problematic as it kills large numbers of animals and frequently degrades or destroys viable habitat.

Recently, O. pumilio has been exported from Central America again in small numbers from frog farms. Because of this, they have seen a huge increase in numbers in the dart frog community and are regularly available.

Common color morphs in captivity[edit]

"Blue jeans" color morph

One example of a color morph is the blue jeans morph. It is most common throughout the species range, but is relatively rare in the United States pet trade. Most of these animals came from imports during the 1990s, or are their descendants.[citation needed] This morph can be found throughout Costa Rica, as well as mainland Panama.[4]

Bastimentos color morph

References[edit]

  1. ^ Solís, F., Ibáñez, R., Jaramillo, C., Chaves, G., Savage, J., Köhler, G. & Cox, N.A. (2010). "Oophaga pumilio". IUCN Red List of Threatened Species. Version 2014.2. International Union for Conservation of Nature. Retrieved 12 September 2014. 
  2. ^ Frost, Darrel R. (2014). "Oophaga pumilio (Schmidt, 1857)". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 12 September 2014. 
  3. ^ a b c Savage, J. M. 2002. The Amphibians and Reptiles of Costa Rica. University of Chicago Press, Chicago and London.
  4. ^ a b Summers, K., Cronin, T.W. and Kennedy, T. 2003. Variation in spectral reflectance among population of Dendrobates pumilio, the strawberry poison frog, in the Bocas del Toro Archipelago, Panama. Journal of Biogeography 30:35-53.
  5. ^ a b Vandendriessche, T., Abdel-Mottaleb, Y., Maertens, C., Cuypers, E., Sudau, A., Nubbemeyer, U., Mebs, D., Tytgat, J. (2008). "Modulation of voltage-gated Na+ and K+ channels by pumiliotoxin 251D: A "joint venture" alkaloid from arthropods and amphibians". Toxicon 51 (3): 334–344. doi:10.1016/j.toxicon.2007.10.011. 
  6. ^ Takada, W., Sakata, T., Shimano, S., Enami, Y., Mori, N., Nishida, R., and Kuwahara, Y. (2005). "Scheloribatid mites as the source of pumiliotoxins in dendrobatid frogs". Journal of Chemical Ecology 31 (10): 2403–2415. PMID 16195851. 
  7. ^ Raspotnig, G., Norton, R.A., Heethoff, M. (2011). "Oribatid mites and skin alkaloids in poison frogs". Biology Letters 7 (4): 555–556. 
  8. ^ Staudt, K., Meneses, O., S., Mebs, D., Proehl, H. (2010). "Foraging behaviour and territoriality of the strawberry poison frog (Oophaga pumilio) in dependence of the presence of ants". Amphibia-Reptilia 31 (2): 217–227. 
  9. ^ Mebs, D., Pogoda, W., Batista, A., Ponce, M., Koelher, G., Kauert, G. (2008). "Variability of alkaloid profiles in Oophaga pumilio (Amphibia: Anura: Dendrobatidae) from Western Panama and Southern Nicaragua". Salamandra 44 (4): 241–247. 
  10. ^ a b Stynoski, J. L.; Torres-Mendoza, Y.; Sasa-Marin, M.; Saporito, R. A. (2014). "Evidence of maternal provisioning of alkaloid-based chemical defenses in the strawberry poison frog Oophaga pumilio". Ecology 95 (3): 587–593. doi:10.1890/13-0927.1. PMID 24804437.  edit
  11. ^ Forsyth, A., Fogden, M., Fogden, P., Wilson, E., O. 2008. Nature of the Rainforest: Costa Rica and Beyond. Cornell University Press. Ithaca, New York, USA.
  12. ^ Donnelly, M. A. 1989. Reproductive phenology and age structure of Dendrobates pumilio in northeastern Costa Rica. Journal of Herpetology, 23:362-367.
  13. ^ a b Grant, T., Frost, D. R., Caldwell, J. P., Gagliardo, R., Haddad, C. F. B., Kok, P. J. R., Means, D. B., Noonan, B. P., Schargel, W. E., and Wheeler, W. C. (2006). "Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia: Athesphatanura: Dendrobatidae)". Bulletin of the American Museum of Natural History 299: 1–262. doi:10.1206/0003-0090(2006)299[1:PSODFA]2.0.CO;2. 
  14. ^ a b c d Haase, A., and H. Prohl. 2002. Female activity patterns and aggressiveness in the strawberry poison frog Dendrobates pumilio (Anura: Dendrobatidae). Amphibia-Reptilia 23: 129-140.
  15. ^ Prohl, H., and W. Hodl. 1999. Parental investment, potential reproductive rates, and mating system in the strawberry dart-poison frog, Dendrobates pumilio. Behavioral Ecological Sociobiology 46: 215-220
  16. ^ Limerick, S. 1980. Courtship behavior and oviposition of the poison-arrow frog Dendrobates pumilio. Herpetologica 36:69-71.
  17. ^ Zimmermann, H. and Zimmermann, E. 1988. Etho-Taxonomie und zoogeographische Artengruppenbildung bei Pfeilgiftfröschen (Anura: Dendrobatidae). Salamandra 24:125-160.
  18. ^ Summers, K., Weigt, L.A., Boag, P., and Bermingham, E. 1999. The evolution of female parental care in poison frogs of the genus Dendrobates: Evidence from mitochondrial DNA sequences. Herpetologica 55(2):254-270.
  19. ^ Roberts, J.L., Brown, J.L., von May, R., Arizabal, W., Presar, A., Symula, R., Schulte, R., and Summers, K. 2006. Phylogenetic relationships among poison frogs of the genus Dendrobates (Dendrobatidae): A molecular perspective from increased taxon sampling. Herpetological Journal 16:377-385.

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