Oophaga sylvatica, the kiki poison dart frog or little devil frog, it is also sometimes known as its Spanish name diablito, is a species of frog in the family Dendrobatidae found in Southwestern Colombia and Northwestern Ecuador. Its natural habitat is lowland and submontane rainforest; it can, however, survive in moderately degraded areas, at least in the more humid parts of its range. It is a very common frog in Colombia, but has disappeared from much of its Ecuadorian range. It is threatened by habitat loss (deforestation) and agricultural pollution and sometimes seen in the international pet trade.
This species occurs in several color morphs. For example, the Bilsa Biological Station (operated by the Jatun Sacha Foundation) boasts three color morphs—red, yellow, and orange—within their 3000-ha protected area located within Ecuador's Mache and Chindul coastal mountain ranges.
Description Oophaga sylvatica only displays sexual dimorphism in body size, as both males and females typically have a snout-vent length of 26 – 38 mm, with the males being only slightly larger on average than females. Amongst other closely related species, they are the largest. These species sport aposematic coloration, exhibiting both polytypic and polymorphic variation. Aposematic coloration serves as a visual warning to potential predators that the species is unpalatable which they will soon realize after making the mistake of trying to attack an Oophaga sylvatica. While the patterning of color varies widely, the colors themselves reliably exhibit chromatic and achromatic contrast. The colors also typically are of a bright and exotic nature that is typically synonymous with toxic and poisonous species. This wide range of pattern variation suggests roughly equal fitness for such variation. The range of colors that O. sylvatica displays is also considerably constrained to varying shades of orange, black, and other similar colors. Such coloration allows them to blend in with the mottled forest floor, where they are typically found. Their skin is smooth, with no webbing between any of their toes.
Population structure, speciation, and phylogeny Oophaga sylvatica is a species in the family Dendrobatidae, commonly known as poison-dart frogs, which are characterized by their bright coloration and the toxic alkaloids found in their skin. The phenotypic diversity in coloration observed in this species has been attributed to sexual and natural selection rather than genetic drift. These frogs are diurnal and exhibit terrestrial egg-laying, as well as parental care behaviors towards eggs and tadpoles.
Also known as Dendrobates sylvaticus, the phylogenetic relationship for this species has been modified a couple of times, with most hypothetical models suggesting its closest relatives to be O. pumilio, O. arborea, O. speciosa, and O. granulifera.
While sometimes the Oophaga sylvatica species is considered to be a complex species due to its high levels of morphological variation, genetic studies suggest different populations of Oophaga sylvatica are in fact only a single species. In populations in northwestern Ecuador, O. sylvatica was found to follow two main genetic lineages, separated by the Santiago River into northern and southern groups. The northern groups consist of San Antonio, Lita, Alto Tambo, Durango, and Otokiki. These populations were distributed within a fairly close proximity to each other and those with overlapping regions often displayed a mix of the two population phenotypes. The southern populations consist of Felfa, Cristóbal Colón, Simón Bolívar, Quingüe, Cube, Puerto Quito, Santo Domingo, and La Maná. Located geographically in between the northern and southern populations in the Mache-Chindul protected area is the Mediana population.Garces-Vasconez, Andres. "Conservation Genetics of the 'Diablito' Poison Frog." University of Saskatchewan, Saksatoon, Head of the Department of Biology, University of Saskatchewan, 2017, pp. 1–59. Compared to the northern populations, the southern populations were found to be geographically distant. Both groups had significantly variable color diversity.
Genetics Similar to their geographical distribution, the northern and southern populations are separated into two distinct mitochondrial clades, then further categorized into three genetic clusters: northern, southeast, and southwest. As the northern populations are closer to each other geographically, their genetic diversity is more homogeneous in comparison to the southern populations. Within-clade variation is greater than between-clades, which can be attributed to a variety of causes, including gene flow, recent separation of populations, and the number and class of genetic markers used for study.
Different O. sylvatica populations have all held relatively stable population numbers over time. Northern and southern populations likely diverged about 1.2 MYA, around the time of the Günz glaciation, which occurred roughly 1.1 MYA. Afterwards, population expansion occurred starting around the late Pleistocene which also marks the beginning of the current interglacial period, during which the northern and southern populations likely hybridized, leading to the formation of the Mediana population.
Habitat and distribution Oophaga sylvatica is natively distributed in regions of Southwestern Colombia and Northwestern Ecuador and has been reported in the provinces of Esmeraldas, Pichincha, Imbabura, Cotopaxi, Manabi, Santo Domingo de los Tsachilas, and Los Rios. It inhabits humid tropical forests in mostly lowland and sub montane rainforest. These species are found in a variety of regions and heights even up to 1000 meters above sea level. Within the Chocó rainforest in Ecuador, neotropical poison frogs including O. sylvatica are found within different types of habitats, including rivers, riparian zones, and interior forest. Rivers typically boast the highest diversity of frog species; riparian zones have unique species compositions that include rare and endangered species; interior forest is more vulnerable to logging and other anthropomorphic alterations.
Conservation Oophaga sylvatica is able to tolerate living in some degraded regions such as plantations. This species prefers to live in the more humid parts of its habitat range. Its habitat is threatened by deforestation for anthropogenic land use, including agriculture, logging, mining, human settlements, and pollution. However, because O. sylvatica raises their young in bromeliads which are absent in secondary and road-edge habitats, this species is overwhelmingly found in primary forest. Besides its distribution being heavily biased towards primary forest, O. sylvatica is commonly observed and easy to identify, vocal during the day, and widespread in the Chocó rainforest, making it a good species indicator of habitat quality. Last assessed by the IUCN, Oophaga sylvatica was categorized as a Near Threatened species, with its population trend decreasing. It is considered of Concern and is part of Appendix II of the Convention on International Trade in Endangered Species of wild fauna and flora, or CITES.
As O. sylvatica is found throughout southwestern Colombia, a megadiverse country with accelerating deforestation, it has been included in recent conservation efforts initiated in Colombia.Bacca-Cortes, Natalia, et al. "Conservation Strategies and Participatory Monitoring of Threatened Amphibians on Peace Implementation Territories in Southwestern Colombia." FrogLog, vol. 27, no. 1, ser. 121, Mar. 2019, pp. 18–20. 121. This effort, known as the EBC initiative (Translation from Spanish: "Binational Strategy for the Conservation and Participatory Monitoring of Threatened Species of the Key Biodiversity Areas in the Tropical Andes"), was built by the Ecological Foundation Los Colibríes de Altaquer (FELCA) with support from the Critical Ecosystem Partnership Fund (CEPF). EBC focuses on environmental education and conservation initiatives of impacted species and has created the "Festival of the Diablito Frog" to raise awareness in local communities about O. sylvatica and related conservation efforts. In collaboration with the Universidad de Nariño, FELCA, and San Francisco School students, members of the "Grupo Ecológico para la Conservación de la Rana Diablito (GERD)" project are currently designing different means of species conservation for O. sylvatica.
Territoriality Male home ranges typically are restricted to small calling territories, whereas the home ranges of the females are much larger. The males home ranges are about 56% smaller than the home ranges of females. Male Oophaga sylvatica also typically can only climb up to 2 meters in height, whereas females can climb up to 10 meters in height. Despite the smaller home range territory and limited climbing ability, when experimentally displaced from their territories, males demonstrated better homing accuracy on average, compared to females. This may be attributed to the androgen spillover hypothesis, which dictates that higher levels of androgen are correlated with better spatial abilities. Males were found to have higher levels of androgen on average, which supports the androgen spillover hypothesis. Within their calling territories, males typically exhibit territorial and aggressive behaviors against other males of their own species. Common territorial and aggressive behaviors by Oophaga sylvatica include simultaneous calling by male conspecifics, advancing and retreating, and wrestling.Silverstone, Philip A. A Revision of the Poison-Arrow Frogs of the Genus Dendrobates Wagler. Natural History Museum of Los Angeles County, 1975.. When inactive, Oophaga sylvatica usually take refuge under litter or wooden logs. Similar to other frogs, O. sylvatica is not a very migration-oriented species and rather stays close in proximity to its home range.
Diet Oophaga sylvaticas diet consists primarily of leaf litter arthropods. Researchers found in an Ecuadorian sample of this species that the majority of its diet consists of ants, ranging anywhere from 40% to 86%. A total of 44 ant genera were found, from 9 subfamilies, with the Myrmicinae subfamily constituting a majority. Other insects the frog consumes include mites, springtails, and insect larvae, however these species are consumed at a much smaller abundance and the consumption of these species are dependent on the abundance present in the frog's ecosystem. The ant and mite species O. sylvatica consumes contributes to its accumulation of and variation in alkaloid toxins stored in its skin, which is used as a defense mechanism.
Deforestation can cause dietary changes in frog populations that live in deforested pastureland compared to frogs that live in the rainforest. The diet of pastureland frogs has a much smaller variety of alkaloids in it due to a reduced variety of ants, mites, and termites available to feed on compared to rainforest frogs. This translates to a reduced variety of alkaloids being sequestered in the pastureland frogs for their own defenses.
Reproduction and life cycle Oophaga sylvatica males fertilize eggs externally. Because their eggs are laid in or near shallow pools on land, this species lays fewer and larger eggs than its water-laying counterparts. Laying fewer eggs is believed to provide each egg with more resources to mature so that at the time of hatching, it has a greater chance of surviving on land, as tadpoles need water to survive. Clutch sizes typically range between 4 and 20 eggs.
Mating