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| Wild adults of Oophaga sylvatica (Paru morph) of the Otokiki population, Esmeraldas province. Site 1 (70 x 40 m): 734 meters asl, sampled area: 2800 square meters. © Centro Jambatu |
Individuals of the the
Paru morph of Oophaga sylvatica (= Dendrobates sylvaticus)
exported by Wikiri are the offspring of a parental population from the Otokiki
reserve (143 acres of tropical rainforests of northwestern Ecuador). Otokiki reserve is located in the Alto Tambo region (Esmeraldas province) at an
altitude of about 700 meters above sea level.
The amount of color
pattern variation within this Otokiki population, which occurs naturally, is
perplexing. See figure depicting variation of wild-caught adult individuals at
one of the study sites (Site 1) in Otokiki. All individuals found in a preliminary
sampling are included, but additional sampling might reveal more individuals
and variation.
At Otokiki, similar large
variation in colors and patterns is represented in quadrats under management
by Wikiri (three habitat-enriched semiclosed enclosures, one enriched
open quadrat), and in one control (not enriched) quadrat.
Also, we have documented
a great amount of intrapopulation variation at other sites in Esmeraldas
province, for example, towards the east of Alto Tambo at Guadal (near Lita,
Esmeraldas province). Less
color pattern variation is seen in lowland populations at Durango and Playón de
San Francisco, which display more uniform colors.
How to interpret this
variation and what are it’s causes?
Underlying causes of this
intrapopulation variation of the Paru morph are largely unknown and currently
are a matter of speculation. For now, we are reluctant to interpret this
variation as the result of hybridization —a phenomenon that can occur between
species as a result of primary or secondary contact (after a period of
isolation). Underlying factors behind the observed variation probably lie in
the evolutionary history of this population. The historical human intervention
in the area could have played a role as well, but the variation is not a
consequence of Wikiri manipulation.
Understanding the
mechanisms that promote intrapopulation divergence (such as the one observed at
Otokiki reserve and surrounding areas) and interpopulation divergence (such as
the one among populations of O. sylvatica in the pacific lowlands of
Ecuador and Colombia), and ultimately speciation, is one of the most
challenging and intriguing tasks in evolutionary biology. Geographical
barriers, ecological gradients, genetic drift, and sexual selection are the
main mechanisms (currently speculative for O. sylvatica populations, as
mentioned before) invoked to explain these processes, which are shaping the
variation observed.
Centro Jambatu has begun
a research program and study projects on the evolution of coloration, morphology and
behavior within and among populations of Oophaga sylvatica. The program
is a cooperative effort among Ecuadorian and USA researchers. We will be doing field,
molecular, and experimental work. The Otokiki population will be critical for
our understanding of coloration evolution because of its huge
variability.
For a better
understanding of this variation and its evolution, we need to conduct
fine-tuned studies including morphological descriptions in relation to
behavior, geography, and molecular population genetic structure. Also, we need
to conduct lab controlled experiments to see the consequences of color
variation. We will need to set up crosses between color morphs in order to
identify color specific SNPs (single nucleotide polymorphisms) and then examine
the expression bias of parental alleles in the offspring. We will study
behavioral issues and also we will address questions of color determination.
Finally, we think that
the hobbyists industry and people who love these frogs should appreciate the
unique opportunity and monumental effort done by Wikiri (see also Ecuafrog of Wikiri and the amphibian trade) in
providing farm and captive raised frogs from a population that displays such a
great intrapopulation variation, which include dull and bright colored
individuals, spotted and non-spotted frogs, orange, red, yellow and brown
colors. Hopefully this variation can be preserved at the site (Otokiki) and
region of Alto Tambo. Backup populations under care of hobbyists are also
important as an ex situ tool helping integrative conservation strategies.
Fundación Otonga
Updated: 4 January 2013
