Date: February 10, 2016
Source: North Carolina Museum
Most species are negatively affected when
humans transform natural habitats into urban areas and agricultural lands, but
a few species actually benefit from these activities. These species -- called
human commensals -- thrive in human-modified environments. One example, the
Asian common toad (Duttaphrynus melanostictus), is extremely abundant in
villages, towns, cities and agricultural areas across much of Southeast Asia,
where it feeds on insects that are attracted to artificial lights. Because of
this long and close association with people, Asian common toads are assumed to
easily disperse over large distances, including saltwater barriers between
islands, when they are accidentally transported with land and sea cargo. Such
long-distance dispersal abilities infers that the toad's genes also easily move
among populations, and that toads in different parts of Southeast
Asia are genetically similar.
A research project by Bryan L. Stuart,
Research Curator of Herpetology at the North Carolina Museum of Natural Sciences,
and colleagues at the University of California , Berkeley ,
and Institut Teknologi in Indonesia ,
tested the hypothesis that Asian common toad populations across Southeast Asia are genetically similar owing to their
commensal nature and high dispersive ability. To the researchers' surprise,
three genetically divergent groups of toads were found, each in a different
geographic area (mainland Southeast Asia, coastal Myanmar
and the islands of Java and Sumatra ). The
ranges of these three groups of toads were also found to have statistically
different climates. This suggests that the toads may be adapting to local
climatic conditions and evolving into separate species. Thus, toads of one
group may not be able to disperse and persist within the range of another group
because of climatic differences.
This research changes the view on the
conservation value of these toads. One common toad may not be the same as
another. What is thought to be a single, common species having a large range
may actually be three distinct species, each having smaller ranges with
specific climatic needs. Asian common toads have recently invaded the Southeast
Asian islands of Borneo, Sulawesi and Seram and the African island of Madagascar
Story Source:
The above post is reprinted from materials provided by North Carolina Museum of Natural Sciences. Note: Materials
may be edited for content and length.
Journal Reference:
Guinevere O. U. Wogan, Bryan L. Stuart,
Djoko T. Iskandar, Jimmy A. McGuire. Deep genetic structure and ecological divergence
in a widespread human commensal toad. Biology Letters, 2016; 12 (1): 20150807
DOI: 10.1098/rsbl.2015.0807
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