ENVIRONMENT
WHEN EVOLUTIONARY TREES GET FROGGY A new study on frogs shows gene flow and population structure should be considered to determine if morphologically similar and genetically distinct animals comprise separate species.
Descriptions of new species have been rapidly on the rise since the turn of the century, especially in biodiversity hotspots like Southeast Asia. Many of these are cryptic species: animal groups that look alike but are genetically quite distinct. Distinguishing cryptic species is notoriously difficult and can lead to overestimates of species numbers. A new study characterizing species boundaries in a group of Southeast Asian spotted stream frogs urges a more cautious approach.
draneil Das, a conservation biologist at Universiti Malaysia Sarawak (UNIMAS). Most new species boundaries are defined using statistical methods that use similarities and differences in genetic characteristics to estimate evolutionary relationships between species and produce a best guess at the family tree. But these conventional methods often ignore other important factors, such as the transfer of genetic material from one population to another, called gene flow.
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“We showed that breeding between populations and then further interbreeding between hybrids and parent populations can produce evolutionary patterns and levels of divergence that resemble distinct species, but they are still part of one species lineage,” says In-
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Further Professor Indraneil Das | idas@unimas.my information Institute of Biodiversity and Environmental Conservation Universiti Malaysia Sarawak
Credit: Pui Yong Min
ASIA RE SEA RC H N EWS
Pulchrana signata, a member of Southeast Asia’s riparian frog assemblage.
The international team of researchers compared conventional methods of species description with more robust genomic analyses that take gene flow and other factors into account, using more than 12,000 genetic markers to produce a more unbiased representation of evo-
