Species Diversity In Vesper Bats Linked To Jumping Genes
If you see flitting groups of bats at dusk in your neighborhood, chances are that they might be vesper bats, also called evening bats or common bats. They are a large family of bats numbering more than 400 species across the globe and are found all over the world, both in tropical and temperate regions, except Antarctica. Among mammals they are second only to rodents in terms of species diversity. Researches have tried to find out the reason behind this diversity and their study has been published in the advanced online edition of Molecular Biology and Evolution, according to a press release Tuesday.
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Genome sequencing was carried out recently for two vesper bat species to get insights on their physiology and longevity. This information was used by author Ray and his group to find out the reason for the diverse speciation in vesper bats. According to them, one reason for this diversity might be jumping elements in the genome, called DNA transposons. The transposons are a DNA sequence that can change its position within the genome, sometimes creating or reversing mutations and altering the cell's genome size. They are important in genome function and evolution. Vesper bats are known to have elevated DNA transposon activity. They are also more recent in the evolutionary history of this family than any other mammal. But why and how the DNA transposon activity increased during the evolutionary cycle of these bats, is as yet unknown.
To confirm their theory, the authors examined the patterns of DNA transposons activity in the genome sequence of the two vesper bat species. They found that the timing of bat species expansion coincides with DNA transposon activity around 30 million years ago. DNA transposons, in turn, gave rise to the introduction of small RNAs, called microRNAs, or miRNAs, which are powerful forces of genetic change, and thus, evolutionary novelties.
Says Ray, "Our results suggest that transposable elements have the potential to shift evolution into overdrive by rapidly introducing large numbers of small RNAs. Those small RNAs don't change the proteins that genes code for but instead impact how and when the genes are expressed, thereby allowing for rapid changes in the way organisms interact with their environment."
The authors further speculate that the DNA transposons influenced diversity in bats occurred at the same time that the Earth was undergoing a huge climate change from warm tropical conditions to a more temperate climate, called the Eocene-Oligocene transition, which occurred 33-34 million years ago.
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