Scientists map bats' family tree using genetic data

Researchers have constructed a family tree for bats using genetic information, according to a paper published in this week's Science journal.

Bats' evolutionary history is poorly understood even though they make up nearly 20 percent of all mammals. Scientists have estimated that approximately 60 percent of the bat fossil record is still missing.

But a research group led by Emma Teeling at US National Cancer Institute compared genetic sequences from each modern-day bat family. They also reconstructed the evolutionary relationships among the microbats that use echolocation and the megabats that do not.

Moreover, they traced the paleogeographic origins of the major bat lineages. The results support the hypothesis that megabats are nested among four major microbat lineages, which originated in the early Eocene (around 50 million years ago).

"With well over half of the Cenozoic history missing for microbat lineages and nearly all of the fossil history missing for megabat lineages, it is not surprising that Paleocene bat ancestors having transitional morphological adaptations for flight and echolocation have never been discovered," they wrote in the paper.

This was also the time of a significant global rise in temperature and an increase in plant and insect diversity, indicating that bats diversified rapidly in response to a similar trend in their prey, researchers said.

"Their results give us a new framework for understanding bat evolution, but it is only the tip of the iceberg," commented Nancy Simmons, zoologist at the American Museum of Natural History.

"As flying predators capable of capturing prey on the wing, they would have had few competitors for the rich resources of the Eocene night," she wrote in a commentary in the same issue of Science.