FoxP2 and Echolocation in Bats and Whales

As I mentioned previously PLOS has an interesting paper on echolocation in bats and whales (you may also recall this post on echolocation in whales). The PloS One paper looks at the FoxP2 gene in bats, cetaceans and various other animals.

FoxP2 has been implicated in some interesting phenomena related to language and to sensorimotor integration and motor learning. In the meantime bats have been reclassified taxonomically speaking. Where before we had microchiropterans and megachiropterans we now have Yinpterochiroptera (megachiropterans and the horseshoe and related bats) and the Yangochiroptera (the rest of the microchiropterans). This new classification raises some interesting questions , which are , unfortunately, outside the scope of this post. At any rate, the Plos paper analyzed the variability of FoxP2 in bats from six different families. The two FoxP2 exons showed high levels of variability (attributed to divergent selection). To follow up, the two exons were examined in a larger number of bats along with 18 species of cetacean (15 from ecolocating toothed whales and 3 from baleen whales). They interpret part of the results as follows:

We instead speculate that observed variation in bats might be associated with aspects of echolocation. As mentioned, amino acid variation at both exons 7 and 17 in bats corresponds well to echolocation types/phylogenetic boundaries, with almost complete conservation across groups of confamilial species but contrasting signatures between families. Such high sequence diversity at exons 7 and 17 in bats relative to other mammals, including echolocating cetaceans, indicates that FoxP2 plays a role in the sensorimotor demands that are peculiar to bat echolocation rather than echolocation in general.

The cetaceans did not show the same diversity in exons and the paper attributes this to the fact that echolocating cetaceans emit their signals through their melon and don’t require the same kind of rapid orofacial coordination seen in bats. They further point out that cetaceans use rather stereotyped clicks that:

…show neither the signal variability of bats nor the dynamic modification of signal design in relation to echo feedback.

There is some other interesting stuff in the paper in support of their contention, but you will have to read the paper yourself to find out more.
One final thought, in the whale article on Science Daily (linked to above) Nicholas Pyenson mentions that bats partition the tree canopy and preferentially hunt insects at specific heights. It would be interesting to see the FoxP2 data analyzed with that taken into consideration…

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