Friday 26 July 2013 | By: Amandine Ronny Montegerai

The coevolution


The coevolution of a predator-prey relationship can lead to an evolutionary arms race, which in the case of bats and one of their prey, moths, has been an ongoing struggle for nearly 65 million years.

Bats primary means of nighttime prey detection is the use of echolocation to which the moths’ best defense was to develop the ability to hear the frequencies bats used to echolocate. Moths were able to interpret those sounds to develop a sophisticated acrobatic flight pattern I response to specific frequencies and evade capture. This did not thwart bats, who continued to capture their prey.

IN 2009, researchers Corcoran, Barber and Conner discovered an amazing ability in the tiger moth, (Bertholdia trigona), to jam the big brown bat’s (Eptesicus fuscus) sonar on approach through the use of sound-producing organs called tymbals. Bats were terribly unsuccessful capturing moths who produced these clicks.

This ability found only in tiger moths and tiger beetles has now been discovered in another at least three species of hawkmoths in Borneo, Cechenena lineosa, Theretra boisduvalii & Theretra nessus. Unlike their distantly cousin the tiger moth, who utilize tymbals, these moths produce the ultrasound using parts of their genitals.

Researchers Jesse Barber of Boise State University in Idaho and Akito Kawahara of the University of Florida in Gainesville showed that the male moths were able to produce sounds by rubbing their genital scales against “claspers” that are used to hold the female moth during mating and females, lacking this functional structure, would also use their genital scales, however they would run them against their abdomen.

This study also displays a wonderful example of convergent evolution- though tiger moths and the hawk moth have no phylogenetically close common ancestor, they have evolved similar tactics to avoid detection by their primary predator, the bat.

John Ratcliffe, a neuroethologist at the University of Southern Denmark in Odense, noted that this convergence is especially magnificent in that these moths have accomplished both the coevolution of auditory detection of the echolocation and predator avoidance in the form of sonar jamming, stating "at both ends, in ears and sound production, it's double convergence, which is really neat.”

Image Credit: goldentakin
http://www.flickr.com/photos/77436133@N03/7002504660/

J. Barber and A.Y. Kawahara. (2013).Hawkmoths produce anti-bat ultrasound. Biology Letters, 9(4), online doi: 10.1098/rsbl.2013.0161
http://rsbl.royalsocietypublishing.org/content/9/4/20130161
http://www.nature.com/news/hawkmoths-zap-bats-with-sonic-blasts-from-their-genitals-1.13333
A.J. Corcoran, J.R. Barber and W.E. Conner. (2009). Tiger moth jams bat sonar. Science, 325(5938), 325-327. DOI: 10.1126/science.1174096
http://scienceblogs.com/neurophilosophy/2009/07/17/tiger-moths-jam-bat-sonar/

Corcoran, A.J., Barber, J. R., Hristov, N. I., and Conner W. E. (2011). How do tiger moths jam bat sonar? The Journal of Experimental Biology 214, 2416-2425. doi:10.1242/jeb.054783
http://jeb.biologists.org/content/214/14/2416.full.pdf+html

Yager DD, Spangler HG. (1997). Behavioral response to ultrasound by the tiger beetle Cicindela marutha dow combines aerodynamic changes and sound production. Journal of Experimental Biology, 200, 649–659.