BEACON Researchers at Work: Males have no taste… at least if you are a Heliconius butterfly

This week’s BEACON Researchers at Work post is by BEACON Faculty Affiliate Adriana Briscoe, from University of California, Irvine.

Males have no taste… at least if you are a Heliconius butterfly

Unlike their male counterparts, female Heliconius butterflies have taste receptors on their forelegs in order to pick non-toxic plants on which to lay their eggs

My research group in the Department of Ecology and Evolutionary Biology at the University of California, Irvine studies the sensory world of butterflies.  We primarily work on vision but have recently extended our scientific gaze to include olfaction and gustation with the publication of reference genomes for the passion-vine butterfly Heliconius melpomene. and the monarch Danaus plexippus.

Aide Macias-Muñoz, PhD student

Aide Macias-Muñoz, PhD student

Nearly a year ago, I visited the Department of Zoology at the University of Cambridge, U.K. as an Overseas Visiting Scholar at St. John’s College.  From that lovely vantage point near the River Cam, I directed a collaborative project that brought together work by my first-year BEACON-sponsored PhD student Aide Macias-Muñoz and work by graduate students Simon Martin and Krzysztof Kozak and undergraduate Gabriel Jamie in Dr. Chris Jiggins’ lab. Our collaborative work was published 11 July, in the journal PLoS Genetics.

Here are some shamelessly lifted words from the press release about our work by the University of Cambridge, U.K.:

“Female Heliconius butterflies have taste receptors embedded in spikes on their legs in order to spear and ‘taste’ plants to find the most beneficial ones on which to lay their eggs, new research reveals. As male Heliconius butterflies do not lay eggs, they have no taste receptors on their [fore]legs.

H. melpomene female laying an egg on a passion-flower vine.

H. melpomene female laying an egg on a passion-flower vine.

For the research, [we] studied the genes that code for the taste receptor proteins. Using new high-throughput sequencing methods [this was Aide’s work on the project], [we] were able to identify genes expressed at very low levels, including the great diversity of taste receptor genes unique to female Heliconius butterflies.

Because, unlike their parents, caterpillars cannot fly away to find a more suitable plant, it is imperative that the female butterflies choose a non-toxic host plant for their eggs. The proteins that are coded for by the taste receptor genes enables the female butterflies to identify non-toxic plants on which to lay their eggs.

It is a long-standing hypothesis that butterflies are so diverse partly because of the complicated co-evolutionary arms race with the plants that their larvae eat – as plants develop new ways to prevent being eaten, butterflies develop new ways to eat plants.

For example, Heliconius butterflies evolved in a way, which allows them to feed on the highly-toxic, cyanide-containing leaves of passion flower vines.

The Heliconius butterflies have not only evolved to overcome the plant’s defences, but can now even synthesise their own cyanide-containing compounds that protect them from predators.”

When I visited BEACON on my way to Cambridge last September this project was just beginning to take shape.  I was inspired by a conversation I had with Danielle Whittaker about BEACON’s public outreach efforts.  This led me to approach a gifted cartoonist, Jay Hosler, to take on the job of translating our discoveries to the public. His gorgeous artwork was published as a supplementary figure to our PLoS Genetics paper and is reproduced below:

“For Bitter or Worse: A Tale of Sexual Dimorphism and Good Taste”, an original cartoon by author and illustrator of science-oriented, Jay S. Hosler.

Heliconius_gustation_FINAL_Page_1

Heliconius_gustation_FINAL_Page_2

Reference: 

Briscoe AD, Macias-Muñoz A, Kozak K, Yuan F, Walters JR, Jamie GA, Martin SH, Dasmahapatra KD, Ferguson LG, Mallet J, Jacquin-Joly E, Jiggins CD. 2013. Female behaviour drives expression and evolution of gustatory receptors in butterflies. PLoS Genetics 9: e1003620. DOI: 10.1371/journal.pgen.1003620

Featured in Scientific American blog Not Bad Science, 24 July 2013

http://blogs.scientificamerican.com/not-bad-science/2013/07/24/how-might-female-butterflies-gain-an-advantage-how-about-having-the-ability-to-taste-through-their-feet/

For more information on Adriana Briscoe’s work, you can contact her at abriscoe at uci dot edu.

About Danielle Whittaker

Danielle J. Whittaker, Ph.D. Managing Director of BEACON
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