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Congratulations all the speakers and exhibitors at the recent Edmonton,
Canada, Biology of Butterflies meeting. For more details see Chris
Jiggins' blog:<br>
<a href="http://www.heliconius.org/2010/butterflies-on-the-prairies/">
http://www.heliconius.org/2010/butterflies-on-the-prairies/</a> <br><br>
I think we'd all agree that the Heliconius talks at Edmonton about
genomics and colour pattern genetics were exciting and interesting.
Jiggins also discusses new findings on butterfly scent, including
Catalina Estrada's work on anti-aphrodisiacs in Heliconius.<br><br>
However, there's other interesting ecology and behavioural work going on
that was not so well represented. I especially liked these three
papers (detailed below) just out on Heliconius charithonia pupal mating
and mating behaviour. I found Catalina Estrada's first paper
especially interesting, as it showed how males search for larvae on the
host plant, and identify them by odour, and also by means of odour of
damaged host plant. <br><br>
The authors are fully aware of the implications that males (as well as
females) searching for host plants; this creates a pleiotropy of a host
shift that can aid speciation via assortative mating as a "magic
trait," and they discuss it extensively.<br><br>
Larry Gilbert and I have both seen male Heliconius melpomene patrolling
only near their host plants in Corcovado National Park, Costa Rica (where
melpomene hosts and the butterfly itself are both rather rare), so the
pleiotropic male host-searching behaviour is probably not limited to the
pupal mating clade of Heliconius. Such effects in non-pupal maters,
however, await appropriate demonstration and experiments of the quality
performed by Estrada and Gilbert, as well as Mendoza and Macías, in these
studies on Heliconius charithonia.<br><br>
Jim Mallet<br><br>
Estrada, C., and L. E. Gilbert. 2010. Host plants and immatures as
mate-searching cues in Heliconius butterflies. Animal Behaviour
80:231-239.<br>
email: catalinaestra72@hotmail.com, lgilbert@mail.utexas.edu<br>
The study of interactions between phytophagous insects and their host
plants extends beyond understanding how insects deal with plant chemical
defences. Sexual behaviour of these herbivores is integrated in several
ways with host plants, as the latter influence timing and location of
reproduction, and can provide clues for finding mates. Nevertheless,
while numerous studies link butterfly evolution to host plant
adaptations, the influence of plants on butterfly sexual behaviour has
been little studied. We conducted experiments to determine the role of
host plant cues in mate-searching behaviour of Heliconius charithonia
butterflies. This species exhibits precopulatory mate guarding behaviour,
wherein males find and perch on pupae, then copulate with eclosing
females ('pupal mating'). We found that males (1) visited plants damaged
by feeding larvae more often than they visited undamaged plants and (2)
displayed searching behaviour around the plant and in front of larvae,
suggesting that odours signal the location of potential partners (pupae).
Although males were attracted to common plant odours released after
tissue damage, plants damaged by heterospecific butterfly larvae were
less attractive, indicating that species recognition can occur at early
life stages. Overall, our results suggest that host plants influence
mate-searching behaviour of Heliconius. This might also be true for other
species of butterflies with more conventional mating strategies,
potentially contributing to the diversification of this group of
phytophagous insects.<br><br>
Mendoza-Cuenca, L., and R. Macías-Ordóñez. 2010. Female asynchrony may
drive disruptive sexual selection on male mating phenotypes in a
Heliconius butterfly. Behavioral Ecology 21:144-152.<br>
email: lmendoza@lca.unam.mx<br>
Alternative male phenotypes may be a source of novel adaptive traits and
may evolve under strong sexual selection. We studied interpopulation
differences in male mating behavior related to receptive female synchrony
in the monandrous pupal-mating butterfly Heliconius charitonia. In the
population in which female-receptive pupae were more synchronous, larger
males were unable to monopolize mates; variance in male mating success
was lower; strength of sexual selection was weak; and all males competed
for access to female pupae using the same strategy (pupal mating). In the
population where no more than one female was receptive at a time (extreme
asynchrony), only large males competed for pupae, and among these, only
the largest individuals successfully mated. Thus, variance in mating
success was higher, and sexual selection within pupal maters was
stronger. In this population, smaller males patrolled large areas as an
alternative mating behavior. When unmated females were experimentally
released, small male size was associated with higher mating success. We
suggest that alternative patrolling behavior may have evolved under
strong sexual selection as a consequence of high asynchrony in receptive
female availability in some populations.<br><br>
Estrada, C., S. Yildizhan, S. Schulz, and L. E. Gilbert. 2010.
Sex-specific chemical cues from immatures facilitate the evolution of
mate guarding in Heliconius butterflies. Proceedings of the Royal Society
B-Biological Sciences 277:407-413.<br>
email: catalinaestra72@hotmail.com, lgilbert@mail.utexas.edu<br>
Competition for mates has substantial effects on sensory systems and
often leads to the evolution of extraordinary mating behaviours in
nature. The ability of males to find sexually immature females and
associate with them until mating is a remarkable example. Although
several aspects of such pre-copulatory mate guarding have been
investigated, little is known about the mechanisms used by males to
locate immature females and assess their maturity. These are not only key
components of the origin and maintenance of this mating strategy, but are
also necessary for inferring the level to which females cooperate and
thus the incidence of sexual conflict. We investigated the cues involved
in recognition of immature females in Heliconius charithonia, a butterfly
that exhibits mate guarding by perching on pupae. We found that males
recognized female pupae using sex-specific volatile monoterpenes produced
by them towards the end of pupal development. Considering the presumed
biosynthetic pathways of such compounds and the reproductive biology of
Heliconius, we propose that these monoterpenes are coevolved signals and
not just sex-specific cues exploited by males. Their maintenance, despite
lack of female mate choice, may be explained by variation in cost that
females pay with this male behaviour under heterogeneous ecological
conditions.<br>
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<font face="Arial, Helvetica">________________________________<br><br>
James Mallet<br>
UCL<br>
<a href="http://www.ucl.ac.uk/taxome/jim" eudora="autourl">
www.ucl.ac.uk/taxome/jim</a></font> </body>
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