| | |
| |
| |
Sexual Selection in Fireflies
Fredric V. Vencl and Albert D. Carlson
Keywords: Behavior, firefly, sexual selection, mate competition, Photinus
Male competition in courtships of the firefly Photinus pyralis is intense. Male
size is variable, possibly exhibiting alternative body plans. We examined the outcomes of
courtships to determine the mechanisms of selection that may have led to differences in
male size.
Two distinct selective events occur in mate competition: (1) searching and (2)
scramble competition. Males approach females through the air, then land and approach
over the substrate of leaves or weeds. Although many courtships failed, those without
rivals were shorter and successful males spent less time in the "mate-guarding" position
than when several males were in competition. Winners flashed more often than losers, but
flash dialogs between males and females averaged similar number across rival densities,
indicating that females require some minimal amount of information before mating.
Female
flash preference was examined in choice tests to evaluate female discrimination ability.
Females preferred the earlier and brighter flashes. This suggests that what might appear to
be flash "synchronization" could really be attempts by males to become flash leaders, not
followers. Large males possess correspondingly large lanterns and therefore greater flash
intensity. Not surprisingly females preferred large males in the searching period, while
small males were favored in scrambles. Simulated scrambles showed that small males have
superior locomotor abilities, allowing them to reach the female more rapidly.
Comparison
with a species lacking scrambles, P. macdermotti, with no size differences among males
revealed that selection in P. pyralis is disruptive, targeting traits alternately, and may have
led to the evolution of greater size difference between males with direct male competition.
Both male competition and female choice are important determinants of the outcome of P.
pyralis courtships.
Reference: Vencl, F.V. and A.D. Carlson (1997) Proximate mechanisms of sexual
selection in the firefly Photinus pyralis (Coleoptera: Lampyridae). J.
Insect Behav. 11:191 - 207.
|
Submitted: 19-Jan-99
The contents of this page are the sole responsibility of the person
named below.
| Albert D. Carlson |
| |
|
|
| Dept of Neurobiology & Behavior |
| |
|
phone: 516-632-8661 |
| SUNY at Stony Brook |
| |
|
|
| Stony Brook, New York 11794 USA |
| |
|
|
|
.
| Research forum
| Bioluminescence Info Page.