Evolution of male dimorphic allometry in a population of the Japanese horned beetle <Emphasis Type="Italic">Trypoxylus dichotomus septentrionalis</Emphasis> |
| |
Authors: | Yoshihito Hongo |
| |
Institution: | (1) Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan |
| |
Abstract: | I conducted a detailed morphological analysis of the Japanese horned beetle Trypoxylus dichotomus septentrionalis to clarify the allometric relationship between horn length and body size and examined its mating success and reproductive
behaviour in the field. The relationship between horn and body size was not discontinuous at the switch point body size, but
the slope of the linear relationship changed at the switch point. Shape of the allometric relationship was initially steep
and became flatten around the switch point in both linear and log scales; that is, minor males showed a positive relationship
and major males showed a negative one. Major males gained more mating success than minor males. Within major males, individuals
with larger horn or body size had higher mating success than individuals with smaller ones. Within minor males there were
no differences in horn and body size between mated and unmated individuals. Although sneak-like behaviours were exhibited
by both morphs, it is likely that these behaviours rarely lead to direct benefit. These results suggest that dimorphic allometry
of T. dichotomus is consistent with the hypothesis of a continuous reaction norm that meets a ceiling, which restrains further allometric
growth. |
| |
Keywords: | Male dimorphism Alternative reproductive behaviour Allometry Horned beetles |
本文献已被 SpringerLink 等数据库收录! |
|