@article {2098,
	title = {Rapid antagonistic coevolution between primary and secondary sexual characters in horned beetles},
	journal = {Evolution},
	volume = {62},
	number = {9},
	year = {2008},
	month = {sep},
	pages = {2423-2428},
	abstract = {Different structures may compete during development for a shared and limited pool of resources to sustain growth and differ- entiation. The resulting resource allocation trade-offs have the potential to alter both ontogenetic outcomes and evolutionary trajectories. However, little is known about the evolutionary causes and consequences of resource allocation trade-offs in natural populations. Here, we explore the significance of resource allocation trade-offs between primary and secondary sexual traits in shaping early morphological divergences between four recently separated populations of the horned beetle Onthophagus taurus as well as macroevolutionary divergence patterns across 10 Onthophagus species. We show that resource allocation trade-offs leave a strong signature in morphological divergence patterns both within and between species. Furthermore, our results suggest that genital divergence may, under certain circumstances, occur as a byproduct of evolutionary changes in secondary sexual traits. Given the importance of copulatory organ morphology for reproductive isolation our findings begin to raise the possibility that secondary sexual trait evolution may promote speciation as a byproduct. We discuss the implications of our results on the causes and consequences of resource allocation trade-offs in insects. },
	keywords = {Aedeagus, Horned beetle, Onthophagus, resource allocation trade-off, speciation},
	author = {Parzer, Harald F. and Moczek, Armin P.}
}
@article {2109,
	title = {Rapid shape divergences between natural and introduced populations of a horned beetle partly mirror divergences between species},
	journal = {Evolution and Development},
	volume = {10},
	number = {2},
	year = {2008},
	pages = {166-175},
	abstract = {Onthophagus taurus is a polyphenic beetle in which males express alternative major (horned) and minor (hornless) morphologies largely dependent on larval nutrition. O. taurus was originally limited to a Turanic--European-- Mediterranean distribution, but became introduced to several exotic regions in the late 1960s. Using geometric morphometrics, we investigate the present-day morphological shape differentiation patterns among native (Italian) and introduced (Western Australian and Eastern US) popu- lations. We then contrast these divergences to those observed between native O. taurus and its sympatric sister species O. illyricus. Our analysis failed to find significant divergences between O. taurus populations in external morphological traits (head, pronotum) when analyses were conducted separately for each sex. However, when sexes and male morphs were analyzed together, three important differences among populations emerged. First, relative warp analyses showed that native and introduced populations diverged in certain shape components that normally distin- guish major and minor male morphs. Second, comparison of covariation of body regions (head vs. pronotum) in the three populations showed that populations diverged in the nature of this covariation, suggesting that different body regions are not totally constrained to evolve in concert. Lastly, and most importantly, the analysis of genitalic shape revealed little to no divergence of female genitalia, but unexpected substantial differentiation of male genitalia among the three O. taurus populations. This suggests that genitalic shape divergence can occur extremely rapidly even in the absence of sympatry and possible reinforcement, and that the genitalia of males and females may diverge independent of one another, at least during the early stage of interpopulational divergence. Interpopulation divergences in O. taurus mirrored aspects of interspecific divergences between O. taurus and O. illyricus in some cases but not others. },
	author = {Pizzo, A. and Roggero, A. and Palestrini, Claudia and Moczek, Armin P. and Rolando, Antonio}
}
