@article {1567,
	title = {Diversity in the weapons of sexual selection: horn evolution in the beetle genus Onthophagus (Coleoptera: Scarabaeidae)},
	journal = {Evolution},
	volume = {59},
	number = {5},
	year = {2005},
	month = {Jan},
	pages = {1060-1084},
	abstract = {Both ornaments and weapons of sexual selection frequently exhibit prolific interspecific diversity of form. Yet, most studies of this diversity have focused on ornaments involved with female mate choice, rather than on the weapons of male competition. With few exceptions, the mechanisms of divergence in weapon morphology remain largely unexplored. Here, we characterize the evolutionary radiation of one type of weapon: beetle horns. We use partial sequences from four nuclear and three mitochondrial genes to develop a phylogenetic hypothesis for a worldwide sample of 48 species from the dung beetle genus Onthophagus (Coleoptera: Scarabaeidae). We then use these data to test for multiple evolutionary origins of horns and to characterize the evolutionary radiation of horns. Although our limited sampling of one of the world{\textquoteright}s most species-rich genera almost certainly underestimates the number of evolutionary events, our phylogeny reveals prolific evolutionary lability of these exaggerated sexually selected weapons (more than 25 separate gains and losses of five different horn types). We discuss these results in the context of the natural history of these beetles and explore ways that sexual selection and ecology may have interacted to generate this extraordinary diversity of weapon morphology. },
	keywords = {Adaptive radiation, beetle horns, character divergence, male competition, Onthophagus, phylogeny, sexual selection, weapons.},
	author = {Emlen, Douglas J. and Marangelo, Jennifer and Ball, Bernard and Cunningham, Clifford}
}
@article {1817,
	title = {Maternal and paternal effects on offspring phenotype in the dung beetle Onthophagus taurus},
	journal = {Evolution},
	volume = {54},
	number = {3},
	year = {2000},
	note = {Using Smart Source ParsingArticleEnglish},
	pages = {936-941},
	abstract = {Parents often have important influences on the development of traits in their offspring. One mechanism by which parents are able to influence offspring phenotype is through the level of care they provide. In onthophagine dung beetles, parents typically provision their offspring by packing dung fragments into a brood mass. Onthophagus taurus males can be separated into two discrete morphs: Large, "major" males have head horns, whereas "minor" males are hornless. Here we show that a switch in parental provisioning strategies adopted by males coincides with the switch in male morphology. Male provisioning results in the production of heavier brood masses than females will produce alone. However, unlike females in which the level of provisioning increases with body size in a continuous manner, the level of provisioning provided by males represents an "all-or-none" tactic with all major males providing a fixed level of provisioning irrespective of their body size. Offspring size is determined largely by the quantity of dung provided to the developing larvae so that paternal and maternal provisioning affects the body size and horn size of offspring produced. The levels of provisioning by individual parents are significantly repeatable, suggesting paternal and maternal effects as candidate indirect genetic effects in the evolution of horn size in the genus Onthophagus.},
	keywords = {Animalia-, Animals-, Arthropoda-, Arthropods-, Behavior-, body-size, brood-mass, Coleoptera-: Insecta-, Evolution-and-Adaptation, horn-: size-, Insects-, Invertebrata-, Invertebrates-, male-, male-p, Onthophagus-taurus [dung-beetle] (Coleoptera-): female-},
	author = {Hunt, J. and Simmons, L. W.}
}
@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.}
}
