02222nas a2200265   4500008004100000245012400041210006900165260000800234300001400242490000700256520131700263653002301580653001701603653002501620653002101645653001601666653001401682653002101696653001301717100002301730700002401753700001801777700002501795856013601820       2005                        eng d00aDiversity in the weapons of sexual selection: horn evolution in the beetle genus Onthophagus (Coleoptera: Scarabaeidae)0 aDiversity in the weapons of sexual selection horn evolution in t  cJan  a1060-10840 v593 aBoth 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’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. 10aAdaptive radiation10abeetle horns10acharacter divergence10amale competition10aOnthophagus10aphylogeny10asexual selection10aweapons.1 aEmlen, Douglas, J.1 aMarangelo, Jennifer1 aBall, Bernard1 aCunningham, Clifford  uhttps://scarabnet.myspecies.info/diversity-weapons-sexual-selection-horn-evolution-beetle-genus-onthophagus-coleoptera-scarabaeidae00732nas a2200193   4500008004100000245011900041210006900160260000800229300001200237490000700249653001700256653002600273653002200299653002300321653002100344100001500365700002300380856013500403       1997                        eng d00aPatterns of fluctuating asymmetry in beetle horns: an experimental examination of the honest signalling hypothesis0 aPatterns of fluctuating asymmetry in beetle horns an experimenta  cmay  a109-1140 v4110abeetle horns10afluctuating asymmetry10ahonest signalling10aOnthophagus taurus10asexual selection1 aHunt, John1 aSimmons, Leigh, W.  uhttps://scarabnet.myspecies.info/patterns-fluctuating-asymmetry-beetle-horns-experimental-examination-honest-signalling-hypothesis02565nas a2200217   4500008004100000245009600041210006900137300001200206490000800218520181500226653001702041653002502058653001402083653001802097653002102115653001602136653003402152100002202186700002202208856011702230       2004                        eng d00aTrade-offs during the development of primary and secondary sexual traits in a horned beetle0 aTradeoffs during the development of primary and secondary sexual  a184-1910 v1633 a Resource allocation trade-offs during development affect the final sizes of adult structures and have the potential to constrain the types and magnitude of evolutionary change that developmental processes can accommodate. Such trade-offs can arise when two or more body parts compete for a limited pool of resources to sustain their growth and differentiation. Recent studies on several holo- metabolous insects suggest that resource allocation trade-offs may be most pronounced in tissues that grow physically close to each other. Here we examine the nature and magnitude of developmental trade-offs between two very distant body parts: head horns and geni- talia of males of the horned scarab beetle Onthophagus taurus. Both structures develop from imaginal disklike tissues that undergo ex- plosive growth during late larval development but differ in exactly when they initiate their growth. We experimentally ablated the pre- cursor cells that normally give rise to male genitalia at several time points during late larval development and examined the degree of horn development in these males compared to that of untreated and sham-operated control males. We found that experimental males developed disproportionately larger horns. Horn overexpression was weakest in response to early ablation and most pronounced in males whose genital disks were ablated just before larvae entered the pre- pupal stage. Our results suggest that even distant body parts may rely on a common resource pool to sustain their growth and that the relative timing of growth may play an important role in deter- mining whether, and how severely, growing organs will affect each other during development. We use our findings to discuss the phys- iological causes and evolutionary consequences of resource allocation trade-offs. 10abeetle horns10adevelopmental timing10agenitalia10aimaginal disk10aJuvenile hormone10aOnthophagus10aresource allocation trade-off1 aMoczek, Armin, P.1 aNijhout, Frederik  uhttps://scarabnet.myspecies.info/trade-offs-during-development-primary-and-secondary-sexual-traits-horned-beetle