01966nas a2200193   4500008004100000245013500041210006900176300001200245490000800257520123000265653001901495653001601514653001401530653002101544653002201565100002401587700002301611856013801634       2003                        eng d00aGenital morphology and fertilization success in the dung beetle Onthophagus taurus: an example of sexually selected male genitalia0 aGenital morphology and fertilization success in the dung beetle   a447-4550 v2703 aIn animals with internal fertilization and promiscuous mating, male genitalia show rapid and divergent evolution. Three hypotheses have been suggested to explain the evolutionary processes responsible for genital evolution: the lock-and-key hypothesis, the pleiotropy hypothesis and the sexual-selection hypoth- esis. Here, we determine whether variation in male genital morphology influences fertilization success in the dung beetle Onthophagus taurus, as predicted by the sexual-selection hypothesis. Variation in four out of five genital sclerites of the endophallus influenced a male’s fertilization success, supporting the general hypothesis that male genitalia can evolve under sexual selection. Furthermore, different genital sclerites were found to enhance first versus second male paternity, indicating that different sclerites serve offensive and defensive roles. Genital-trait variability was comparable to that in other species but was less variable than a non-genital sexually selected trait (head horns). We suggest that directional selection for genital elaboration may be countered by natural selection, which should favour genitalia of a size and shape necessary for efficient coupling and sperm transfer. 10amale genitalia10aOnthophagus10apaternity10asexual selection10aSperm competition1 aHouse, Clarissa, M.1 aSimmons, Leigh, W.  uhttps://scarabnet.myspecies.info/genital-morphology-and-fertilization-success-dung-beetle-onthophagus-taurus-example-sexually-selecte01741nas a2200193   4500008004100000245011700041210006900158300001200227490000700239520101400246653001901260653001901279653001901298653002301317653002201340100002401362700002301386856013801409       2006                        eng d00aOffensive and defensive sperm competition roles in the dung beetle Onthophagus taurus (Coleoptera: Scarabaeidea)0 aOffensive and defensive sperm competition roles in the dung beet  a131-1360 v603 aSperm competition is predicted to generate op- posing selection pressures on males. On one hand, selec- tion should favour ‘defensive’ adaptations that protect a male’s ejaculate from displacement, while, on the other hand, selection should favour ‘offensive’ adaptations that overcome paternity assurance mechanisms of rivals. Here, we use the sterile male technique to assess sperm pre- cedence when a male dung beetle Onthophagus taurus mates in both a defensive (first male) and an offensive (second male) role. Significant variation in a male’s sperm precedence (both P1 and P2) was detected, and an individual’s defensive (P1) and offensive (P2) abilities were positively correlated. Thus, it appears that sexual selection simultaneously selects for ‘defensive’ and ‘of- fensive’ adaptations in O. taurus. We discuss a variety of male traits in O. taurus that potentially contribute to a male’s ability to be successful whenmatinginan‘of-fensive’ and a ‘defensive’ role. 10aDefensive role10amale genitalia10aOffensive role10aOnthophagus taurus10aSperm competition1 aHouse, Clarissa, M.1 aSimmons, Leigh, W.  uhttps://scarabnet.myspecies.info/offensive-and-defensive-sperm-competition-roles-dung-beetle-onthophagus-taurus-coleoptera-scarabaeid02702nas a2200253   4500008004100000245017000041210006900211300001000280490000700290520175800297653001402055653002902069653004702098653002402145653001902169653002202188653000802210100001402218700001702232700002402249700001602273700002102289856013802310       2006                        eng d00aMale differentiation patterns in two polyphenic sister species of the genus Onthophagus Latreille, 1802 (Coleoptera: Scarabaeidae): a geometric morphometric approach0 aMale differentiation patterns in two polyphenic sister species o  a54-620 v443 aThis paper focuses on morphological (both shape and size) differences that quite similar polyphenic sister species evolve during divergence processes. Traits were analysed using a geometrical morphometric approach, which has the ability to evidence also very subtle differences in shape. As a case study, we considered males of the dung beetle sister species pair Onthophagus taurus and Onthophagus illyricus (Coleoptera, Scarabaeidae); these species represent a typical example of polyphenic trait expression concerning the facultative development of horns and considerable body size differences. External shape morphology failed to discriminate O. taurus from O. illyricus, whereas the reproductive system shape showed significant interspecific discrimination power. However, the head of O. taurus was significantly larger than that of O. illyricus and the reverse was true for the elytra. The two species also showed different allometric values of the head with respect to body size. This complex pattern of interspecific morphological divergence is discussed in the light of the differential trait divergence rate hypothesis. In both species, differences between major and minor forms concern the overall shape of head and pronotum: we suggest that such different forms, which likely reflect morphological readjustment to accommodate horns of considerable bulk and disproportionate length, may be nevertheless advantageously used by the two male morphs in their alternative reproductive tactics. Male genitalia sizes were virtually constant with respect to body size; however, the ratio between phallotheca and body size was significantly higher in minor males, in keeping with the hypothesis of a higher investment in genitalia borne by this morph.10aallometry10adevelopmental investment10adifferentiation between species and morphs10aexternal morphology10amale genitalia10aSperm competition10a–1 aPizzo, A.1 aMercurio, D.1 aPalestrini, Claudia1 aRoggero, A.1 aRolando, Antonio  uhttps://scarabnet.myspecies.info/male-differentiation-patterns-two-polyphenic-sister-species-genus-onthophagus-latreille-1802-coleopt