00721nas a2200181   4500008004100000245012700041210006900168260000800237300001200245490000700257653003800264653001900302653002100321653002000342653001600362100002300378856013800401       1997                        eng d00aAlternative reproductive tactics and male-dimorphism in the horne beetle Onthophagus acuminatus (Coleoptera: Scarabaeidae)0 aAlternative reproductive tactics and maledimorphism in the horne  cAug  a335-3410 v4110aalternative reproductive behavior10ahorned beetles10amale competition10amale dimorphism10aOnthophagus1 aEmlen, Douglas, J.  uhttps://scarabnet.myspecies.info/alternative-reproductive-tactics-and-male-dimorphism-horne-beetle-onthophagus-acuminatus-coleoptera-01741nas 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-scarabaeid00732nas 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-hypothesis01698nas a2200301   4500008004100000245013300041210006900174300001200243490000700255520067200262653001400934653001300948653001600961653001600977653002600993653001301019653001801032653001901050653001001069653002001079653001601099653006201115653002501177653001801202100001501220700002301235856013801258       1998                        eng d00aPatterns of parental provisioning covary with male morphology in a horned beetle (Onthophagus taurus) (Coleoptera: Scarabaeidae)0 aPatterns of parental provisioning covary with male morphology in  a447-4510 v423 aMale dung beetles, Onthophagus taurus, are dimorphic for a secondary sexual trait, head horns. Horned males participate in the production of brood masses while hornless male do not. Here we examine the reproductive performance of females mated with males exhibiting alternative horn morphologies. We found that exposure to males may be costly for females in that it reduced the total number of brood masses produced. However, females paired with horned males produced significantly larger brood masses than females paired with hornless males or females producing broods alone. We discuss the possible selection pressures that may underly horn evolution in this genus.10aAnimalia-10aAnimals-10aArthropoda-10aArthropods-10aColeoptera-: Insecta-10aInsects-10aInvertebrata-10aInvertebrates-10amale-10amale-dimorphism10amorphology-10aOnthophagus-taurus [horned-beetle] (Coleoptera-): female-10aparental-care-patter10aReproduction-1 aHunt, John1 aSimmons, Leigh, W.  uhttps://scarabnet.myspecies.info/patterns-parental-provisioning-covary-male-morphology-horned-beetle-onthophagus-taurus-coleoptera-sc03021nas a2200205   4500008004100000245007100041210006900112300001200181490000700193520235800200653002002558653002302578653003402601653001802635653002102653653000702674100001502681700002302696856009602719       2004                        eng d00aOptimal maternal investment in the dung beetle Onthophagus taurus?0 aOptimal maternal investment in the dung beetle Onthophagus tauru  a302-3120 v553 aOptimal investment theory is based on the assumption that the proximate constraint acting on parental investment is resource based. A trade-off between per offspring investment and total investment seems intuitive. Consequently, a parent’s investment strategy is expected to represent a trade-off between the benefits of investment for current offspring and the costs to future reproduction for parents. In this study, we provide clear evidence that the costs and benefits of maternal provisioning in the dung beetle Onthophagus taurus influence the amount of provisions provided by the mother. Horse dung is typically of a higher nutritional value than cow dung and females were shown to provide 20% less dung to offspring when provisioning with horse dung. By reducing their investment per offspring and exhibiting a clear preference to provision offspring with horse dung, females were able to produce significantly more offspring. Females provisioning with horse dung received greater fitness returns per unit of investment and experienced lower provisioning costs, in terms of the minimum amount of dung required to produce a surviving offspring, than females provisioning with cow dung. Females provisioning in soil of low moisture content were found to have higher tunneling costs than those provi- sioning in soil of high moisture content, while the fitness returns per unit of investment did not differ. We adopted a marginal value theorem (MVT) approach to calculate the theoretical optimal level of investment for each dung type and for each soil moisture. Predicted levels of provision- ing were lower for horse dung than for cow dung and for moist soil than for dry soil. Therefore, the results of this study are in qualitative agreement with MVT predictions and provide empirical support for the proposal that females can adaptively adjust their level of investment in response to resource and/or habitat quality. However, the theoretically predicted optimal investment yielded a poor quantitative fit with our observed levels of investment, with females providing over twice the investment predicted by the MVT approach. We suggest that this difference may reflect either our inability in directly quantifying all the necessary costs and benefits of investment in O. taurus and/or the applicability of the underlying assumptions of MVT.10aHabitat quality10aOnthophagus taurus10aOptimal investment strategies10aParental care10aResource quality10a·1 aHunt, John1 aSimmons, Leigh, W.  uhttps://scarabnet.myspecies.info/optimal-maternal-investment-dung-beetle-onthophagus-taurus02277nas a2200193   4500008004100000245009700041210006900138300001200207490000700219520159100226653001601817653001601833653002301849653002201872653002701894100001901921700002301940856012001963       2008                        eng d00aOptimal investment in sons and daughters when parents do not know the sex of their offspring0 aOptimal investment in sons and daughters when parents do not kno  a607-6150 v623 aOptimal parental i nvestment usually differs depending on the sex of the offspring. However, parents in most organisms cannot discriminate the sex of their young until those young are energetically independent. In a species with physical male–male competition, males are often larger and usually develop sexual ornaments, so male offspring are often more costly to produce. However, Onthophagus dung beetles (Coleoptera; Scarabaeidae) are highly dimorphic in secondary sexual characters, but sexually monomorphic in body size, despite strong male–male competition for mates. We demonstrate that because parents provide all resources required by their offspring before adulthood, O. atripennis exhibits no sexual size dimorphism irrespective of sexual selection pressure favoring sexual dimorphism. By con- structing a graphic model with three fitness curves (for sons, daughters, and expected fitness return for parents), we demonstrate that natural selection favors parents that provide both sons and daughters with the optimal amount of investment for sons, which is far greater than that for daughters. This is because the cost of producing small sons, that are unable to compete for mates, is far greater than the cost of producing daughters that are larger than necessary. This theoretical prediction can explain sexual dimorphism without sexual size dimorphism, widely observed in species with crucial parental care such as dung beetles and leaf- rolling beetles, and may provide an insight into the enigmatic relationship between sexual size dimorphism and sexual dimorphism.10adung beetle10aOnthophagus10aOptimal investment10aSexual dimorphism10aSexual size dimorphism1 aKishi, Shigeki1 aNishida, Takayoshi  uhttps://scarabnet.myspecies.info/optimal-investment-sons-and-daughters-when-parents-do-not-know-sex-their-offspring01935nas a2200217   4500008004100000245015900041210006900200300001000269490000700279520109300286653002201379653002701401653001901428653001701447653002201464100002101486700001901507700003301526700002001559856013801579       2005                        eng d00aSperm competition and evidence of sperm fertilization patterns in the carrion ball-roller Canthon cyanellus cyanellus LeConte (Scarabaeidae: Scarabaeinae)0 aSperm competition and evidence of sperm fertilization patterns i  a38-430 v593 aField observation and laboratory experiments were conducted to investigate sperm competition and pat- terns of sperm fertilization under different experimental conditions in the carrion ball-roller beetle Canthon cyanel- lus cyanellus. Males in nature can mate with females whose spermathecae contains fertile sperm from other males. Sperm precedence was investigated using a visible genetic marker. The progeny of red (homozygous recessive) virgin females mated once with a red male and afterward, once with a green beetle (homozygous dominant) and vice versa, revealed that regardless of its color, the last male to mate fertilized c.a. 50% of the eggs, suggesting strong sperm competition. Males were able to achieve higher levels of pa- ternity (more than 80%) when mated ad libitum with previ- ously mated females, although large amount of variance in paternity does not exclude the possibility of first male sperm precedence or female cryptic choice. These results suggest that repeated mating and sperm replacement are the mech- anisms by which last males achieve sperm precedence.10aCanthon cyanellus10aFertilization patterns10aGenetic marker10aScarabaeidae10aSperm competition1 aFavila, Mario, E1 aNolasco, Janet1 aFlorescano, Ivette, Chamorro1 aEquihua, Miguel  uhttps://scarabnet.myspecies.info/sperm-competition-and-evidence-sperm-fertilization-patterns-carrion-ball-roller-canthon-cyanellus-cy