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-scarabaeidae01957nas a2200193   4500008004100000245007300041210006900114300001200183490000700195520133700202653001401539653001101553653001601564653002101580653002101601100002301622700002201645856009601667       2000                        eng d00aThe development and evolution of exaggerated morphologies in insects0 adevelopment and evolution of exaggerated morphologies in insects  a661-7080 v453 aWe discuss a framework for studying the evolution of morphology in insects, based on the concepts of ‘‘phenotypic plasticity’’ and ‘‘reaction norms.’’ We illustrate this approach with the evolution of some of the most extreme morphologies in insects: exaggerated, sexually selected male ornaments and weapons, and elaborate social insect soldier castes. Most of these traits scale with body size, and these scaling relationships are often nonlinear. We argue that scaling relationships are best viewed as reaction norms, and that the evolution of exaggerated morphological traits results from genetic changes in the slope and/or shape of these scaling relationships. After reviewing literature on sexually selected and caste-specific structures, we suggest two possible routes to the evolution of exaggerated trait dimensions: (a) the evolution of steeper scaling relationship slopes and (b) the evolution of sigmoid or discontinuous scaling relationship shapes. We discuss evolutionary implications of these two routes to exaggeration and suggest why so many of the most exaggerated insect structures scale nonlinearly with body size. Finally, we review literature on insect development to provide a comprehensive picture of how scaling relationships arise and to suggest how they may be modified through evolution.10aallometry10acastes10aPolyphenism10asexual selection10athreshold traits1 aEmlen, Douglas, J.1 aNijhout, Frederik  uhttps://scarabnet.myspecies.info/development-and-evolution-exaggerated-morphologies-insects01966nas 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-selecte00732nas 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-hypothesis02242nas a2200313   4500008004100000245010700041210006900148260001200217300001200229490000700241520132400248653002901572653002501601653001801626653001301644653002001657653002401677653000801701653002401709653001901733653001601752653003801768653001401806653002101820653002101841653001201862100002001874856003401894       2002                        eng d00aSexual selection and condition dependence of courtship display in three species of horned dung beetles0 aSexual selection and condition dependence of courtship display i  cNov-Dec  a791-7990 v133 aSexual selection has traditionally been divided into competition over mates and mate choice. Currently, models of sexual selection predict that sexual traits are expressed in proportion to the condition of their bearer. In horned beetles, male contest competition is well established, but studies on female preferences are scarce. Here I present data on male mating success and condition dependence of courtship rate in three species of horn-dimorphic thing beetles, Onthaphagus taurus, Onthophagus binodis, and Onthophagus australis. I found that in the absence of male contest competition, mating success of O. taurus and O. australis was unrelated to their horn length and body size, whereas in O. binodis horn size had a negative effect but body size had a positive effect on male mating success. Overall, in O. binodis major morph males had greater mating success than minor morph males. In all three species male mating success was affected by courtship rate, and the Courtship rate was condition dependent such that when males were manipulated to be in poor condition they had lower courtship rates than males that were manipulated to be in good condition. My findings provide new insight into the mating systems of horned dung beetles and support an important assumption in indicator models of sexual selection.10aalternative reproductive10acondition dependence10aFEMALE CHOICE10agradient10ahorn dimorphism10ahorned dung beetles10alek10alogistic regression10amating success10aOnthophagus10aonthophagus-acuminatus coleoptera10aSELECTION10asexual selection10astalk-eyed flies10atactics1 aKotiaho, J., S.  u<Go to ISI>://00017950430001102675nas a2200193   4500008004100000245010000041210006900141300000900210490000600219520196900225653003702194653001802231653002602249653001602275653002102291100002202312700002202334856012502356       2006                        eng d00aHorn possession reduces maneuverability in the horn-polyphenic beetle, Onthophagus nigriventris0 aHorn possession reduces maneuverability in the hornpolyphenic be  a1-100 v63 aAlternative male morphologies are common in a wide range of organisms and particularly extreme in horned beetles. Here, large males (majors) commonly develop extravagant weaponry such as horns or enlarged mandibles, whereas small males (minors) develop only rudimentary traits. In some taxa, including the genusOnthophagus, the transition from minors to majors occurs over a very small range of body sizes causing intermediate morphologies to be rare or absent from natural populations. Several studies have shown that majors use horns as weapons during male combat over females and that the possession of horns increases male fighting success, and presumably fitness. However, the advantages of a hornless morphology, if any, have remained elusive. Here the alternative male morphs are examined in the horn-polyphenic beetleOnthophagus nigriventris. In particular, the hypothesis was tested that lack of horns in minors increases their maneuverability inside tunnel systems in which these males sneak matings from major males. Using a simple behavioral assay the effects of horn possession on maneuverability were quantified inside an artificial tunnel. Minors were found to be significantly more mobile compared to majors. No such differences were found in mobility between similarly small and large females, which always lack horns. This suggests that mobility differences observed among male morphs are due to the presence or absence of horns rather than differences in body size. This notion was further supported in a second experiment in which surgical removal of horns significantly improved maneuverability, while subsequent re-attachment of horns reversed this effect. These results suggest that lack of horns increases male maneuverability inside tunnels and may thus be advantageous in the context of the particular social niche inhabited by minor males. The results are discussed in the context of the evolutionary ecology of horn-polyphenic beetles. 10aALTERNATIVE REPRODUCTIVE TACTICS10aHorned beetle10aphenotypic plasticity10aPolyphenism10asexual selection1 aMadewell, Richard1 aMoczek, Armin, P.  uhttps://scarabnet.myspecies.info/horn-possession-reduces-maneuverability-horn-polyphenic-beetle-onthophagus-nigriventris00760nas a2200193   4500008004100000245012800041210006900169300001200238490000700250653001200257653003600269653002200305653001600327653002600343653001600369653002100385100002200406856013800428       1999                        eng d00aFacultative paternal investment in the polyphenic beetle Onthophagus taurus; the role of male morphology and social context0 aFacultative paternal investment in the polyphenic beetle Onthoph  a641-6470 v1010abeetles10afacultative parental investment10ahonest indicators10aOnthophagus10aphenotypic plasticity10aPolyphenism10asexual selection1 aMoczek, Armin, P.  uhttps://scarabnet.myspecies.info/facultative-paternal-investment-polyphenic-beetle-onthophagus-taurus-role-male-morphology-and-social02245nas a2200205   4500008004100000245007900041210006900120300001200189490000700201520158800208653001301796653001101809653001801820653002001838653002101858653001601879100002401895700002201919856009801941       2006                        eng d00aImmunity and the expression of a secondary sexual trait in a horned beetle0 aImmunity and the expression of a secondary sexual trait in a hor  a466-4720 v173 aResource-based trade-offs are known to be important in determining investment in both sexual ornamentation and immunity in insects. Because of the strict resource limitation experienced during metamorphosis, we predict that if insects are trading off ornament size and immunity this should be most apparent immediately after eclosion and that the relationship between sexual ornament size and immunity should change with maturation feeding because of the changing patterns of resource availability during this process. We therefore present an investigation into the relationship between morphology, sex, and two measures of immune response (phenoloxidase [PO] activity and encapsulation ability) in the horned beetle Euoniticellus intermedius, imme- diately after eclosion and after maturation feeding. Both measures increased with maturation, with sex differences in PO activity becoming discernable after maturation feeding. PO activity was positively correlated with horn length in male beetles both on eclosion and after maturation feeding, and encapsulation ability was positively correlated with elytra length. We conclude that resource limitation in the pupating insect does have effects on immunity but that this resource limitation does not translate into a measurable trade-off between horn length and immunity. The correlation between horn length and PO activity may arise because both horn length and PO activity are correlated with the same elements of the animal’s biology that allow some animals both to grow a long horn and to sustain a higher level of PO activity.10aimmunity10ainsect10ametamorphosis10asex differences10asexual selection10atrade-offs.1 aPomfret, Joanne, C.1 aKnell, Robert, J.  uhttps://scarabnet.myspecies.info/immunity-and-expression-secondary-sexual-trait-horned-beetle