02304nas a2200277   4500008004100000020001400041245015800055210006900213260000800282300001000290490000700300520147100307653003701778653001401815653001501829653001801844653001701862653001101879653002001890653002301910653001401933653001101947653001501958100001801973856003501991       2006                        eng d  a0010-065X00aPhylogenetic evidence for an association between tunneling behavior and the evolution of horns in dung beetles (Coleoptera : Scarabaeidae : Scarabaeinae)0 aPhylogenetic evidence for an association between tunneling behav  cDec  a47-560 v603 aDung beetles employ numerous behavioral strategies to sequester dung away from other insects, and these have been broadly grouped into two categories: species that dig tunnels beneath the dung (tunnelers) and species that roll dung on the surface of the soil (rollers). Many species also are armed with rigid exoskeletal outgrowths called horns. Horns function as weapons, and horn sizes can be extreme. One widespread pattern within dung beetles is that tunneling species often have horns, whereas rolling species almost always do not, suggesting that residing (and fighting) inside tunnels at the dung deposition site may be an important ecological prerequisite for the evolution of horns in dung beetles. Here, we test explicitly for an historical association between tunneling behavior and the evolution of horns using a recent phylogeny for the scarabaeine dung beetles. We show that all eight of the independent gains of horns included in our analyses occurred on branches of the phylogeny reconstructed as tunneling, and that one of the three evolutionary losses of horns occurred on a branch that had lost tunneling behavior. We interpret this as evidence for a biologically meaningful association between tunneling behavior and the evolution of enlarged or exaggerated weapons such as horns, supporting the ideas of Eberhard and others that beetle horns may be most "beneficial" when used within the confines of restricted spaces such as burrows or tunnels.10aALTERNATIVE REPRODUCTIVE TACTICS10abody-size10aDIMORPHISM10aFEMALE CHOICE10aFIDDLER-CRAB10aFIGHTS10aFOOD RELOCATION10aonthophagus-taurus10aSELECTION10aSEXUAL10aTRADE-OFFS1 aEmlen, D., J.  u<Go to ISI>://000243611100005 00318nas a2200109   4500008004100000245003600041210003200077300001200109490000700121100001800128856006200146       2008                        eng d00aThe Evolution of Animal Weapons0 aEvolution of Animal Weapons  a387-4130 v391 aEmlen, D., J.  uhttps://scarabnet.myspecies.info/evolution-animal-weapons03111nas a2200313   4500008004100000245011200041210006900153300001000222490000700232520208700239653001502326653001402341653001302355653001602368653001602384653001402400653002602414653002902440653002002469653001302489653001802502653001902520653000802539653005802547653002302605100001902628700001802647856013202665       1999                        eng d00aProximate determination of male horn dimorphism in the beetle Onthophagus taurus (Coleoptera: Scarabaeidae)0 aProximate determination of male horn dimorphism in the beetle On  a27-370 v123 aThe existence of discrete phenotypic variation within one sex poses interesting questions regarding how such intrasexual polymorphisms are produced and modified during the course of evolution. Approaching these kinds of questions requires insights into the genetic architecture underlying a polymorphism and an understanding of the proximate mechanisms determining phenotype expression. Here we explore the genetic underpinnings and proximate factors influencing the expression of beetle horns - a dramatic sexually selected trait exhibiting intramale dimorphism in many species. Two relatively discrete male morphs are present in natural populations of the dung beetle Onthophagus taurus (Scarabaeidae, Onthophagini). Males exceeding a critical body size develop a pair of long, curved horns on their heads, while those smaller than this critical body size remain essentially hornless. We present results from laboratory breeding experiments designed to assess the relative importance of inherited and environmental factors as determinants of male morphology. Using father-son regressions, our findings demonstrate that horn length and body size of male progeny are not predicted from paternal morphology. instead, natural variation in an environmental factor, the amount of food available to larvae, determined both the body sizes exhibited by males as adults and the presence or absence of horns. The nonlinear scaling relationship between the body size and horn length of males bred in the laboratory did not differ from the pattern of variation present in natural populations, suggesting that nutritional conditions account for variation in male morphology in natural populations as well. We discuss our results by extending ideas proposed to explain the evolution of conditional expression of alternative phenotypes in physically heterogeneous environments toward incorporating facultative expression of secondary sexual traits. We use this synthesis to begin characterizing the potential origin and subsequent evolution of facultative horn expression in onthophagine beetles.10aallometry-10aAnimalia-10aAnimals-10aArthropoda-10aArthropods-10abody-size10aColeoptera-: Insecta-10aEvolution-and-Adaptation10ahorn-dimorphism10aInsects-10aInvertebrata-10aInvertebrates-10amor10aOnthophagus-taurus [dung-beetle] (Coleoptera-): male-10aPopulation-Studies1 aMoczek, A., P.1 aEmlen, D., J.  uhttps://scarabnet.myspecies.info/proximate-determination-male-horn-dimorphism-beetle-onthophagus-taurus-coleoptera-scarabaeidae