摘要: Intrasexual selection occurs in male-male competition over access to females and usually results in the larger male winning. While much research has documented that size matters, little is known about how the larger male wins. Dendroctonus valens is an aggregating monogamous bark beetle in which males have large variation in body size and display intense competition over females. Behavioral observation showed two males fight each other within the gallery by pushing/shoving and stridulated more when two males encountered each other. Experiments using two different-sized males synchronously competing showed that larger males won 95% of contests. Reciprocal displacement experiments using muted and intact males of different or equal size were used to simulate male-male competition. Larger males displaced the smaller resident male in 90% of contests, while smaller males prevailed over larger residents in 6.7% of contests. With both males silenced, larger males displaced smaller males in 80% of contests, while smaller males prevailed in 8% of contests. Further experiments using equal-sized males showed aggressive sound-emitting males displaced muted males in 67% of contests, yet intact males displaced other intact males in only 37.5% of contests. Sound analysis showed sound pressure level is an honest signal of body size and males chose soft sounds over loud aggressive sounds in assays. Therefore, D. valens males have evolved dual behaviors, fighting and aggressive sounds associated with body size, to assess rivals to compete for a partner, gaining insights in male-male competition for this species and for other animals.

摘要: Odorant-binding proteins (OBPs) are crucial in insect's olfactory perception, which participate in the initial step of odorant molecules transporting from the external environment to olfactory receptor neurons. To better understand the roles for OBPs in olfactory perception inCotesia vestalis, a solitary larval endoparasitoid of diamondback moth,Plutella xylostella, we have comprehensively screened the genome ofC. vestalis, and obtained 20 CvesOBPs, including 18 classic OBPs and two minus-C OBPs. Motif-pattern analysis indicates that the motifs ofC. vestalisOBPs are highly conserved in Hymenoptera. The results of tissue expression analysis show that five OBPs (CvesOBP1/11/12/14/16) are highly expressed in male antennae, whereas six other OBP genes (CvesOBP7/8/13/17/18/19) are significantly transcriptionally enriched in female antennae. The results of RNA interference experiments for three most highly expressed OBP genes (CvesOBP17/18/19) in female antennae demonstrate that they are likely involved in parasitic processes of female wasps, as the wasps take a longer time to target the hosts when they are knocked down.

摘要: Iron is essential to life, but surprisingly little is known about how iron is managed in nonvertebrate animals. In mammals, the well-characterizedtransferrinsbind iron and are involved in iron transport or immunity, whereas other members of thetransferrinfamily do not have a role in iron homeostasis. In insects, the functions oftransferrinsare still poorly understood. The goals of this project were to identify thetransferringenes in a diverse set of insect species, resolve the evolutionary relationships among these genes, and predict which of thetransferrinsare likely to have a role in iron homeostasis. Our phylogenetic analysis oftransferrinsfrom 16 orders of insects and two orders of noninsect hexapods demonstrated that there are four orthologous groups of insecttransferrins. Our analysis suggests thattransferrin 2arose prior to the origin of insects, andtransferrins 1,3, and4arose early in insect evolution. Primary sequence analysis of each of the insecttransferrinswas used to predict signal peptides, carboxyl-terminal transmembrane regions, GPI-anchors, and iron binding. Based on this analysis, we suggest thattransferrins 2,3, and4are unlikely to play a major role in iron homeostasis. In contrast, thetransferrin 1orthologs are predicted to be secreted, soluble, iron-binding proteins. We conclude thattransferrin 1orthologs are the most likely to play an important role in iron homeostasis. Interestingly, it appears that the louse, aphid, and thrips lineages have lost thetransferrin 1gene and, thus, have evolved to manage iron withouttransferrins.

摘要: Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature. In particular, niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions. Lizards of the genusPhymaturusare viviparous, mainly herbivorous, and inhabit only rock promontories in the steppe environments of Patagonia and the Andes. Herein, we examine the vulnerability of the southernmostPhymaturusspecies to global warming: the endemicPhymaturus calcogaster, which lives in a mesic environment in eastern Patagonia. We studied body temperatures in the field (T-b), preferred body temperatures in a thermogradient (T-pref), the operative (T-e) and environmental temperatures, and the dependence of running performance on body temperature.P. calcogasterhad a meanT(b)(27.04 degrees C) and a meanT(e)(31.15 degrees C) both lower than their preferred temperature (T-pref= 36.61 degrees C) and the optimal temperature for running performance (T-o= 37.13 degrees C). Lizard activity seems to be restraint during the early afternoon due high environmental temperatures. However, both, the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming (IPCC report in 2018) would not threaten, but indeed enhance locomotor performance in this population.

摘要: While wing form is known to differ between males and females of the genus Culicoides, detailed studies of sexual dimorphism are lacking. In this study, we analyze sex-specific differences in the wing form of 5 species of the subgenus Avaritia, using geometric morphometrics and comparative phylogenetic methods. Our results confirm the existence of marked sexual dimorphism in the wing form of the studied species and reveal for the first time that while there is a shared general pattern of sexual shape dimorphism within the subgenus, sexual size dimorphism, and particular features of sexual shape dimorphism differ among species. Sexual shape dimorphism was found to be poorly associated to size and the evolutionary history of the species. The tight association of sexual shape dimorphism with aspect ratio suggests that the shape of the wing is optimized for the type of flight of each sex, that is, dispersal flight in females versus aerobatic flight in males. Moreover, the fact that interspecific shape differences are greater and more strongly associated to aspect ratio in males than in females might be indicating that in males the selective pressures affecting flight performance characteristics are more heterogeneous and/or stronger than in females among the studied species.