Convergence, recurrence and diversification of complex sperm traits in diving beetles (Dytiscidae)

Sperm display remarkable morphological diversity among even closely related species, a pattern that is widely attributed to postcopulatory sexual selection. Surprisingly few studies have used phylogenetic analyses to discern the details of evolutionary diversification in ornaments and armaments subject to sexual selection, and the origins of novel sperm traits and their subsequent modification are particularly poorly understood. Here we investigate sperm evolution in diving beetles (Dytiscidae), revealing dramatic diversification in flagellum length, head shape, presence of sperm heteromorphism, and the presence/type of sperm conjugation, an unusual trait where two or more sperm unite for motility or transport. Sperm conjugation was found to be the ancestral condition in diving beetles, with subsequent diversification into three forms, each exhibiting varying degrees of evolutionary loss, convergence, and recurrence. Sperm head shape, but not length or heteromorphism, was found to evolve in a significantly correlated manner with conjugation, consistent with the different mechanisms of head alignment and binding required for the different forms of conjugation. Our study reveals that sperm morphological evolution is channeled along particular evolutionary pathways (i.e., conjugate form), yet subject to considerable diversification within those pathways through modification in sperm length, head shape, and heteromorphism.     

Evolution of helping and harming in heterogeneous populations

There has been much interest in understanding how demographic factors can mediate social evolution in viscous populations. Here, we examine the impact of heterogeneity in patch quality--that is, the availability of reproductive resources for each breeder--upon the evolution of helping and harming behaviors. We find that, owing to a cancellation of relatedness and kin competition effects, the evolution of obligate and facultative helping and harming is not influenced by the degree of viscosity in populations characterized by either spatial or temporal heterogeneity in patch quality. However, facultative helping and harming may be favored when there is both spatial and temporal heterogeneity in patch quality, with helping and harming being favored in both high-quality and low-quality patches. We highlight the prospect for using kin selection theory to explain within-population variation in social behavior, and point to the need for further theoretical and empirical investigation of this topic.     

Microevolution of sympatry: landscape genetics of hedgehogs Erinaceus europaeus and E. roumanicus in Central Europe

We used the mitochondrial control region and nuclear microsatellites to assess the distribution patterns, population structure, demography and landscape genetics for the hedgehogs Erinaceus europaeus and Erinaceus roumanicus in a transect of the mid-European zone of sympatry. E. roumanicus was less frequent and restricted to regions with lower altitudes. Demographic analyses suggested recent population growth in this species. A comparison of patterns in the spatial variability of mitochondrial and nuclear DNA indicated less sex-biased dispersal and higher levels of gene flow in E. roumanicus. No evidence of recent hybridisation or introgression was detected. We interpreted these results by comparing with phylogeographic and palaeontological studies as well as with the occurrence of hybridisation in the Russian contact zone. We propose that Central Europe was colonised by E. roumanicus by the beginning of the Neolithic period and that there was a subsequent reinforcement stage as well as the formation of a zone of sympatry after the complete reproductive isolation of both species.     

Allotetraploid Mimulus sookensis are highly interfertile despite independent origins

Polyploidy (whole‐genome duplication) has contributed significantly to angiosperm evolution and diversification. To date, it has been found that most polyploids are the result of multiple formation events, which may contribute to genetic diversity and affect interfertility among polyploid lineages of independent origin. A recently discovered allotetraploid derivative of Mimulus guttatus and M. nasutus, Mimulus sookensis, is found throughout the valleys of western Oregon and Vancouver Island. Here, we analyse the patterns of nucleotide diversity at three chloroplast and six nuclear loci in M. guttatus, M. nasutus and M. sookensis, to gain insight into the formation of M. sookensis. By analysing the patterns of genetic variation seen in the diploid progenitors in comparison with the variation seen in M. sookensis, we are able to show that M. sookensis has recurrently formed. We also observed that most M. sookensis individuals are fixed heterozygotes at all of the nuclear loci examined, suggesting that duplicate gene loss is not extensive in M. sookensis. To assess the possibility that hybridization among M. sookensis has contributed to genetic diversity, we conducted crossing experiments within M. sookensis. We found that M. sookensis of independent origin are highly interfertile, suggesting that crossing barriers do not exist within M. sookensis, and that hybridization among M. sookensis may result in new recombinant genotypes. Together, the data suggest that although recurrent origins may be common, they can contribute to genetic diversity without contributing to reproductive isolation among independently arisen polyploid lineages.     

Promiscuous mating produces offspring with higher lifetime fitness

In many species, each female pairs with a single male for the purpose of rearing offspring, but may also engage in extra-pair copulations. Despite the prevalence of such promiscuity, whether and how multiple mating benefits females remains an open question. Multiple mating is typically thought to be favoured primarily through indirect benefits (i.e. heritable effects on the fitness of offspring). This prediction has been repeatedly tested in a variety of species, but the evidence has been equivocal, perhaps because such studies have focused on pre-reproductive survival rather than lifetime fitness of offspring. Here, we show that in a songbird, the dark-eyed junco (Junco hyemalis), both male and female offspring produced by extra-pair fertilizations have higher lifetime reproductive success than do offspring sired within the social pair. Furthermore, adult male offspring sired via extra-pair matings are more likely to sire extra-pair offspring (EPO) themselves, suggesting that fitness benefits to males accrue primarily through enhanced mating success. By contrast, female EPO benefited primarily through enhanced fecundity. Our results provide strong support for the hypothesis that the evolution of extra-pair mating by females is favoured by indirect benefits and shows that such benefits accrue much later in the offspring's life than previously documented.     

Variation in annual and lifetime reproductive success of lance-tailed manakins: alpha experience mitigates effects of senescence on siring success

The causes of variation in individual reproductive success over a lifetime are not well understood. In long-lived vertebrates, reproductive output usually increases during early adulthood, but it is difficult to disentangle the roles of development and learning on this gain of reproductive success. Lekking lance-tailed manakins provide an opportunity to separate these processes, as the vast majority of male reproduction occurs after a bird obtains alpha status and maintains a display area in the lek, but the age at which males achieve alpha status varies widely. Using 11 years of longitudinal data on age, social status and genetic siring success, I assessed the factors influencing variation in siring success by individuals over their lifetimes. The data show increases in annual reproductive success with both age and alpha experience. At advanced ages, these gains were offset by senescence in fecundity. Individual ontogeny, rather than compositional change of the population, generated a nonlinear relationship of breeding tenure with lifetime success; age of assuming alpha status was unrelated to tenure as a breeder, or success in the alpha role. Importantly, these findings suggest that social experience can mitigate the negative effects of senescence in older breeders.     

笼养绿尾虹雉繁殖参数的观察与分析

观察并分析了1993 ～2011年四川蜂桶寨国家级自然保护区笼养绿尾虹雉的产卵数、受精率和产卵持续天数等3个繁殖参数.结果发现,笼养绿尾虹雉的雌鸟平均产卵数为3.62枚(n=19),平均产卵天数为41.63 d(n=19),平均受精率为14.13％ (n=19).与北京笼养种群相关数据比较,其产卵数、产卵持续天数没有显著差异(均P ＞0.05),但受精率远低于北京种群(P＜0.05).     

智利小植绥螨密度对朱砂叶螨产卵能力的影响

智利小植绥螨是朱砂叶螨的专性捕食者。本研究在室内,研究了智利小植绥螨密度对朱砂叶螨存活及生殖的影响。智利小植绥螨对朱砂叶螨存活干扰结果表明:干扰后24 h各处理朱砂叶螨的死亡率均显著高于对照,且死亡率随干扰密度增大而提高,10头捕食螨/叶碟处理高达76.67%,为对照处理的14.38倍。但是干扰48 h后对叶螨存活影响不大。对朱砂叶螨产卵干扰结果表明:干扰后各时间段朱砂叶螨单雌产卵量均随智利小植绥螨干扰密度的增加而降低。干扰24 h后,除1头捕食螨/叶碟处理与对照差异不显著外,其他各处理均与对照有显著差异。干扰48 h后,10头捕食螨/叶碟处理的叶螨单头产卵量是2.80粒,仅为对照的28.5%。但是干扰96h后,除10头捕食螨/叶碟处理与对照差异显著外,其余各处理与对照均差异不显著。本研究还分析了干扰对96 h内朱砂叶螨单雌总产卵量影响,处理5头/叶碟和10头/叶碟均显著低于对照,并且10头/叶碟显著低于5头/叶碟;1头/叶碟和3头/叶碟与对照相当,但是均显著高于10头/叶碟。结果显示,智利小植绥螨密度对朱砂叶螨有较强的生殖干扰作用,并且捕食螨密度越大,干扰作用越强,后代增殖潜能越小。     

An airborne sex pheromone in snakes

Most reptile sex pheromones so far described are lipid molecules too large to diffuse through the air; instead, they are detected via direct contact (tongue-flicking) with another animal's body or substrate-deposited trails, using the vomeronasal system. The only non-lipid pheromone reported in snakes involves courtship termination in red-sided gartersnakes (Thamnophis sirtalis parietalis): males that encounter copulatory fluids cease courtship, presumably reflecting the futility of courting an already-mating female. Our field experiments at a communal den in Manitoba show that this pheromone can work via olfaction: courtship is terminated by exposure to airborne scents from mating conspecifics, and does not require direct contact (tongue-flicking). Hence, the sexual behaviour of reptiles can be affected by airborne as well as substrate-bound pheromones.     

Two Kazal-type protease inhibitors from Macrobrachium nipponense and Eriocheir sinensis: comparative analysis of structure and activities

Kazal-type inhibitors (KPIs) play important roles in many biological and physiological processes, such as blood clotting, the immune response and reproduction. In the present study, two male reproductive tract KPIs, termed Man-KPI and Ers-KPI, were identified in Macrobrachium nipponense and Eriocheir sinensis, respectively. The inhibitory activities of recombinant Man-KPI and Ers-KPI against chymotrypsin, elastase, trypsin and thrombin were determined. The results showed that both of them strongly inhibit chymotrypsin and elastase. Kinetic studies were performed to elucidate their inhibition mechanism. Furthermore, individual domains were also expressed to learn further which domain contributes to the inhibitory activities of intact KPIs. Only Man-KPI_domain3 is active in the inhibition of chymotrypsin and elastase. Meanwhile, Ers-KPI_domain2 and 3 are responsible for inhibition of chymotrypsin, and Ers-KPI_domains2, 3 and 4 are responsible for the inhibition of elastase. Meanwhile, the inhibitory activities of these two KPIs toward Macrobrachium rosenbergii, M. nipponense and E. sinensis sperm were compared with that of the Kazal-type peptidase inhibitor (MRPINK) characterized from the M. rosenbergii reproductive tract in a previous study. The results demonstrated that KPIs can completely inhibit the gelatinolytic activities of sperm proteases from their own species, while different levels of cross-inhibition were observed between KPI and proteases from different species. These results may provide new perspective to further clarify the mechanism of KPI-proteases interaction in the male reproductive system.