Sexual Selection and Viability in the Wild: the Evolution of Sex Differences

性选择解释了诸如装饰和性竞争行为等性别差异的进化。尽管调查这一过程的重要研究使用了实验室模式生物，但有一些方面只能在野外完全解决。其中包括对性选择的一个核心问题的测试：它是相反的（达尔文1871）还是与生存能力选择方向一致？我们的研究解决了这个问题，以及被认为控制性别差异的因素，通过使用新颖的昆虫交配系统，雌性在竞争雄性有价值的捐赠时进行性选择。在两个系统中，女性拥有“男性般的”装饰物。******我们建议使用正式选择分析和实地实验来衡量野外雌性性状的生存能力和性选择：(a)雌性Rhamphomyia舞蝇在展示装饰物时冒着被蜘蛛捕食的风险，以吸引携带猎物礼物的雄性（雌性唯一的蛋白质来源）；(b)雌性海棘树蟋蟀在移动时，如接近配偶以获取珍贵的礼物分泌物时，受寄生蜂寄生的风险比雄性大。此外，行为观察和实验将验证预测，即雄鱼的选择会导致雌鱼的性选择。系统(c)涉及到许多种类的半蜥蜴（与蟋蟀有关），其中雄性向装饰性的雌性提供“礼物”餐以及精子包。******性选择和生存能力选择将在同一时间框架内通过比较交配成功率和被捕食者的死亡率来估计。对于苍蝇和蟋蟀，我们将使用新开发的微卫星DNA变异来分析新鲜捕获的雌性与幸存者的精子储存，以确定雌性一生的交配频率，从而确定性状的性选择。达尔文的一个预测是，高度装饰、频繁交配的雌性更容易被捕食。为了进行生存能力选择，我们将被捕食的雌性动物的特征与幸存者的特征进行比较。我们还将通过标记和重新捕获来估计雌性的寿命。由于对未经操纵的自然种群的选择分析是相关的，因此将对猎物和幸存者进行抽样，然后使用既定的方法在安装在框架中的网附近释放具有不同特征表达水平的舞蝇雌性。研究系统(c)涉及一种湿地属，半湿地属。除了选择分析之外，由合作者开发的分子系统发育学将允许对性选择和女性装饰品的进化进行比较。一些种类表现出母系照料和一些腹部装饰。在有母亲照顾的物种中，频繁的雌性交配（获得礼物）被假设为在照顾期间促进长时间饥饿的生存。这预示了一种与母性照料有关的装饰品的系统发育关系

Sexual selection explains the evolution of sex differences such as ornamentation and sexually-competitive behaviour. Although important research investigating this process uses lab model organisms, there are some aspects that can only be fully addressed in the wild. These include tests of a central issue about sexual selection: is it opposed (Darwin 1871) or in the same direction as viability selection? Our research addresses this, and the factors thought to control sex differences, by using novel insect mating systems with sexual selection on females in competition for valuable donations from males. In two systems females possess "male-like" ornaments.******We propose to use formal selection analyses and field experiments to measure viability and sexual selection on female traits in the wild using: (a) female Rhamphomyia dance flies that risk predation by spiders when displaying ornaments that attract males bearing prey gifts (the only source of protein for females); (b) Female Oecanthus tree crickets at greater risk than males from wasp parasitoids when moving, as when approaching their mates to obtain valuable gift secretions. Additionally, behavioural observations and experiments will test the prediction that male choice in Oecanthus causes sexual selection on females. System (c) involves many species of Hemiandrus weta (related to crickets) where males deliver to ornamented females `gift' meals along with a sperm package. ******Sexual and viability selection will be estimated in the same time frame by comparing both mating success and mortality from predation. For the flies and crickets, we will analyze sperm stores of fresh-prey females compared to survivors using newly developed microsatellite DNA variation to determine lifetime female mating frequency and thus sexual selection on traits. A Darwinian prediction is that highly-ornamented, frequently mating females run a greater risk of predation. For viability selection we compare traits of our prey females to those of survivors. We will also estimate lifespans of females by marking and recapturing. As selection analyses on unmanipulated natural populations are correlative, sampling of prey and survivors will be followed by field experiments using established methods of releasing dance fly females with differing levels of trait expression near webs mounted in frames. Study system (c) involves a speciose weta genus, Hemiandrus. In addition to selection analyses, a molecular phylogeny developed by collaborators will allow a comparative approach to sexual selection and the evolution of female ornaments. Some species exhibit maternal care and some, abdominal ornamentation. Frequent female mating (gift acquisition) in species with maternal care is hypothesized to promote survival through a long period of starvation while caring. This predicts a phylogenetic association of ornaments with maternal care.**