Negative frequency-dependent selection should result in equal sex ratios in large populations of dioecious flowering plants, but deviations from equality are commonly reported. A variety of ecological and genetic factors can explain biased sex ratios, although the mechanisms involved are not well understood. Most dioecious species are long-lived and/or clonal complicating efforts to identify st...

Efforts to develop formulas for contrasting genetic interests of workers and queens in social Hymenoptera are complicated by many factors, including multiple matings by queens, oviposition by unmated females, and mating rivalry among genetic relatives (Hamilton's "local mate competition"). Because of haplodiploid sex determination in Hymenoptera, when such influences are absent, queens benefit ...

There is good evidence that paternal (and maternal) hormone levels at the time of conception are associated with offspring sex ratios (proportions male) at birth. The mechanisms underlying this association (pre- or postzygotic) are not of primary relevance here. When people are exposed to endocrine-disrupting agents, these agents may have different hormonal effects on men and women. So, if endo...

In fig wasps, mating takes place among the offspring of one or a few foundress mothers inside the fig from which mated females disperse to found new broods. Under these conditions, related males will compete with each other for mating and several studies have shown female bias in brood sex ratios as a response to Local Mate Competition (LMC). Studying Pegoscapus tonduzi which pollinates Ficus c...

Adult sex ratio (ASR) exhibits immense variation in nature, although neither the causes nor the implications of this variation are fully understood. According to theory, the ASR is expected to influence sex roles and breeding systems, as the rarer sex in the population has more potential partners to mate with than the more common sex. Changes in mate choice, mating systems and parental care sug...

Fritzsche, K. 2015. Sexual selection and the evolution of sex-role reversal in honeylocust beetles. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1240. 46 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9209-0. Sexual selection is the prime evolutionary force that makes males and females different. This process has long been vie...

Spotted lanternflies (SLF) Lycorma delicatula are economically important invasive planthoppers discovered in North America 2014. SLF gregarious, but how they locate each other, or who finds whom and when, is poorly understood. Here we describe adult behavior phenology on their preferred host, Ailanthus altissima , under field conditions, the context of both aggregation mate-location, since demo...

The costs and benefits of polyandry are central to understanding the near-ubiquity of female multiple mating. Here, we present evidence of a novel cost of polyandry: disrupted sex allocation. In Nasonia vitripennis, a species that is monandrous in the wild but engages in polyandry under laboratory culture conditions, sexual harassment during oviposition results in increased production of sons u...

Selection on males to mate at a higher rate than females often results in male harassment of females and counteracting female responses. When the reproductive value of copulation changes over time, these mating strategies are expected to be time dependent. Here, we demonstrate that variation in the intensity of male harassment leads to drastic changes in female daily mating patterns. In feral p...