Search results for "sex"

Love at first sniff: a spermatophore-associated pheromone mediates partner attraction in a collembolan species

2017

Mate choice is essential in most animals, as a good choice of mating partner largely determines reproductive success. Much evidence shows that olfactory cues play an important role in mate choice. However, the integration of chemical, visual and acoustic cues, often used when both partners meet, makes it hard to test whether olfaction alone can mediate reproductive decisions. Interestingly, several invertebrates have adopted a mating system where males deposit their sperm (packed in spermatophores) in the environment for females to pick up with no visual contact between the sexes. In this case the male cue is conveyed by the spermatophore only. Earlier studies on a species with indirect spe…

Postmating–prezygotic isolation between two allopatric populations of Drosophila montana: fertilisation success differs under sperm competition

2016

This study was funded by the Academy of Finland (grant 250999 to O. A.-H.). Postmating but prezygotic (PMPZ) interactions are increasingly recognized as a potentially important early-stage barrier in the evolution of reproductive isolation. A recent study described a potential example between populations of the same species: single matings between Drosophila montana populations resulted in differential fertilisation success because of the inability of sperm from one population (Vancouver) to penetrate the eggs of the other population (Colorado). As the natural mating system of D. montana is polyandrous (females remate rapidly), we set up double matings of all possible crosses between the sa…

Energy intake functions and energy budgets of ectotherms and endotherms derived from their ontogenetic growth in body mass and timing of sexual matur…

2017

Abstract Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of sexual maturation within life, and energy intake functions. Here, we present a mathematical model applicable to ectothermic and endothermic vertebrates. It is designed to test whether differences in the timing of sexual maturation within an animal's life (age at which sexual maturity is reached vs. longevity) together with its ontogenetic gain in body mass (growth curve) can predict the energy intake throughout the animal's life (food intake curve) and can explain differences in energy partitioning (between growth, repro…

Repeated switches from cooperative to selfish worker oviposition during stingless bee evolution

2018

Reproductive division of labour is a defining feature of insect societies. Stingless bees (Meliponini) are an interesting exception among the highly eusocial insects in that workers of many species contribute significantly to the production of males. Since workers remain sterile in other species of this large tropical tribe, it has been hypothesized that, in the latter species, ancestral queens have won the conflict over who produces the males. The fact that sterile workers of some species lay trophic eggs to feed the queen and display ritualized behaviours towards her during oviposition has been interpreted as an evolutionary relic of this ancient conflict. Here, I used ancestral state est…

2017

Because they can form seasonal mixed-species groups during mating and maternal care, bats are exciting models for studying interspecific hybridization. Myotis myotis and M. blythii are genetically close and morphologically almost identical, but they differ in some aspects of their ecology and life-history traits. When they occur in sympatry, they often form large mixed maternity colonies, in which their relative abundance can vary across time due to a shift in the timing of parturition. For the first time, we used non-invasive genetic methods to assess the hybridization rate and colony composition in a maternity colony of M. myotis and M. blythii located in the French Alps. Bat guano was co…

Strength of sexual and postmating prezygotic barriers varies between sympatric populations with different histories and species abundances.

2019

The impact of different reproductive barriers on species or population isolation may vary in different stages of speciation depending on evolutionary forces acting within species and through species' interactions. Genetic incompatibilities between interacting species are expected to reinforce prezygotic barriers in sympatric populations and lead to cascade reinforcement between conspecific populations living within and outside the areas of sympatry. We tested these predictions and studied whether and how the strength and target of reinforcement between Drosophila montana and Drosophila flavomontana vary between sympatric populations with different histories and species abundances. All barri…

Living in a harsh habitat: epidemiology of the whale louse, Syncyamus aequus (Cyamidae), infecting striped dolphins in the Western Mediterranean

2017

Whale lice (Cyamidae) are ectoparasitic amphipods exclusive to cetaceans. Data on their epidemiology usually come from species infecting baleen whales, which are large, slow-moving hosts. In this study, we provide data on infection parameters, population structure and microhabitat selection in a whale louse exclusive to delphinids, Syncyamus aequus, with the aim of comparing them with those from cyamid species from large whales. A total of 176 striped dolphins Stenella coeruleoalba stranded along the Mediterranean coast of Spain during 1980–2016 were examined. The prevalence of S. aequus was 27.3% (95% CI: 20.9–34.3), and populations were sparse, with a mean number of whale lice per infecte…

Female sexual signaling in a capital breeder, the European glow-worm Lampyris noctiluca

2021

AbstractTheory predicts that because costs constrain female sexual signaling, females are expected to have a low signaling effort that is increased with passing time until mating is secured. This pattern of signaling is expected to result from females balancing the costs associated with a higher than optimal signaling effort and those costs associated with a low signaling effort that increase the likelihood of delayed mating. We tested whether this prediction applies in the common glow-worm Lampyris noctiluca (Coleoptera, Lampyridae), a capital breeding species in which females glow at night to attract males. Contrary to predictions, we found that the duration of female sexual signaling sig…

The “unguarded-X” and the genetic architecture of lifespan: Inbreeding results in a potentially maladaptive sex-specific reduction of female lifespan…

2018

Sex differences in ageing and lifespan are ubiquitous in nature. The "unguarded-X" hypothesis (UXh) suggests they may be partly due to the expression of recessive mutations in the hemizygous sex chromosomes of the heterogametic sex, which could help explain sex-specific ageing in a broad array of taxa. A prediction central to the UX hypothesis is that inbreeding will decrease the lifespan of the homogametic sex more than the heterogametic sex, because only in the former does inbreeding increase the expression of recessive deleterious mutations. In this study, we test this prediction by examining the effects of inbreeding on the lifespan and fitness of male and female Drosophila melanogaster…

2018

Parasitism is considered a major selective force in natural host populations. Infections can decrease host condition and vigour, and potentially influence, for example, host population dynamics and behavior such as mate choice. We studied parasite infections of two common marine fish species, the sand goby (Pomatoschistus minutus) and the common goby (Pomatoschistus microps), in the brackish water Northern Baltic Sea. We were particularly interested in the occurrence of parasite taxa located in central sensory organs, such as eyes, potentially affecting fish behavior and mate choice. We found that both fish species harbored parasite communities dominated by taxa transmitted to fish through …