Data from: Age, experience and sex – do female bulb mites prefer young mating partners?

In species where advancing sire age is associated with decreased progeny fitness, female resistance to mating with old partners can be expected to evolve. In polyandrous species, such resistance may be contingent on female mating experience: virgins should be relatively indiscriminate to ensure egg fertility, whereas non-virgins can be expected to base their re-mating decisions on the age of their previous versus potential new partners, and ‘trade up’ if previously mated with old males. Here, we tested these predictions using a promiscuous and relatively long-living bulb mite (Rhizoglyphus robini), in which old sire age is associated with decreased fecundity of daughters. In a fully factorial design, we applied two male treatments: young and old, and three female treatments: virgin, previously mated to an old male and previously mated to a young male. Consistent with earlier studies, we observed a reduced mating success of old males. However, we found no support for attributing this result to female discrimination, as female behaviour in response to male mounting attempts was not affected by the age of the suitor, or by its interaction with the age of the female’s previous mate. Interestingly, females were passive during 93% of male mounting attempts observed, suggesting that once they are located by a male, they exert little control over copulation. Old males had lower mate searching activity and were less efficient in obtaining matings (lower success rate per mounting attempt), suggesting a decreased mate securing ability due to aging. Overall, our results suggest that in bulb mites, male ability to secure mates declines with age, whereas they do not support the prediction that females actively discriminate against old partners

Data from: Mating system affects population performance and extinction risk under environmental challenge

Failure of organisms to adapt to sudden environmental changes may lead to extinction. Mating system, by affecting fertility and the strength of sexual selection, may have a major impact on a population’s chances to adapt and survive. Here, we use experimental evolution in bulb mites (Rhizoglyphus robini) to examine the effects of mating system on population performance under environmental change. We demonstrate that populations in which monogamy was enforced suffered a dramatic fitness decline when evolving at an increased temperature, whereas the negative effects of change in thermal environment were alleviated in polygamous populations. Strikingly, within 17 generations, all monogamous populations experiencing higher temperature went extinct, whereas all polygamous populations survived. Our results show that mating systems may have dramatic effects on the risk of extinction under environmental change

Male age and female preferences in bulb mite

Male age and female preferences in bulb mit

plesnar_et_al_2012_data

Data from fecundity, fertility and trans-generation effects assays on the experimental evolution lines of R. robin

Evolution of fertilization ability in obligatorily outcrossing populations of Caenorhabditis elegans

In species reproducing by selfing, the traits connected with outcrossing typically undergo degeneration, a phenomenon called selfing syndrome. In Caenorhabditis elegans nematodes, selfing syndrome affects many traits involved in mating, rendering cross-fertilization highly inefficient. In this study, we investigated the evolution of cross-fertilization efficiency in populations genetically modified to reproduce by obligatory outcrossing. Following the genetic modification, replicate obligatorily outcrossing were maintained for over 100 generations, at either optimal (20 °C) or elevated (24 °C) temperatures, as a part of a broader experimental evolution program. Subsequently, fertilization rates were assayed in the evolving populations, as well as their ancestors who had the obligatory outcrossing introduced but did not go through experimental evolution. Fertilization effectivity was measured by tracking the fractions of fertilized females in age-synchronized populations, through 8 h since reaching adulthood. In order to check the robustness of our measurements, each evolving population was assayed in two or three independent replicate blocks. Indeed, we found high levels of among-block variability in the fertilization trajectories, and in the estimates of divergence between evolving populations and their ancestors. We also identified five populations which appear to have evolved increased fertilization efficiency, relative to their ancestors. However, due to the abovementioned high variability, this set of populations should be treated as candidate, with further replications needed to either confirm or disprove their divergence from ancestors. Furthermore, we also discuss additional observations we have made concerning fertilization trajectories

Estimating optimal sample size for tardigrade morphometry

Stec, Daniel, Siorek, Piotr G, Morek, Witold, Kosztyła, Paulina, Zawierucha, Krzysztof, Michno, Klaudia, Kaczmarek, Łukasz, Prokop, Zofia M., Michalczyk, Łukasz (2016): Estimating optimal sample size for tardigrade morphometry. Zoological Journal of the Linnean Society 178 (4): 776-784, DOI: 10.1111/zoj.12404, URL: http://dx.doi.org/10.1111/zoj.1240

Schematic representation of the design of Assay II.

<p>Schematic representation of the design of Assay II and the way of calculating mate choice and post-zygotic reproductive isolation on the example of a male’s line 1. Procedures are described in the text.</p