Timothy Mousseau | Papers

Abundance of birds in Fukushima as judged from Chernobyl

The effects of radiation on abundance of common birds in Fukushima can be assessed from the effects of
radiation in Chernobyl. Abundance of birds was negatively related to radiation, with a significant
difference between Fukushima and Chernobyl. Analysis of 14 species common to the two areas revealed
a negative effect of radiation on abundance, differing between areas and species. The relationship
between abundance and radiation was more strongly negative in Fukushima than in Chernobyl for the
same 14 species, demonstrating a negative consequence of radiation for birds immediately after the
accident on 11 March 2011 during the main breeding season in MarcheJuly, when individuals work close
to their maximum sustainable level.

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Møller, A. P., A. Bonisoli-Alquati, G. Rudolfsen, and T.A. Mousseau. 2011. Chernobyl birds have smaller brains. PLoS One 6(2): e16862.

Abstract
Background: Animals living in areas contaminated by radioactive material from Chernobyl suffer from increased oxidative stress and low levels of antioxidants. Therefore, normal development of the nervous system is jeopardized as reflected by high frequencies of developmental errors, reduced brain size and impaired cognitive abilities in humans. Alternatively, associations between psychological effects and radiation have been attributed to post-traumatic stress in humans.

Methodology/Principal Finding: Here we used an extensive sample of 550 birds belonging to 48 species to test the
prediction that even in the absence of post-traumatic stress, there is a negative association between relative brain size and
level of background radiation. We found a negative association between brain size as reflected by external head volume and level of background radiation, independent of structural body size and body mass. The observed reduction in brain size in relation to background radiation amounted to 5% across the range of almost a factor 5,000 in radiation level. Species differed significantly in reduction in brain size with increasing background radiation, and brain size was the only morphological character that showed a negative relationship with radiation. Brain size was significantly smaller in yearlings than in older individuals.

Conclusions/Significance: Low dose radiation can have significant effects on normal brain development as reflected by
brain size and therefore potentially cognitive ability. The fact that brain size was smaller in yearlings than in older individuals implies that there was significant directional selection on brain size with individuals with larger brains experiencing a viability advantage.

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Møller, A. P., T.A. Mousseau and G. Rudolfsen. 2008. Females affect sperm swimming performance : a field experiment with barn swallows Hirundo rustica. Behavioral Ecology 19(6):1343-1350.

http://cricket.biol.sc.edu/chernobyl/Chernobyl_Research_Initiative/Publications.html

Sexual conflict over fertilization may in animals with internal fertilization initiate an evolutionary arms race that causes the female reproductive tract to become hostile to sperm performance if females with more selective reproductive tracts have their eggs fertilized by sperm of superior quality. This hypothesis suggests that sperm should perform better when tested in a physi- ologically neutral cell culture medium (neutral medium) than in the same ‘‘neutral medium’’ to which fluid derived from the female reproductive tract has been added (female medium). We tested this prediction using in vitro tests on sperm collected from barn swallows Hirundo rustica by recording sperm performance on video in neutral medium and ‘‘female medium.’’ Sperm performance differed significantly among males but also between neutral and female medium. Sperm performed less well in female medium compared with neutral medium in terms of velocity. A principal component (PC) analysis of the 12 sperm parameters produced 4 PCs that explained 86% of the variance. The difference in the second and the third PC between neutral and female medium, reflecting sperm with a high degree of lateral head displacement and absence of straight and linear movement, many static sperm, and a small fraction of sperm with medium velocity, respectively, was positively related to an indicator of female quality: tail length. The latter result may suggest that high-quality females differentially affected the relative performance of sperm in their reproductive tract, consistent with the theory of sexual conflict. Key words: sexual conflict, sexual selection, sperm, swimming performance.

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Material and genetic benefits of female multiple mating and polyandry

The maintenance of female polyandry has traditionally been attributed to the material (direct) benefits derived from male mating resources (e.g. nuptial gifts) accrued by multiple mating. However, genetic (indirect) benefits offer amore robust explanation since only polyandrous, not monandrous, females may gain both material benefits from multiple mating and genetic benefits from multiple sires. Discriminating between material and genetic benefits is essential when addressing the mechanism by which polyandry is adaptively maintained, but are difficult to disentangle because they affect fitness in similar ways. To test the hypothesis that genetic benefits maintain polyandry, we compared four components of fitness (longevity, fecundity, hatching success and survivorship) between monandrous and polyandrous females in the ground cricket, Allonemobius socius. We discovered that females derived nongenetic benefits from mating multiply, in that the magnitude of the nuptial gift was positively associated with the number of eggs produced. However, polyandrous females had over a two-fold greater hatching success and a 43% greater offspring survivorship, leading to a significantly higher relative fitness than the monandrous strategy. These results were independent of the confounding effects of material benefits, implying that genetic contributions play a large role in the maintenance of polyandry and potentially in the antagonistic coevolutionary relationship between polyandry and male nuptial gifts.

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Maternal effects in insects: examples, constraints, and geographic variation

Mousseau, T.A., and H. Dingle. 1991. Maternal effects in insects: Examples, constraints, and geographic variation. In: The Unity of Evolutionary Biology, (ed. E.C. Dudley), Dioscorides Press, Portland, OR. Pp. 745-761.

A sentiment shared by many plant and animal breeders has been that maternal effects are often an annoying source of variance that must be analytically dealt with prior to reaching useful conclusions concerning response to selection or evolution. The objective of this paper is to convince the reader that there are sound biological reasons to consider maternal effects. Out central thesis is that many maternal effects in insects have evolved as a special form of phenotypic plasticity that permits adaptive fine tuning or programming of life cycle response to heterogeneous environments.

In outline, we present a series of examples of maternal effects associated with life cycle regulation. This is followed by a summary of a literature review of 74 species found to display maternal effects. We also present evidence that maternal effects are most often observed between an adult mother and her embryos, suggesting some constraint on the distance between life cycle stages over which maternal effects may act. In the final section of the paper we present data indicating that maternal effects often vary geographically within species, and that this variation is usually correlated to the seasonal characteristics of the habitat from which the population was collected, suggesting genetic divergence and local adaptation of these maternal characters.