Darker female pigeons transmit more specific antibodies to their eggs than do paler ones

Melanin‐based coloration is widespread among vertebrates, yet the adaptive significance of such pigments remains elusive, particularly with regard to the link between melanin and immune‐mediated maternal effects. The aim of this study was to investigate whether melanin‐based coloration could signal the ability of mothers to mount a humoral response and to transfer maternal antibodies (Ab) to their young. We injected differently coloured (pale and dark) female feral pigeons (Columba livia) with Chlamydiae (a natural antigen) and Keyhole Limpet Haemocyanin (KLH, an artificial antigen), and found no significant difference in humoral response between differently coloured females. However, darker females transferred more Ab against Chlamydiae into their eggs than paler ones, despite similar circulating levels of Ab. In addition to this, melanin‐based coloration showed a high heritability value. This suggests that a genetically based coloured trait might be linked to the ability of females to transfer specific Ab against Chlamydiae (but not against KLH) to their offspring, independent of their ability to produce Ab. This suggests that transmission of maternal Ab is antigen dependent, and that melanin‐based coloration might signal female ability to transmit specific Ab against natural pathogens. © 2013 The Linnean Society of London     

Insect diapause of very variable duration: the case of the palm nut bruchid Pachymerus nucleorum (Coleoptera: Chrysomelidae)

Data are provided here showing that larval diapause in the tropical palm nut bruchid Pachymerus nucleorum (Fabricius) can extend up to a maximum of about five years, although for most individuals the duration ranges from 15 to 48 months. The data were obtained for insects originating from one source only that were held under one set of temperature and photoperiod conditions only so the wide variation in duration is attributed to maternal control. Staggering the adult emergence times of a parent’s progeny can be regarded as an evolutionary strategy that increases the chance that some at least encounter favourable biotic or abiotic conditions. It is believed that extended diapause may be quite widespread amongst insects, including those of temperate climates.     

The neonate nutrition hypothesis: early feeding affects the body stoichiometry of Daphnia offspring

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Genetic architecture of survival and fitness-related traits in two populations of Atlantic salmon

The additive genetic effects of traits can be used to predict evolutionary trajectories, such as responses to selection. Non-additive genetic and maternal environmental effects can also change evolutionary trajectories and influence phenotypes, but these effects have received less attention by researchers. We partitioned the phenotypic variance of survival and fitness-related traits into additive genetic, non-additive genetic and maternal environmental effects using a full-factorial breeding design within two allopatric populations of Atlantic salmon (Salmo salar). Maternal environmental effects were large at early life stages, but decreased during development, with non-additive genetic effects being most significant at later juvenile stages (alevin and fry). Non-additive genetic effects were also, on average, larger than additive genetic effects. The populations, generally, did not differ in the trait values or inferred genetic architecture of the traits. Any differences between the populations for trait values could be explained by maternal environmental effects. We discuss whether the similarities in architectures of these populations is the result of natural selection across a common juvenile environment.     

Transgenerational soil‐mediated differences between plants experienced or naïve to a grass invasion

Invasive species may undergo rapid change as they invade. Native species persisting in invaded areas may also experience rapid change over this short timescale relative to native populations in uninvaded areas. We investigated the response of the native Achillea millefolium to soil from Holcus lanatus‐invaded and uninvaded areas, and we sought to determine whether differential responses between A. millefolium from invaded (invader experienced) and uninvaded (invader naïve) areas were mediated by soil community changes. Plants grown from seed from experienced and naïve areas responded differently to invaded and uninvaded soil with respect to germination time, biomass, and height. Overall, experienced plants grew faster and taller than their naïve counterparts. Naïve native plants showed negative feedbacks with their home soil and positive feedbacks with invaded soil; experienced plants were less responsive to soil differences. Our results suggest that native plants naïve to invasion may be more sensitive to soil communities than experienced plants, consistent with recent studies. While differences between naïve and experienced plants are transgenerational, our design cannot differentiate between differences that are genetically based, plastic, or both. Regardless, our results highlight the importance of seed source and population history in restoration, emphasizing the restoration potential of experienced seed sources.     

Partial genotyping at polymorphic markers can improve heritability estimates in sibling groups

Accurate estimates of heritability () are necessary to assess adaptive responses of populations and evolution of fitness‐related traits in changing environments. For plants, estimates generally rely on maternal progeny designs, assuming that offspring are either half‐sibs or unrelated. However, plant mating systems often depart from half‐sib assumptions, this can bias estimates. Here, we investigate how to accurately estimate in nonmodel species through the analysis of sibling designs with a moderate genotyping effort. We performed simulations to investigate how microsatellite marker information available for only a subset of offspring can improve estimates based on maternal progeny designs in the presence of nonrandom mating, inbreeding in the parental population or maternal effects. We compared the basic family method, considering or not adjustments based on average relatedness coefficients, and methods based on the animal model. The animal model was used with average relatedness information, or with hybrid relatedness information: associating one‐generation pedigree and family assumptions, or associating one‐generation pedigree and average relatedness coefficients. Our results highlighted that methods using marker‐based relatedness coefficients performed as well as pedigree‐based methods in the presence of nonrandom mating (i.e. unequal male reproductive contributions, selfing), offering promising prospects to investigate in situ heritabilities in natural populations. In the presence of maternal effects, only the use of pairwise relatednesses through pedigree information improved the accuracy of estimates. In that case, the amount of father‐related offspring in the sibling design is the most critical. Overall, we showed that the method using both one‐generation pedigree and average relatedness coefficients was the most robust to various ecological scenarios.