The mechanisms underlying heterozygosity-fitness correlations (HFCs) are subject of intense debates, especially about how important population features such as size or degree of isolation influence HFCs. Here, variation is reported in HFCs between Large and Small populations of a self-compatible shrub occurring within an extremely fragmented landscape. Whereas heterozygosity explained most of the variance in growth rate of seedling families within Large populations, this relationship was absent within Small populations. Results suggest that inbreeding may explain the observed HFCs within Large populations, and that different genetic processes (such as genetic drift and/or selection) could have overridden HFCs within Small populations. Results open new research perspectives on how different genetic processes underlie variation in HFCs under different population contexts. informacion[at]ebd.csic.es: González-Varo et al (2012) Contrasting heterozygosity-fitness correlations between populations of a self-compatible shrub in a fragmented landscape. Genetica. Doi 10.1007/s10709-012-9655-8

The main factors responsible for the assembly of nectar yeast communities were assessed characterizing the physiological abilities of all yeast species forming the pool of potential colonizers for two Spanish flowering plants. Yeasts were most frequent in external sources (air, flower-visiting insects), less so in the proximate floral environment (phylloplane), and least in pollen and nectar. Nectar communities appeared to be considerably impoverished versions of those in insect glossae and phylloplane. Nectar, pollen, and insect yeast assemblages differed in physiological characteristics from those in other substrates. Nectarivorous Metschnikowia were not more resistant than other yeast species to plant secondary compounds and high sugar concentrations typical of nectar, but their higher growth rates may be decisive for their dominance in ephemeral nectar communities. informacion[at]ebd.csic.es: Pozo et al (2012) Nectar yeasts of two southern Spanish plants: The roles of immigration and physiological traits in community assembly. FEMS Microbiology Ecology 80: 281-293. DOI: 10.1111/j.1574-6941.2011.01286.x

Although larger brains (correcting for body size) are thought to confer fitness advantages, energetic limitations of this costly organ may lead to trade-offs. Here, the patterns of selection on male and female brain size were examined in pinnipeds, a group where the strength of sexual selection differs markedly among species and between the sexes. Relative brain size was negatively associated with the intensity of sexual selection in males but not females. However, analyses of the rates of body and brain size evolution showed that this apparent trade-off between sexual selection and brain mass is driven by selection for increasing body mass rather than by an actual reduction in male brain size. Results suggest that sexual selection has important effects on the allometric relationships of neural development. información[at]ebd.csic.es: Fitzpatrick et al (2012) Sexual selection uncouples the evolution of brain and body size in pinnipeds, J. Evol Biol. DOI 10.1111/j.1420-9101.2012.02520.x