Single-nucleotide polymorphism (SNP) analyses are a powerful tool for population genetics, pedigree reconstruction and phenotypic trait mapping. SNPs could also be useful for sexing individuals in species with reduced sexual dimorphism, yet this possibility remains poorly explored. Here, we develop a novel protocol for molecular sexing of birds based on the detection of unique Z- and W-linked SNP markers. Our method is based on the identification of two unique loci, one in each sexual chromosome. Individuals are considered males when they are heterozygotic for the Z-linked SNP and females when they are homozygote for the Z-linked SNP and have the W-linked SNP. We validated the method in the Jackdaw (Corvus monedula), a species whose reduced sexual dimorphism makes it difficult to sex individuals in the wild. We assessed the reliability of the method with 36 individuals of known sex, and found that their sex was correctly assigned in 100% of cases. The sex-linked markers also proved to be widely applicable to discriminate males and females from a sample of 927 genotyped individuals of different maturity stages with an accuracy of 99.5%. Given that SNP markers are increasingly used in quantitative genetic analyses of wild populations, the approach we propose has a great potential to be integrated into broader genetic research programmes without the need of additional sexing techniques.

Coevolution played a central role in shaping biodiversity. However, coevolutionary events driving reciprocal diversification between interacting partners lack empirical evidences. Examples of diversification arising from mutualisms and antagonisms at different trophic levels are scarce, which limits our understanding on how complex relationships between species arise within communities. By adopting a cophylogenetic framework, we investigated whether congruence in plant-lemur phylogenies are driven by mutualisms and antagonisms in Madagascar, where endemic species have evolved within a unique isolated biogeographical context. Although we found weak support for coevolution, this is not to say that lemurs and plants did not share evolutionary history. Weak cophylogenetic signals do not necessarily imply lack of co-diversification. Rather, our results suggest that vertebrates and plants influenced each other evolution, but in a multi-specific context where the cophylogenetic process leaded to spatio-temporal asymmetries and shifts between periods of coevolution and independent evolution, ultimately resulting in a weak, continuous and diffuse process.

Despite biological invasions are one of the main environmental problems of the twenty-first century, there is still no theoretical or empirical agreement on whether a high phylogenetic relatedness between exotic and native species positively or negatively affect invasion success. To resolve this conundrum, it has been proposed that the effect might be scale-dependent, being negative at smaller spatial scales and positive at larger scales. Here we show that this scale-dependent pattern may be a sampling artefact associated with species-area effects and a non-random pattern of species introductions. We support this conclusion with simulations and empirical data on invaded and non-invaded avian communities in regions from five continents. We further show that at smaller-scales ---where these artifacts are negligible--- invasion success generally increases with the presence of closely-related species, but that predictive accuracy largely depends on considering the influence of human-related disturbances in facilitating invasions.

Growing evidence that individuals of many generalist animals behave as resource specialists has attracted research interest for its ecological and evolutionary implications. Although variation in resource preferences is critical for developing a general theory of individual specialization, it remains to be shown whether diverging preferences can arise among individuals sharing a similar environment and whether these are stable enough to be ecologically relevant. We addressed these issues by means of common garden experiments in feral pigeons (Columba livia), a species known to exhibit resource specialization in the wild. Food-choice experiments on wild-caught pigeons and their captive-bred descendants showed that variation in food preferences can easily arise within a population and that this variation may represent a substantial fraction of the population niche. However, a cross-fostering experiment revealed that the genetic and early common-environment components of food preferences were low, reducing their stability and eroding niche variation in the long-term.