Marcos Robalinho Lima

Low prevalence of haemosporidian parasites in the introduced house sparrow (Passer domesticus) in Brazil

Species that are introduced to novel environments can lose their native pathogens and parasites during the process of introduction. The escape from the negative effects associated with these natural enemies is commonly employed as an explanation for the success and expansion of invasive species, which is termed the enemy release hypothesis (ERH). In this study, nested PCR techniques and microscopy were used to determine the prevalence and intensity (respectively) of Plasmodium spp. and Haemoproteus spp. in introduced house sparrows and native urban birds of central Brazil. Generalized linear mixed models were fitted by Laplace approximation considering a binomial error distribution and logit link function. Location and species were considered as random effects and species categorization (native or non-indigenous) as fixed effects. We found that native birds from Brazil presented significantly higher parasite prevalence in accordance with the ERH. We also compared our data with the literature, and found that house sparrows native to Europe exhibited significantly higher parasite prevalence than introduced house sparrows from Brazil, which also supports the ERH. Therefore, it is possible that house sparrows from Brazil might have experienced a parasitic release during the process of introduction, which might also be related to a demographic release (e.g. release from the negative effects of parasites on host population dynamics).

Genetic and Morphometric Divergence of an Invasive Bird: The Introduced House Sparrow (Passer domesticus) in Brazil

Introduced species are interesting systems for the study of contemporary evolution in new environments because of their spatial and temporal scales. For this study we had three aims: (i) to determine how genetic diversity and genetic differentiation of introduced populations of the house sparrow (Passer domesticus) in Brazil varies with range expansion, (ii) to determine how genetic diversity and differentiation in Brazil compares to ancestral European populations; and (iii) to determine whether selection or genetic drift has been more influential on phenotypic divergence. We used six microsatellite markers to genotype six populations from Brazil and four populations from Europe. We found slightly reduced levels of genetic diversity in Brazilian compared to native European populations. However, among introduced populations of Brazil, we found no association between genetic diversity and time since introduction. Moreover, overall genetic differentiation among introduced populations was low indicating that the expansion took place from large populations in which genetic drift effects would likely have been weak. We found significant phenotypic divergence among sites in Brazil. Given the absence of a spatial genetic pattern, divergent selection and not genetic drift seems to be the main force behind most of the phenotypic divergence encountered. Unravelling whether microevolution (e.g., allele frequency change), phenotypic plasticity, or both mediated phenotypic divergence is challenging and will require experimental work (e.g., common garden experiments or breeding programs).

Group Composition, Mating System, and Relatedness in the Communally Breeding Guira Cuckoo (Guira guira) in Central Brazil

ABSTRACT. Guira Cuckoos (Guira guira) are cooperative breeders with joint nests, where several breeding and nonbreeding males and females remain in a cohesive unit through repeated breeding attempts within a single territory. We used nine microsatellite markers to analyze parentage and relatedness in a population of Guira Cuckoos in central Brazil, comprising 225 progeny from 51 breeding attempts. The Guira Cuckoos presented a variety of mating patterns, polygynandry and monogamy being the most common. We found low levels of extragroup fertilization, and cobreeding males and females within groups shared reproduction to some extent. Relatedness among group members varied. In some groups, adult males were more related to each other than expected by chance and, overall, males within groups were genetically more similar than background genetic relatedness. In addition, for some of the groups, males were more genetically similar than expected by chance in different years, which indicates some degree of male philopatry or possible joint dispersal by male kin. Male Guira Cuckoos were more likely to breed closer to their natal territories than females, a pattern of dispersal commonly found in birds. We also found that nonbreeding adult males had a higher number of nondescendent kin (chicks and embryos) in the nest than expected from background genetic relatedness, which implies that possible indirect reproductive benefits may have been a significant factor in the evolution of this breeding system.