Abstract
Several sources of threats to the maintenance of biodiversity may interact and reinforce each other but the role of hybridization (crosses between species) in driving patterns of extinction remains largely unknown. Surprisingly, hybridization and species replacement are often treated as independent subjects in conservation biology. This is probably because patterns of hybridization, and especially patterns of backcrossing are difficult to detect and evaluate in natural populations. In animals, most studies are performed on domesticated or laboratory species because of the difficulties in measuring fitness in the field. However, investigating patterns of hybridization in a natural setting would provide valuable insights on the possible mechanisms of species replacement and thus local extinction. The main aim of this study is to investigate the relative role (and interaction) between introgressive hybridization (i.e. hybridization leading to gene exchange between species) and inter-specific competition in determining population dynamics of two closely related species of flycatchers. The possibility to achieve this goal rests on several facts (1) a unique possibility to estimate fitness in the wild, (2) access to study plots with various composition of the two species and in different types of habitat, (3) access to an extensive number of blood samples collected since 2001, and (4) access to recently developed species-specific markers.
Sweden