BioEnv-seminar: "The evolution of elaborate nest design in weaverbirds"

Abstract:  The maxim “form ever follows function” is most often associated with human architecture, but it is also reflected throughout the natural world: Whether it be the aerodynamic shape of a bird’s wing or the bright warning coloration of a toxic newt, functional design is everywhere, also in external structures (or ‘extended phenotypes’ sensu Richard Dawkins) such as spider webs or bird nests. Among the most striking and complex examples of animal architecture are the nests of weaverbirds (family Ploceidae); enclosed nests, assembled using a series of intricate knots, resulting in amazingly strong and secure structures. While some nest features are shared among weaver species, there is also tremendous variation in size, shape, material composition, as well as placements in e.g. trees, bushes, reeds or grass. This variation is likely a reflection of ecological, behavioral, and morphological diversity exhibited by the family, whose members have diversified into virtually all habitat types across Africa and (for a few species) southern Asia. In my research I seek to understand the evolution of avian nest architecture through a species-level phylogenetic and comparative analysis of nest character trait evolution in Ploceidae. In addition, through ancestral character reconstruction, I explore the hypothesis that nests have tended to increase in complexity over evolutionary time.

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