Abstracts (first author)

Talk 

Evolution of acoustic and visual signals in Asian barbets

Author(s): Gonzalez-Voyer A, Castelló A, Leonard J

Summary:

The study of animal communication systems is an important step towards gaining greater understanding of the processes influencing diversification because signals often play an important role in mate choice and can lead to reproductive isolation. Signal evolution can be influenced by a diversity of factors such as biophysical constraints on the emitter, the signalling environment, or selection to avoid heterospecific matings. Furthermore, because signals can be costly to produce, trade-offs may exist between different types of signals. Here, we apply phylogenetic comparative analyses to study the evolution of acoustic and visual signals in Asian barbets, a clade of non-Passerine, forest-dependent birds. Our results suggest that evolution of acoustic and visual signals in barbets is influenced by diverse factors, such as morphology and signalling environment, suggesting a potential effect of sensory drive. We found no trade-offs between visual and acoustic signals. Quite to the contrary, more colourful species sing significantly longer songs. Song characteristics presented distinct patterns of evolution. Song frequency diverged early on and the rate of evolution of this trait appears to be constrained by body size. On the other hand, characteristics associated with length of the song presented evidence for more recent divergence. Finally, our results indicate that there is a spatial component to the evolution of visual signals, and that visual signals are more divergent between closely related taxa than acoustic signals. Hence, visual signals in these species could play a role in speciation or reinforcement of reproductive isolation following secondary contacts.


Video


Abstracts (coauthor)

Summary:

Brain size is enormously variable among vertebrates and this variation is thought to be maintained through the balance of adaptations, trade-offs, and constraints. Although intuitive in theory, the impact on brain size evolution from constructional constraints exerted by head morphology has so far been largely overlooked. We used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate whether head morphology co-evolves with brain size. We examined the relationship between head shape and brain size while controlling for phylogenetic relationships and potentially confounding ecological factors. The analyses revealed significant associations between head shape and brain size. We found that species with curved, wide and high heads had large brains while narrow pointed head profiles were associated with small brains. This finding supports the hypothesis that constructional constraints can play a role in brain evolution. Our result, together with previous works on other groups of vertebrates, suggests that eco-morphological adaptation to specific feeding technique might cause constructional constraints on vertebrate brain evolution.

Summary:

The increasing availability of phylogenetic reconstructions presents the opportunity to test relevant hypotheses about the origin and diversity of plant sexual polymorphisms. Heterostyly, a pervasive discrete floral polymorphism across lineages of flowering plants, has attracted the interest of evolutionary biologists since Darwin’s book The different forms of flowers.... Early evolutionary models based on genetics explained the origin and maintenance of heterostyly as an anti-selfing mechanism. The genetic hypothesis contrasted with Darwinian views, which considered heterostyly as a device to promote outcrossing in hermaphroditic plants without the constraints imposed by self-interference between male and female functions and lack of precision in pollen transfer in hermaphroditic flowers. The mostly ecological Darwinian hypothesis posits a key role for particular pollinators, which are able to efficiently transfer pollen between different morphs. Both hypotheses agree on the fact that heterostyly is a typical mechanism for disassortative mating and is governed by negative frequency-dependent selection, although the factors proposed as important for the evolution of the trait differ. We surveyed occurrence of heterostyly across angiosperms families and genera to trace its evolution across the phylogeny. We determined the number of independent evolutionary transitions from monomorphism to heterostyly, and also the ancestral condition of heterostyly (approach herkogamy or non-herkogamy as suggested by the two competing evolutionary models). Finally we analysed whether the presence of heterostyly is evolutionarily correlated with flower architecture and developmental constraints, such as (1) tubular flowers which restrict pollinator movements and ensure more exact pollen deposition on their bodies, (2) regular flowers which do not restrict pollinator movements within the flower, and (3) flower with free stamens (not connate to the perianth).

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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