EEB Seminar: November 20th


This Thursday, PhD students Haley Kenyon and Mike Lavender will talk about

Genes vs culture: song variation across an avian hybrid zone


The role of competition in community assembly

respectively, in a special grad student shared EEB seminar

at 12:30 in the EEB lounge (BioSciences 4338)

The seminar is hosted by Dr. Paul Martin and Dr. Shelley Arnott

Elucidating the relationship between genetic and cultural evolution is important in understanding speciation, as learned premating barriers are often involved in maintaining species differences. I explored this relationship by examining a widely recognized premating barrier, bird song, in a narrow hybrid zone between black-throated green (Setophaga virens) and Townsend’s warblers (S. townsendi). I used song analysis, genomic techniques and playback experiments to characterize the cultural and genetic backgrounds of individuals in this region to determine whether song acts as an important reproductive barrier between these species.
Talk by Haley Kenyon.
Competition between species is believed to play an important role in community assembly by affecting species co-occurrence patterns with trait-based limiting similarity and negative co-occurrence null models commonly used to assess competition’s role in community assembly. Negative co-occurrence patterns are suggestive of competitive interactions while under limiting similarity, competition is expected to drive the segregation of species that overlap in niche. A recent review indicates that these null models produce significant results less than half the time. The lack of findings that indicate competition is an important interaction in community assembly may simply represent the true state of things; however, it is also possible that this lack of support is due to the failure of the null models under certain conditions (i.e., due to poor statistical power). To test this we generated synthetic communities that varied in size and in the strength of the signal of limiting similarity or negative co-occurrence. We then explored the power of common null models to pick up this signal. The statistical power for both null models decreased rapidly as the strength of the signal decreased. Sufficient statistical power (β < 0.30) was achieved when 80% or more of species contributed to the signal of limiting similarity, and 60% or more of species contributed signal to patterns of negative co-occurrence. Common community-scale null models of limiting similarity and negative co-occurrence fail to report patterns that occur at the sub-community level. This problem will likely be relevant for most communities, given existing evidence that multiple processes contribute to the assembly of species within a community. While these models are useful for assessing the predominance of a pattern in communities, alternative approaches are needed to assess the influence of competition on species organization within communities in more detail.
Talk by Mike Lavender.
Visit Haley’s and Mike’s respective labs by going to the Martin Lab or Arnott Lab.

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