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Divergent oviposition preferences of sister species are not driven by nest survival: The evidence for neutrality
Citation:
Ruskin, K., T. Hodgman, M. Etterson, AND B. Olsen. Divergent oviposition preferences of sister species are not driven by nest survival: The evidence for neutrality. Behavioral Ecology and Sociobiology. Springer, Heidelburg, Germany, 69(10):1639-1647, (2015).
Impact/Purpose:
This manuscript is directed primarily at an academic audience. This subject of the investigation is the relationship between measured nest survival and failure rates and preference for nest location in birds. The manuscript shows that the two are not necessarily in agreement, suggesting that birds may choose nest sites for reasons other than maximizing nest survival rates. This raises important questions for the underlying premise of many nest survival studies. This research is not directly relevant to a specific EPA product. However, the model employed by the project team (MCestimate) was developed at EPAs Mid-Continent Ecology Division for use in avian risk assessment for multiple stressors. The work in the manuscript confirms the wide applicability of the concept of multiple stressors and will serve to highlight the model development underway at USEPA to the academic community.
Description:
Both adaptive and neutral trait evolution can contribute to divergence, but the relative contributions of the two remain unclear. Oviposition preference, a trait that has been demonstrated to contribute to divergence among populations, is often presumed to be an adaptive trait. Few studies explicitly test this assumption, however, and several researchers have demonstrated non-adaptive oviposition preferences in wildlifepopulations. In this study, we test whether adaptive divergence can explain current differences in the oviposition preferences of two sister species. In 2012 and 2013, we conducted a demographic study of sympatrically breeding populations of two sparrow species (Ammodramus caudacutus and A. nelsoni) and measured vegetation characteristics at nest and non-nest points. We found evidence for ovipositionpreference in both species and significant differences between the species' preferences. The vegetation characteristics that vary between species did not predict nest survival or offspring production, however. Our results provide an example of oviposition preference at a population level that appears non-adaptive as measured by productivity. We discuss other mechanisms by which oviposition preference can beadaptive, and make a case for the role of neutral evolution in shaping the oviposition preferences of these species. If divergence in oviposition preference is at least periodically neutral, as we hypothesize, such differences could provide fodder for future adaptation or reproductive isolation among populations.
