Birds of Indian Subcontinent

Non-random infection across individuals and populations supports that parasites can change morphology within an adaptive radiation

Publication Type:Journal Article
Year of Publication:2011
Authors:Edelaar, P, van Eerde, K
Journal:Journal of Zoology
Date Published:2011
ISBN Number:1469-7998
Keywords:Adaptive radiation, directional natural selection, Fringillidae, Loxia, Loxia curvirostra, parasites, population differentiation
Abstract:Adaptive radiation is characterized by rapid phenotypic diversification as a result of utilizing different environments. Red crossbills (Loxia curvirostra Linnaeus – complex) have diversified in bill size and shape, and overall size, in response to differences in the conifer cones that hold the seeds they almost exclusively feed upon. However, a recent study showed how a bill of suboptimal size for foraging has evolved due to antagonistic selection by scaly leg mites Knemidokoptes jamaicensis. This suggests that the current variation in morphology within the adaptive radiation of crossbills may not be exclusively the result of adaptation to alternative resources. Using an independent set of populations, we found that the surprising and little-understood relationship between crossbill morphology and infection with mites is repeatable. Assuming mites depress survival, this relationship would result in directional, not stabilizing selection on morphology. We also find that the rates of infection can differ dramatically between populations, potentially depending on their ecologies. These findings suggest that morphological evolution within the adaptive radiation of crossbills may partly occur for reasons unrelated to resource use.
Short Title:Journal of Zoology
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith