Dr. Luis Fernando De León
Postdoctoral Researcher

Summary of previous research

My previous work focused mainly on understanding the interplay between ecological differences, morphological variation and genetic diversity in promoting and maintaining adaptive divergence in Darwin's finches. My first major finding was that the coexistence of sympatric, closely related species is facilitated by partial differences in diets (imperfect generalism), promoted by high spatial and temporal environmental heterogeneity. My second major finding was that a single generalist species (G. fortis) might be composed of a number of individual specialists. This individual specialization might be important in promoting the initial stages of adaptive divergence. My third major finding was that there is strong reproductive isolation between coexisting large versus small beak size morphs within the medium ground finch (G. fortis). This result suggests that adaptive divergence may drive genetic divergence in the face of initially high levels of gene flow between sympatric populations on a single island. My final major finding was that human activities appear to be negatively impacting adaptive divergence between the small and large beak size morphs of G. fortis. Specifically, I showed how the diet and performance (bite force) differences that characterize the two morphs at an undisturbed site, where the morphs remain distinct, have degraded at a human-disturbed site where the morphs are no longer distinct. These findings confirmed some of the major predictions of the ecological theory of adaptive radiation by revealing how resource (diet) differences that cause adaptive (beak) divergence promote ongoing ecological speciation in Darwin’s finches. Overall, my previous research illustrates how the study of ecological interactions is central to understanding the factors that promote and maintain the process of adaptive radiation.

This figures shows other species of Darwin's finches that are found on Santa Cruz Island.
(Photo credit: L. F. De León)

Summary of previous research | Research in progress | Future research