March 14 2019

5:00 pm TLSB 1100

This seminar is sponsored by EEB

EcoEvoPub Series

EcoEvoPub Series


Thursday, March 14th, 2019
5:00 PM
1100 Terasaki Life Science Building

Ryan S. Terrill
Occidental College

"Molt-migration in the Mexican Monsoon: 90 years of specimens reveal a phenological mismatch caused by anthropogenic climate change"

Understanding the full annual cycle of migratory birds is essential for their conservation, especially events directly tied to investment in adult survival such as feather replacement. Birds that undergo long-distance migrations have annual cycles that are tightly linked to the predictable availability of resources along their migratory path. Studies have found that global climate change has begun to cause mismatches in the migratory timing of birds and availability of food along their paths. The timing of arrival on breeding grounds has received significant attention in this respect, but little attention has been paid to the potential effects of these phenological mismatches where birds undergo their annual molt. Many species of migratory birds take advantage of heavy late summer rains and the associated increase in primary productivity in the Mexican Monsoon to undergo their molt before continuing southward for the winter. This molt is energetically expensive, and many of these species travel hundreds of miles to molt their feathers during this resource-rich time. This monsoonal region receives >90% of its annual rainfall during the monsoons, and is an arid desert during the rest of the year. Over the past 90 years, anthropogenic climate change has induced a shift in the onset of the monsoon so that the onset and peak of the monsoon is a month later than in pre-industrial times. We examined the onset and duration of molt in 340 specimens collected over 90 years from 15 species of migratory birds that undergo a stopover molt in the monsoon and found no support for a phenological shift in their molt timing. Experimental studies have shown that molting with insufficient food causes mortality instead of suspension of molt, and these birds may arrive on their molting ground to find a dry and foodless desert. This finding is concerning for the conservation of these species, because these birds may become stuck starting their molt before the food they rely on to undergo molt is available.

Daniel Chavez
Department of Ecology and Evolutionary Biology, UCLA

"Comparative genomics provides new insights into the remarkable adaptations of canids"

One of the main purpose of evolutionary biology is to understand the genetic basis of species adaptations. The availability of a growing number of whole-genome sequences provide researches with the unique opportunity to identify the genetic basis of adaptive evolution in non-model organisms. Members of the family Canidae are excellent models to study adaptation in natural populations. Particularly, the African wild dog (Lycaon pictus) is the most specialized canid with regards to cursorial adaptations (fast runners), having only four compact digits on their forefeet. Also, despite being sister taxa, South American bush dog (Speothos venaticus) and maned wolf (Chrysocyon brachyurus) have strikingly differences in limb size. Using complete genome sequences from 12 species of canids, we investigated the genetic basis for adaptations associated with cursoriality, and limb size. Genome-wide scans revealed unique genetic variations to African wild dogs that suggest a mode of evolutionary digit loss through expanded apoptosis in the developing first digit. Bush dog-specific signals of positive selection also uncovered a mechanism of limb length modification through changes in genes associated with chondrocytes differentiation. Our results provide new insight in long standing question in evolutionary biology and demonstrate that complete genomes provide a powerful source of information to investigate the genetic basis of unique adaptations in natural populations.











































































































































































































































































































































































































































































































































































































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