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Evolving Adaptive Reproductive Capacity: A Systems Approach Using Drosophila Models

Wednesday, February 16, 2022 - 3:00pm to 4:00pm

Speaker

Cassandra Extavour, Ph.D.
Timken Professor of Organismic and Evolutionary Biology and of Molecular and Cellular Biology
Harvard University

The Extavour laboratory is interested in understanding early embryonic development, the genes that control this development, the evolutionary origins of these genes and how their functions have changed over evolutionary time. The lab is particularly interested in the development and evolution of reproductive systems, including both germ cells, which are cells that make eggs and sperm in sexually reproducing animals, and somatic gonad cells, which create the structures to house and protect the germ cells, and regulate egg and sperm production.

Dr. Extavour began working on germ cell development in graduate school. In her Ph.D. thesis, she used classical Drosophila genetics to explore the genetic requirements of germ cells during development. Using clonal analysis, she showed that primordial germ cells engage in cell-cell competition prior to gametogenesis, revealing a level of natural selection that operates not only pre-zygotically, but in the very precursors of gametes themselves. This means that allele frequencies can potentially be changed from one generation to the next, not only by natural selection operating on sexually mature adult individuals, but also on the cells responsible for producing the gametes that will ultimately give rise to those individuals. Because of the critical role of germ cells not only in development but also in evolution, her subsequent work has focused on germ cell development in a comparative context.

Summary

Key Lecture Points: Adult reproductive fitness traits can be regulated by local cell behaviour decisions during early development. No single “smoking gun” gene regulatory network regulates complex reproductive trait. Environment-sensing molecular mechanisms may link heritability and plasticity. Establishing null expectations for evolutionary changes helps focus the search for adaptive mechanisms. Nothing explains everything: broad taxon sampling is still important


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