Retroviral impact on mammalian placenta evolution

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The placenta plays a fundamental role supporting pregnancy in all mammals, but exhibits unexpected and striking morphological and physiological variation across species. The rapid evolutionary diversification of the mammalian placenta is hypothesized to be a product of recurrent genetic conflict between parent and offspring. In this work, I investigate the genetic basis of rapid placenta evolution by using high-throughput genomic approaches, and address three major issues in placental biology. First, given that highly conserved genes govern placental development, the molecular mechanisms underlying the rapid diversification of placental morphology have remained unresolved. Our study reveals that the genome-wide regulatory landscape of placental development is highly divergent between closely related species, strongly implicating non-coding regulatory evolution as the major force driving placental morphological diversity. Second, endogenous retroviruses (ERVs) that are normally repressed throughout the embryo are rampantly expressed in the placenta, but the biological rationale—if any— behind this apparent paradox has been unclear. We demonstrate that species-specific ERVs serve as a major source of functional enhancers during placental development, which provides a clear mechanism where placental ERV activity may facilitate the evolutionary diversification of placental morphology. Finally, our findings suggest a novel evolutionary model where placental ERVs provide an adaptive benefit under parent-offspring conflict. Given that genetic conflict predicts rapid diversifying evolution to maintain maximal fitness, we propose that placental ERVs act to dramatically increase the developmental evolvability of the placenta by serving as a rapidly evolving, epigenetically restricted source of polymorphic regulatory elements.


Type of resource text
Form electronic; electronic resource; remote
Extent 1 online resource.
Publication date 2013
Issuance monographic
Language English


Associated with Chuong, Edward Bo-yi
Associated with Stanford University, Department of Genetics.
Primary advisor Baker, Julie, (Professor of genetics)
Thesis advisor Baker, Julie, (Professor of genetics)
Thesis advisor Bustamante, Carlos
Thesis advisor Sherlock, Gavin
Thesis advisor Sidow, Arend
Advisor Bustamante, Carlos
Advisor Sherlock, Gavin
Advisor Sidow, Arend


Genre Theses

Bibliographic information

Statement of responsibility Edward Bo-yi Chuong.
Note Submitted to the Department of Genetics.
Thesis Thesis (Ph.D.)--Stanford University, 2013.
Location electronic resource

Access conditions

© 2013 by Edward Bo-yi Chuong
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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