Ecological Adaptations and Trancriptome Evolution of the Malaria Mosquito Anopheles gambiae

Doctoral Dissertation
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Abstract

Anopheles gambiae has adapted to flourish in spatially diverse ecological conditions, from the humid rainforests to arid Sahel savannas. Within a region, An. gambiae is capable of surviving considerable temporal fluctuations in rainfall and temperature. This extraordinary adaptive flexibility of An. gambiae is largely attributed to complex chromosomal inversion polymorphisms. In addition, An. gambiae is subject to an ongoing incipient speciation process that also appears strongly associated with adaptive phenotypic traits. A long-standing goal is to identify genomic regions/genes/pathways involved in both evolutionary processes. With the intent of exploring the genetic basis of adaptive phenotypes associated with both the nascent speciation process and chromosomal inversion polymorphisms, we focus on transcriptome evolution because there is increasing empirical support that gene regulation contributes to adaptive/species differences; and the lack of discrete phenotypic differences between M and S precludes using powerful quantitative techniques that require such a priori information (e.g., QTL mapping). Transcription profiles can unravel phenotypes not readily visible via these approaches, thereby providing novel insights into the divergence. Chapter 2 reports on the 2La chromosomal inversion, which is strongly linked to degree of aridity in Africa. Gene expression profiles were generated at three time points following acute heat exposure. In Chapter 3, global oligonucleotide arrays were employed to search for transcriptome variation at key developmental stages most likely associated with the speciation. Chapter 4 extended the virgin female time point to include six additional time points and corresponding mated females across a two hour window encompassing dusk. Ten candidate genes linked to olfaction were targeted. Because premating behavioral isolation involves the interaction between trait and preference in different sexes, corresponding reproductively active virgin male global expression was profiled in chapter 5.
Chapter 6 explores the relationship between molecular form transcriptome variation and degree of swarm segregation in nuptial males and females from Mali and Burkina Faso. Chapter 7 focuses on the ecological segregation between M and S. Specifically, the divergence in larval breeding habitats in southern Cameroon, where M occupies polluted urbanized habitats. Transplantation experiments explored the genetic basis of M form larval tolerance to the environmental stressors in their habitats.

Attributes

Attribute NameValues
URN
  • etd-06222011-230434

Author Bryan Joseph Cassone
Advisor Jeffrey Feder
Contributor Jeffrey Feder, Committee Member
Contributor Dave Severson, Committee Member
Contributor Michael Ferdig, Committee Member
Degree Level Doctoral Dissertation
Degree Discipline Biological Sciences
Degree Name PhD
Defense Date
  • 2011-06-06

Submission Date 2011-06-22
Country
  • United States of America

Subject
  • gene expression

  • speciation

  • malaria

  • adaptation

Publisher
  • University of Notre Dame

Language
  • English

Record Visibility Public
Content License
  • All rights reserved

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