New species arise when populations evolve incompatible alleles that lead to lethality or sterility in hybrid offspring between isolated populations. Understanding the evolution of reproductive isolation between species requires functional characterization of the genes that cause barriers to genetic exchange and determining how they kill or sterilize hybrids. Two striking patterns in speciation biology are the early accumulation of hybrid male sterility in animal taxa with X and Y chromosomes (Haldane's Rule), and the enrichment of hybrid sterility factors on the X chromosome (the large X-effect). Speciation in XY species such as mammals and fruit flies is therefore associated with the rapid evolution of X-linked alleles that cause male sterility in interspecific hybrids. Multiple evolutionary models have been proposed to explain both these patterns, but there is insufficient empirical data to test these hypotheses. The long-term objectives of the proposed research are to identify previously unknown X-linked genes that cause hybrid male sterility between closely related species of Drosophila, and to characterize the mechanisms by which these genes disrupt spermatogenesis. These objectives will increase our understanding of the biological processes of speciation, evolutionary divergence in genes and genomes, and the developmental process of spermatogenesis. The proposed research will use genetic and transgenic approaches to identify, verify, and investigate X-linked hybrid sterility genes. Genome-wide gene expression and cytological analyses will determine how these genes disrupt spermatogenesis in hybrids; and population and evolutionary genomic resources will be used to determine the evolutionary history of these genes.

Public Health Relevance

Speciation occurs when previously interbreeding populations become reproductively isolated from one another. Such reproductive isolation frequently involves the evolution of incompatibilities located on the X chromosome that render hybrids sterile, but the causes of this process remain unknown. We propose to determine the genetic basis for hybrid male sterility between two Drosophila species in order to provide insight into this fundamental aspect of biological systems.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM123194-04
Application #
9994318
Study Section
Genetic Variation and Evolution Study Section (GVE)
Program Officer
Janes, Daniel E
Project Start
2017-09-15
Project End
2021-07-31
Budget Start
2020-08-01
Budget End
2021-07-31
Support Year
4
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Nebraska Lincoln
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
555456995
City
Lincoln
State
NE
Country
United States
Zip Code
68503
Payseur, Bret A; Presgraves, Daven C; Filatov, Dmitry A (2018) Introduction: Sex chromosomes and speciation. Mol Ecol 27:3745-3748