# Investigating the special role of sex chromosomes in speciation: discovering the molecular identities, functions, and evolutionary histories of X-linked hybrid male sterility genes in Drosophila

> **NIH NIH R01** · UNIVERSITY OF NEBRASKA LINCOLN · 2020 · $321,724

## Abstract

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.

## Key facts

- **NIH application ID:** 9994318
- **Project number:** 5R01GM123194-04
- **Recipient organization:** UNIVERSITY OF NEBRASKA LINCOLN
- **Principal Investigator:** COLIN D MEIKLEJOHN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $321,724
- **Award type:** 5
- **Project period:** 2017-09-15 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9994318

## Citation

> US National Institutes of Health, RePORTER application 9994318, Investigating the special role of sex chromosomes in speciation: discovering the molecular identities, functions, and evolutionary histories of X-linked hybrid male sterility genes in Drosophila (5R01GM123194-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9994318. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*