The Relative Roles of Reproductive and Ecological Traits in Producing Biodiversity

EPA Grant Number: U915980
Title: The Relative Roles of Reproductive and Ecological Traits in Producing Biodiversity
Investigators: Braswell, Warren E.
Institution: New Mexico State University - Main Campus
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $77,867
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2001) RFA Text |  Recipients Lists
Research Category: Biology/Life Sciences , Academic Fellowships , Fellowship - Natural and Life Sciences


Understanding the production of biodiversity is a fundamental problem in biology. It is thought that a major component of speciation is the achievement of population divergence, suggesting that with time, divergence will result in speciation. However, evolutionary biologists have learned that the relationship between population divergence and speciation is not straightforward. In other words, speciation does not appear to be simply the result of population divergence. Rather, it appears that speciation may be driven by selection. This and recent evidence of rapid speciation suggest that the study of biodiversity may benefit from focusing on the forces driving speciation. The objective of this research project is to test mechanisms for reproductive isolation in the ground crickets of the genus Allonemobius.


Recently, two types of driving forces for speciation have received much attention: sexual conflict (i.e., antagonistic intergenomic coevolution) and ecological speciation (i.e., divergent natural selection in distinct environments). Theoretical models suggest that each of these driving forces may result in rapid speciation. In addition, initial evidence suggests that these mechanisms may be common. The evolution of trait differences that isolate two lineages is viewed as an especially important aspect of speciation—the event that separates two lineages and assures their future independence. Moreover, the nature of these trait differences provides insight into the forces driving speciation. For example, each hypothesized speciation mechanism (sexual conflict or ecological speciation) makes unique predictions regarding trait differences between sister species.

I propose to test these mechanisms for reproductive isolation in the ground crickets of the genus Allonemobius. Of the 10 species in this genus, there are two pairs of closely related sister species. One sister pair has been the subject of intense study. This sister pair, Allonemobius fasciatus and Allonemobius socius, has been developed into a model system for studying speciation. They have been the subject of several genetic (allozyme, amplified fragment-length polymorphism, random amplified polymorphic DNA, and quantitative trait loci), behavioral, and ecological studies by Dan Howard and his colleagues. These studies show that this sister pair is isolated by reproductive traits and probably diverged by sexual conflict as a result of sexually antagonistic coevolution between males and females in geographically separated populations. However, several lines of evidence suggest that ecological factors may have played a role in the speciation of other members of the genus. For example, the other pair of closely related sister species exhibits variation in both ecological (habitat) and reproductive (male calling song) traits. By using a multidisciplinary approach (phylogenetic, behavioral, and ecological), I will dissect the relative roles of sexual conflict and ecology in driving speciation in this group.

Supplemental Keywords:

fellowship, reproductive traits, ecological traits, biodiversity, speciation, population divergence, reproductive isolation, ground crickets, Allonemobius, Allonemobius fasciatus, Allonemobius socius, sexual conflict, ecological speciation, sister species., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, exploratory research environmental biology, Ecosystem/Assessment/Indicators, Monitoring/Modeling, Ecological Effects - Environmental Exposure & Risk, Biology, biodiversity, animal responses, biological transformation, ecological speciation, environmental consequences, adaptive management, Allonemobius, evolution, biological effects, ground cricket

Progress and Final Reports:

  • 2001
  • 2002
  • Final