Low genetic differentiation between populations of an endemic prairie katydid despite habitat loss and fragmentation

Abstract

Tallgrass prairie habitats within North America have suffered severe fragmentation and habitat loss as land has been converted for agricultural purposes. Habitat loss and fragmentation can affect gene flow and the genetic structure of insect populations. Neoconocephalus bivocatus is a prairie obligate katydid found only in isolated prairie patches. We compared genetic diversity and population differentiation using AFLP markers in N. bivocatus and N. robustus, a grassland generalist that is not isolated to prairie fragments and occupies a more contiguous range. Similar levels of genetic diversity were present within populations of both species. While population genetic structure was found in both species, there was no relationship between assigned genotypes and sampling localities. This genetic structure may instead be evidence of a past barrier to gene flow that has since been removed. Genetic differentiation within both species was low, with no evidence of a correlation with geographic distance, indicating neither species is dispersal limited at these distances. We see no significant reduction in genetic diversity or genetic differentiation within N. bivocatus when compared to N. robustus. We therefore conclude that while N. bivocatus utilizes a fragmented landscape, long-distance dispersal likely maintains gene flow between isolated prairie patches.