Bath, Devon2026-04-272026-04-272026-02-042026-02-042026-04-272026-04-27http://hdl.handle.net/1993/39773Biodiversity continues to be lost at unprecedented rates; a loss that is in part underpinned by the erosion of intraspecific genetic diversity. Estimates of up to a tenth of intraspecific genetic diversity has been lost in the past two centuries. Habitat fragmentation is a proposed candidate driving this loss of genetic diversity. However, the predicted negative effects of fragmentation on genetic diversity may not generalize across species. Ecological differences between species and landscapes can alter the effects of fragmentation in species-specific ways. Studies have typically found that genetic diversity is negatively affected by fragmentation, yet these are often single-species studies or meta-analyses that may compound biases from single-species studies. To begin answering whether habitat fragmentation has a generalizable effect across species’ genetic diversity, we use a macrogenetics approach to assemble a large dataset of genetic diversity while standardizing the measurement of habitat fragmentation. The combined framework provides a standardized methodology across a broad range of taxa and geographic regions that controls for methodological inconsistencies in the current literature, thereby enabling the synthesis of existing knowledge. In our analysis of North American mammals, birds, and amphibians, we found that genetic diversity in mammals and amphibians was generally negatively associated with fragmentation, whereas genetic diversity in birds was weakly negatively associated with fragmentation. These associations depended on multiple aspects of fragmentation and habitat area being controlled for; when these were not controlled for, associations disappeared. This result implies that fragmentation should be treated as an interdependent process. Given our coarse measure of habitat fragmentation, we consider these results robust and consistent with current theory and empirical work. For conservation and management, habitat fragmentation is generally associated with reduced mammal and amphibian genetic diversity and little to no association with bird genetic diversity.engHabitat FragmentationGenetic DiversityPopulation Genetics