How does pyrodiversity influence small mammal abundance and genetic diversity?

Abstract Spatial and temporal variation in fires shapes animal populations from local to global scales. However, few studies have examined how pyrodiversity—variation in fire regimes—influences animal abundance and genetic diversity from a landscape perspective. To understand how fires impact animal populations, we tested how mammal abundance and genetic diversity are shaped by the temporal and spatial dimensions of fires in semi‐arid woodlands of Australia. We collected field data on the relative abundance and genetic diversity of the insectivorous marsupial mallee ningaui ( Ningaui yvonneae ) and the omnivorous rodent Bolam's mouse ( Pseudomys bolami ) at 58 sites varying in fire history. Genome‐wide SNPs were used to calculate individual‐based genetic diversity. Non‐linear regression was used to quantify how the amount, diversity and configuration of fire‐age classes, fire frequency, and time since fire influence the relative abundance and genetic diversity of both species. Relative abundance and genetic diversity were influenced by fire patterns in different ways. Modelled relative abundance of N. yvonneae peaked at sites aged from 25 to 35 years since fire and at sites surrounded by the mid fire‐age class, while genetic diversity of individuals declined with time since fire. Modelled relative abundance of P. bolami was highest at sites from 1 to 5 years since fire and at sites surrounded by a mix of fire‐age classes, with no relationships detected between genetic diversity and fire patterns for this species. Synthesis and applications . Exploring both abundance and genetic data for small mammals revealed new ecological insights: N. yvonneae is more abundant decades after fire when hummock grass cover is high, but fire‐driven habitat shifts may also contribute to gene flow and genetic diversity by encouraging dispersal to suitable habitats. We reason that maintaining a mix of early, mid and late fire‐age classes within nature reserves and other managed areas will support small mammal conservation in semi‐arid Australia by supplying suitable habitats that sustain a high abundance of individuals while promoting gene flow through the landscape.