Urban conservation genetics: Study of a terrestrial salamander in the city

Urbanization is a global process that negatively affects ecosystems in various ways. It is namely an important cause of habitat loss, and animal species inhabiting cities often exhibit highly fragmented populations. Those populations may be prone to problems associated with reduced abundance and isolation such as genetic drift and inbreeding. However, few studies have dealt with animal populations living in cities. In this paper, we assessed the genetic structure of urban red-backed salamander populations located in remnant forested areas within a major city (Montréal) and on two nearby islands. Microsatellite analysis revealed a high degree of genetic differentiation among populations from Montréal and from neighboring islands. Within Montréal island, no clear genetic structure was detected, with some populations as far as 35 km apart not being differentiated. On the other hand, genetic differentiation was observed at a small spatial scale (0.7–1.7 km) for three populations located near downtown area where anthropogenic perturbations are older. We believe these populations had very low effective population size for a long time, allowing for fast genetic drift and subsequent population differentiation. Although no inbreeding was detected in any population, genetic variation was relatively low. These results illustrate the importance of preserving large forested areas within cities, especially given that these patches may also harbor rarer and threatened species which may be even more negatively affected by urbanization.