A DECADE OF GENETIC MONITORING REVEALS INCREASED INBREEDING FOR THE ENDANGERED WESTERN LEOPARD TOAD, SCLEROPHRYS PANTHERINA.

Genetic monitoring is a useful tool for tracking the status and trends of threatened species; and, as such, can be valuable toward their effective management and conservation. Because threatened species are often made up of small, fragmented populations, they are at increased risk of reduced genetic diversity, which can lower their ability to adapt to a changing environment, and hence increase their extinction risk. Within South Africa, specific amphibian species have been targeted for long-term genetic monitoring studies due to their short generation times, their threat status, and the availability of temporally varied tissue samples. One of these species is the Endangered Western Leopard Toad (Sclerophrys pantherina). This species is endemic to the south-western Western Cape of South Africa and exists as two disjunct populations approximately 100 km apart - the City of Cape Town (CoCT) population and the Overstrand Municipality population. The predominant threats are increased urbanisation and agricultural expansion that modify their habitat and fragment their populations. Using samples collected from roadkills in 2008 and 2018, we looked for changes in genetic diversity in the CoCT population by genotyping 78 individuals across 12 microsatellite loci. Of the seven genetic diversity metrics investigated, one (FIS: inbreeding coefficient) showed significant differences between sampling periods, with 2018 showing increased levels of relatedness (i.e. inbreeding) compared to 2008 (FIS-2008: -0.039; FIS-2018: 0.124). A trend toward higher levels of inbreeding over time might be expected for populations in demographic decline, whereby population sizes are decreasing. Indeed, the Western Leopard Toad is thought to be heavily impacted through roadkills, and this could cause a population decline. These results will form the baseline for future monitoring to better understand the genetic status and trends of diversity within this Endangered species. [ABSTRACT FROM AUTHOR]