Investigating the cause of the disjunct distribution of Amietophrynus pantherinus, the Endangered South African western leopard toad

Abstract

More amphibians are threatened through loss of habitat than any other single factor. Conservation measures to restore habitat are dependent on historical data indicating the original extent of a species. When historical data is absent, disjunct distributions create a special problem for conservationists who need to determine whether they have an anthropogenic cause. The Endangered western leopard toad (Amietophrynus pantherinus) has a disjunct distribution in the south-western tip of South Africa. We use mitochondrial sequences from 153 individuals to show that the disjunct distribution is unlikely to have an anthropogenic origin. Two distinct populations are separated by 100 km, with highest probability for the most recent common ancestor arising some 5 Kya. The causes of this disjunct distribution appear to be too recent to be attributable to changes in sea level; instead we suggest that there was a range retraction associated with a distinct drying period in the area during the Holocene, possibly indicating that this species will be susceptible to future climate change. Further, we find that the eastern population is less genetically diverse and appears to be undergoing a serious reduction in range, despite its occurrence in the least urbanized habitat. Conservation measures suggested include surveys for breeding sites in the eastern population, custodian agreements for existing breeding sites and foraging areas and the need for a Biodiversity Management Plan to be drawn up and implemented.

Limited genetic structure in a wood frog (Lithobates sylvaticus) population in an urban landscape inhabiting natural and constructed wetlands

“…Even when genetic divergence is found in an amphibian population fragmented by urban development, it may not have an anthropogenic cause and could be due to historic, pre-settlement patterns of gene flow and environmental variation (Measey and Tolley 2011). One result is clear-proper land management and habitat enrichment projects, such as constructing storm water wetlands, offers the best chance in supporting amphibian's life history requirements and maintaining suitable connectivity across urban landscapes in order to counter the negative effects of development, and to prevent future genetic defects.…”

Assessing the effects of climate change on distributions of Cape Floristic Region amphibians

“…Occurrence records were obtained from the South African Frog Atlas Project (SAFAP) 33 , CapeNature and iSpot, as well as records published in recent literature 26,29,36 and our own observations. We included only records with accuracy to the nearest second or higher.…”

Conservation Genetics of the Largest Cluster of Federally Threatened Gopher Tortoise (Gopherus polyphemus) Colonies with Implications for Species Management

“…In some cases, genetic differentiation might be greater than expected due to subtle land-use changes or barriers that fragment populations (Booth et al, 2009), differences between dispersal estimates based on mark-recapture data and actual gene flow (Cabe et al, 2007), or incorrect assumptions of panmixia based on spatial distribution of individuals (Elmer et al, 2007). Therefore, to accurately interpret spatial genetic structure, one must not only examine spatial ecology and movement behavior of focal species (ChaputBardy et al, 2008;Darvill et al, 2009;Lowe et al, 2008), but also land-use legacy, because genetic data have the signature of historical events and processes (Jordan et al, 2009;Measey and Tolley, 2009). The sensitivity of molecular markers and genetic diversity measures and the ability to detect genetic 5 PRESENT ADDRESS: Department of Interior, Bureau of Ocean Energy Management, New Orleans, LA 70123, USA 6 CORRESPONDENCE: e-mail, stephen.richter@eku.edu discontinuities on a continuous landscape will depend on spatial ecology of study species, temporal scale, and statistical approaches (Anderson et al, 2010;Landguth et al, 2010;McCoy et al, 2010;Murphy et al, 2008).…”

“…Current population size and distribution of populations across the landscape may indicate future persistence of a species. However, these contemporary data may not be accurate estimators of current status or indicators of long-term persistence probability, because historic events, which are not always obvious from examination of populations, can have major impacts on probability of future persistence (Hoelzel et al, 2002;Measey and Tolley, 2009). For example, if population size and geographic extent were diminished in the past and followed by recovery, this may not be obvious based on current abundance and distribution (Hoelzel et al, 2002;Johnson and Dunn, 2006;Jordan et al, 2009).…”