PS 35-69 - Factors affecting the geographic distribution of Drosera (Droseraceae) species in the Cape Floristic Region of South Africa and implications of global climate change

Wednesday, August 9, 2017
Exhibit Hall, Oregon Convention Center
Alexander J. Dietrick, Biology, Seattle Central College, Seattle, WA

The Cape Floristic Region of South Africa is known for both its high biodiversity and high number of endemic species. Among such species are sundews in the genus Drosera, which are small, herbaceous, and carnivorous flowering plants. Of the 34 species of Drosera in Africa and Madagascar, 21 of them are endemic to South Africa. Drosera in South Africa can be grouped into two categories: generalist species that are widespread in their distribution, and specialist species with highly restricted ranges, often known from only a few sites. The high diversity and variety of life history strategies of Drosera makes the genus an excellent model system for the study of species distribution through the lens of global change. For this project, occurrence data was sourced from citizen science platforms iNaturalist and iSpot, as well as from herbarium and biodiversity databases. Using MaxEnt niche modeling software, occurrence data for Drosera in South Africa were used in combination with geographic and climatic data from WorldClim to create a niche occupancy model, which predicted the distribution of these species. This model was used in combination with future climate estimates from WorldClim to predict changes in the distribution of Drosera species in South Africa in response to climate change.


Factors that most strongly affected the current ranges of the Drosera species studied included average monthly precipitation and average monthly maximum temperature. When the effects of climate change were estimated, results from this study suggested that generalist species are less susceptible to climate change than specialist species with already highly restricted ranges. Several species, including those restricted to the upper elevations of montane habitats, were found to have no projected suitable habitat. When phylogeny was considered, species that were more closely related had more similar responses to climate change estimates than those that were more unrelated. Understanding how species respond to global climate change is crucial for the success of long-term conservation initiatives.