Global climate change is a dramatic force which shapes the distributions of flora and fauna across our planet. Shifts in temperature, rainfall, and seasonal coupling have already been linked to changes in species distributions, as well as increases in the rate of fragmentation of many environments. Much of the work focusing on the impact of human mediated climate change has centered on recently fragmented landscapes. Research on the population dynamics of naturally fragmented populations, however, has largely been overlooked. In order to maintain natural diversity we need to understand what characteristics allow for resilience to long term fragmentation.
My research interests focus on the effects of climate change on plant population dynamics by way of gene flow and reproduction in naturally fragmented habitats. Given a historically patchy distribution, species may exist as they do in similar landscape structures: metapopulations with intermittent migration where connectivity is essential. Alternatively, species may exist as a set of relatively separate populations, and are therefore resilient to the negative effects associated with isolation. A key question is to what extent have populations in naturally fragmented environments experienced gene exchange in the past, and will they become vulnerable to current and future threats.
Acacia senegal is a wind and insect pollinated tree that occurs naturally throughout the Sahel region of Africa. The species is monoecious but self incompatible. The flowers give off a small amount of nectar and are visited by a variety of insect species. The tree is the source of the true form of gum arabic, a stabilizer used by the food industry in most soft drinks and many candies.
In the West African country of Mauritania, Acacia senegal was, until recently, widespread and almost continuous. Due to a prolonged drought beginning in the 60s continuing to the mid 80s, many populations have become fragmented into isolated remnant groups. Desertification has ravaged much of the country dwarfing once huge desert oasis zones that formerly spanned the entire country. Although the decline in the tree has had an effect on the economy, few real efforts have been made by the country to stabilize dune advancement in threatened areas.
I am interested in finding out what effects this semi recent fragmentation has had on the pollen flow of this species of Acacia and at what distance we see gene flow between sites. To what degree has recent desertification altered oases sizes and distributions? What role do pollinators play in species viability? What implications does all of this have on the future of diversity in this zone?