Leo Khasoha - Pathways to abundance-occupancy relationships: a mechanistic test of the resource breadth hypothesis
I am excited to be a recipient of the 2022 Biodiversity Institute Graduate Student Enhancement Grant. This grant is a major boost for my PhD research on how biodiversity is maintained in a small mammal community of a Kenyan savanna. This award will help me understand the underlying mechanisms to one of the most pervasive patterns in ecology, the positive relationship between abundance and distribution of species (AOR). I will be able to complete the final step of my research by disentangling the isolated and combined roles of (1) resource flexibility and (2) movement of species through the landscape in maintaining abundance and occupancy in an AOR. I am thankful to Biodiversity Institute for their generosity and giving me a chance to develop as a small mammal ecologist and be part of those shaping the next pool of mammologists through a collaborative internship program with National Museums of Kenya.
Leo Khasona
Biodiversity Graduate Student Research Enhancement Grant Awardee
Department of Zoology and Physiology
Graduate Advisor: Jacob Goheen
About the Project
Have you ever wondered why some species are abundant and widespread, while others are rare and occur in only a few places? This macroecological pattern—known as the abundanceoccupancy relationship (AOR)—is among the most general in all of ecology. From North American songbirds to helminth parasites, widely distributed species tend to be common where they occur, while those with restricted distributions tend to be locally rare. Because AORs have been noted across a diversity of taxa, geographic locales, and sampling regimes, this macroecological pattern begs for a mechanistic explanation.
Abundance-occupancy relationships have been prominently attributed to two distinct (but not necessarily exclusive) processes. First, Hanski proposed that differences among species in their abilities to move through the landscape should significantly boost the local abundances of “core” species (i.e., those that are abundant and widespread), but should lead to frequent local extinctions and lack of recolonization of “satellite” species (i.e., those that are rare and restricted). Second, Brown hypothesized that differences in diet flexibility among species underlie AORs: species that are able to use a broad array of foods should occur at more sites and be relatively abundant where they occur, while those that are more selective should be relatively rare at the few sites where they occur.
I ask the question: how do responses in the diet, abundance, and occupancy of common, widespread species differ from those of rare, restricted species when food availability changes? I will test two predictions under the Resource Breadth hypothesis; prediction 1: rare and restricted species are more selective in their diets than abundant and widespread species, thus requiring one or few specific foods to persist, and prediction 2: abundant and widespread species have flexible diets and thus can persist in the absence of preferred foods.
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