Parker, L. D. | Search bioRxiv

bioRxiv2025

President Roosevelt's lions reveal a century of population fragmentation in Africa's largest carnivore

Over the past century, lion (Panthera leo) populations across Africa have experienced rapid and severe declines. Despite this, East Africa is considered a modern-day lion stronghold. Here, we use whole-genome sequencing of both recent and historical lion populations, primarily collected during the Smithsonians Roosevelt East African (1909-1911) and Rainey (1911-1912) Expeditions, to investigate changes in population structure, connectivity, and diversity over the last [~]100 years in East Africa. We find a clear signal of population fragmentation when comparing historical (1896-1946) and recent (1990-present) lion populations. Our analyses reveal genetic distinctions between remaining lion populations in Kenya and Tanzania and document loss of genetic diversity over time including reduced heterozygosity and the accumulation of runs of homozygosity. We detect a severe bottleneck in both Kenya and Tanzania approximately 25 generations ago, coinciding with a severe rinderpest outbreak in the region that is known to have decimated bovid and ultimately carnivore populations in the area. Nevertheless, modern lions in East Africa still exhibit overall high levels of diversity and low levels of inbreeding. Our results provide direct evidence of the effects of increasing habitat fragmentation and the significance of temporal data for contextualizing current patterns of population connectivity and diversity.

evolutionary biology↗

bioRxiv2019

Abundance, density, and social structure of African forest elephants (Loxodonta cyclotis) in a human-modified landscape in southwestern Gabon

The noninvasive monitoring of population size and demography is critical to effective conservation, but forest living taxa can be difficult to directly observe due to elusiveness and/or inaccessible habitat. This has been true of African forest elephants (Loxodonta cyclotis), for which we have limited information regarding population size and social behavior despite their threatened conservation status. In this study, we estimated demographic parameters focusing specifically on population size and density using genetic capture-recapture of forest elephants in the southern Industrial Corridor of the Gamba Complex of Protected Areas, which is considered a global stronghold for forest elephants in southwestern Gabon. Additionally, we examined forest elephant sociality through analysis of social networks, predicting that we would find matrilineal structure as exhibited by savanna elephants and other forest elephants. Given 95% confidence intervals, we estimate the size of the population in the sampled area to be between 754 and 1,502 individuals and our best density estimate ranges from 0.47 to 0.80 elephants per km2. When extrapolated across the entire Industrial Corridor, this estimate suggests an elephant population size of 3,033 to 6,043 in this area based on abundance or 1,684 to 2,832 based on density, which is 40 - 83% smaller than previously suggested. Furthermore, our social network analysis revealed approximately half of network components included females with different mitochondrial haplotypes; this suggests a wider range of variation in forest elephant sociality than has previously been reported. This study emphasizes the threatened status of forest elephants and demonstrates the need to further refine baseline estimates of population size and knowledge on social behavior in this taxon, both of which will aid in determining how population dynamics in this keystone species may be changing through time in relation to increasing conservation threats.

genetics↗