Biology subjects

Helgen, K. M.

Publications and source records attributed to Helgen, K. M..

3 recordsLinked to original sources

bioRxiv2025

Genomic and morphometric evidence for Austronesian-mediated pig translocation in the Pacific

Human mediated translocation of non-native pig species (genus Sus) to the islands of Wallacea and Oceania has significantly altered local ecosystems. To investigate the timing and trajectory of these introductions, we conducted both genomic analyses of 576 pig nuclear genomes and a geometric morphometric analysis of 714 modern and ancient dental remains. Our analyses demonstrate that feral and domestic pigs in Wallacea and Oceania possess diverse ancestries resulting from the introduction of multiple, sequential pig populations followed by gene flow. Despite the variability in their genomic ancestry these pigs all possess a distinct tooth morphology, and a genetic link to the Chinese domestic pig populations that accompanied the dispersal of Austronesian language speakers [~]4,000-3,000 years ago via Taiwan and the Philippines.

evolutionary biology↗

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↗

bioRxiv2020

Introgression, hominin dispersal and megafaunal survival in Late Pleistocene Island Southeast Asia

The hominin fossil record of Island Southeast Asia (ISEA) indicates that at least two endemic super-archaic species - Homo luzonensis and H. floresiensis - were present around the time anatomically modern humans (AMH) arrived in the region >50,000 years ago. Contemporary human populations carry signals consistent with interbreeding events with Denisovans in ISEA - a species that is thought to be more closely related to AMH than the super-archaic endemic ISEA hominins. To query this disparity between fossil and genetic evidence, we performed a comprehensive search for super-archaic introgression in >400 modern human genomes. Our results corroborate widespread Denisovan ancestry in ISEA populations but fail to detect any super-archaic admixture signals. By highlighting local megafaunal survival east of the Wallace Line as a potential signature of deep, pre-H. sapiens hominin-faunal interaction, we propose that this understudied region may hold the key to unlocking significant chapters in Denisovan prehistory.

evolutionary biology↗