Biology subjects

Maris, K.

Publications and source records attributed to Maris, K..

2 recordsLinked to original sources

bioRxiv2025

Parasite-mediated inbreeding depression in wild red deer

Inbreeding depression is the reduction in fitness of inbred individuals relative to their more outbred counterparts. Parasitism also reduces fitness and is a route by which inbreeding depression may operate, yet the complete pathway from inbreeding to parasitism to fitness has almost never been documented in the wild. Using high-quality, individual-level data on fitness in juveniles and adult females, longitudinal infection data for three gastrointestinal helminth parasites, and genomic inbreeding coefficients we test for parasite-mediated inbreeding depression in a wild ungulate population (red deer, Cervus elaphus). We found evidence for parasite-mediated inbreeding depression via strongyle nematodes in juvenile survival, independent of direct adverse effects of inbreeding on survival and indirect effects of inbreeding on survival via birth weight. Inbreeding also reduced fitness in reproductive adults by reducing overwinter survival. Our study reveals three independent pathways by which inbreeding depresses fitness and highlights the rarely-studied route of parasitism.

ecology↗

bioRxiv2024

Population density drives increased parasitism via greater exposure and reduced resource availability in wild hosts

Exposure to environmental parasites should increase with host population density due to the accumulation of infective parasites in space. However, competition for resources also increases with density, lowering condition and increasing susceptibility, which offers an alternative pathway for density-dependent infection to act. To test how these two processes act independently or together to drive greater parasite counts, we used a long-term study of red deer to examine associations between host density, resource availability, and counts of three common helminth parasites. We found that greater density correlated with reduced resource availability, and while density was positively associated with both strongyle and tissue worm burdens, resource availability was independently and negatively associated with the same burdens, supporting separate roles of density-dependent exposure and susceptibility in driving infection. This study provides evidence that competition for resources is an important driver of infection in higher-density areas, exacerbating the effects of density-dependent increases in exposure.

ecology↗