Parasite-mediated inbreeding depression in wild red deer

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Inbreeding depression reduces individual fitness, and parasitism is a known factor influencing fitness.
• The complete pathway from inbreeding to parasitism to fitness reduction is rarely documented in wild populations.
• Understanding these pathways is crucial for conservation and evolutionary studies.

Purpose of the Study:

• To investigate parasite-mediated inbreeding depression in a wild red deer (Cervus elaphus) population.
• To identify the specific pathways through which inbreeding affects fitness, including parasitic infections.
• To quantify the impact of inbreeding on juvenile and adult female fitness.

Main Methods:

• Utilized individual-level fitness data for juvenile and adult female red deer.
• Collected longitudinal infection data for three gastrointestinal helminth parasites.
• Calculated genomic inbreeding coefficients for each individual.

Main Results:

• Found evidence of parasite-mediated inbreeding depression affecting juvenile survival through strongyle nematodes.
• Inbreeding depression impacts were independent of direct inbreeding effects on survival and indirect effects via birth weight.
• Inbreeding also reduced overwinter survival in reproductive adult females.

Conclusions:

• Inbreeding depression operates through at least three independent pathways in this wild red deer population.
• Parasitism, specifically strongyle nematodes, represents a significant, rarely studied route of inbreeding depression.
• These findings underscore the complex interplay between inbreeding, parasitism, and fitness in natural populations.