Spatial and Temporal Admixture Patterns From Farm Oysters Supplementing Wild Population Recruitment.

Area of Science:

• Marine Biology
• Ecology
• Population Genomics

Background:

• Bivalve aquaculture offers economic benefits and ecosystem services, including water filtration and habitat provision.
• Declining wild shellfish populations raise concerns about the ecological role of aquaculture, particularly regarding recruitment supplementation.
• Domestication in farmed species may lead to reduced fitness in wild environments, posing risks to wild populations.

Purpose of the Study:

• To investigate farm-source recruitment in wild eastern oyster populations using population genomics.
• To contrast genetic diversity and admixture in wild oysters from areas with and without aquaculture.
• To assess the demographic and evolutionary consequences of introgression from domesticated oyster strains.

Main Methods:

• Population genomic analysis of wild eastern oyster populations.
• Utilized double digest restriction site-associated DNA sequencing (ddRAD) and low-coverage whole-genome sequencing (lcWGS) data.
• Compared genetic admixture patterns in oysters from the Hudson River (no aquaculture) and Long Island Sound (aquaculture present).

Main Results:

• No significant admixture was detected in wild oysters from the Hudson River.
• Frequent low-level introgression was observed in wild oysters from Long Island Sound.
• Admixed oysters were predominantly later-generation backcrosses, indicating historical recruitment from aquaculture and low recent immigration.

Conclusions:

• Aquaculture farming of eastern oysters can contribute to recruitment in wild populations within estuarine systems.
• Introgression from domesticated strains may have both demographic benefits and evolutionary impacts on wild oyster populations.
• Further research is needed to fully understand the long-term ecological and evolutionary consequences of farm-source recruitment.