Relationship between effective population size, inbreeding and adult fitness-related traits in a steelhead (Oncorhynchus mykiss) population released in the wild.

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Relationship between effective population size, inbreeding and adult fitness-related traits in a steelhead (Oncorhynchus mykiss) population released in the wild.

Mol Ecol. 2013 Mar;22(5):1295-309

Authors: Naish KA, Seamons TR, Dauer MB, Hauser L, Quinn TP

Abstract
Inbreeding is of concern in supportive breeding programmes in Pacific salmonids, Oncorhynchus spp, where the number of breeding adults is limited by rearing space or poor survival to adulthood, and large numbers are released to supplement wild stocks and fisheries. We reconstructed the pedigree of 6602 migratory hatchery steelhead (Oncorhynchus mykiss) over four generations, to determine the incidence and fitness consequences of inbreeding in a northwest USA programme. The hatchery maintained an effective population size, Ñ(e) = 107.9 from F(0) to F(2), despite an increasing census size (N), which resulted in a decreasing N(e)/N ratio (0.35 in F(0) to 0.08 in F(2)). The reduced ratio was attributed to a small broodstock size, nonrandom transfers and high variance in reproductive success (particularly in males). We observed accumulation of inbreeding from the founder generation (in F(4), percentage individuals with inbreeding coefficients Δf > 0 = 15.7%). Generalized linear mixed models showed that body length and weight decreased significantly with increasing Δf, and inbred fish returned later to spawn in a model that included father identity. However, there was no significant correlation between Δf and age at return, female fecundity or gonad weight. Similarly, there was no relationship between Δf and reproductive success of F(2) and F(3) individuals, which might be explained by the fact that reproductive success is partially controlled by hatchery mating protocols. This study is one of the first to show that small changes in inbreeding coefficient can affect some fitness-related traits in a monitored population propagated and released to the wild.

PMID: 23379933 [PubMed – indexed for MEDLINE]

via pubmed: school of aquatic an… http://www.ncbi.nlm.nih.gov/pubmed/23379933?dopt=Abstract

Relationship between effective population size, inbreeding and adult fitness-related traits in a steelhead (Oncorhynchus mykiss) population released in the wild.

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Relationship between effective population size, inbreeding and adult fitness-related traits in a steelhead (Oncorhynchus mykiss) population released in the wild.

Mol Ecol. 2013 Feb 4;

Authors: Naish KA, Seamons TR, Dauer MB, Hauser L, Quinn TP

Abstract
Inbreeding is of concern in supportive breeding programmes in Pacific salmonids, Oncorhynchus spp, where the number of breeding adults is limited by rearing space or poor survival to adulthood, and large numbers are released to supplement wild stocks and fisheries. We reconstructed the pedigree of 6602 migratory hatchery steelhead (Oncorhynchus mykiss) over four generations, to determine the incidence and fitness consequences of inbreeding in a northwest USA programme. The hatchery maintained an effective population size, N˜e = 107.9 from F(0) to F(2) , despite an increasing census size (N), which resulted in a decreasing N(e) /N ratio (0.35 in F(0) to 0.08 in F(2) ). The reduced ratio was attributed to a small broodstock size, nonrandom transfers and high variance in reproductive success (particularly in males). We observed accumulation of inbreeding from the founder generation (in F(4) , percentage individuals with inbreeding coefficients Δf > 0 = 15.7%). Generalized linear mixed models showed that body length and weight decreased significantly with increasing Δf, and inbred fish returned later to spawn in a model that included father identity. However, there was no significant correlation between Δf and age at return, female fecundity or gonad weight. Similarly, there was no relationship between Δf and reproductive success of F(2) and F(3) individuals, which might be explained by the fact that reproductive success is partially controlled by hatchery mating protocols. This study is one of the first to show that small changes in inbreeding coefficient can affect some fitness-related traits in a monitored population propagated and released to the wild.

PMID: 23379933 [PubMed – as supplied by publisher]

via pubmed: school of aquatic an… http://www.ncbi.nlm.nih.gov/PubMed/23379933?dopt=Abstract

Can interbreeding of wild and artificially propagated animals be prevented by using broodstock selected for a divergent life history?

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Can interbreeding of wild and artificially propagated animals be prevented by using broodstock selected for a divergent life history?

Evol Appl. 2012 Nov;5(7):705-19

Authors: Seamons TR, Hauser L, Naish KA, Quinn TP

Abstract
TWO STRATEGIES HAVE BEEN PROPOSED TO AVOID NEGATIVE GENETIC EFFECTS OF ARTIFICIALLY PROPAGATED INDIVIDUALS ON WILD POPULATIONS: (i) integration of wild and captive populations to minimize domestication selection and (ii) segregation of released individuals from the wild population to minimize interbreeding. We tested the efficacy of the strategy of segregation by divergent life history in a steelhead trout, Oncorhynchus mykiss, system, where hatchery fish were selected to spawn months earlier than the indigenous wild population. The proportion of wild ancestry smolts and adults declined by 10-20% over the three generations since the hatchery program began. Up to 80% of the naturally produced steelhead in any given year were hatchery/wild hybrids. Regression model selection analysis showed that the proportion of hatchery ancestry smolts was lower in years when stream discharge was high, suggesting a negative effect of flow on reproductive success of early-spawning hatchery fish. Furthermore, proportions of hybrid smolts and adults were higher in years when the number of naturally spawning hatchery-produced adults was higher. Divergent life history failed to prevent interbreeding when physical isolation was ineffective, an inadequacy that is likely to prevail in many other situations.

PMID: 23144657 [PubMed – in process]

via pubmed: school of aquatic an… http://www.ncbi.nlm.nih.gov/PubMed/23144657?dopt=Abstract