PEDIGREE STUDIES
In order to understand how populations evolve and how rapidly they can adapt to environmental change, we need to understand the genetic basis of the phenotypic variation on which selection acts. Pedigree-based analysis is a powerful framework for separating genetic and environmental effects on the phenotype and can provide insight into a range of important issues in evolutionary and conservation biology. However, pedigree studies of wild populations are few and restricted mainly to birds and mammals. Fish, and salmon in particular, provide unique study opportunities in many ways because of their high fecundity and interesting life histories. These features (e.g. high fecundity but massive mortality early in life, external fertilisation, lack of parental care once eggs are buried, population 'disappears' off into the ocean for half the life cycle) act as a double-edged sword, as they make it difficult to match offspring to their parents via physical tagging and behavioral observations. Recent advances in molecular genetics and computing power, however, now make it possible to reconstruct pedigrees using 'genetic markers' and fancy statistical machinery. This, along with the fact that so much is already known about the natural history of salmon, is opening the door for a new wave of studies on the evolutionary ecology of wild salmonid populations.
The Burrishoole Atlantic salmon system offers an excellent opportunity for reconstructing multi-generation pedigrees because of intensive sampling of the the population over four decades, facilitated by total trapping facilities. Together with our collaborators in Craig Primmer's lab in Finland, we have recently completed a pilot study where a partial pedigree was reconstructed using genetic material obtained from archived scale samples (Aykanat et al. 2014). In the near future we hope to flesh out this pedigree with data from more years, and the long-term goal is to continue collecting phenotypic data such as size at age, migration timing, years in freshwater, sea age, egg size, etc. These data can then be used for a range of interesting downstream analyses, such as the dissection of quantitative genetic architecture, estimation of rates of inbreeding and extent of inbreeding depression, determination of fitness components and relative lifetime reproductive success of wild versus ranched fish, and possibly even the detection of microevolutionary responses to environmental change.
Together with Scottish collaborators, we are also involved in a pedigree reconstruction project with Atlantic salmon from the Girnock Burn system in Aberdeenshire, which holds similar promise for evolutionary ecology studies as the Burrishoole system in Ireland.
References:
Pemberton, J. M. Wild pedigrees: the way forward. Proceedings of the Royal Society B: Biological Sciences 275, no. 1635 (2008): 613-621.
Aykanat,T., Johnston, S.E., Cotter, D, Cross, T.F., Poole, R., Prodőhl, P.A., Reed, T.E., Rogan,G., McGinnity,P, Primmer, C.R. Molecular pedigree reconstruction and estimation of evolutionary parameters in a wild Atlantic salmon river system with incomplete sampling: a power analysis. (2014) 14:68
In order to understand how populations evolve and how rapidly they can adapt to environmental change, we need to understand the genetic basis of the phenotypic variation on which selection acts. Pedigree-based analysis is a powerful framework for separating genetic and environmental effects on the phenotype and can provide insight into a range of important issues in evolutionary and conservation biology. However, pedigree studies of wild populations are few and restricted mainly to birds and mammals. Fish, and salmon in particular, provide unique study opportunities in many ways because of their high fecundity and interesting life histories. These features (e.g. high fecundity but massive mortality early in life, external fertilisation, lack of parental care once eggs are buried, population 'disappears' off into the ocean for half the life cycle) act as a double-edged sword, as they make it difficult to match offspring to their parents via physical tagging and behavioral observations. Recent advances in molecular genetics and computing power, however, now make it possible to reconstruct pedigrees using 'genetic markers' and fancy statistical machinery. This, along with the fact that so much is already known about the natural history of salmon, is opening the door for a new wave of studies on the evolutionary ecology of wild salmonid populations.
The Burrishoole Atlantic salmon system offers an excellent opportunity for reconstructing multi-generation pedigrees because of intensive sampling of the the population over four decades, facilitated by total trapping facilities. Together with our collaborators in Craig Primmer's lab in Finland, we have recently completed a pilot study where a partial pedigree was reconstructed using genetic material obtained from archived scale samples (Aykanat et al. 2014). In the near future we hope to flesh out this pedigree with data from more years, and the long-term goal is to continue collecting phenotypic data such as size at age, migration timing, years in freshwater, sea age, egg size, etc. These data can then be used for a range of interesting downstream analyses, such as the dissection of quantitative genetic architecture, estimation of rates of inbreeding and extent of inbreeding depression, determination of fitness components and relative lifetime reproductive success of wild versus ranched fish, and possibly even the detection of microevolutionary responses to environmental change.
Together with Scottish collaborators, we are also involved in a pedigree reconstruction project with Atlantic salmon from the Girnock Burn system in Aberdeenshire, which holds similar promise for evolutionary ecology studies as the Burrishoole system in Ireland.
References:
Pemberton, J. M. Wild pedigrees: the way forward. Proceedings of the Royal Society B: Biological Sciences 275, no. 1635 (2008): 613-621.
Aykanat,T., Johnston, S.E., Cotter, D, Cross, T.F., Poole, R., Prodőhl, P.A., Reed, T.E., Rogan,G., McGinnity,P, Primmer, C.R. Molecular pedigree reconstruction and estimation of evolutionary parameters in a wild Atlantic salmon river system with incomplete sampling: a power analysis. (2014) 14:68