FishBase 2014: Mats Grahn
Channel: Fishbase Sweden
Date: 19/12/2014

Mats Grahn, Södertörn University, Stockholm, Sweden, gave a lecture on "Fishing for population structure with genomic markers".

Abstract: The architecture of gene organization into genomes imply that selection pressures from environmental factors and neutral genetic processes as genetic drift, mutation, recombination and gene flow will affect regions of the genome differently. These processes are explored in population genomics scans, mostly as a way to detect genetic regions under divergent selection in relation to environmental factors. I will present the result from some studies where we have used the same kind of methods and data to make inferences about population structure and about the nature and impact of environmental factors by estimating the potential for local adaptation. The projects have mostly used Amplified Fragment Length Polymorhism, AFLP to study the population structure in several species of fish, stickleback, salmons, mullets and Siganides. Evolutionary adaptation require intra-specific genetic diversity and genetic diversity and population genetic structure may affect the persistence of species and ecosystems by increased resistance to disturbances. Findings by us and others show that rapid change at the genomic level can occur in local populations and allow for local adaptation probably also in high gene flow situations. 
I will also argue that genomic analyses of wild populations can potentially be more effective than screening for the occurrence of tolerant individuals in populations affected by environmental change. Several recent examples suggest that adaptation can involve multiple and distinct regions of the genome and highlights the danger of extrapolating from studies involving a limited number of genetic markers, and reinforces the notion that local demographic history and population-level variability are important factors influencing the ability to adapt to changing environments.

This abstract draws on the work presented in the following three PhD thesis, and all authors should be credited for the above:
Oskar Henriksson, 2013. Genetic connectivity of fish in the Western Indian Ocean. Stockholm University
Emma Lind, 2013, Genetic response to pollution in sticklebacks; natural selection in the wild, Stockholm University
Jakob Lohm, 2002, MHC and genomic diversity in Atlantic salmon (Salmo salar L.). Lund University.


FishBase is the world's largest encyclopedia of fish, freely available on the net. The Swedish office every year holds an annual public symposium on a current theme related to fish biology, fish systematics and fish ecology. FishBase Symposium 2014 was held in Stockholm, Monday 20th October, in the Main Auditorium of the Swedish Museum of Natural History, and the theme was "Fishes and Genes". Molecular biology is increasingly a vital part of the study and management of fish, and seven invited experts gave talks different facets of Fishes and Genes.