Profiles

Johan Fredrik Wallén

Johan Fredrik Wallén

Forskningsbiträde

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Works at Department of Zoology
Telephone 08-16 40 34
Email johan.wallen@zoologi.su.se
Visiting address Svante Arrheniusväg 18 B
Room D 151
Postal address Zoologiska institutionen: Ekologi 106 91 Stockholm

Publications

A selection from Stockholm University publication database
  • 2018. Johan Wallén (et al.). Biological Journal of the Linnean Society 124 (4), 621-632

    Understanding the response of boreal species to past climate warming can help to predict future responses to climate change. In the Northern Hemisphere, the distribution and abundance of northern populations have been influenced by previous glaciations. In this study, we investigated the population history of the Fennoscandian red fox (Vulpes vulpes), which is a generalist carnivore currently undergoing range expansion in the tundra ecosystem. By analysing a 696 bp sequence of the mitochondrial DNA (N = 259) and two Y chromosome-specific microsatellite loci (N = 120), we specifically investigated where the red fox survived the Last Glacial Maximum and how Fennoscandia was recolonized. There was high genetic continuity across most of Fennoscandia, and we identified at least two recolonization pathways: one from continental Europe and one from the northeast (Siberia). Mitochondrial haplotype diversity displayed a significant decline with increasing latitude, consistent with expectations of unidirectional colonization. Each region displayed signatures of recent demographic and/or range expansions. For Finland, an additional recolonization route was suggested from the mismatch distribution analysis and identification of novel haplotypes. We concluded that, as with many boreal generalist species, the Fennoscandian red fox originates from multiple refugia, suggesting that it has benefited from diverse evolutionary histories, potentially enhancing its tolerance to different habitat conditions.

  • 2017. Karin Norén (et al.). Polar Research 36 (suppl. 1)

    Three decades have passed since the Arctic fox (Vulpes lagopus) was first put into a population genetic perspective. With the aim of addressing how microevolution operates on different biological levels, we here review genetic processes in the Arctic fox at the level of species, populations and individuals. Historical and present dispersal patterns, especially in the presence of sea ice, are the most powerful factors that create a highly homogeneous genetic structure across the circumpolar distribution, with low detectable divergence between the coastal and lemming ecotypes. With dispersal less pronounced or absent, other processes emerge; populations that are currently isolated, for example, because of the lack of sea ice, are genetically divergent. Moreover, small populations generally display signatures of genetic drift, inbreeding, inbreeding depression and, under specific situations, hybridization with domestic fox breeds. Mating system and social organization in the Arctic fox appear to be determined by the ecological context, with complex mating patterns and social groups being more common under resource-rich conditions. In isolated populations, complex social groups and inbreeding avoidance have been documented. We emphasize the value of genetic data to decipher many previously unknown aspects of Arctic fox biology, while these data also raise numerous questions that remain unanswered. Pronounced intra-specific ecological variation makes the Arctic fox an ideal study organism for population genetic processes and the emergence of functional genomics will generate an even deeper understanding of evolution, ecology and conservation issues for several species.

  • 2017. Bodil Elmhagen (et al.).
  • 2016. Karin Norén (et al.). Conservation Genetics
  • 2015. Rasmus Erlandsson (et al.). Härjedalen
Show all publications by Johan Fredrik Wallén at Stockholm University

Last updated: October 29, 2018

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