Southern introgression increases adaptive immune gene variability in northern range margin populations of Fire-bellied toad

Binia De Cahsan, Katrin Kiemel, Michael V. Westbury, Maike Lauritsen, Marijke Autenrieth, Günter Gollmann, Silke Schweiger, Marika Stenberg, Per Nyström, Hauke Drews, Ralph Tiedemann

Publications: Contribution to journalArticlePeer Reviewed

Abstract

Northern range margin populations of the European fire-bellied toad (Bombina bombina) have rapidly declined during recent decades. Extensive agricultural land use has fragmented the landscape, leading to habitat disruption and loss, as well as eutrophication of ponds. In Northern Germany (Schleswig-Holstein) and Southern Sweden (Skåne), this population decline resulted in decreased gene flow from surrounding populations, low genetic diversity, and a putative reduction in adaptive potential, leaving populations vulnerable to future environmental and climatic changes. Previous studies using mitochondrial control region and nuclear transcriptome-wide SNP data detected introgressive hybridization in multiple northern B. bombina populations after unreported release of toads from Austria. Here, we determine the impact of this introgression by comparing the body conditions (proxy for fitness) of introgressed and nonintrogressed populations and the genetic consequences in two candidate genes for putative local adaptation (the MHC II gene as part of the adaptive immune system and the stress response gene HSP70 kDa). We detected regional differences in body condition and observed significantly elevated levels of within individual MHC allele counts in introgressed Swedish populations, associated with a tendency toward higher body weight, relative to regional nonintrogressed populations. These differences were not observed among introgressed and nonintrogressed German populations. Genetic diversity in both MHC and HSP was generally lower in northern than Austrian populations. Our study sheds light on the potential benefits of translocations of more distantly related conspecifics as a means to increase adaptive genetic variability and fitness of genetically depauperate range margin populations without distortion of local adaptation.
Original languageEnglish
Pages (from-to)9776–9790
Number of pages15
JournalEcology and Evolution
Volume11
Issue number14
DOIs
Publication statusPublished - 27 Jun 2021

Austrian Fields of Science 2012

  • 106013 Genetics
  • 106012 Evolutionary research
  • 106054 Zoology

Keywords

  • Bombina bombina, heat shock protein, introgression, major histocompatibility complex, scaled mass index
  • EVOLUTIONARY
  • BODY CONDITION
  • Bombina bombina
  • heat shock protein
  • MAJOR HISTOCOMPATIBILITY COMPLEX
  • major histocompatibility complex
  • BOMBINA-BOMBINA
  • SEXUAL SELECTION
  • introgression
  • HAPLOTYPE RECONSTRUCTION
  • HEAT-SHOCK PROTEINS
  • CONSERVATION
  • NATURAL-SELECTION
  • scaled mass index
  • MHC CLASS-II

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