Poster Presentation Society for Molecular Biology and Evolution Conference 2016

Sand dunes drive asymmetric gene flow between arid-zone Thick-billed grasswren subspecies (#535)

Amy L Slender 1 , Marina Louter 1 , Tessa Bradford 1 2 , Michael G Gardner 1 2 , Sonia Kleindorfer 1
  1. Flinders University, Adelaide, SA, Australia
  2. South Australian Regional Facility for Molecular Evolution and Ecology, Adelaide, SA, Australia

Gene flow is a useful tool for understanding evolutionary processes such as genetic drift and natural selection. This is because gene flow is limited across geographic barriers that cause genetic drift or by genetic incompatibilities that develop due to natural selection. The Thick-billed grasswren (Amytornis modestus) is one species which show evidence of limited gene flow. Two arid zone subspecies of this threatened species have a parapatric distribution but show 1.7% mitochondiral divergence on either side of a 50km wide divide that runs between the South Australian salt lakes, Lake Eyre and Lake Torrens. Thick-billed grasswrens do not occur on sand dunes yet there are many sand dunes within this divide. Therefore this study investigates whether sand dunes are a barrier to gene flow between the two subspecies, A. m. indulkanna, which occurs to the west of the divide and A. m. raglessi, which occurs to the east. We identified approximately 3000 SNPs using genotype by sequencing (GBS) methodologies and then measured gene flow between 65 individuals to the east of the sand dunes and 37 individuals to the west. Preliminary results showed that the genotypes of individuals within the divide but to the east of the sand dunes were predominantly A. m. raglessi but were introgressed with genotypes of A. m. indulkanna indicating that limited gene flow is occurring across the sand dunes between Thick-billed grasswren subspecies. Introgressed individuals were only found to the east of the sand dunes suggesting that gene flow is asymmetric across the sand dunes from the west (A. m. indulkanna) into the east (A. m. raglessi). In the past, sand dunes were likely to be more abundant and may have been a substantial geographic barrier to gene flow that meant isolated populations were effected by genetic drift.