Abstract
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Island biogeography and landscape genetics offer valuable insights into species evolution during extended periods of isolation. In this study, we applied these concepts to explore genetic diversity and gene flow among populations of Eriocaulon species in isolated springs associated with the Great Artesian Basin (GAB) in Australia. The GAB groundwater discharges from small springs in a vast arid and semiarid region, creating clusters of wetlands that harbor isolated populations of endemic taxa.
We focused on E. carsonii subsp. orientale, and two microendemics, E. giganticum, and E. aloefolium, using dd-RADSeq data from eight populations of E. carsonii subsp. orientale, considering differences in ploidy. Our findings revealed varying levels of genetic diversity and inbreeding across the populations. Habitats consisting of sub-population clusters showed higher genetic diversity compared to single populations, with E. aloefolium exhibiting greater genetic diversity and lower inbreeding than E. giganticum.
The non-GAB population used in the study displayed elevated genetic diversity and negative inbreeding levels, indicating recent admixture from distinct colonization events or significant expansion. Limited admixture between populations from different complexes and high genetic differentiation (Fst) suggested minimal gene flow between these populations. These results provide valuable insights into genetic diversity and gene flow patterns in plant populations across the GAB, indicating that the ancestor of Eriocaulon carsonii was already isolated in the springs before the aridification of Australia around 4-6 million years ago. Understanding the evolutionary history and long-term persistence of these species within the isolated springs of the Great Artesian Basin emphasizes the importance of maintaining genetic diversity and connectivity among populations for the continued survival of these unique taxa.
Keywords: Great Artesian Basin, springs, Eriocaulon, genetics.
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