Limited phylogeographic and genetic connectivity in Acacia species of low stature in an arid landscape. Issue 7 (6th July 2022)

• Record Type: Journal Article
• Authors: Millar, Melissa A.; Binks, Rachel M.; Tapper, Sarah‐Louise; Macdonald, Bronwyn M.; McArthur, Shelley L.; Hankinson, Margaret; Coates, David J.; van Leeuwen, Stephen; Byrne, Margaret
• Is Part Of: Ecology and evolution. Volume 12:Issue 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-06
• Subjects: Acacia -- arid zone -- genetic connectivity -- genetic diversity -- Pilbara -- stature; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.9052
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Widespread plant species are expected to maintain genetic diversity and gene flow via pollen and seed dispersal. Stature is a key life history trait that affects seed and potentially pollen dispersal, with limited stature associated with limited dispersal and greater genetic differentiation. We sampled Hill's tabletop wattle ( Acacia hilliana ) and curry wattle ( Acacia spondylophylla ), two co‐distributed, widespread, Acacia shrubs of low stature, across the arid Pilbara region of north‐western Australia. Using chloroplast sequence and nuclear microsatellite data we evaluated patterns of population genetic and phylogeographic diversity and structure, demographic signals, ratios of pollen to seed dispersal, evidence for historical refugia, and association between elevation and diversity. Results showed strong phylogeographic (chloroplast, G ST = 0.831 and 0.898 for A. hilliana and A. spondylophylla, respectively) and contemporary (nuclear, F ST = 0.260 and 0.349 for A. hilliana and A. spondylophylla, respectively) genetic structure in both species. This indicates limited genetic connectivity via seed and pollen dispersal associated with Acacia species of small stature compared to taller tree and shrub acacias across the Pilbara bioregion. This effect of stature on genetic structure is superimposed on moderate levels of genetic diversity that were expected based on widespread ranges (haplotype diversity h = 25 and 12; nuclear diversity H e = 0.60 and 0.47 for A. hilliana and A. spondylophylla, respectively). Contemporary genetic structure was congruent at the greater landscape scale, especially in terms of strong genetic differentiation among geographically disjunct populations in less elevated areas. Measures of diversity and connectivity were associated with traits of greater geographic population proximity, population density, population size, and greater individual longevity, and some evidence for range expansion in A. hilliana . Results illustrate that low stature is associated with limited dispersal and greater patterns of genetic differentiation for congenerics in a common landscape and highlight the complex influence of taxon‐specific life history and ecological traits to seed and pollen dispersal. Abstract : We assessed phylogeographic and population genetic diversity and structure in two Acacia shrubs of low stature with widespread ranges and co‐distributions across the arid Pilbara region of north‐western Australia: Hill's tabletop wattle ( Acacia hilliana ) and curry wattle ( Acacia spondylophylla ). Both species showed strong phylogeographic and contemporary genetic structure indicating reduced genetic connectivity when compared to taller shrub and tree Acacias in the Pilbara but maintained levels of genetic diversity comparable to that of other widespread Acacia