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<p>Habitat fragmentation is a key driver of reduced genetic connectivity and loss of genetic variation among populations, elevating the risk of inbreeding depression and reduced adaptive potential. The black-throated finch (<i>Poephila cincta</i>) is an endemic Australian finch with two recognised subspecies, a northern (<i>P. c. atropygialis</i>) and southern form (<i>P. c. cincta</i>) separated by a biogeographic barrier in northern Australia. The southern subspecies is nationally endangered and has experienced severe range contractions since the rise of pastoralism, with only two stronghold populations remaining (Townsville Coastal Plain and Desert Uplands Bioregion). Using a panel of more than 14,000 genome-wide single nucleotide polymorphisms for 107 individuals, we characterised spatial genetic structure for the Desert Uplands population. We mapped effective migration surfaces and tested for isolation by resistance to identify potential barriers to gene flow, estimated contemporary effective population sizes and reconstructed the demographic history of this population. We found evidence of restricted gene flow between localities only 16&#xa0;km apart and strong isolation by geographic distance. Landscape resistance modelling identified areas of suitable woodland habitat that facilitated effective dispersal. More restricted gene flow in the southern range of this population is likely influenced by the fragmentation of suitable vegetation communities. Contemporary effective population sizes were near or below 1000, and we detected two historical population bottlenecks (&gt; 50% decline) occurring around 60–100 and 700 years ago. Given recent evidence that the Desert Uplands population is genetically isolated from the only other stronghold population in Townsville, the results of this study suggest future losses of genetic diversity and adaptive potential may continue without effective management. To improve the long-term persistence of southern-black throated finch across their range, prioritising the conservation and restoration of habitat that promotes genetic connectivity is essential.</p>

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Historical bottlenecks and restricted gene flow in one of the last remaining stronghold populations of the southern black-throated finch (Poephila cincta cincta)

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月15日

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  • Skye Davis,
  • Adam J. Stow,
  • Jemma McCrossin,
  • Wilbur Ashley,
  • John M. van Osta,
  • Brad Dreis,
  • Simon C. Griffith

摘要

Habitat fragmentation is a key driver of reduced genetic connectivity and loss of genetic variation among populations, elevating the risk of inbreeding depression and reduced adaptive potential. The black-throated finch (Poephila cincta) is an endemic Australian finch with two recognised subspecies, a northern (P. c. atropygialis) and southern form (P. c. cincta) separated by a biogeographic barrier in northern Australia. The southern subspecies is nationally endangered and has experienced severe range contractions since the rise of pastoralism, with only two stronghold populations remaining (Townsville Coastal Plain and Desert Uplands Bioregion). Using a panel of more than 14,000 genome-wide single nucleotide polymorphisms for 107 individuals, we characterised spatial genetic structure for the Desert Uplands population. We mapped effective migration surfaces and tested for isolation by resistance to identify potential barriers to gene flow, estimated contemporary effective population sizes and reconstructed the demographic history of this population. We found evidence of restricted gene flow between localities only 16 km apart and strong isolation by geographic distance. Landscape resistance modelling identified areas of suitable woodland habitat that facilitated effective dispersal. More restricted gene flow in the southern range of this population is likely influenced by the fragmentation of suitable vegetation communities. Contemporary effective population sizes were near or below 1000, and we detected two historical population bottlenecks (> 50% decline) occurring around 60–100 and 700 years ago. Given recent evidence that the Desert Uplands population is genetically isolated from the only other stronghold population in Townsville, the results of this study suggest future losses of genetic diversity and adaptive potential may continue without effective management. To improve the long-term persistence of southern-black throated finch across their range, prioritising the conservation and restoration of habitat that promotes genetic connectivity is essential.