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<p>Anthropogenic impacts threaten biodiversity, sometimes necessitating the establishment of insurance populations through translocation. Ideally such populations provide a robust means to maintain a threatened species and its genetic diversity. This study investigates the genetic diversity and integrity of translocated populations of the freshwater fish, Pedder galaxias (<i>Galaxias pedderensis</i>), and contrasts their genetic diversity with related species. <i>Galaxias pedderensis</i> was once abundant in Lake Pedder, Tasmania, but declined following the artificial raising of water levels for hydroelectricity generation in 1972. This resulted in habitat modification and the invasion of brown trout (<i>Salmo trutta</i>) and climbing galaxias (<i>Galaxias brevipinnis</i>), both considered threats to other galaxiid fishes through predation and competition. In 1991, prior to <i>G. pedderensis</i> extirpation in Lake Pedder, a translocated population was established based on 45 individuals, then in 2001 a second (serial) translocated population was established from the first. We examined genetic diversity in both translocated populations using double digest restriction-site associated DNA sequencing. The two <i>G. pedderensis</i> populations had similar levels of heterozygosity and low genetic differentiation, indicating that there is desirable replication of standing genetic variation. <i>Galaxias pedderensis</i> showed lower heterozygosity than the widespread and common <i>G. brevipinnis</i>, but higher heterozygosity than swan galaxias (<i>Galaxias fontanus</i>), another translocated endangered species, potentially reflecting differences in the duration of their low abundances. We also tested and found evidence of introgression from <i>G. brevipinnis</i> into <i>G. pedderensis</i>, but this may pre-date their anthropogenic contact. This research can inform future genetic management of <i>G. pedderensis</i>, including ongoing exchange and sourcing of individuals for any additional translocated populations.</p>

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Evaluating genetic diversity, population structure, and introgression in insurance populations of one of Australia’s most threatened species: the freshwater fish Galaxias pedderensis

  • 期刊论文

  • 发表日期：

    2025年11月28日

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  • Kayleigh Horner,
  • Charlotte Jense,
  • Elize Y. X. Ng,
  • Rob Freeman,
  • Bruce Deagle,
  • Christopher P. Burridge

摘要

Anthropogenic impacts threaten biodiversity, sometimes necessitating the establishment of insurance populations through translocation. Ideally such populations provide a robust means to maintain a threatened species and its genetic diversity. This study investigates the genetic diversity and integrity of translocated populations of the freshwater fish, Pedder galaxias (Galaxias pedderensis), and contrasts their genetic diversity with related species. Galaxias pedderensis was once abundant in Lake Pedder, Tasmania, but declined following the artificial raising of water levels for hydroelectricity generation in 1972. This resulted in habitat modification and the invasion of brown trout (Salmo trutta) and climbing galaxias (Galaxias brevipinnis), both considered threats to other galaxiid fishes through predation and competition. In 1991, prior to G. pedderensis extirpation in Lake Pedder, a translocated population was established based on 45 individuals, then in 2001 a second (serial) translocated population was established from the first. We examined genetic diversity in both translocated populations using double digest restriction-site associated DNA sequencing. The two G. pedderensis populations had similar levels of heterozygosity and low genetic differentiation, indicating that there is desirable replication of standing genetic variation. Galaxias pedderensis showed lower heterozygosity than the widespread and common G. brevipinnis, but higher heterozygosity than swan galaxias (Galaxias fontanus), another translocated endangered species, potentially reflecting differences in the duration of their low abundances. We also tested and found evidence of introgression from G. brevipinnis into G. pedderensis, but this may pre-date their anthropogenic contact. This research can inform future genetic management of G. pedderensis, including ongoing exchange and sourcing of individuals for any additional translocated populations.