Conservation significance of island versus mainland populations: a case study of dibblers (<i>Parantechinus apicalis</i>) in Western Australia

Mills, Harriet; Moro, Dorian; Spencer, Peter B. S.

doi:10.1017/s1367943004001568

Cited by 41 publications

(33 citation statements)

References 66 publications

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“…This observation is consistent with previous findings in other species (Eldridge et al 2004;Mills et al 2004;Boessenkool et al 2007), emphasizing that mainland populations are likely to retain more of the evolutionary potential necessary for long-term persistence (Frankham 1997;Lacy 1997;Frankham et al 2002). The low genetic differentiation observed between the DWN and Kakadu National Park populations (Table 4b; Fig.…”

Section: Mainland Populationssupporting

confidence: 92%

“…As population size decreases, a number of genetic and environmental factors are likely to drive individual populations to extinction . The genetic effects of translocations can sometimes be exacerbated when animals are taken to islands (Eldridge et al 1999), with the major concern being that island populations, through isolation and genetic drift, are more prone to extinction due to genetic erosion than their mainland counterparts (Frankham 1997;Eldridge et al 2004;Mills et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Effects of founder events on the genetic variation of translocated island populations: implications for conservation management of the northern quoll

Cardoso

Eldridge

Oakwood³

et al. 2008

Conserv Genet

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Translocation is a strategy commonly used to maximize the persistence of threatened species, but it may sometimes lead to undesirable genetic consequences. The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that is critically endangered in Australia's Northern Territory due to rapid population declines in areas recently colonized by the exotic cane toad Chaunus [Bufo] marinus. In 2003, 64 quolls were translocated to two offshore islands to establish insurance populations and reduce the species' risk of extinction. In this study, we assessed genetic diversity at five microsatellite loci in the translocated populations, two endemic islands and three mainland populations. In the short-term (three generations), the translocated populations showed a slight but non-significant reduction in genetic diversity (A = 4.1-4.2; H e = 0.56-0.59) compared to the mainland source populations (A = 5.0-8.4; H e = 0.56-0.71). In comparison, high genetic erosion was observed in the endemic island populations (A = 1.5-2.9; H e = 0.11-0.34). Genetic bottlenecks were detected on both endemic islands and in one mainland population, indicating recent reductions in population size. Our results are consistent with previous studies describing greater losses of genetic diversity on islands compared to mainland populations. Divergence from ancestral allele frequencies in the translocated populations also suggests effects due to founder events. This study, although short-term, highlights the importance of continued monitoring for detecting changes in genetic diversity over time and makes a significant contribution to our understanding of the effects of founder events on island populations.

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Section: Mainland Populationssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Effects of founder events on the genetic variation of translocated island populations: implications for conservation management of the northern quoll

Cardoso

Eldridge

Oakwood³

et al. 2008

Conserv Genet

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“…Several islands showed mode-shift distortions in their allele frequencies, consistent with genetic signatures expected under a population bottleneck (Luikart et al 1998;Mills et al 2004). A loss of rare alleles on continental islands is a likely event due to small founder sizes at the time of isolation, followed by prolonged periods of low effective population size (Nei et al 1975).…”

Section: Genetic Variation Within Island Populationssupporting

confidence: 67%

“…The significant genetic bottleneck observed within the Irvine Island population following fire shows that environmental stochasticity can have a substantial impact on these populations, leading to a loss of rare alleles and an overall reduction in genetic variability. The many vertebrate species that are less abundant than Ct. inornatus, or have intrinsic characteristics that impact mortality, may be even more susceptible to the effects of environmental change (Mills et al 2004). As a result, the increased intensity or frequency of disturbance events poses a considerable threat to island populations.…”

Section: Population Differentiation Among Island and Mainland Populatmentioning

confidence: 99%

Island size and remoteness have major conservation significance for how spatial diversity is partitioned in skinks

et al. 2015

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Islands are often acknowledged as a refuge for species with declining mainland distributions. However, as the finite size of islands coupled with isolation can lead to genetic deterioration within insular populations, the study of these systems is of great interest to the conservation of biological diversity and persistence. The remote Kimberley region in Western Australia is facing increased impacts from invasive species, habitat fragmentation, grazing, mining and altered fire regimes, and many of the 2633 islands in the Kimberley have come into focus as a significant conservation resource. The Barshouldered skink (Ctenotus inornatus) is a habitat generalist that is highly abundant throughout the Kimberley and its diverse islands. This study encompasses 41 islands and seven mainland populations in the vast Kimberley environment, and genetically characterises them using 18 nuclear (microsatellite) markers. The island populations lost heterozygosity at a rate of 1 % per kilometre from the mainland. Diversity was significantly lower on islands of small size (\500 ha) and greater than 2 km from the coastline. The scope of this study is unparalleled and addresses an important gap in our understanding of the genetic diversity throughout ecosystems. The findings illustrate how populations, operating within these pristine island systems, conform to the general rule of decreased genetic diversity with decreasing island area and increased distance from the mainland and identifies islands that may hold the most potential for conserving biodiversity.

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“…Freudenthal 1972;Prothero & Sereno 1982;Ganem et al 1995;Capasso Barbato & Petronio 1986;Nor 1996;Mills et al 2004;Meiri et al 2006). Nevertheless, the "island rule" continues to be a key topic in island biogeography.…”

Section: Introductionmentioning

confidence: 99%

Body size structure of Pleistocene mammalian communities: what support is there for the “island rule”?

Palombo

2009

Integrative Zoology

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Islands are often regarded by scientists as living laboratories of evolution and an optimal context for the study of forces influencing evolution and diversification. Two main issues have been attentively scrutinized and debated: the loss of biodiversity and the peculiar changes undergone by island settlers, primarily changes in size of endemic vertebrates. Over time, several hypotheses have been formulated to explain the causal mechanism of body size modification. Faunas of those islands where mainland taxa migrate more than once provide the most interesting data to answer the question of whether or not trends of insular taxa result from a predictable response to differences in competition and availability of niches between insular and mainland environments. To contribute to the debate, the body size structure of the Pleistocene mammalian faunas from two Mediterranean islands, Sicily and Crete, were analyzed and compared with the structure of coeval mainland faunas. The results obtained suggest that: (i) size of endemic species does not directly depend on the area of islands; (ii) evolution and size of endemic species seems somewhat affected by the degree of isolation (constraining colonization from mainland) and physiography (sometimes permitting adaptive radiation); (iii) in unbalanced insular communities, the shift in size of non-carnivorous species largely depends on the nature of competing species; and (iv) body size of carnivorous species mainly depends on the size of the most available prey. Consequently, it is rational to suppose that the body size of insular mammals mainly results from the peculiar biological dynamics that characterizes unbalanced insular communities. Ecological interaction, particularly the intraguild competition, is the major driver behind the evolution of insular communities, leading towards an optimization of energy balance through a change in body size of endemic settlers.

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Conservation significance of island versus mainland populations: a case study of dibblers (Parantechinus apicalis) in Western Australia

Cited by 41 publications

References 66 publications

Effects of founder events on the genetic variation of translocated island populations: implications for conservation management of the northern quoll

Effects of founder events on the genetic variation of translocated island populations: implications for conservation management of the northern quoll

Island size and remoteness have major conservation significance for how spatial diversity is partitioned in skinks

Body size structure of Pleistocene mammalian communities: what support is there for the “island rule”?

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