Abstract:Habitat fragmentation is affecting greater numbers of species as human land use requirements increase. Melaleuca irbyana R.T.Baker (Myrtaceae) is an endangered tea tree which dominates critically endangered, south-east Queensland swamp tea tree forest. It is restricted to isolated populations in south-east Queensland. New disjunct populations have recently been found adjacent to gas pipeline developments in the Brigalow Belt in central Queensland. A population genetics study was undertaken on the species to in… Show more
“…Habitat loss and fragmentation are globally significant causes of biodiversity loss (Fahrig, 2003 ; Krauss et al., 2010 ; Wilson et al., 2016 ). As a result, previously widespread and connected plant populations can become small and isolated (Burrough et al., 2018 ; Field et al., 2008 ; Hobbs & Yates, 2003 ; Young et al., 1996 ). While conservation strategies for threatened plant species generally rely on protection of habitats, maintenance of genetic diversity and gene flow is critical for long‐term persistence and should be factored into species conservation plans (Bezemer et al., 2019 ; Ottewell et al., 2016 ; Ralls et al., 2018 ).…”
Habitat fragmentation can increase the chance of population bottlenecks and inbreeding, and may ultimately lead to reduced fitness and local extinction. Notelaea lloydii is a native olive species endemic to Australia and listed as vulnerable due to its restricted distribution. A recent molecular systematics study has revealed there might be some geographic structuring among N. lloydii populations. Therefore, we undertook a genome‐wide single nucleotide polymorphism (SNP) analysis to determine levels and patterns of genetic diversity, inbreeding and gene flow within and among N. lloydii populations in south‐eastern Queensland. Furthermore, as the reproductive phase of a plant's life history has a profound influence on genetic diversity, life history reproductive traits were also studied. Our SNP analysis revealed low genetic diversity, inbreeding and significant genetic structuring even among proximate populations. Results of a flower and fruit bagging experiment in two consecutive seasons revealed that N. lloydii produced many flowers but only a few fruits survived to maturity. There were no differences in bagged and un‐bagged flowering and fruiting rates, and therefore, we conclude that the high fruit abortion rate was probably due to inbreeding depression and/or suboptimal conditions, rather than pollinator availability and insect attack. Overall, results of this study indicate that the populations of N. lloydii are small, inbred and genetically isolated and represent unique management units that require local conservation management due to ongoing threats associated with urbanisation.
“…Habitat loss and fragmentation are globally significant causes of biodiversity loss (Fahrig, 2003 ; Krauss et al., 2010 ; Wilson et al., 2016 ). As a result, previously widespread and connected plant populations can become small and isolated (Burrough et al., 2018 ; Field et al., 2008 ; Hobbs & Yates, 2003 ; Young et al., 1996 ). While conservation strategies for threatened plant species generally rely on protection of habitats, maintenance of genetic diversity and gene flow is critical for long‐term persistence and should be factored into species conservation plans (Bezemer et al., 2019 ; Ottewell et al., 2016 ; Ralls et al., 2018 ).…”
Habitat fragmentation can increase the chance of population bottlenecks and inbreeding, and may ultimately lead to reduced fitness and local extinction. Notelaea lloydii is a native olive species endemic to Australia and listed as vulnerable due to its restricted distribution. A recent molecular systematics study has revealed there might be some geographic structuring among N. lloydii populations. Therefore, we undertook a genome‐wide single nucleotide polymorphism (SNP) analysis to determine levels and patterns of genetic diversity, inbreeding and gene flow within and among N. lloydii populations in south‐eastern Queensland. Furthermore, as the reproductive phase of a plant's life history has a profound influence on genetic diversity, life history reproductive traits were also studied. Our SNP analysis revealed low genetic diversity, inbreeding and significant genetic structuring even among proximate populations. Results of a flower and fruit bagging experiment in two consecutive seasons revealed that N. lloydii produced many flowers but only a few fruits survived to maturity. There were no differences in bagged and un‐bagged flowering and fruiting rates, and therefore, we conclude that the high fruit abortion rate was probably due to inbreeding depression and/or suboptimal conditions, rather than pollinator availability and insect attack. Overall, results of this study indicate that the populations of N. lloydii are small, inbred and genetically isolated and represent unique management units that require local conservation management due to ongoing threats associated with urbanisation.
Melaleuca deanei F.Muell. is a rare, serotinous shrub with a naturally restricted distribution centred over the sandstone ridges around Sydney. Sexual reproduction and seedling recruitment occur rarely, and plants appear to spread and persist largely by clonal root suckering. A potentially outcrossing breeding system, combined with extensive clonality, place M. deanei at a high risk of reproductive failure. Knowledge of the extent of its clonality and breeding system, and an understanding of the distribution and abundance of genetic diversity within and among its populations, will assist conservation management. The present study reports on the extent of clonality, breeding system, levels of genetic diversity, and population differentiation within small, medium and large populations of M. deanei from the northern and southern distribution regions. Multiple stems were found to comprise single genets up to ~10 m diameter on the ground and molecular evidence points to an outcrossing breeding system. Genetic diversity was positively correlated with population size and significant genetic differentiation was shown between northern and southern regions using clustering analyses. Recommendations for in situ and ex situ conservation management based on these results are provided.
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