David Coates - Academia.edu (original) (raw)
Papers by David Coates
Nuytsia—The journal of the Western Australian Herbarium
Taxonomic research and the conservation status of flora in the Yilgarn Banded Iron Formation rang... more Taxonomic research and the conservation status of flora in the Yilgarn Banded Iron Formation ranges Nuytsia 17: 1-12 (2007) A special edition funded by the Western Australian Government's 'Saving our Species' biodiversity conservation initiative.
Genes
Phylogeographic studies can be used as a tool to understand the evolutionary history of a landsca... more Phylogeographic studies can be used as a tool to understand the evolutionary history of a landscape, including the major drivers of species distributions and diversity. Extensive research has been conducted on phylogeographic patterns of species found in northern hemisphere landscapes that were affected by glaciations, yet the body of literature for older, unaffected landscapes is still underrepresented. The Pilbara region of north-western Australia is an ancient and vast landscape that is topographically complex, consisting of plateaus, gorges, valleys, and ranges, and experiences extreme meteorological phenomena including seasonal cyclonic activity. These features are expected to influence patterns of genetic structuring throughout the landscape either by promoting or restricting the movement of pollen and seed. Whilst a growing body of literature exists for the fauna endemic to this region, less is known about the forces shaping the evolution of plant taxa. In this study we inves...
Frontiers in Ecology and Evolution, 2018
Failing to test multiple or non-standard variables in studies that investigate the effects of hab... more Failing to test multiple or non-standard variables in studies that investigate the effects of habitat fragmentation on plant populations may limit the detection of unexpected causative relationships. Here, we investigated the impacts of habitat fragmentation on the pollination, reproduction, mating system and progeny performance of Eucalyptus wandoo, a foundation tree that is bird and insect pollinated with a mixed-mating system. We explored a range of possible causative mechanisms, including soil properties that are likely to be altered in the agricultural matrix of a landscape that has naturally nutrient-poor soils and secondary soil salinization caused by the removal of native vegetation. We found very strong negative relationships between soil salinity and fruit production, thus providing some of the first evidence for the effects of salinity on reproduction in remnant plant populations. Additionally, we found unexpectedly higher rates of seedling survival in linear populations, most likely driven by increased soil P content from adjacent cereal cropping. Higher rates of seed germination in small populations were related to both higher pollen immigration and greater nutrient availability. Trees in small populations had unexpectedly much higher levels of pollination than in large populations, but they produced fewer seeds per fruit and outcrossing rates did not vary consistently with fragmentation. These results are consistent with small populations having much higher insect abundances but also increased rates of self-pollination, combined with seed abortion mechanisms that are common in the Myrtaceae. This study highlights the need to better understand and mitigate sub-lethal effects of secondary soil salinity in plants growing in agricultural remnants, and indicates that soil properties may play an important role in influencing seed quality.
Frontiers in Ecology and Evolution, 2018
Current approaches to biodiversity conservation are largely based on geographic areas, ecosystems... more Current approaches to biodiversity conservation are largely based on geographic areas, ecosystems, ecological communities, and species, with less attention on genetic diversity and the evolutionary continuum from populations to species. Conservation management generally rests on discrete categories, such as identified species, and, for threated taxa, intraspecific units. Species, in particular, provide a common measure of biodiversity yet in both theory and nature, speciation is typically a protracted process progressing from connected populations to unambiguous species with variable rates of phenotypic, ecological and genetic divergence. Thus, most recognized species are not genetically uniform and are sometimes highly structured into historically isolated populations worthy of consideration as intraspecific units that represent unique genetic diversity for conservation. Genome screens offer unprecedented resolution of structure across taxonomic boundaries in species complexes, and have the potential to oversplit species if not interpreted conservatively. This highlights the blurred line between populations and species, and can confound simple dichotomies of "species" vs. "not species." At the same time, like plants, there is increasing evidence that even distantly related animal species can hybridize and exchange genes. A review of conservation legislation reveals that legal definitions of "species" are quite flexible and can accommodate a range of infra-specifictaxa and divergent populations, as well as taxonomically recognized species. For example, the legislative definition of a species around the world can include: species, subspecies, varieties, and geographically and/or genetically distinct populations. In principle, this flexibility allows for protection of genetic diversity and maintenance of evolutionary processes at a broad range of infra-specific levels. However, evolutionary biologists often fail to adequately justify and then translate their evidence for genetically defined units into categories suited to assessment under local legislation. We recommend that (i) genomic data should be interpreted conservatively when formally naming species, (ii) concomitantly, there should be stronger impetus and a more uniform approach to identifying clearly justified intraspecific units, (iii) guidelines be developed for recognizing and labeling intraspecific data that align with best scientific practice, and (iv) that the more nuanced view of species and speciation emerging from genomic analyses is communicated more effectively by scientists to decision makers.
Plant Diversity, 2017
Australia is a large, old and flat island continent that became isolated following the breakup of... more Australia is a large, old and flat island continent that became isolated following the breakup of the Gondwanan super continent. After more than 40e50 M years of independent evolution, approx. 600,000 e700,000 species now call Australia home. More than 21,000 of these species are plants, with at least 84% of these being endemic. Plant taxa are protected, conserved and managed under a range of legislation at the State-and Territory-level as well as Federally for matters of national significance. This can create issues of misalignment among threatened species lists but generally there is cooperation among conservation agencies to reduce misalignments and to manage species irrespective of jurisdictional borders. Despite significant investment in programs designed to assist the recovery of Australian biodiversity, threatened plants in particular appear to be continuing to decline. This can be attributed to a range of factors including major threatening processes associated with habitat loss and invasive species, lack of public awareness of the cultural and socioeconomic value of plant conservation, and our relatively poor understanding of basic species taxonomy and biology, especially for those species that have specific interactions with pollinators, symbionts and herbivores. A recent shift in Federally-based conservation programs has been to identify 30 key plant species for recovery through the setting of measurable targets, improving the support provided to recovery teams and encouraging industry, business and philanthropy to support conservation actions.
Pacific Conservation Biology, 2011
Assisted Colonization (AC) has been proposed as one method of aiding species to adapt to the impa... more Assisted Colonization (AC) has been proposed as one method of aiding species to adapt to the impacts of climate change. AC is a form of translocation and translocation protocols for threatened species, mostly for reintroduction, are well established in Australia. We evaluate the information available from implementation of translocations to understand how existing policies and guidelines should be varied to plan, review and regulate AC. While the risks associated with AC are potentially greater than those of reintroductions, AC is likely to be the only available method, other than germplasm storage and establishment of captive populations, of conserving many taxa under future climate change. AC may also be necessary to maintain ecosystem services, particularly where keystone species are affected. Current policies and procedures for the preparation of Translocation Proposals will require modification and expansion to deal with Assisted Colonization, particularly in relation to risk m...
Botanical Journal of the Linnean Society, 2014
Effective conservation management should target appropriate conservation units, but evolutionaril... more Effective conservation management should target appropriate conservation units, but evolutionarily and genetically divergent lineages within nominal taxa are often unrecognized. The southwestern Australian biodiversity hotspot may harbour many cryptic taxa, as it contains many plant species with naturally fragmented population distributions. Using microsatellite markers, we tested the hypothesis that disjunct population groups in the rare species Eremophila microtheca and E. rostrata (Scrophulariaceae: Myoporeae) are highly genetically divergent and represent separate evolutionarily significant units (ESUs). Chromosome counts indicated that all individuals assessed were diploid (2n = 36). Genetic differentiation among disjunct population groups was highly significant (P < 0.001) for both E. microtheca (FST = 0.301-0.383; Dest = 0.756-0.774) and E. rostrata (FST = 0.325-0.346; Dest = 0.628-0.660), and was similar to their differentiation from allied species. These results, including high incidences of private alleles, suggest historical divergence among cryptic taxa within E. microtheca and E. rostrata. Population groups in E. rostrata have recently been taxonomically recognized as two subspecies. Our study suggests that E. microtheca should also be reassessed as two taxa or considered as two ESUs, and the southern occurrence should be listed as Critically Endangered. We suggest a precautionary approach for flora in this and similar landscapes, whereby historically wide geographical disjunctions are assumed to indicate separate units for conservation.
Heredity, 1999
Allozyme diversity was surveyed at 16 loci across 16 populations of the monospeci®c, but morpholo... more Allozyme diversity was surveyed at 16 loci across 16 populations of the monospeci®c, but morphologically diverse, endemic shrub Geleznowia verrucosa Turcz. (Rutaceae). Single-locus diversity measures portrayed G. verrucosa as a genetically depauperate genus (A, 1.4; P, 29.6%), with total genetic diversity (H T , 0.304) partitioned between populations (D ST , 0.175), rather than within (H S , 0.129). Some 58% of the total genetic diversity was attributable to interpopulational dierences. Although restricted distribution, bottlenecks and/or founder eects and small population size have probably contributed to the low levels of genetic diversity found within this genus, it is evident from this investigation that the genus is not monospeci®c. The partitioning of genetic diversity, and possible dierences in reproductive strategy, suggest that the small-and large-¯owered forms represent distinct taxa. Higher levels of divergence between the intermediate-form populations and increased heterozygosity at the Lap locus suggest that this form is of hybrid origin and has arisen through a series of hybrid events between the small and large forms.
Heredity, 2002
The Acacia acuminata complex is a group of woody shrubs and small trees comprised of three formal... more The Acacia acuminata complex is a group of woody shrubs and small trees comprised of three formally described taxa (A. oldfieldii, A. acuminata ssp. acuminata and ssp. burkittii) and two informal taxa ('small seed' and 'narrow phyllode') with contrasting geographical distributions within the southwest of Western Australia. In addition, a series of variant populations of possible hybrid origin exist. Population genetic structure was investigated in 25 populations representing the taxa and variants using 16 polymorphic allozyme loci. All taxa and variants exhibited relatively high levels of genetic variation compared with other woody angiosperms with similar geographic distributions. Levels of genetic diversity in the widely distributed ssp. burkittii and 'narrow phyllode' taxon were considerably higher (H e , 0.311
Heredity, 1999
Population genetic structure and the mating system were investigated in the endangered plant Lamb... more Population genetic structure and the mating system were investigated in the endangered plant Lambertia orbifolia. This species is geographically restricted with two disjunct groups of populations. Twelve out of 19 allozyme loci were polymorphic and four were suitable for mating system studies. Levels of genetic variation within populations were comparable to other long-lived woody shrub endemics. Genetic divergence between population groups was very high (D 0.252) and the F ST over all populations was 0.441. Gene¯ow estimates within population groups were low even though the maximum geographical distance between any pair of populations is 15 km and could be attributed to the localized movement of bird pollinators. Mating system studies on four populations showed consistently low levels of outcrossing, compared with other Proteaceae. Correlations of outcrossed paternity were moderately high and all were signi®cantly greater than zero. Values ranged from r p 0.33, in the two largest and very dense populations, to the highest value of r p 0.54 in a smaller low-density population. The current population genetic structure in L. orbifolia is probably the result of local extinction of intervening populations because of Pleistocene climatic change and increased aridity, and extended isolation of the two remnants. It is proposed that the phylogenetically distinct Narrikup population group be recognized as a separate conservation unit and be given high priority for conservation action.
Heredity, 1985
A temporal analysis of the chromosomal structure of the hybrid zone in the grasshopper Caledia ca... more A temporal analysis of the chromosomal structure of the hybrid zone in the grasshopper Caledia captive has revealed that, over a period of six generations, the position of the zone has remained unchanged when assessed in terms of chromosomal frequencies. In complete contrast however, chromosomal genotypic frequencies have changed dramatically and asymmetrically over the same period. The frequencies of chromosomal heterozygotes have been significantly reduced on one side of the zone accompanied by increases in the frequencies of homozygous metacentric chromosomes. These asymmetrical genotypic changes are also reflected in a complete reversal of the patterns of gametic disequilibria (Tr2) across the zone. It is proposed that undirectional selection has favoured a metacentric karyotype on one side of the zone during a major climatic change. The structure of the hybrid zone involves two major and independent features. First, as a secondary consequence of hybridisation, recombinational change in F1 hybrids disrupts the internal organisation within chromosomes. This results in the production of inviable F2 and backcross progeny and hence, explains the structure of the zone in terms of the sharp change in chromosomal frequencies. Secondly, the asymmetrical nature of the gametic disequilibria between chromosomes represents the direction of selection which favours an acrocentric Torresian karyotype in dry years and a metacentric Moreton karyotype during mesic years. Variation in both chromosome structure and embryonic weight is associated with the predictability of the environment. The acrocentric Torresian karyotype and its associated larger embryos are correlated with a univoltine life history in drier, unpredictable habitats. A similar pattern exists within the Moreton subspecies in the form of a chromosomal dine in S.E. Australia. At the southern limit of this dine the karyotype is totally acrocentric, the life history is univoltine and the embryos are the same weight as the Torresian. It is speculated that variation in chromosomal structure, in terms of the relationship between centromeres and telomeres, may provide a mechanism for altering cellular phenotype through changes in such factors as replication patterns or chromatin packaging which may act quite independently of the informational content of the chromosome.
Assessing the benefits and risks of translocations in changing environments: a genetic perspective
Evolutionary Applications, 2011
Conservation Biology, 2011
Many of the skills and resources associated with botanic gardens and arboreta, including plant ta... more Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed-bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing
The chromosomal component of reproductive isolation in the grasshopper Caledia captiva
Chromosoma, 1982
... Abstract. A comparison of chiasma distribution patterns between two chromosomal taxa, Moreton... more ... Abstract. A comparison of chiasma distribution patterns between two chromosomal taxa, Moreton and Torresian, and their F1 hybrids demon-strates highly significant differences between all chromosomes analysed. ... 1. Moreton taxon acrocentric X population (MAX). Fig. ...
Biological Conservation, 2001
A fundamental role of government conservation agencies is to set priorities for the conservation ... more A fundamental role of government conservation agencies is to set priorities for the conservation and management of biodiversity. This is particulary important in an area such as Western Australia which has a rich and highly endemic¯ora with over 11,000 listed native vascular plants. Legislation provides an initial focus for priority setting through the listing and protection of threatened¯ora, although this excludes over 1900 Western Australian plant taxa which are poorly known but may be of conservation signi®cance. The priority setting process for the conservation of this¯ora, discussed herein, focuses on single taxa, groups of taxa within geographic regions, populations and threatening processes. This process is particularly applicable to the highly diverse and endemic ora of the southwest Botanical Province. Within this region there has been extensive habitat loss and degradation over the last 100 years. Currently the prioritisation process has identi®ed 95 critically endangered taxa in the southwest which require immediate remedial action to prevent extinction. Actions such as translocations are already showing promise, but with this number of critically endangered taxa and limited resources there may also need to be some ranking of taxa for immediate translocation. Although the priority setting process outlined here relates primarily to taxa, we emphasise that the conservation of this¯ora is also addressed at ecosystem and ecological community levels, and that each approach has its merits depending upon land tenure, location within the State and, in particular, the level of land degradation.
Australian Journal of Botany, 2000
Conservation of Australian plants depends on a spectrum of activities from descriptive and experi... more Conservation of Australian plants depends on a spectrum of activities from descriptive and experimental biological studies to active management and restoration of wild ecosystems by local communities who value their native biota. On the basis of the premise that available resources for conservation will not allow for all threatened biodiversity to be saved, some systematists and conservation geneticists argue that phylogenetic relationships should be used to set conservation priorities. The principle advocated is that characters, not species number, should become the currency of conservation, that cladistic analysis of phylogenetic pattern provides a predictive means of modelling the underlying distribution of characters among taxa, and that priority should be given to that subset of taxa with the greatest number of character states. This approach has been applied for some time in the conservation of genetic resources within species (e.g. Eucalyptus caesia), and has been an extra im...
American Journal of Botany, 2003
The Stylidium caricifolium (Stylidiaceae) complex consists of seven currently recognized species ... more The Stylidium caricifolium (Stylidiaceae) complex consists of seven currently recognized species and a taxon of putative hybrid origin endemic to southwest Western Australia. These taxa vary in geographical distribution from widespread, extending over a range of 500 km, to extremely localized, covering a range of only 0.5 km. Patterns of allozyme variation were investigated in 61 populations covering all taxa and two closely related species. Measures of genetic diversity were consistently lower and in some cases significantly lower in four rare and geographically restricted taxa compared with their widespread relatives. In contrast, genetic diversity in two other localized taxa was comparable or higher than in the widespread taxa. The level of divergence among populations was moderate to high, with a significant trend of higher F ST values for the widespread species to lower values for the geographically restricted and rare taxa. Phylogenetic relationships and levels of divergence indicate that most taxa are probably relictual rather than recently evolved. Geographical localization and rarity in this complex can be attributed to a range of factors associated with habitat specificity, historical and ecological processes that characterize the southwest region, and mode of origin.
Conservation of the Kwongan Flora: Threats and Challenges
Heredity, 1992
The genetic consequences of a bottleneck, and the spatial genetic structure within and between po... more The genetic consequences of a bottleneck, and the spatial genetic structure within and between populations, were studied in the rare and geographically restricted species Stylidium coroniforme. Thirteen out of 15 allozyme loci analysed were polymorphic. The level of polymorphism was relatively high for an insect-pollinated outcrossing species. In one population, which was subjected to a prolonged decline in numbers resulting in a bottleneck, probably of three plants, there was no measurable reduction in either allelic diversity of average heterozygosity. Maintenance of heterozygosity in this population could be attributed to rapid recovery after the bottleneck, the progressive elimination of selfed or otherwise inbred products during seed development and selection favouring heterozygotes as plants mature. Evidence for the latter was a significant decrease in the fixation index from younger (F= 0.28) to older plants (F= 0.14). Bottleneck-flush cycles are considered to be a major factor contributing to the relatively high level of differentiation observed between the three Wongan Hills populations, which suggests that the bottleneck observed was not atypical for these populations. The allozyme divergence between the two population systems within this taxon (D = 0.29) may be indicative of two different but morphologically cryptic species. Spatial autocorrelation techniques revealed no spatial genetic structure in one population sampled at its maximum density. It was concluded that high levels of genetic diversity in small populations are typical of S. coroniforme, which is relatively short lived, disturbance-adapted and has population systems which probably undergo frequent bottleneck-flush cycles.
Nuytsia—The journal of the Western Australian Herbarium
Taxonomic research and the conservation status of flora in the Yilgarn Banded Iron Formation rang... more Taxonomic research and the conservation status of flora in the Yilgarn Banded Iron Formation ranges Nuytsia 17: 1-12 (2007) A special edition funded by the Western Australian Government's 'Saving our Species' biodiversity conservation initiative.
Genes
Phylogeographic studies can be used as a tool to understand the evolutionary history of a landsca... more Phylogeographic studies can be used as a tool to understand the evolutionary history of a landscape, including the major drivers of species distributions and diversity. Extensive research has been conducted on phylogeographic patterns of species found in northern hemisphere landscapes that were affected by glaciations, yet the body of literature for older, unaffected landscapes is still underrepresented. The Pilbara region of north-western Australia is an ancient and vast landscape that is topographically complex, consisting of plateaus, gorges, valleys, and ranges, and experiences extreme meteorological phenomena including seasonal cyclonic activity. These features are expected to influence patterns of genetic structuring throughout the landscape either by promoting or restricting the movement of pollen and seed. Whilst a growing body of literature exists for the fauna endemic to this region, less is known about the forces shaping the evolution of plant taxa. In this study we inves...
Frontiers in Ecology and Evolution, 2018
Failing to test multiple or non-standard variables in studies that investigate the effects of hab... more Failing to test multiple or non-standard variables in studies that investigate the effects of habitat fragmentation on plant populations may limit the detection of unexpected causative relationships. Here, we investigated the impacts of habitat fragmentation on the pollination, reproduction, mating system and progeny performance of Eucalyptus wandoo, a foundation tree that is bird and insect pollinated with a mixed-mating system. We explored a range of possible causative mechanisms, including soil properties that are likely to be altered in the agricultural matrix of a landscape that has naturally nutrient-poor soils and secondary soil salinization caused by the removal of native vegetation. We found very strong negative relationships between soil salinity and fruit production, thus providing some of the first evidence for the effects of salinity on reproduction in remnant plant populations. Additionally, we found unexpectedly higher rates of seedling survival in linear populations, most likely driven by increased soil P content from adjacent cereal cropping. Higher rates of seed germination in small populations were related to both higher pollen immigration and greater nutrient availability. Trees in small populations had unexpectedly much higher levels of pollination than in large populations, but they produced fewer seeds per fruit and outcrossing rates did not vary consistently with fragmentation. These results are consistent with small populations having much higher insect abundances but also increased rates of self-pollination, combined with seed abortion mechanisms that are common in the Myrtaceae. This study highlights the need to better understand and mitigate sub-lethal effects of secondary soil salinity in plants growing in agricultural remnants, and indicates that soil properties may play an important role in influencing seed quality.
Frontiers in Ecology and Evolution, 2018
Current approaches to biodiversity conservation are largely based on geographic areas, ecosystems... more Current approaches to biodiversity conservation are largely based on geographic areas, ecosystems, ecological communities, and species, with less attention on genetic diversity and the evolutionary continuum from populations to species. Conservation management generally rests on discrete categories, such as identified species, and, for threated taxa, intraspecific units. Species, in particular, provide a common measure of biodiversity yet in both theory and nature, speciation is typically a protracted process progressing from connected populations to unambiguous species with variable rates of phenotypic, ecological and genetic divergence. Thus, most recognized species are not genetically uniform and are sometimes highly structured into historically isolated populations worthy of consideration as intraspecific units that represent unique genetic diversity for conservation. Genome screens offer unprecedented resolution of structure across taxonomic boundaries in species complexes, and have the potential to oversplit species if not interpreted conservatively. This highlights the blurred line between populations and species, and can confound simple dichotomies of "species" vs. "not species." At the same time, like plants, there is increasing evidence that even distantly related animal species can hybridize and exchange genes. A review of conservation legislation reveals that legal definitions of "species" are quite flexible and can accommodate a range of infra-specifictaxa and divergent populations, as well as taxonomically recognized species. For example, the legislative definition of a species around the world can include: species, subspecies, varieties, and geographically and/or genetically distinct populations. In principle, this flexibility allows for protection of genetic diversity and maintenance of evolutionary processes at a broad range of infra-specific levels. However, evolutionary biologists often fail to adequately justify and then translate their evidence for genetically defined units into categories suited to assessment under local legislation. We recommend that (i) genomic data should be interpreted conservatively when formally naming species, (ii) concomitantly, there should be stronger impetus and a more uniform approach to identifying clearly justified intraspecific units, (iii) guidelines be developed for recognizing and labeling intraspecific data that align with best scientific practice, and (iv) that the more nuanced view of species and speciation emerging from genomic analyses is communicated more effectively by scientists to decision makers.
Plant Diversity, 2017
Australia is a large, old and flat island continent that became isolated following the breakup of... more Australia is a large, old and flat island continent that became isolated following the breakup of the Gondwanan super continent. After more than 40e50 M years of independent evolution, approx. 600,000 e700,000 species now call Australia home. More than 21,000 of these species are plants, with at least 84% of these being endemic. Plant taxa are protected, conserved and managed under a range of legislation at the State-and Territory-level as well as Federally for matters of national significance. This can create issues of misalignment among threatened species lists but generally there is cooperation among conservation agencies to reduce misalignments and to manage species irrespective of jurisdictional borders. Despite significant investment in programs designed to assist the recovery of Australian biodiversity, threatened plants in particular appear to be continuing to decline. This can be attributed to a range of factors including major threatening processes associated with habitat loss and invasive species, lack of public awareness of the cultural and socioeconomic value of plant conservation, and our relatively poor understanding of basic species taxonomy and biology, especially for those species that have specific interactions with pollinators, symbionts and herbivores. A recent shift in Federally-based conservation programs has been to identify 30 key plant species for recovery through the setting of measurable targets, improving the support provided to recovery teams and encouraging industry, business and philanthropy to support conservation actions.
Pacific Conservation Biology, 2011
Assisted Colonization (AC) has been proposed as one method of aiding species to adapt to the impa... more Assisted Colonization (AC) has been proposed as one method of aiding species to adapt to the impacts of climate change. AC is a form of translocation and translocation protocols for threatened species, mostly for reintroduction, are well established in Australia. We evaluate the information available from implementation of translocations to understand how existing policies and guidelines should be varied to plan, review and regulate AC. While the risks associated with AC are potentially greater than those of reintroductions, AC is likely to be the only available method, other than germplasm storage and establishment of captive populations, of conserving many taxa under future climate change. AC may also be necessary to maintain ecosystem services, particularly where keystone species are affected. Current policies and procedures for the preparation of Translocation Proposals will require modification and expansion to deal with Assisted Colonization, particularly in relation to risk m...
Botanical Journal of the Linnean Society, 2014
Effective conservation management should target appropriate conservation units, but evolutionaril... more Effective conservation management should target appropriate conservation units, but evolutionarily and genetically divergent lineages within nominal taxa are often unrecognized. The southwestern Australian biodiversity hotspot may harbour many cryptic taxa, as it contains many plant species with naturally fragmented population distributions. Using microsatellite markers, we tested the hypothesis that disjunct population groups in the rare species Eremophila microtheca and E. rostrata (Scrophulariaceae: Myoporeae) are highly genetically divergent and represent separate evolutionarily significant units (ESUs). Chromosome counts indicated that all individuals assessed were diploid (2n = 36). Genetic differentiation among disjunct population groups was highly significant (P < 0.001) for both E. microtheca (FST = 0.301-0.383; Dest = 0.756-0.774) and E. rostrata (FST = 0.325-0.346; Dest = 0.628-0.660), and was similar to their differentiation from allied species. These results, including high incidences of private alleles, suggest historical divergence among cryptic taxa within E. microtheca and E. rostrata. Population groups in E. rostrata have recently been taxonomically recognized as two subspecies. Our study suggests that E. microtheca should also be reassessed as two taxa or considered as two ESUs, and the southern occurrence should be listed as Critically Endangered. We suggest a precautionary approach for flora in this and similar landscapes, whereby historically wide geographical disjunctions are assumed to indicate separate units for conservation.
Heredity, 1999
Allozyme diversity was surveyed at 16 loci across 16 populations of the monospeci®c, but morpholo... more Allozyme diversity was surveyed at 16 loci across 16 populations of the monospeci®c, but morphologically diverse, endemic shrub Geleznowia verrucosa Turcz. (Rutaceae). Single-locus diversity measures portrayed G. verrucosa as a genetically depauperate genus (A, 1.4; P, 29.6%), with total genetic diversity (H T , 0.304) partitioned between populations (D ST , 0.175), rather than within (H S , 0.129). Some 58% of the total genetic diversity was attributable to interpopulational dierences. Although restricted distribution, bottlenecks and/or founder eects and small population size have probably contributed to the low levels of genetic diversity found within this genus, it is evident from this investigation that the genus is not monospeci®c. The partitioning of genetic diversity, and possible dierences in reproductive strategy, suggest that the small-and large-¯owered forms represent distinct taxa. Higher levels of divergence between the intermediate-form populations and increased heterozygosity at the Lap locus suggest that this form is of hybrid origin and has arisen through a series of hybrid events between the small and large forms.
Heredity, 2002
The Acacia acuminata complex is a group of woody shrubs and small trees comprised of three formal... more The Acacia acuminata complex is a group of woody shrubs and small trees comprised of three formally described taxa (A. oldfieldii, A. acuminata ssp. acuminata and ssp. burkittii) and two informal taxa ('small seed' and 'narrow phyllode') with contrasting geographical distributions within the southwest of Western Australia. In addition, a series of variant populations of possible hybrid origin exist. Population genetic structure was investigated in 25 populations representing the taxa and variants using 16 polymorphic allozyme loci. All taxa and variants exhibited relatively high levels of genetic variation compared with other woody angiosperms with similar geographic distributions. Levels of genetic diversity in the widely distributed ssp. burkittii and 'narrow phyllode' taxon were considerably higher (H e , 0.311
Heredity, 1999
Population genetic structure and the mating system were investigated in the endangered plant Lamb... more Population genetic structure and the mating system were investigated in the endangered plant Lambertia orbifolia. This species is geographically restricted with two disjunct groups of populations. Twelve out of 19 allozyme loci were polymorphic and four were suitable for mating system studies. Levels of genetic variation within populations were comparable to other long-lived woody shrub endemics. Genetic divergence between population groups was very high (D 0.252) and the F ST over all populations was 0.441. Gene¯ow estimates within population groups were low even though the maximum geographical distance between any pair of populations is 15 km and could be attributed to the localized movement of bird pollinators. Mating system studies on four populations showed consistently low levels of outcrossing, compared with other Proteaceae. Correlations of outcrossed paternity were moderately high and all were signi®cantly greater than zero. Values ranged from r p 0.33, in the two largest and very dense populations, to the highest value of r p 0.54 in a smaller low-density population. The current population genetic structure in L. orbifolia is probably the result of local extinction of intervening populations because of Pleistocene climatic change and increased aridity, and extended isolation of the two remnants. It is proposed that the phylogenetically distinct Narrikup population group be recognized as a separate conservation unit and be given high priority for conservation action.
Heredity, 1985
A temporal analysis of the chromosomal structure of the hybrid zone in the grasshopper Caledia ca... more A temporal analysis of the chromosomal structure of the hybrid zone in the grasshopper Caledia captive has revealed that, over a period of six generations, the position of the zone has remained unchanged when assessed in terms of chromosomal frequencies. In complete contrast however, chromosomal genotypic frequencies have changed dramatically and asymmetrically over the same period. The frequencies of chromosomal heterozygotes have been significantly reduced on one side of the zone accompanied by increases in the frequencies of homozygous metacentric chromosomes. These asymmetrical genotypic changes are also reflected in a complete reversal of the patterns of gametic disequilibria (Tr2) across the zone. It is proposed that undirectional selection has favoured a metacentric karyotype on one side of the zone during a major climatic change. The structure of the hybrid zone involves two major and independent features. First, as a secondary consequence of hybridisation, recombinational change in F1 hybrids disrupts the internal organisation within chromosomes. This results in the production of inviable F2 and backcross progeny and hence, explains the structure of the zone in terms of the sharp change in chromosomal frequencies. Secondly, the asymmetrical nature of the gametic disequilibria between chromosomes represents the direction of selection which favours an acrocentric Torresian karyotype in dry years and a metacentric Moreton karyotype during mesic years. Variation in both chromosome structure and embryonic weight is associated with the predictability of the environment. The acrocentric Torresian karyotype and its associated larger embryos are correlated with a univoltine life history in drier, unpredictable habitats. A similar pattern exists within the Moreton subspecies in the form of a chromosomal dine in S.E. Australia. At the southern limit of this dine the karyotype is totally acrocentric, the life history is univoltine and the embryos are the same weight as the Torresian. It is speculated that variation in chromosomal structure, in terms of the relationship between centromeres and telomeres, may provide a mechanism for altering cellular phenotype through changes in such factors as replication patterns or chromatin packaging which may act quite independently of the informational content of the chromosome.
Assessing the benefits and risks of translocations in changing environments: a genetic perspective
Evolutionary Applications, 2011
Conservation Biology, 2011
Many of the skills and resources associated with botanic gardens and arboreta, including plant ta... more Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed-bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing
The chromosomal component of reproductive isolation in the grasshopper Caledia captiva
Chromosoma, 1982
... Abstract. A comparison of chiasma distribution patterns between two chromosomal taxa, Moreton... more ... Abstract. A comparison of chiasma distribution patterns between two chromosomal taxa, Moreton and Torresian, and their F1 hybrids demon-strates highly significant differences between all chromosomes analysed. ... 1. Moreton taxon acrocentric X population (MAX). Fig. ...
Biological Conservation, 2001
A fundamental role of government conservation agencies is to set priorities for the conservation ... more A fundamental role of government conservation agencies is to set priorities for the conservation and management of biodiversity. This is particulary important in an area such as Western Australia which has a rich and highly endemic¯ora with over 11,000 listed native vascular plants. Legislation provides an initial focus for priority setting through the listing and protection of threatened¯ora, although this excludes over 1900 Western Australian plant taxa which are poorly known but may be of conservation signi®cance. The priority setting process for the conservation of this¯ora, discussed herein, focuses on single taxa, groups of taxa within geographic regions, populations and threatening processes. This process is particularly applicable to the highly diverse and endemic ora of the southwest Botanical Province. Within this region there has been extensive habitat loss and degradation over the last 100 years. Currently the prioritisation process has identi®ed 95 critically endangered taxa in the southwest which require immediate remedial action to prevent extinction. Actions such as translocations are already showing promise, but with this number of critically endangered taxa and limited resources there may also need to be some ranking of taxa for immediate translocation. Although the priority setting process outlined here relates primarily to taxa, we emphasise that the conservation of this¯ora is also addressed at ecosystem and ecological community levels, and that each approach has its merits depending upon land tenure, location within the State and, in particular, the level of land degradation.
Australian Journal of Botany, 2000
Conservation of Australian plants depends on a spectrum of activities from descriptive and experi... more Conservation of Australian plants depends on a spectrum of activities from descriptive and experimental biological studies to active management and restoration of wild ecosystems by local communities who value their native biota. On the basis of the premise that available resources for conservation will not allow for all threatened biodiversity to be saved, some systematists and conservation geneticists argue that phylogenetic relationships should be used to set conservation priorities. The principle advocated is that characters, not species number, should become the currency of conservation, that cladistic analysis of phylogenetic pattern provides a predictive means of modelling the underlying distribution of characters among taxa, and that priority should be given to that subset of taxa with the greatest number of character states. This approach has been applied for some time in the conservation of genetic resources within species (e.g. Eucalyptus caesia), and has been an extra im...
American Journal of Botany, 2003
The Stylidium caricifolium (Stylidiaceae) complex consists of seven currently recognized species ... more The Stylidium caricifolium (Stylidiaceae) complex consists of seven currently recognized species and a taxon of putative hybrid origin endemic to southwest Western Australia. These taxa vary in geographical distribution from widespread, extending over a range of 500 km, to extremely localized, covering a range of only 0.5 km. Patterns of allozyme variation were investigated in 61 populations covering all taxa and two closely related species. Measures of genetic diversity were consistently lower and in some cases significantly lower in four rare and geographically restricted taxa compared with their widespread relatives. In contrast, genetic diversity in two other localized taxa was comparable or higher than in the widespread taxa. The level of divergence among populations was moderate to high, with a significant trend of higher F ST values for the widespread species to lower values for the geographically restricted and rare taxa. Phylogenetic relationships and levels of divergence indicate that most taxa are probably relictual rather than recently evolved. Geographical localization and rarity in this complex can be attributed to a range of factors associated with habitat specificity, historical and ecological processes that characterize the southwest region, and mode of origin.
Conservation of the Kwongan Flora: Threats and Challenges
Heredity, 1992
The genetic consequences of a bottleneck, and the spatial genetic structure within and between po... more The genetic consequences of a bottleneck, and the spatial genetic structure within and between populations, were studied in the rare and geographically restricted species Stylidium coroniforme. Thirteen out of 15 allozyme loci analysed were polymorphic. The level of polymorphism was relatively high for an insect-pollinated outcrossing species. In one population, which was subjected to a prolonged decline in numbers resulting in a bottleneck, probably of three plants, there was no measurable reduction in either allelic diversity of average heterozygosity. Maintenance of heterozygosity in this population could be attributed to rapid recovery after the bottleneck, the progressive elimination of selfed or otherwise inbred products during seed development and selection favouring heterozygotes as plants mature. Evidence for the latter was a significant decrease in the fixation index from younger (F= 0.28) to older plants (F= 0.14). Bottleneck-flush cycles are considered to be a major factor contributing to the relatively high level of differentiation observed between the three Wongan Hills populations, which suggests that the bottleneck observed was not atypical for these populations. The allozyme divergence between the two population systems within this taxon (D = 0.29) may be indicative of two different but morphologically cryptic species. Spatial autocorrelation techniques revealed no spatial genetic structure in one population sampled at its maximum density. It was concluded that high levels of genetic diversity in small populations are typical of S. coroniforme, which is relatively short lived, disturbance-adapted and has population systems which probably undergo frequent bottleneck-flush cycles.