PremiseThe distribution of genetic diversity on the landscape has critical ecological and evoluti... more PremiseThe distribution of genetic diversity on the landscape has critical ecological and evolutionary implications. This may be especially the case on a local scale for foundation plant species because they create and define ecological communities, contributing disproportionately to ecosystem function.MethodsWe examined the distribution of genetic diversity and clones, which we defined first as unique multilocus genotypes (MLG), and then by grouping similar MLGs into multilocus lineages. We used 186 markers from inter‐simple sequence repeats (ISSR) across 358 ramets from 13 patches of the foundation grass Leymus chinensis. We examined the relationship between genetic and clonal diversities, their variation with patch size, and the effect of the number of markers used to evaluate genetic diversity and structure in this species.ResultsEvery ramet had a unique MLG. Almost all patches consisted of individuals belonging to a single multilocus lineages. We confirmed this with a clusterin...
Better understanding and prediction of tree growth is important because of the many ecosystem ser... more Better understanding and prediction of tree growth is important because of the many ecosystem services provided by forests and the uncertainty surrounding how forests will respond to anthropogenic climate change. With the ultimate goal of improving models of forest dynamics, here we construct a statistical model that combines complementary data sources – tree-ring and forest inventory data. A Bayesian hierarchical model is used to gain inference on the effects of many factors on tree growth – individual tree size, climate, biophysical conditions, stand-level competitive environment, tree-level canopy status, and forest management treatments – using both diameter at breast height (DBH) and tree-ring data. The model consists of two multiple regression models, one each for the two data sources, linked via a constant of proportionality between coefficients that are found in parallel in the two regressions. The model was applied to a dataset developed at a single, well-studied site in th...
Evolutionary radiations with extreme levels of diversity present a unique opportunity to study th... more Evolutionary radiations with extreme levels of diversity present a unique opportunity to study the role of the environment in plant evolution. If environmental adaptation played an important role in such radiations, we expect to find associations between functional traits and key climatic variables. Similar trait-environment associations across clades may reflect common responses, while contradictory associations may suggest lineage-specific adaptations. Here, we explore trait-environment relationships in two evolutionary radiations in the fynbos biome of the highly biodiverse Cape Floristic Region (CFR) of South Africa. Protea and Pelargonium are morphologically and evolutionarily diverse genera that typify the CFR yet are substantially different in growth form and morphology. Our analytical approach employs a Bayesian multiple-response generalized linear mixed-effects model, taking into account covariation among traits and controlling for phylogenetic relationships. Of the pairwise trait-environment associations tested, 6 out of 24 were in the same direction and 2 out of 24 were in opposite directions, with the latter apparently reflecting alternative life-history strategies. These findings demonstrate that trait diversity within two plant lineages may reflect both parallel and idiosyncratic responses to the environment, rather than all taxa conforming to a global-scale pattern. Such insights are essential for understanding how trait-environment associations arise and how they influence species diversification.
Abstract The evolution of a selectively neutral locus that controls the degree to which alleles a... more Abstract The evolution of a selectively neutral locus that controls the degree to which alleles at a single selected locus are linked with a particular set of chromosomes in a permanent translocation heterozygote is studied. With complete selfing and fitness overdominance a new allele at the modifying locus will increase in frequency if it increases the linkage of all alleles at the selected locus to a particular set of chromosomes. With random mating a new allele at the modifying locus will increase when rare if it increases the linkage of alleles at ...
Adaptive radiations likely underlie much of the world’s diversity, especially that of hyper‐diver... more Adaptive radiations likely underlie much of the world’s diversity, especially that of hyper‐diverse regions. They are usually characterized by a burst of speciation early in their evolutionary history, a pattern which can be detected using population genetic tools. The Cape Floristic Region (CFR) of southwestern South Africa is home to many spectacular plant radiations. Here, we investigate the white proteas (Protea section Exsertae), a typical CFR radiation, to determine if it demonstrates the burst of speciation associated with adaptive radiations in recent models. Inferences from individual assignment, tree‐based population relationships, and pairwise F‐statistics based on 10 microsatellite loci reveal that while the white proteas radiated recently they did not radiate explosively. In addition, we found evidence that there is little gene flow between sampled populations of most species. Taken together, these results demonstrate that within a small clade, the processes underlying ...
The goal of this work was to determine whether mating system differences induced by environmental... more The goal of this work was to determine whether mating system differences induced by environmental differences affect the amount and distribution of genetic variability in Impatiens capensis, an herbaceous species characterized by a mixed mating system. All individuals of this species produce cleistogamous Żowers, whereas Keywords: gene Żow;
Recent studies of mating system evolution have attempted to include aspects of pollination biolog... more Recent studies of mating system evolution have attempted to include aspects of pollination biology in analysis of both theoretical models and experimental systems. In light of this growing trend, we propose a simple population genetic model for the evolution of gametophytic self‐incompatibility, incorporating parameters for pollen discounting and pollen export/capture. In this model, we consider several cases that span the spectrum for dominance of the mutant self‐incompatibility allele and for the degree of incompatibility conferred by the allele. We confirm earlier results that inbreeding depression is required for successful invasion of the self‐incompatibility allele and we demonstrate that, unless pollen discounting is very low, the level of inbreeding depression must be very high for an allele conferring self‐incompatibility to become established. Finally, we show that the dominance of the mutant allele has a greater impact on the fate of a newly arisen self‐incompatibility al...
Copyright® 1996 by Chapman & Hall Printed in the United States of America For mor... more Copyright® 1996 by Chapman & Hall Printed in the United States of America For more information contact: Chapman & Hall 115 Fifth Avenue New York, NY 10003 Thomas Nelson Australia 102 Dodds Street South Melbourne, 3205 Victoria, Australia International Thomson Editores ...
PremiseThe distribution of genetic diversity on the landscape has critical ecological and evoluti... more PremiseThe distribution of genetic diversity on the landscape has critical ecological and evolutionary implications. This may be especially the case on a local scale for foundation plant species because they create and define ecological communities, contributing disproportionately to ecosystem function.MethodsWe examined the distribution of genetic diversity and clones, which we defined first as unique multilocus genotypes (MLG), and then by grouping similar MLGs into multilocus lineages. We used 186 markers from inter‐simple sequence repeats (ISSR) across 358 ramets from 13 patches of the foundation grass Leymus chinensis. We examined the relationship between genetic and clonal diversities, their variation with patch size, and the effect of the number of markers used to evaluate genetic diversity and structure in this species.ResultsEvery ramet had a unique MLG. Almost all patches consisted of individuals belonging to a single multilocus lineages. We confirmed this with a clusterin...
Better understanding and prediction of tree growth is important because of the many ecosystem ser... more Better understanding and prediction of tree growth is important because of the many ecosystem services provided by forests and the uncertainty surrounding how forests will respond to anthropogenic climate change. With the ultimate goal of improving models of forest dynamics, here we construct a statistical model that combines complementary data sources – tree-ring and forest inventory data. A Bayesian hierarchical model is used to gain inference on the effects of many factors on tree growth – individual tree size, climate, biophysical conditions, stand-level competitive environment, tree-level canopy status, and forest management treatments – using both diameter at breast height (DBH) and tree-ring data. The model consists of two multiple regression models, one each for the two data sources, linked via a constant of proportionality between coefficients that are found in parallel in the two regressions. The model was applied to a dataset developed at a single, well-studied site in th...
Evolutionary radiations with extreme levels of diversity present a unique opportunity to study th... more Evolutionary radiations with extreme levels of diversity present a unique opportunity to study the role of the environment in plant evolution. If environmental adaptation played an important role in such radiations, we expect to find associations between functional traits and key climatic variables. Similar trait-environment associations across clades may reflect common responses, while contradictory associations may suggest lineage-specific adaptations. Here, we explore trait-environment relationships in two evolutionary radiations in the fynbos biome of the highly biodiverse Cape Floristic Region (CFR) of South Africa. Protea and Pelargonium are morphologically and evolutionarily diverse genera that typify the CFR yet are substantially different in growth form and morphology. Our analytical approach employs a Bayesian multiple-response generalized linear mixed-effects model, taking into account covariation among traits and controlling for phylogenetic relationships. Of the pairwise trait-environment associations tested, 6 out of 24 were in the same direction and 2 out of 24 were in opposite directions, with the latter apparently reflecting alternative life-history strategies. These findings demonstrate that trait diversity within two plant lineages may reflect both parallel and idiosyncratic responses to the environment, rather than all taxa conforming to a global-scale pattern. Such insights are essential for understanding how trait-environment associations arise and how they influence species diversification.
Abstract The evolution of a selectively neutral locus that controls the degree to which alleles a... more Abstract The evolution of a selectively neutral locus that controls the degree to which alleles at a single selected locus are linked with a particular set of chromosomes in a permanent translocation heterozygote is studied. With complete selfing and fitness overdominance a new allele at the modifying locus will increase in frequency if it increases the linkage of all alleles at the selected locus to a particular set of chromosomes. With random mating a new allele at the modifying locus will increase when rare if it increases the linkage of alleles at ...
Adaptive radiations likely underlie much of the world’s diversity, especially that of hyper‐diver... more Adaptive radiations likely underlie much of the world’s diversity, especially that of hyper‐diverse regions. They are usually characterized by a burst of speciation early in their evolutionary history, a pattern which can be detected using population genetic tools. The Cape Floristic Region (CFR) of southwestern South Africa is home to many spectacular plant radiations. Here, we investigate the white proteas (Protea section Exsertae), a typical CFR radiation, to determine if it demonstrates the burst of speciation associated with adaptive radiations in recent models. Inferences from individual assignment, tree‐based population relationships, and pairwise F‐statistics based on 10 microsatellite loci reveal that while the white proteas radiated recently they did not radiate explosively. In addition, we found evidence that there is little gene flow between sampled populations of most species. Taken together, these results demonstrate that within a small clade, the processes underlying ...
The goal of this work was to determine whether mating system differences induced by environmental... more The goal of this work was to determine whether mating system differences induced by environmental differences affect the amount and distribution of genetic variability in Impatiens capensis, an herbaceous species characterized by a mixed mating system. All individuals of this species produce cleistogamous Żowers, whereas Keywords: gene Żow;
Recent studies of mating system evolution have attempted to include aspects of pollination biolog... more Recent studies of mating system evolution have attempted to include aspects of pollination biology in analysis of both theoretical models and experimental systems. In light of this growing trend, we propose a simple population genetic model for the evolution of gametophytic self‐incompatibility, incorporating parameters for pollen discounting and pollen export/capture. In this model, we consider several cases that span the spectrum for dominance of the mutant self‐incompatibility allele and for the degree of incompatibility conferred by the allele. We confirm earlier results that inbreeding depression is required for successful invasion of the self‐incompatibility allele and we demonstrate that, unless pollen discounting is very low, the level of inbreeding depression must be very high for an allele conferring self‐incompatibility to become established. Finally, we show that the dominance of the mutant allele has a greater impact on the fate of a newly arisen self‐incompatibility al...
Copyright® 1996 by Chapman & Hall Printed in the United States of America For mor... more Copyright® 1996 by Chapman & Hall Printed in the United States of America For more information contact: Chapman & Hall 115 Fifth Avenue New York, NY 10003 Thomas Nelson Australia 102 Dodds Street South Melbourne, 3205 Victoria, Australia International Thomson Editores ...
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Papers by Kent Holsinger