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Aaron M. Ellison - One of the best experts on this subject based on the ideXlab platform.
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regime shifts and hysteresis in the pitcher plant microecosystem
Ecological Modelling, 2018Co-Authors: Matthew K Lau, Nicholas J. Gotelli, Benjamin Baiser, Amanda C Northrop, Aaron M. EllisonAbstract:Abstract Changes in environmental conditions can lead to rapid shifts in the state of an ecosystem (“regime shifts”), which, even after the environment has returned to previous conditions, subsequently recovers slowly to the previous state (“hysteresis”). Large spatial and temporal scales of dynamics, and the lack of frameworks linking observations to models, are challenges to understanding and predicting ecosystem responses to perturbations. The naturally-occurring microecosystem inside leaves of the northern pitcher plant (Sarracenia purpurea) exhibits oligotrophic and eutrophic states that can be induced by adding insect prey. Here, we further develop a model for simulating these dynamics, parameterize it using data from a prey addition experiment and conduct a sensitivity analysis to identify critical zones within the parameter space. Simulations illustrate that the microecosystem model displays regime shifts and hysteresis. Parallel results were observed in the plant itself after experimental enrichment with prey. Decomposition rate of prey was the main driver of system dynamics, including the time the system remains in an anoxic state and the rate of return to an oxygenated state. Biological oxygen demand influenced the shape of the system's return trajectory. The combination of simulated results, sensitivity analysis and use of empirical results to parameterize the model more precisely demonstrates that the Sarracenia microecosystem model displays behaviors qualitatively similar to models of larger ecological systems.
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regime shifts and hysteresis in the pitcher plant microecosystem
bioRxiv, 2018Co-Authors: Matthew K Lau, Nicholas J. Gotelli, Benjamin Baiser, Amanda C Northrop, Aaron M. EllisonAbstract:Changes in environmental conditions can lead to rapid shifts in ecosystem state ("regime shifts"), which subsequently returns slowly to the previous state ("hysteresis"). Large spatial and temporal scales of dynamics, and the lack of frameworks linking observations to models, are challenges to understanding and predicting ecosystem responses to perturbations. The naturally-occurring microecosystem inside leaves of the northern pitcher plant ( Sarracenia purpurea ) exhibits oligotrophic and eutrophic states that can be induced by adding insect "prey." Here, we further develop a model for simulating these dynamics, parameterize it using data from a prey addition experiment and conduct a sensitivity analysis to identify critical zones within the parameter space. Simulations illustrate that the microecosystem model displays regime shifts and hysteresis. Parallel results were observed in the plant itself after experimental enrichment with prey. Decomposition rate of prey was the main driver of system dynamics, including the time the system remains in an anoxic state and the rate of return to an oxygenated state. Biological oxygen demand influenced the shape of the system9s return trajectory. The combination of simulated results, sensitivity analysis and use of empirical results to parameterize the model more precisely demonstrates that the Sarracenia microecosystem model displays behaviors qualitatively similar to models of larger ecological systems.
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regime shifts and hysteresis in the Sarracenia microecosystem
bioRxiv, 2017Co-Authors: Matthew K Lau, Nicholas J. Gotelli, Benjamin Baiser, Amanda C Northrop, Aaron M. EllisonAbstract:Changes in environmental conditions can lead to rapid shifts in ecosystem state ("regime shifts"), which subsequently returns slowly to the previous state ("hysteresis"). Large spatial and temporal scales of dynamics, and the lack of frameworks linking observations to models, are challenges to understanding and predicting ecosystem responses to perturbations. The naturally-occurring microecosystem inside leaves of the northern pitcher plant ( Sarracenia purpurea ) exhibits oligotrophic and eutrophic states that can be induced by adding insect "prey." Here, we further develop a model for simulating these dynamics, parameterize it using data from a prey addition experiment and conduct a sensitivity analysis to identify critical zones within the parameter space. Simulations illustrate that the microecosystem model displays regime shifts and hysteresis. Parallel results were observed in the plant itself after experimental enrichment with prey. Decomposition rate of prey was the main driver of system dynamics, including the time the system remains in an anoxic state and the rate of return to an oxygenated state. Biological oxygen demand influenced the shape of the system9s return trajectory. The combination of simulated results, sensitivity analysis and use of empirical results to parameterize the model more precisely demonstrates that the Sarracenia microecosystem model displays behaviors qualitatively similar to models of larger ecological systems.
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regime shifts alternative states and hysteresis in the Sarracenia microecosystem
bioRxiv, 2016Co-Authors: Matthew K Lau, Nicholas J. Gotelli, Benjamin Baiser, Aaron M. EllisonAbstract:Changes in environmental conditions can lead to a rapid shift in the state of an ecosystem ("regime shift"), which subsequently returns to the previous state slowly, if ever ("hysteresis"). Studies of ecological regime shifts have been hampered by the large spatial and temporal scales over which they occur and the lack of a common framework linking observational and experimental data to models. The naturally-occurring aquatic micro-ecosystem inside leaves of the northern pitcher plant ( Sarracenia purpurea ) occurs in both oligotrophic and eutrophic states. These alternative states also can be induced experimentally by enriching oligotrophic pitchers with additional insect prey, which elevates oxygen demand by microbes and leads to rapid eutrophication. This regime shift of the Sarracenia micro-ecosystem has been modeled with discrete-time difference equations that include parameters for the photosynthetic rate of the pitcher plant, consequent diffusion of oxygen through the pitcher liquid, rate of prey input, and biological oxygen demand by microbes as they decompose and mineralize the prey. We elaborated the regime-shift model of the Sarracenia micro-ecosystem and used sensitivity analysis to identify the parameters that control most strongly the dynamics of the system as it switches between oligotrophic and eutrophic states. Three main findings emerged. 1) Simulations accurately captured the regime shift and subsequent hysteresis that follows from prey enrichment; 2) When modeled as a modified Hill function, the interaction of prey input and decomposition rates drove the regime shift; 3) The interaction between biological oxygen demand of the food web and decomposition rate yielded a threshold that altered the hysteresis dynamics, shifting the sign of the effect of increasing the oxygen demand parameter. Because the model of the Sarracenia micro-ecosystem displays behaviors that are qualitatively similar to larger scale models of dynamic systems, we suggest that the Sarracenia micro-ecosystem itself represents a valuable and scalable experimental system for studying ecological regime shifts.
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Phylogeny and Biogeography of the Carnivorous Plant Family Sarraceniaceae
2016Co-Authors: Aaron M. Ellison, Elena D Butler, Emily Jean Hicks, Robert F C Naczi, Patrick J Calie, Charles D Bell, Charles C DavisAbstract:The carnivorous plant family Sarraceniaceae comprises three genera of wetland-inhabiting pitcher plants: Darlingtonia in the northwestern United States, Sarracenia in eastern North America, and Heliamphora in northern South America. Hypotheses concerning the biogeographic history leading to this unusual disjunct distribution are controversial, in part because genus- and species-level phylogenies have not been clearly resolved. Here, we present a robust, species-rich phylogeny of Sarraceniaceae based on seven mitochondrial, nuclear, and plastid loci, which we use to illuminate this family’s phylogenetic and biogeographic history. The family and genera are monophyletic: Darlingtonia is sister to a clade consisting of Heliamphora+Sarracenia. Within Sarracenia, two clades were strongly supported: one consisting of S. purpurea, its subspecies, and S. rosea; the other consisting of nine species endemic to the southeastern United States. Divergence time estimates revealed that stem group Sarraceniaceae likely originated in South America 44–53 million years ago (Mya) (highest posterior density [HPD] estimate = 47 Mya). By 25–44 (HPD = 35) Mya, crown-group Sarraceniaceae appears to have been widespread across North and South America, and Darlingtonia (western North America) had diverged from Heliamphora+Sarracenia (eastern North America+South America). This disjunction and apparent range contraction is consistent with late Eocene cooling and aridification, which may have severed the continuity of Sarraceniaceae across much of North America. Sarracenia and Heliamphora subsequently diverged in the late Oligocene, 14–32 (HPD = 23) Mya, perhap
Bryan C. Carstens - One of the best experts on this subject based on the ideXlab platform.
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the carnivorous plant described as Sarracenia alata contains two cryptic species
Biological Journal of The Linnean Society, 2013Co-Authors: Bryan C. Carstens, Jordan D SatlerAbstract:Modern methods for species delimitation provide biologists with the power to detect cryptic diversity in nearly any system. To illustrate the application of such methods, we collected data (21 sequence loci) from a carnivorous plant in southeastern North America and applied several recently developed methods (Gaussian clustering, Structurama, BPP, spedeSTEM). The pale pitcher plant Sarracenia alata inhabits the southeastern USA along the northern coast of the Gulf of Mexico. Sarracenia alata populations are separated by the Mississippi River and Atchafalaya Basin, a known biogeographical barrier in this region, but the cohesiveness of S. alata as currently classified has not been tested rigorously. Multiple analytical approaches (including allelic clustering and species trees methods) suggest that S. alata comprises two cryptic lineages that correspond to the eastern and western portions of the plant's distribution. That such clear genetic evidence for cryptic diversity exists within S. alata and is in conflict with other sources of data (e.g. morphology, environmental differentiation) illustrates a conundrum faced by those who investigate species boundaries: genetic data are often the first type of data to accumulate evidence of differentiation, but most existing taxonomic treatments are based on nongenetic data. Our results suggest that S. alata as currently described contains two cryptic species, and we recommend the elevation of the western populations to species status. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 737–746.
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deep phylogeographic structure and environmental differentiation in the carnivorous plant Sarracenia alata
Systematic Biology, 2012Co-Authors: Amanda J Zellmer, Sarah M. Hird, Margaret M Hanes, Bryan C. CarstensAbstract:We collected ~29 kb of sequence data using Roche 454 pyrosequencing in order to estimate the timing and pattern of diversification in the carnivorous pitcher plant Sarracenia alata. Utilizing modified protocols for reduced representation library construction, we generated sequence data from 86 individuals across 10 populations from throughout the range of the species. We identified 76 high-quality and high-coverage loci (containing over 500 SNPs) using the bioinformatics pipeline PRGmatic. Results from a Bayesian clustering analysis indicate that populations are highly structured, and are similar in pattern to the topology of a population tree estimated using *BEAST. The pattern of diversification within Sarracenia alata implies that riverine barriers are the primary factor promoting population diversification, with divergence across the Mississippi River occurring more than 60,000 generations before present. Further, significant patterns of niche divergence and the identification of several outlier loci suggest that selection may contribute to population divergence. Our results demonstrate the feasibility of using next-generation sequencing to investigate intraspecific genetic variation in nonmodel species.
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The Microbial Phyllogeography of the Carnivorous Plant Sarracenia alata
Microbial Ecology, 2011Co-Authors: Margaret M. Koopman, Bryan C. CarstensAbstract:Carnivorous pitcher plants host diverse microbial communities. This plant–microbe association provides a unique opportunity to investigate the evolutionary processes that influence the spatial diversity of microbial communities. Using next-generation sequencing of environmental samples, we surveyed microbial communities from 29 pitcher plants ( Sarracenia alata ) and compare community composition with plant genetic diversity in order to explore the influence of historical processes on the population structure of each lineage. Analyses reveal that there is a core S . alata microbiome, and that it is similar in composition to animal gut microfaunas. The spatial structure of community composition in S . alata ( phyllo geography) is congruent at the deepest level with the dominant features of the landscape, including the Mississippi river and the discrete habitat boundaries that the plants occupy. Intriguingly, the microbial community structure reflects the phylogeographic structure of the host plant, suggesting that the phylogenetic structure of bacterial communities and population genetic structure of their host plant are influenced by similar historical processes.
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conservation genetic inferences in the carnivorous pitcher plant Sarracenia alata Sarraceniaceae
Conservation Genetics, 2010Co-Authors: Margaret M. Koopman, Bryan C. CarstensAbstract:Conservation geneticists make inferences about their focal species from genetic data, and then use these inferences to inform conservation decisions. Since different biological processes can produce similar patterns of genetic diversity, we advocate an approach to data analysis that considers the full range of evolutionary forces and attempts to evaluate their relative contributions in an objective manner. Here we collect data from microsatellites and chloroplast loci and use these data to explore models of historical demography in the carnivorous Pitcher Plant, Sarracenia alata. Findings indicate that populations of S. alata exhibit high degrees of population genetic structure, likely caused by dispersal limitation, and that population sizes have decreased in western populations and increased in eastern populations. These results provide new insight to the management and conservation of plants restricted to small, declining populations isolated in increasingly scarce and highly threatened habitat, including other rare and endangered species of Sarracenia.
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The Carnivorous Pale Pitcher Plant Harbors Diverse, Distinct, and Time-Dependent Bacterial Communities
Applied and environmental microbiology, 2010Co-Authors: Margaret M. Koopman, Danielle M. Fuselier, Sarah M. Hird, Bryan C. CarstensAbstract:The ability of American carnivorous pitcher plants (Sarracenia) to digest insect prey is facilitated by microbial associations. Knowledge of the details surrounding this interaction has been limited by our capability to characterize bacterial diversity in this system. To describe microbial diversity within and between pitchers of one species, Sarracenia alata, and to explore how these communities change over time as pitchers accumulate and digest insect prey, we collected and analyzed environmental sequence tag (454 pyrosequencing) and genomic fingerprint (automated ribosomal intergenic spacer analysis and terminal restriction fragment length polymorphism) data. Microbial richness associated with pitcher plant fluid is high; more than 1,000 unique phylogroups were identified across at least seven phyla and 50 families. We documented an increase in bacterial diversity and abundance with time and observed repeated changes in bacterial community composition. Pitchers from different plants harbored significantly more similar bacterial communities at a given time point than communities coming from the same genetic host over time. The microbial communities in pitcher plant fluid also differ significantly from those present in the surrounding soil. These findings indicate that the bacteria associated with pitcher plant leaves are far from random assemblages and represent an important step toward understanding this unique plant-microbe interaction.
J L Hamrick - One of the best experts on this subject based on the ideXlab platform.
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high genetic diversity in Sarracenia leucophylla Sarraceniaceae a carnivorous wetland herb
Journal of Heredity, 2004Co-Authors: Z Wang, J L Hamrick, M J W GodtAbstract:Eighteen allozyme loci were used to examine genetic diversity in 10 natural populations of Sarracenia leucophylla Raf., a pitcher plant restricted to the southeastern United States. One ex situ population propagated for restoration in Georgia was also analyzed. S. leucophylla is an insect-pollinated, outcrossing perennial wetland herb that is threatened over much of its geographic range. Fifteen loci (83.3%) were polymorphic, with a mean number of alleles of 3.33. Compared to species having similar life-history traits and to previously analyzed Sarracenia species, S. leucophylla displayed unexpectedly high genetic diversity. For example, genetic diversity within the species (Hes) was 0.224 and mean population genetic diversity (Hep) was 0.183. Although small S. leucophylla populations maintained less genetic diversity than larger ones, these differences were not statistically significant. Nonetheless, this suggests that small populations may have lost rare alleles. Statistically significant genetic differentiation among populations was found (theta = 0.192, P < .01), although it was not atypical considering the species' life-history characteristics. A significant correlation (P < .01) between genetic and geographic distance was found, indicating an isolation-by-distance effect. However, the correlation coefficient for this relationship was low (r = 0.46), suggesting that factors other than gene flow play a prominent role in the geographic distribution of genetic diversity within the species. The ex situ population captured most of the allozyme variation found in its source population.
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genetic divergence among infraspecific taxa of Sarracenia purpurea
Systematic Botany, 1998Co-Authors: Mary Jo W Godt, J L HamrickAbstract:Allozyme diversity and genetic divergence were estimated for eight populations within Sar- racenia putrpotrea. Two populations of each infraspecific taxon (i.e., subsp. piurpuirea, and subsp. venosa vars. biurkii, montana and venosa) were analyzed. In addition, genetic diversity was estimated in an ex situ collection of var. montana propagated for restoration purposes. Twenty-three allozyme loci were resolved using 14 enzyme systems. Striking genetic differences were found among infraspecific taxa; mean genetic identity among these taxa was 0.80 (SD = 0.07), whereas mean genetic identity between populations within taxa was 0.97 (SD = 0.04). Populations within each subsp. venosa variety clustered on a UPGMA phenogram, as did subsp. prurpuirea populations. The percentage of total genetic variation found among populations was higher than reported, on average, for outcrossing, insect-pollinated species (Gst = 0.55), indicating significant genetic divergence among populations, most (90%) of which was attributable to differences among infraspecific taxa. Overall genetic diversity was moderate within the S. putrputrea complex (P = 60.9%, AP = 2.89 and H = 0.189). Compared with outcrossing animal-pollinated perennials, however, mean within-population genetic diversity was low (P = 23.4%, AP = 2.14, and H = 0.055). These genetic results, coupled with morphological differ- ences described within this widespread species, indicate that the infraspecific taxa are genetically distinct enti- ties. The high level of allozyme divergence among the named taxa suggests that taxonomic revision of the com- plex may be warranted and that the conservation status of the varieties should be evaluated. Finally, because genetic diversity was comparatively low within the ex situ collection of var. montana, the collection should be supplemented with propagules from other var. montana populations in the vicinity of the restoration site.
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allozyme diversity in the endangered pitcher plant Sarracenia rubra ssp alabamensis Sarraceniaceae and its close relative s rubra ssp rubra
American Journal of Botany, 1998Co-Authors: Mary Jo W Godt, J L HamrickAbstract:Genetic variability in the federally endangered pitcher plant Sarracenia rubra ssp. alabamensis was assessed in eight Alabama populations using starch gel electrophoresis. Ten populations of the more widespread Sarracenia rubra ssp. rubra were sampled in the southeastern United States for comparison. Fifteen allozyme loci representing 13 enzyme systems were scored for each species. In contrast to S. oreophila and S. jonesii, two previously analyzed endangered pitcher plants, genetic diversity was high for both S. rubra subspecies. Within ssp. alabamensis the percentage polymorphic loci (P s ) was 80.0, the mean number of alleles per polymorphic locus was (APs) 5 2.58, and expected heterozygosity (Hes) was 0.209. Genetic diversity was slightly lower for ssp. rubra (Ps 5 73.3, APs 5 2.91, and Hes 5 0.177). The proportion of total genetic diversity found among populations was fairly low for both species (GST 5 0.09 for ssp. alabamensis and 0.14 for ssp. rubra). Little genetic divergence has occurred between the two subspecies as indicated by the lack of diagnostic alleles, the proportion of total genetic diversity between taxa (GST 5 0.09), and the genetic identity estimate (I 5 0.90). The relatively high genetic diversity found for ssp. alabamensis indicates that the maintenance of its evolutionary potential is possible if population sizes are maintained or increased. Low levels of genetic diversity found within small Georgia ssp. rubra populations indicate that genetic erosion may increase extinction risks for these populations.
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genetic structure of two endangered pitcher plants Sarracenia jonesii and Sarracenia oreophila Sarraceniaceae
American Journal of Botany, 1996Co-Authors: Mary Jo W Godt, J L HamrickAbstract:Sarracenia jonesii and S. oreophila are insectivorous perennial plants of the southeastern United States. Both pitcher plant taxa are rare and endangered. Allozyme diversity was assessed for eight of the ten extant populations of S. jonesii and 14 of the 35 remaining S. oreophila populations. Genetic diversity was low and comparable for both species (Hes = 0.086 and 0.082 for S. jonesii and S. oreophila, respectively). Mean population genic diversity (Hep) was 0.061 for S. jonesii and 0.060 for S. oreophila. Estimates of genetic diversity were typical of those commonly associated with endemic species. Small populations of each species and geographically disjunct populations tended to maintain less genetic diversity. Indirect estimates of gene flow were comparable for S. oreophila (Nm = 1.62) and S. jonesii (Nm = 1.07).
Margaret M. Koopman - One of the best experts on this subject based on the ideXlab platform.
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The Microbial Phyllogeography of the Carnivorous Plant Sarracenia alata
Microbial Ecology, 2011Co-Authors: Margaret M. Koopman, Bryan C. CarstensAbstract:Carnivorous pitcher plants host diverse microbial communities. This plant–microbe association provides a unique opportunity to investigate the evolutionary processes that influence the spatial diversity of microbial communities. Using next-generation sequencing of environmental samples, we surveyed microbial communities from 29 pitcher plants ( Sarracenia alata ) and compare community composition with plant genetic diversity in order to explore the influence of historical processes on the population structure of each lineage. Analyses reveal that there is a core S . alata microbiome, and that it is similar in composition to animal gut microfaunas. The spatial structure of community composition in S . alata ( phyllo geography) is congruent at the deepest level with the dominant features of the landscape, including the Mississippi river and the discrete habitat boundaries that the plants occupy. Intriguingly, the microbial community structure reflects the phylogeographic structure of the host plant, suggesting that the phylogenetic structure of bacterial communities and population genetic structure of their host plant are influenced by similar historical processes.
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conservation genetic inferences in the carnivorous pitcher plant Sarracenia alata Sarraceniaceae
Conservation Genetics, 2010Co-Authors: Margaret M. Koopman, Bryan C. CarstensAbstract:Conservation geneticists make inferences about their focal species from genetic data, and then use these inferences to inform conservation decisions. Since different biological processes can produce similar patterns of genetic diversity, we advocate an approach to data analysis that considers the full range of evolutionary forces and attempts to evaluate their relative contributions in an objective manner. Here we collect data from microsatellites and chloroplast loci and use these data to explore models of historical demography in the carnivorous Pitcher Plant, Sarracenia alata. Findings indicate that populations of S. alata exhibit high degrees of population genetic structure, likely caused by dispersal limitation, and that population sizes have decreased in western populations and increased in eastern populations. These results provide new insight to the management and conservation of plants restricted to small, declining populations isolated in increasingly scarce and highly threatened habitat, including other rare and endangered species of Sarracenia.
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The Carnivorous Pale Pitcher Plant Harbors Diverse, Distinct, and Time-Dependent Bacterial Communities
Applied and environmental microbiology, 2010Co-Authors: Margaret M. Koopman, Danielle M. Fuselier, Sarah M. Hird, Bryan C. CarstensAbstract:The ability of American carnivorous pitcher plants (Sarracenia) to digest insect prey is facilitated by microbial associations. Knowledge of the details surrounding this interaction has been limited by our capability to characterize bacterial diversity in this system. To describe microbial diversity within and between pitchers of one species, Sarracenia alata, and to explore how these communities change over time as pitchers accumulate and digest insect prey, we collected and analyzed environmental sequence tag (454 pyrosequencing) and genomic fingerprint (automated ribosomal intergenic spacer analysis and terminal restriction fragment length polymorphism) data. Microbial richness associated with pitcher plant fluid is high; more than 1,000 unique phylogroups were identified across at least seven phyla and 50 families. We documented an increase in bacterial diversity and abundance with time and observed repeated changes in bacterial community composition. Pitchers from different plants harbored significantly more similar bacterial communities at a given time point than communities coming from the same genetic host over time. The microbial communities in pitcher plant fluid also differ significantly from those present in the surrounding soil. These findings indicate that the bacteria associated with pitcher plant leaves are far from random assemblages and represent an important step toward understanding this unique plant-microbe interaction.
Mary Jo W Godt - One of the best experts on this subject based on the ideXlab platform.
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genetic divergence among infraspecific taxa of Sarracenia purpurea
Systematic Botany, 1998Co-Authors: Mary Jo W Godt, J L HamrickAbstract:Allozyme diversity and genetic divergence were estimated for eight populations within Sar- racenia putrpotrea. Two populations of each infraspecific taxon (i.e., subsp. piurpuirea, and subsp. venosa vars. biurkii, montana and venosa) were analyzed. In addition, genetic diversity was estimated in an ex situ collection of var. montana propagated for restoration purposes. Twenty-three allozyme loci were resolved using 14 enzyme systems. Striking genetic differences were found among infraspecific taxa; mean genetic identity among these taxa was 0.80 (SD = 0.07), whereas mean genetic identity between populations within taxa was 0.97 (SD = 0.04). Populations within each subsp. venosa variety clustered on a UPGMA phenogram, as did subsp. prurpuirea populations. The percentage of total genetic variation found among populations was higher than reported, on average, for outcrossing, insect-pollinated species (Gst = 0.55), indicating significant genetic divergence among populations, most (90%) of which was attributable to differences among infraspecific taxa. Overall genetic diversity was moderate within the S. putrputrea complex (P = 60.9%, AP = 2.89 and H = 0.189). Compared with outcrossing animal-pollinated perennials, however, mean within-population genetic diversity was low (P = 23.4%, AP = 2.14, and H = 0.055). These genetic results, coupled with morphological differ- ences described within this widespread species, indicate that the infraspecific taxa are genetically distinct enti- ties. The high level of allozyme divergence among the named taxa suggests that taxonomic revision of the com- plex may be warranted and that the conservation status of the varieties should be evaluated. Finally, because genetic diversity was comparatively low within the ex situ collection of var. montana, the collection should be supplemented with propagules from other var. montana populations in the vicinity of the restoration site.
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allozyme diversity in the endangered pitcher plant Sarracenia rubra ssp alabamensis Sarraceniaceae and its close relative s rubra ssp rubra
American Journal of Botany, 1998Co-Authors: Mary Jo W Godt, J L HamrickAbstract:Genetic variability in the federally endangered pitcher plant Sarracenia rubra ssp. alabamensis was assessed in eight Alabama populations using starch gel electrophoresis. Ten populations of the more widespread Sarracenia rubra ssp. rubra were sampled in the southeastern United States for comparison. Fifteen allozyme loci representing 13 enzyme systems were scored for each species. In contrast to S. oreophila and S. jonesii, two previously analyzed endangered pitcher plants, genetic diversity was high for both S. rubra subspecies. Within ssp. alabamensis the percentage polymorphic loci (P s ) was 80.0, the mean number of alleles per polymorphic locus was (APs) 5 2.58, and expected heterozygosity (Hes) was 0.209. Genetic diversity was slightly lower for ssp. rubra (Ps 5 73.3, APs 5 2.91, and Hes 5 0.177). The proportion of total genetic diversity found among populations was fairly low for both species (GST 5 0.09 for ssp. alabamensis and 0.14 for ssp. rubra). Little genetic divergence has occurred between the two subspecies as indicated by the lack of diagnostic alleles, the proportion of total genetic diversity between taxa (GST 5 0.09), and the genetic identity estimate (I 5 0.90). The relatively high genetic diversity found for ssp. alabamensis indicates that the maintenance of its evolutionary potential is possible if population sizes are maintained or increased. Low levels of genetic diversity found within small Georgia ssp. rubra populations indicate that genetic erosion may increase extinction risks for these populations.
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genetic structure of two endangered pitcher plants Sarracenia jonesii and Sarracenia oreophila Sarraceniaceae
American Journal of Botany, 1996Co-Authors: Mary Jo W Godt, J L HamrickAbstract:Sarracenia jonesii and S. oreophila are insectivorous perennial plants of the southeastern United States. Both pitcher plant taxa are rare and endangered. Allozyme diversity was assessed for eight of the ten extant populations of S. jonesii and 14 of the 35 remaining S. oreophila populations. Genetic diversity was low and comparable for both species (Hes = 0.086 and 0.082 for S. jonesii and S. oreophila, respectively). Mean population genic diversity (Hep) was 0.061 for S. jonesii and 0.060 for S. oreophila. Estimates of genetic diversity were typical of those commonly associated with endemic species. Small populations of each species and geographically disjunct populations tended to maintain less genetic diversity. Indirect estimates of gene flow were comparable for S. oreophila (Nm = 1.62) and S. jonesii (Nm = 1.07).