ORCID Profile
0000-0001-8934-0033
Current Organisation
San Diego State University
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Publisher: California Botanical Society
Date: 22-01-2020
Publisher: Wiley
Date: 03-2011
DOI: 10.3732/AJB.1000428
Abstract: Mononucleotide microsatellites markers are useful for detecting genetic variation among in iduals however, scoring can be error-prone. We developed a new approach to improve the accuracy of allele scoring. A set of 14 mononucleotide microsatellite primers of the chloroplast were developed based on published Pinus spp. chloroplast genomes. Due to substantial scoring error for mononucleotide repeats≥10 bp, we included part of the microsatellite in the reverse primer to reduce slippage and improve the scoring of these polymorphic markers. For markers 10-20 bp, the error rate in scoring with this method has a binomial 95% confidence interval of 0.7-2.1%. These new primers provide variable chloroplast markers in species of subsection Cembroides and other Pinus spp. with more accurate assignment of the alleles. This approach can be used to improve the allele scoring of mononucleotide or dinucleotide repeats from nuclear and chloroplast genomes.
Publisher: Wiley
Date: 03-2013
DOI: 10.3732/AJB.1200068
Abstract: Even though dioecy is a dominant sexual system among gymnosperms, little is known about its evolutionary history. Pinus johannis may represent a model system because unisexual and monoecious in iduals compose its populations. The presence of unisexual in iduals in other Pinus species is a consequence of sexual lability. Here we determined whether P. johannis represents the first ex le of a dioecious or nearly dioecious reproductive system in conifers by evaluating its sexual stability. • To assess the stability of sexual expression, we quantified the proportion of male vs. female reproductive structures produced by trees over multiple years and tested for the presence of sexual dimorphism. Sexual lability hypotheses were also examined by looking at the relationship between environmental factors and sexual expression and by comparing the reproductive behavior of P. johannis with its closest labile relative, P. edulis. • Pinus johannis is nearly dioecious: ~99% of in iduals are unisexual or express a low proportion of the opposite gender with few changes in sexual expression through time. We found sexual dimorphism consistent with sexual stability. Sexual expression did not vary with tree size/age, abiotic environment, or herbivore removal, providing evidence against sexual lability. In iduals of P. johannis tended to produce only male or female strobili, whereas those of P. edulis were mainly monoecious with a gradient in the female to male strobili ratio. • This study represents the first report of a nearly stable dioecious Pinus species. The variety of sexual morphs coexisting in the same population makes P. johannis a model for studying the evolution of dioecy in gymnosperms.
Publisher: Elsevier BV
Date: 12-2016
Publisher: Frontiers Media SA
Date: 30-04-2018
Publisher: Wiley
Date: 20-12-2010
DOI: 10.3732/AJB.1000275
Abstract: Bisexuality (male and female function in one structure) has been reported as a key innovation of angiosperms. Although there are several reports of "teratological" bisporangiate (bisexual) cones in gymnosperms, there have been none on the viability of their ovules and pollen. Analyses of the development and arrangement of female and male structures on bisporangiate cones of Pinus johannis enables us to gain insight on the origin of bisexuality in seed plants, for both angiosperms and gymnosperms. Viability of bisporangiate cones was assayed by performing manual crosses and using anatomical and histological methods. We determined that bisporangiate cones of P. johannis produce functional pollen and ovules. Male and female organs occupy basal and apical positions, respectively, the same positions found in almost all bisporangiate strobili in gymnosperms and bisexual flowers in angiosperms. The viability and spatial distribution of female and male organs of bisporangiate cones and their frequent occurrence in gymnosperms suggest a common mechanism in all seed plants for the production of bisporangiate structures. This idea is further supported by the presence of homologous genes for sexual organ identity in gymnosperms and angiosperms as reported by other authors. The lack of bisporangiate structure in gymnosperms may be primarily due to selection to avoid inbreeding rather than to genetic constraint.
Publisher: MDPI AG
Date: 05-2021
DOI: 10.3390/F12050570
Abstract: A seed zone or provenance region is an area within which plants can be moved with little risk of maladaptation because of the low environmental variation. Delineation of seed zones is of great importance for commercial plantations and reforestation and restoration programs. In this study, we used AFLP markers associated with environmental variation for locating and delimiting seed zones for two widespread and economically important Mexican pine species (Pinus arizonica Engelm. and P. durangensis Martínez), both based on recent climate conditions and under a predicted climate scenario for 2030 (Representative Concentration Pathway of ~4.5 Wm−2). We expected to observe: (i) associations between seed zones and local climate, soil and geographical factors, and (ii) a meaning latitudinal shift of seed zones, along with a contraction of species distributions for the period 1990–2030 in a northward direction. Some AFLP outliers were significantly associated with spring and winter precipitation, and with phosphorus concentration in the soil. According to the scenario for 2030, the estimated species and seed zone distributions will change both in size and position. Our modeling of seed zones could contribute to reducing the probabilities of maladaptation of future reforestations and plantations with the pine species studied.
Publisher: Frontiers Media SA
Date: 22-10-2020
Publisher: Wiley
Date: 29-04-2019
DOI: 10.1111/EVA.12795
Abstract: A lack of optimal gene combinations, as well as low levels of genetic ersity, is often associated with the formation of species range margins. Conservation efforts rely on predictive modelling using abiotic variables and assessments of genetic ersity to determine target species and populations for controlled breeding, germplasm conservation and assisted migration. Biotic factors such as interspecific competition and hybridization, however, are largely ignored, despite their prevalence across erse taxa and their role as key evolutionary forces. Hybridization between species with well‐developed barriers to reproductive isolation often results in the production of offspring with lower fitness. Generation of novel allelic combinations through hybridization, however, can also generate positive fitness consequences. Despite this possibility, hybridization‐mediated introgression is often considered a threat to bio ersity as it can blur species boundaries. The contribution of hybridization towards increasing genetic ersity of populations at range margins has only recently gathered attention in conservation studies. We assessed the extent to which hybridization contributes towards range dynamics by tracking spatio‐temporal changes in the central location of a hybrid zone between two recently erged species of pines: Pinus strobiformis and P. flexilis . By comparing geographic cline centre estimates for global admixture coefficient with morphological traits associated with reproductive output, we demonstrate a northward shift in the hybrid zone. Using a combination of spatially explicit, in idual‐based simulations and linkage disequilibrium variance partitioning, we note a significant contribution of adaptive introgression towards this northward movement, despite the potential for differences in regional population size to aid hybrid zone movement. Overall, our study demonstrates that hybridization between recently erged species can increase genetic ersity and generate novel allelic combinations. These novel combinations may allow range margin populations to track favourable climatic conditions or facilitate adaptive evolution to ongoing and future climate change.
Publisher: Informa UK Limited
Date: 05-2014
DOI: 10.3852/13-263
Abstract: Species of the genus Geopora are important ectomycorrhizal associates that can dominate the communities of some plant taxa, such as pinyon pine (Pinus edulis), a widespread tree of the western United States. Several members of the genus Geopora are known only from ectomycorrhizal root tips and thus have not been described formally. The sporocarps of some Geopora species occur infrequently because they depend on wet years for sporulation. In addition, Geopora sporocarps can be small and may be hypogeous at some developmental stage, limiting the opportunities for describing their morphology. Using molecular and morphological data, we have described a new species of fungus, Geopora pinyonensis, which produced ascocarps after unusually high precipitation at a northern Arizona site in summer 2012. Based on analysis of the ITS and nuLSU regions of the rDNA, G pinyonensis is a new species of Geopora. It has small sporocarps and ascospores relative to other members of the genus however, these morphological features overlap with other species. Using rDNA data from sporocarps and ectomycorrhizal root tips, we show that the sporocarps correspond to an abundant species of ectomycorrhizal fungus associated with pinyon pines that is increasing in abundance in drought-affected landscapes and may promote drought tolerance.
Publisher: Oxford University Press (OUP)
Date: 21-07-2013
DOI: 10.1093/AOB/MCT141
Publisher: Wiley
Date: 22-07-2013
DOI: 10.3732/APPS.1200552
Publisher: Wiley
Date: 30-09-2021
DOI: 10.1002/ECE3.8169
Abstract: We have investigated the impact of recognized biogeographic barriers on genetic differentiation of grey box ( Eucalyptus moluccana ), a common and widespread tree species of the family Myrtaceae in eastern Australian woodlands, and its previously proposed four subspecies moluccana , pedicellata , queenslandica , and crassifolia . A range of phylogeographic analyses were conducted to examine the population genetic differentiation and subspecies genetic structure in E. moluccana in relation to biogeographic barriers. Slow evolving markers uncovering long term processes (chloroplast DNA) were used to generate a haplotype network and infer phylogeographic barriers. Additionally, fast evolving, hypervariable markers (microsatellites) were used to estimate demographic processes and genetic structure among five geographic regions (29 populations) across the entire distribution of E. moluccana . Morphological features of seedlings, such as leaf and stem traits, were assessed to evaluate population clusters and test differentiation of the putative subspecies. Haplotype network analysis revealed twenty chloroplast haplotypes with a main haplotype in a central position shared by in iduals belonging to the regions containing the four putative subspecies. Microsatellite analysis detected the genetic structure between Queensland (QLD) and New South Wales (NSW) populations, consistent with the McPherson Range barrier, an east‐west spur of the Great Dividing Range. The substructure was detected within QLD and NSW in line with other barriers in eastern Australia. The morphological analyses supported differentiation between QLD and NSW populations, with no difference within QLD, yet some differentiation within NSW populations. Our molecular and morphological analyses provide evidence that several geographic barriers in eastern Australia, including the Burdekin Gap and the McPherson Range have contributed to the genetic structure of E. moluccana . Genetic differentiation among E. moluccana populations supports the recognition of some but not all the four previously proposed subspecies, with crassifolia being the most differentiated.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Humana Press
Date: 2013
DOI: 10.1007/978-1-62703-389-3_21
Abstract: Microsatellites have been utilized for decades for genotyping in iduals in various types of research. Automated scoring of microsatellite loci has allowed for rapid interpretation of large datasets. Although the use of software produces an automated process to score or genotype s les, several sources of error have to be taken into account to produce accurate genotypes. A variety of problems (from extracting DNA to entering a genotype into a database) which can arise throughout this process might result in erroneous genotype assignment to one or more s les, potentially confounding the conclusions of your study. Correctly assigning a genotype to a s le requires knowledge of the chemistry you use to generate the data as well as the software you use to analyze these results. In this chapter we describe the critical and more common points that researchers experience when scoring microsatellite loci. More importantly we provide insight from an experienced perspective for these challenges.
Publisher: Springer Science and Business Media LLC
Date: 06-01-2021
DOI: 10.1186/S13007-020-00700-7
Abstract: Forest dieback driven by rapid climate warming threatens ecosystems worldwide. The health of forested ecosystems depends on how tree species respond to warming during all life history stages. While it is known that seed development is temperature-sensitive, little is known about possible effects of climate warming on seed development and subsequent seedling performance. Exposure of seeds to high air temperatures may influence subsequent seedling performance negatively, though conversely, warming during seed development may aid acclimation of seedlings to subsequent thermal stress. Technical challenges associated with in-situ warming of developing tree seeds limit understanding of how tree species may respond to seed development in a warmer climate. We developed and validated a simple method for passively warming seeds as they develop in tree canopies to enable controlled study of climate warming on seedling performance. We quantified thermal effects of the cone-warming method across in idual pine trees and stands by measuring the air temperature surrounding seed cones using thermal loggers and the temperature of seed cone tissue using thermocouples. We then investigated seedling phenotypes in relation to the warming method through a common garden study. We assessed seedling morphology, physiology, and mycorrhizal nodulation in response to experimental cone-warming in 20 seed-source-tree canopies on the San Francisco Peaks in northern Arizona, USA. The warming method increased air temperature surrounding developing seed cones by 2.1 °C, a plausible increase in mean air temperature by 2050 under current climate projections. Notable effect sizes of cone-warming were detected for seedling root length, shoot length, and diameter at root collar using Cohen’s Local f 2 . Root length was affected most by cone-warming, but effect sizes of cone-warming on root length and diameter at root collar became negligible after the first year of growth. Cone-warming had small but significant effects on mycorrhizal fungal richness and seedling multispectral near-infrared indices indicative of plant health. The method was shown to reliably elevate the temperature surrounding seed cones and thereby facilitate experimental in-situ climate warming research on forest trees. The method was furthermore shown to influence plant traits that may affect seedling performance under climate warming.
Publisher: Springer Science and Business Media LLC
Date: 05-02-2021
DOI: 10.1038/S42003-020-01632-7
Abstract: Extant conifer species may be susceptible to rapid environmental change owing to their long generation times, but could also be resilient due to high levels of standing genetic ersity. Hybridisation between closely related species can increase genetic ersity and generate novel allelic combinations capable of fuelling adaptive evolution. Our study unravelled the genetic architecture of adaptive evolution in a conifer hybrid zone formed between Pinus strobiformis and P. flexilis . Using a multifaceted approach emphasising the spatial and environmental patterns of linkage disequilibrium and ancestry enrichment, we identified recently introgressed and background genetic variants to be driving adaptive evolution along different environmental gradients. Specifically, recently introgressed variants from P. flexilis were favoured along freeze-related environmental gradients, while background variants were favoured along water availability-related gradients. We posit that such mosaics of allelic variants within conifer hybrid zones will confer upon them greater resilience to ongoing and future environmental change and can be a key resource for conservation efforts.
Publisher: Canadian Science Publishing
Date: 09-2020
Abstract: In forestry, common garden experiments traditionally require manual measurements and visual inspections. Unmanned aircraft systems (UAS) are a newer method of monitoring plants that is potentially more efficient than traditional techniques. This study had two objectives: to assess the size and mortality of Pinus strobiformis Engelm. seedlings using UAS and to predict the second-year seedling size using manual measurements from the first year and from UAS size estimates. Raised boxes containing 150 seedlings were surveyed twice, one year apart, using multispectral UAS. Seedling heights and diameters at root collar (DRC) were measured manually in both years. We found that size estimates made using a vegetation mask were suitable predictors for size, while spectral indices were not. Furthermore, we provided evidence that inclusion of UAS size estimates as predictors improves the fit of the models. Our study suggests that common variables used in forest monitoring are not necessarily best suited for seedlings. Therefore, we created a new variable, called the longitudinal area (height × DRC), which proved to be a significant predictor for both height and DRC. Finally, we demonstrate that seedling mortality can be effectively measured from remotely sensed data, which is useful for common garden and regeneration studies.
Publisher: Frontiers Media SA
Date: 18-02-2019
Publisher: Proceedings of the National Academy of Sciences
Date: 25-09-2017
Abstract: Soil microbes influence plant performance and may be critical to the persistence of some plants with climate change. However, microbes are highly erse, and in iduals of the same plant species often associate with different microbes. We examined the importance of soil microbes to the growth and survival of a widespread pine under drought conditions. We found that specific beneficial fungus–host genotype combinations promoted drought tolerance in field and greenhouse studies. Drought tolerance, and associations with particular fungi, were passed from mother trees to their offspring, indicating the traits are genetic. These results demonstrate the interlinked importance of the genetics of a tree and its microbiome, which can be used to restore forest losses resulting from drought.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.YMPEV.2017.01.019
Abstract: Reticulate evolution by hybridization is considered a common process shaping the evolution of many plant species, however, reticulation could also be due to incomplete lineage sorting in bio erse systems. For our study we selected a group of closely related plant taxa with contrasting yet partially overlapping geographic distributions and different population sizes, to distinguish between reticulated patterns due to hybridization and incomplete lineage sorting. We predicted that sympatric or proximal populations of different species are more likely to have gene flow than geographically distant populations of the same widespread species. Furthermore, for species with restricted distributions, and therefore, small effective population sizes, we predicted complete lineage sorting. Eastern grey box eucalypt species (Eucalyptus supraspecies Moluccanae) provide an ideal system to explore patterns of reticulate evolution. They form a erse, recently evolved and phylogenetically undefined group within Eucalyptus, with overlapping morphological features and hybridization in nature. We used a multi-faceted approach, combining analyses of chloroplast and nuclear DNA, as well as seedling morphology, flowering time and ecological spatial differentiation in order to test for species delimitation and reticulate evolution in this group. The multiple layers of results were consistent and suggested a lack of monophyly at different hierarchical levels due to multidirectional gene flow among several species, challenging species delimitation. Chloroplast and nuclear haplotypes were shared among different species in geographic proximity, consistent with hybridization zones. Furthermore, species with restricted distributions appeared better resolved due to lineage sorting in the absence of hybridization. We conclude that a combination of molecular, morphological and ecological approaches is required to disentangle patterns of reticulate evolution in the box eucalypts.
Publisher: Wiley
Date: 09-10-2014
DOI: 10.1111/MEC.12503
Abstract: Although the importance of plant‐associated microbes is increasingly recognized, little is known about the biotic and abiotic factors that determine the composition of that microbiome. We examined the influence of plant genetic variation, and two stressors, one biotic and one abiotic, on the ectomycorrhizal ( EM ) fungal community of a dominant tree species, Pinus edulis . During three periods across 16 years that varied in drought severity, we s led the EM fungal communities of a wild stand of P . edulis in which genetically based resistance and susceptibility to insect herbivory was linked with drought tolerance and the abundance of competing shrubs. We found that the EM fungal communities of insect‐susceptible trees remained relatively constant as climate dried, while those of insect‐resistant trees shifted significantly, providing evidence of a genotype by environment interaction. Shrub removal altered the EM fungal communities of insect‐resistant trees, but not insect‐susceptible trees, also a genotype by environment interaction. The change in the EM fungal community of insect‐resistant trees following shrub removal was associated with greater shoot growth, evidence of competitive release. However, shrub removal had a 7‐fold greater positive effect on the shoot growth of insect‐susceptible trees than insect‐resistant trees when shrub density was taken into account. Insect‐susceptible trees had higher growth than insect‐resistant trees, consistent with the hypothesis that the EM fungi associated with susceptible trees were superior mutualists. These complex, genetic‐based interactions among species (tree‐shrub‐herbivore‐fungus) argue that the ultimate impacts of climate change are both ecological and evolutionary.
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.YMPEV.2013.06.010
Abstract: Elucidating phylogenetic relationships and species boundaries within complex taxonomic groups is challenging for intrinsic and extrinsic (i.e., technical) reasons. Mexican pinyon pines are a complex group whose phylogenetic relationships and species boundaries have been widely studied but poorly resolved, partly due to intrinsic ecological and evolutionary features such as low morphological and genetic differentiation caused by recent ergence, hybridization and introgression. Extrinsic factors such as limited s ling and difficulty in selecting informative molecular markers have also impeded progress. Some of the Mexican pinyon pines are of conservation concern but others may remain unprotected because the species boundaries have not been established. In this study we combined approaches to resolve the phylogenetic relationships in this complex group and to establish species boundaries in four recently erged taxa: P. discolor, P. johannis, P. culminicola and P. cembroides. We performed phylogenetic analyses using the chloroplast markers matK and psbA-trnH as well as complete and partial chloroplast genomes of species of Subsection Cembroides. Additionally, we performed a phylogeographic analysis combining genetic data (18 chloroplast markers), morphological data and geographical data to define species boundaries in four recently erged taxa. Ecological ergence was supported by differences in climate among localities for distinct genetic lineages. Whereas the phylogenetic analysis inferred with matK and psbA-trnH was unable to resolve the relationships in this complex group, we obtained a resolved phylogeny with the use of the chloroplast genomes. The resolved phylogeny was concordant with a haplotype network obtained using chloroplast markers. In species with potential for recent ergence, hybridization or introgression, nonhierarchical network-based approaches are probably more appropriate to protect against misclassification due to incomplete lineage sorting. The boundaries among genetic lineages were delimited by the inclusion of morphological, geographical and ecological data in the haplotype network. These multiple lines of evidence help to assign species boundaries in this complex group. P. johannis, P. discolor, P. culminicola and P. cembroides are different species based on their genetic, morphological and ecological niche differences. We suggest a reevaluation of the conservation status of these species considering the information generated in this study.
Publisher: Wiley
Date: 03-2018
DOI: 10.1111/MEC.14505
Abstract: Interactions between extrinsic factors, such as disruptive selection and intrinsic factors, such as genetic incompatibilities among loci, often contribute to the maintenance of species boundaries. The relative roles of these factors in the establishment of reproductive isolation can be examined using species pairs characterized by gene flow throughout their ergence history. We investigated the process of speciation and the maintenance of species boundaries between Pinus strobiformis and Pinus flexilis. Utilizing ecological niche modelling, demographic modelling and genomic cline analyses, we illustrated a ergence history with continuous gene flow. Our results supported an abundance of advanced generation hybrids and a lack of loci exhibiting steep transition in allele frequency across the hybrid zone. Additionally, we found evidence for climate-associated variation in the hybrid index and niche ergence between parental species and the hybrid zone. These results are consistent with extrinsic factors, such as climate, being an important isolating mechanism. A build-up of intrinsic incompatibilities and of coadapted gene complexes is also apparent, although these appear to be in the earliest stages of development. This supports previous work in coniferous species demonstrating the importance of extrinsic factors in facilitating speciation. Overall, our findings lend support to the hypothesis that varying strength and direction of selection pressures across the long lifespans of conifers, in combination with their other life history traits, delays the evolution of strong intrinsic incompatibilities.
Publisher: Wiley
Date: 16-07-2018
DOI: 10.1111/NPH.15352
Abstract: The interactions among climate change, plant genetic variation and fungal mutualists are poorly understood, but probably important to plant survival under drought. We examined these interactions by studying the ectomycorrhizal fungal (EMF) communities of pinyon pine seedlings (Pinus edulis) planted in a wildland ecosystem experiencing two decades of climate change-related drought. We established a common garden containing P. edulis seedlings of known maternal lineages (drought tolerant, DT drought intolerant, DI), manipulated soil moisture and measured EMF community structure and seedling growth. Three findings emerged: EMF community composition differed at the phylum level between DT and DI seedlings, and ersity was two-fold greater in DT than in DI seedlings. EMF communities of DT seedlings did not shift with water treatment and were dominated by an ascomycete, Geopora sp. By contrast, DI seedlings shifted to basidiomycete dominance with increased moisture, demonstrating a lineage by environment interaction. DT seedlings grew larger than DI seedlings in high (28%) and low (50%) watering treatments. These results show that inherited plant traits strongly influence microbial communities, interacting with drought to affect seedling performance. These interactions and their potential feedback effects may influence the success of trees, such as P. edulis, in future climates.
Publisher: Wiley
Date: 04-03-2013
DOI: 10.1111/MEC.12268
Abstract: Arbuscular mycorrhizal (AM) fungi are widespread root symbionts that often improve the fitness of their plant hosts. We tested whether local adaptation in mycorrhizal symbioses would shape the community structure of these root symbionts in a way that maximizes their symbiotic functioning. We grew a native prairie grass (Andropogon gerardii) with all possible combinations of soils and AM fungal inocula from three different prairies that varied in soil characteristics and disturbance history (two native prairie remnants and one recently restored). We identified the AM fungi colonizing A. gerardii roots using PCR lification and cloning of the small subunit rRNA gene. We observed 13 operational taxonomic units (OTUs) belonging to six genera in three families. Taxonomic richness was higher in the restored than the native prairies with one member of the Gigaspora dominating the roots of plants grown with inocula from native prairies. Inoculum source and the soil environment influenced the composition of AM fungi that colonized plant roots. Correspondingly, host plants and AM fungi responded significantly to the soil-inoculum combinations such that home fungi often had the highest fitness and provided the greatest benefit to A. gerardii. Similar patterns were observed within the soil-inoculum combinations originating from two native prairies, where five sequence types of a single Gigaspora OTU were virtually the only root colonizers. Our results indicate that indigenous assemblages of AM fungi were adapted to the local soil environment and that this process occurred both at a community scale and at the scale of fungal sequence types within a dominant OTU.
Publisher: Oxford University Press (OUP)
Date: 28-03-2020
DOI: 10.1093/AOB/MCAA045
Abstract: Pinyon pine hybridization is widely acknowledged, but the frequency of and contributors to such interspecific mating remain largely unstudied. Pinus quadrifolia has three to four needles per fascicle, suggesting that it is a result of hybridization between the five-needled P. juarezensis and the single-needled P. monophylla. In this study we address the taxonomic validity of P. juarezensis, the hybrid origin of P. quadrifolia and the presence of hybridization and intermediate morphology as a result of interspecific hybridization in this complex. We address these questions by combining a genomic and morphological approach. We generated 1868 single nucleotide polymorphisms (SNPs) to detect genetic clusters using principal co-ordinates analyis, discriminant analysis of principal components, fastSTRUCTURE and ADMIXTURE analyses, and performed a morphological analysis of the leaves. We found that the five-needled pinyons did not differ genetically from the four-needled P. quadrifolia, reducing the status of P. juarezensis to P. quadrifolia. We also found no evidence that P. quadrifolia is of hybrid origin from P. juarezensis × P. monophylla but is instead a genetically distinct species with natural needle number variation that has yet to be explained. Hybridization does occur in this complex, but mostly between P. quadrifolia and P. californiarum, and less commonly between P. quadrifolia and P. monophylla. Interestingly, some hybrid derivatives were detected between both single-needled taxa, P. monophylla and P. californiarum, a hybrid combination that has not yet been proposed. Hybrids have intermediate morphology when they have similar genetic contributions from both parental species however, when one parent contributes more, hybrid derivatives resemble the parent with higher genetic contribution, resulting in cryptic introgression. Our detailed s ling across the distribution of this complex allows us to describe the patterns of hybridization among these taxa, resolves an ancient taxonomic conflict and provides insights into the challenges of exclusively using morphological traits when identifying these taxa with cryptic hybridization and variable morphology.
Publisher: Elsevier BV
Date: 03-2022
Publisher: Wiley
Date: 19-11-2022
DOI: 10.1111/NPH.18543
Abstract: Multispecies interbreeding networks, or syngameons, have been increasingly reported in natural systems. However, the formation, structure, and maintenance of syngameons have received little attention. Through gene flow, syngameons can increase genetic ersity, facilitate the colonization of new environments, and contribute to hybrid speciation. In this study, we evaluated the history, patterns, and consequences of hybridization in a pinyon pine syngameon using morphological and genomic data to assess genetic structure, demographic history, and geographic and climatic data to determine niche differentiation. We demonstrated that Pinus edulis , a dominant species in the Southwestern US and a barometer of climate change, is a core participant in the syngameon, involved in the formation of two drought‐adapted hybrid lineages including the parapatric and taxonomically controversial fallax ‐type. We found that species remain morphologically and genetically distinct at range cores, maintaining species boundaries while undergoing extensive gene flow in areas of sympatry at range peripheries. Our study shows that sequential hybridization may have caused relatively rapid speciation and facilitated the colonization of different niches, resulting in the rapid formation of two new lineages. Participation in the syngameon may allow adaptive traits to be introgressed across species barriers and provide the changes needed to survive future climate scenarios.
Publisher: Canadian Science Publishing
Date: 06-2016
Abstract: Invasive, non-native plant species can alter soil microbial communities in ways that contribute to their persistence. While most studies emphasize mycorrhizal fungi, invasive plants also may influence communities of dark septate fungi (DSF), which are common root endophytes that can function like mycorrhizas. We tested the hypothesis that a widespread invasive plant in the western United States, cheatgrass (Bromus tectorum L.), influenced the abundance and community composition of DSF by examining the roots and rhizosphere soils of cheatgrass and two native plant species in cheatgrass-invaded and noninvaded areas of sagebrush steppe. We focused on cheatgrass because it is negatively affected by mycorrhizal fungi and colonized by DSF. We found that DSF root colonization and operational taxonomic unit (OTU) richness were significantly higher in sagebrush (Artemisia tridentata Nutt.) and rice grass (Achnatherum hymenoides (Roem. & Schult.) Barkworth) from invaded areas than noninvaded areas. Cheatgrass roots had similar levels of DSF colonization and OTU richness as native plants. The community composition of DSF varied with invasion in the roots and soils of native species and among the roots of the three plant species in the invaded areas. The substantial changes in DSF we observed following cheatgrass invasion argue for comparative studies of DSF function in native and non-native plant species.
Publisher: Springer Science and Business Media LLC
Date: 02-03-2022
DOI: 10.1186/S12870-022-03431-0
Abstract: In certain unisexual flowers, non-functional sexual organs remain vestigial and unisexuality can be overlooked leading to the ambiguous description of the sexual systems. Therefore, to accurately describe the sexual system, detailed morphological and developmental analyses along with experimental crosses must be performed. Cylindropuntia wolfii is a rare cactus endemic to the Sonoran Desert in southern California and northern Baja California that was described as gynodioecious by morphological analysis. The aims of our project include accurately identifying the sexual system of C. wolfii using histological and functional studies and characterizing the developmental mechanisms that underlie its floral development. Histological analyses were carried out on different stages of C. wolfii flowers and controlled crosses were performed in the field. Our results identified C. wolfii to be functionally dioecious. The ovule and anther development differed between staminate and pistillate flowers. In vivo pollen germination tests showed that the pollen of staminate and pistillate flowers were viable and the stigma and style of both staminate and pistillate flowers were receptive. This suggests that there are no genetic or developmental barriers in the earlier stages of pollen recognition and pollen germination. Despite being functionally dioecious, we observed that functionally pistillate in iduals produced fruits with a large number of aborted seeds. This implies that not only does this species have low reproductive success, but its small population sizes may lead to low genetic ersity.
Location: Australia
Start Date: 2018
End Date: 2022
Funder: Directorate for Biological Sciences
View Funded ActivityStart Date: 2015
End Date: 2021
Funder: Directorate for Biological Sciences
View Funded Activity