Jason P Sexton

Jason P Sexton
University of California, Merced | UCM · Department of Life and Environmental Sciences

PhD

About

44
Publications
8,833
Reads
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4,509
Citations
Citations since 2017
15 Research Items
2729 Citations
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Introduction
Jason P Sexton currently works at the Department of Life and Environmental Sciences, University of California, Merced. Jason does research in Evolutionary Biology and Ecology.
Additional affiliations
July 2019 - present
University of California, Merced
Position
  • Professor (Associate)
January 2014 - present
University of California, Merced
Position
  • Professor (Assistant)
January 2011 - December 2013
University of Melbourne
Position
  • NSF Postdoctoral Fellow

Publications

Publications (44)
Article
Full-text available
Vernal pools are temporary wetlands that can form during a rainy season, often in Mediterranean climates, and serve as ideal testing grounds to understand species detection using eDNA and how biological communities may shift across time and spatial and environmental heterogeneity. Most vernal pools exhibit high plant and animal diversity and endemi...
Article
Full-text available
Biogeographic patterns in microorganisms are poorly understood, despite the importance of microbial communities for a range of ecosystem processes. Our knowledge of microbial ecology and biogeography is particularly deficient in rare and threatened ecosystems. We tested for three ecological patterns in microbial community composition within ephemer...
Article
Full-text available
Earth is changing rapidly and so are many plant species’ ranges. Here, we synthesize eco-evolutionary patterns found in plant range studies and how knowledge of species ranges can inform our understanding of species conservation in the face of global change. We discuss whether general biogeographic “rules” are reliable and how they can be used to d...
Article
Quantitative genetic variation (QGV) represents a major component of adaptive potential and, if reduced toward range-edge populations, could prevent a species’ expansion or adaptive response to rapid ecological change. It has been hypothesized that QGV will be lower at the range edge due to small populations—often the result of poor habitat quality...
Preprint
Full-text available
Biogeographic patterns in microorganisms are poorly understood, despite the importance of microbial communities for a range of ecosystem processes. Our knowledge of microbial ecology and biogeography is particularly deficient in rare and threatened ecosystems. We tested for three ecological patterns in microbial diversity and community composition...
Article
The genetic swamping hypothesis proposes that gene flow from central to peripheral populations inhibits local adaptation and is one of the most widely recognized explanations for range limitation. We evaluated empirical support for this hypothesis in studies quantifying patterns of gene flow to peripheral populations and their resulting fitness out...
Article
Full-text available
Climate change is leading to habitat shifts that threaten species persistence throughout California's unique ecosystems. Baseline biodiversity data would provide opportunities for habitats to be managed under short-term and long-term environmental change. Aiming to provide biodiversity data, the UC Conservation Genomics Consortium launched the Cali...
Chapter
Full-text available
In this review, we propose research focused on the study of microbial groups (archaea, bacteria, fungi, protista) within vernal pools, which are well-delimited ecosystems but can vary in many environmental characteristics. In order to understand the diversity and community composition of microorganisms within vernal pools, we suggest research based...
Article
Full-text available
As climatic conditions change, species will be forced to move or adapt to avoid extinction. Exacerbated by ongoing climate change, California recently experienced a severe and exceptional drought from 2011 to 2017. To investigate whether an adap-tive response occurred during this event, we conducted a "resurrection" study of the cutleaf monkeyflowe...
Article
Full-text available
Why do species fail to adapt? Implicit in this question is what happens to a single species that limits its adaptive potential and relegates it to a smaller niche than could otherwise be gained. One problem with this question is it views species or populations in isolation, as separate units, instead of as branches of a great tree of life. There ar...
Poster
Full-text available
All plants have a community of asymptomatic microbes inhabiting their tissue known as endophytes. Increasing evidence suggests that microbes are an extension of plant host phenotype and can ultimately help them adapt in response to stress, including drought (Compant et al. 2010). Additionally, stressful conditions may select for distinct endophyte...
Preprint
Full-text available
Global change is leading to habitat shifts that threaten species persistence throughout California's unique ecosystems. Baseline biodiversity data provide opportunities for ecosystems to be managed for community complexity and connectivity. In 2017, the University of California Conservation Genomics Consortium launched the California Environmental...
Article
How ecological niche breadth evolves is central to adaptation and speciation and has been a topic of perennial interest. Niche breadth evolution research has occurred within environmental, ecological, evolutionary, and biogeographical contexts, and although some generalities have emerged, critical knowledge gaps exist. Performance breadth trade-off...
Article
Full-text available
Relatively common species within a clade are expected to perform well across a wider range of conditions than their rarer relatives, yet experimental tests of this “niche breadth—range size” hypothesis remain surprisingly scarce. Rarity may arise due to trade-offs between specialization and performance across a wide range of environments. Here we u...
Data
Figure S1. Means plotted for the (A) width and (B) height of the different planting sites and sites of origin for data from field transplant experiment at different census points, with each group split according to whether the plants were alive or dead at the ensuing census point. Figure S2. Changes in plant traits across time in the field transpl...
Data
Table S1. Additional information on the reciprocal field based experiment, the common garden and field survey; number of individuals per experiment, habitat information, and species localities with latitude (south), longitude (east) and elevation (metres).
Article
Full-text available
Alpine plants often occupy diverse habitats within a similar elevation range, but most research on local adaptation in these plants has focused on elevation gradients. In testing for habitat-related local adaptation, local effects on seed quality and initial plant growth should be considered in designs that encompass multiple populations and habita...
Article
Full-text available
Premise of the study: Understanding the evolutionary and ecological factors that determine plant distributions is of primary importance in botanical research. These factors may vary in predictable ways across different spatial scales, and thus, we can leverage scale to reveal the underlying processes limiting plant distributions. Methods: We rev...
Article
Gene flow may influence the formation of species range limits, yet little is known about the patterns of gene flow with respect to environmental gradients or proximity to range limits. With rapid environmental change it is especially important to understand patterns of gene flow to inform conservation efforts. Here we investigate the species range...
Article
Full-text available
Speciation can occur on both large and small geographical scales. In plants, local speciation, where small populations split off from a large-ranged progenitor species, is thought to be the dominant mode, yet there are still few examples to verify speciation has occurred in this manner. A recently described morphological species in the yellow monke...
Article
Closely related species (e.g., sister taxa) often occupy very different ecological niches and can exhibit large differences in geographic distributions despite their shared evolutionary history. Budding speciation is one process that may partially explain how differences in niche and distribution characteristics may rapidly evolve. Budding speciati...
Article
Gene flow among populations can enhance local adaptation if it introduces new genetic variants available for selection, but strong gene flow can also stall adaptation by swamping locally beneficial genes. These outcomes can depend on population size, genetic variation, and the environmental context. Gene flow patterns may align with geographic dist...
Article
Full-text available
The fern-leaved monkeyflower, Mimulus filicifolius (Phrymaceae, Section Simiolus), is a new species described from the northwestern corner of the Sierra Nevada of California. The new taxon is differentiated from close relatives of Mimulus L. (M. laciniatus Gray and M. guttatus DC.) mostly by having many finely divided, bi-pinnately compound leaves....
Article
The range of resources that a species uses (i.e. its niche breadth) might determine the geographical area it can occupy, but consensus on whether a niche breadth-range size relationship generally exists among species has been slow to emerge. The validity of this hypothesis is a key question in ecology in that it proposes a mechanism for commonness...
Article
Full-text available
Niche partitioning among close relatives may reflect trade-offs underlying species divergence and coexistence (e.g., between stress tolerance and competitive ability). We quantified the effects of habitat and congeneric species interactions on fitness for two closely related herbaceous plant species, Mimulus guttatus and Mimulus laciniatus, in thre...
Conference Paper
Background/Question/Methods Theoretical models have suggested that gene flow coupled with selection are critical determinants of species’ range limits. To evaluate these models, population size, genetic diversity, and contemporary gene flow were examined along three transects spanning the entire warm-to-cold elevational range of the annual plant,...
Article
Full-text available
According to theory, gene flow to marginal populations may stall or aid adaptation at range limits by swamping peripheral populations with maladaptive gene flow or by enhancing genetic variability and reducing inbreeding depression, respectively. We tested these contrasting predictions by manipulating patterns of gene flow of the annual plant, Mimu...
Article
Aim To highlight the importance of combining the geographies of sociocultural adaptation and biodiversity risk for creating global change conservation strategies. Location Global. Methods We review global conservation adaptation strategies and the geographies that influence biological risk, as well as sociocultural capacity to set priorities for a...
Article
Full-text available
Species range limits involve many aspects of evolution and ecology, from species distribution and abundance to the evolution of niches. Theory suggests myriad processes by which range limits arise, including competitive exclusion, Allee effects, and gene swamping; however, most models remain empirically untested. Range limits are correlated with a...
Conference Paper
Background/Question/Methods Gene flow from central to edge populations along an ecological gradient has been hypothesized to either cause range limits, by preventing adaptation through maladaptive gene swamping, or enhance the adaptive process at range limits, by introducing the genetic variation necessary to adapt. The role of gene flow was inves...
Article
Full-text available
Private landowners are often de facto stewards of biodiversity and ecosystem services. In California's Sierra Nevada foothills, ranchers frequently present the only defense against biological invasions in private rangelands. Although ranchers' land management goals (e.g., the desire to control invasive species) can be consistent with ecosystem prot...
Article
Control of biological invasions depends on the collective decisions of resource managers across invasion zones. Regions with high land-use diversity, which we refer to as "management mosaics", may be subject to severe invasions, for two main reasons. First, as land becomes increasingly subdivided, each manager assumes responsibility for a smaller p...
Article
Full-text available
Species range limits involve many aspects of evolution and ecology, from species distribution and abundance to the evolution of niches. Theory suggests myriad processes by which range limits arise, including competitive exclusion, Allee effects, and gene swamping; however, most models remain empirically untested. Range limits are correlated with a...
Article
Full-text available
Saltcedar (Tamarix spp.), a shrub native to Eurasia, is associated with major alterations to wetland and riparian systems in the southwestern United States. Since the 1960s saltcedar has been naturalized in northern states of the U.S. where its growth potential and impacts are not well known. Here, we describe the occurrence, age, size, and relativ...
Article
Full-text available
Two major mechanisms have been proposed to explain the ability of intro- duced populations to colonize over large habitat gradients, despite significant population bottlenecks during introduction: (1) Broad environmental tolerance—successful invaders possess life history traits that confer superior colonizing ability and/or phenotypic plasticity, a...
Article
Typescript. Thesis (M.S.)--University of Montana, 2000. Includes bibliographical references.

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