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75
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Introduction
Currently working on Earth.
Additional affiliations
August 2011 - present
August 2003 - May 2009
Education
September 2003 - May 2009
Publications
Publications (75)
Models of species’ distributions and niches are frequently used to infer the importance of range‐ and niche‐defining variables. However, the degree to which these models can reliably identify important variables and quantify their influence remains unknown. Here we use a series of simulations to explore how well models can 1) discriminate between v...
Aim
Museum and herbarium specimen records are frequently used to assess the conservation status of species and their responses to climate change. Typically, occurrences with imprecise geolocality information are discarded because they cannot be matched confidently to environmental conditions and are thus expected to increase uncertainty in downstre...
Species distribution models are useful for estimating the distribution and environmental preferences of rare species, but these same species are challenging to model on account of sparse data. We contrast a traditional single‐species approach (generalized linear models, GLMs) with two promising frameworks for modeling rare species: ensembles of sma...
Premise:
Although changes in plant phenology are largely attributed to changes in climate, the roles of other factors, such as genetic constraints, competition, and self-compatibility, are underexplored.
Methods:
We compiled >900 herbarium records spanning 117 years for all 8 nominal species of the winter-annual genus Leavenworthia (Brassicaceae...
Abstract Species distribution and ecological niche models (SDMs and ENMs) are popular tools used in a wide variety of research and conservation applications. However, their use in understanding community‐level patterns and processes is an emerging and rapidly developing field. Here, we examine a set of important and challenging topics that are cent...
Many organisms leave evidence of their former occurrence, such as scat, abandoned burrows, middens, ancient eDNA or fossils, which indicate areas from which a species has since disappeared. However, combining this evidence with contemporary occurrences within a single modeling framework remains challenging. Traditional binary species‐distribution m...
The increasing online availability of biodiversity data and advances in ecological modeling have led to a proliferation of open‐source modeling tools. In particular, R packages for species distribution modeling continue to multiply without guidance on how they can be employed together, resulting in high fidelity of researchers to one or several pac...
A massive expansion of renewable energy (RE) is underway to meet the world’s climate goals. Although serves to reduce threats from climate change, it can also pose threats to species whose current and future ranges intersect with RE installations. Here, we propose a ‘‘Climate-Smart Siting’’ framework for addressing potential conflicts between RE ex...
Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly).
We combined long‐term field (1937–2012) and herbarium records (1850–2017) of 68 species in a flowering plant community in central North America...
Climate change poses a threat to biodiversity, and it is unclear whether species can adapt to or tolerate new conditions, or migrate to areas with suitable habitats. Reconstructions of range shifts that occurred in response to environmental changes since the last glacial maximum (LGM) from species distribution models (SDMs) can provide useful data...
Climate change has widespread effects on the distribution, abundance, and behavior of species around the world, leading to the reshuffling of ecological communities. However, it remains unclear whether individual species' range shifts scale up to result in communities whose rate of change lag, lead, or track the rate of climate change. We capitaliz...
Fossil fuel dependence can be reduced, in part, by renewable energy expansion. Increasingly, renewable energy siting seeks to avoid significant impacts on biodiversity but rarely considers how species ranges will shift under climate change. Here we undertake a systematic literature review on the topic and overlay future renewable energy siting maps...
Aim
Biogeographers have used three primary data types to examine shifts in tree ranges in response to past climate change: fossil pollen, genetic data and contemporary occurrences. Although recent efforts have explored formal integration of these types of data, we have limited understanding of how integration affects estimates of range shift rates...
Contemporary climate change is modifying the distribution, morphology, phenology, physiology, evolution, and interspecific interactions of species. Effects of climate change are mediated not only through the magnitude of change experienced (exposure) and an animal's sensitivity to such changes, but also through the ability of the population or spec...
Determining the distribution and environmental preferences of rare species threatened by global change has long been a focus of conservation. Typical minimum suggested number of occurrences ranges from ~5 to 30, but many species are represented by even fewer occurrences. However, several newer methods may be able to accommodate such low samples siz...
Premise:
Although the balance between cross‐and self‐fertilization is driven by the environment, no long‐term study has documented whether anthropogenic climate change is affecting reproductive strategy allocation in species with mixed mating systems. Here, we test whether the common blue violet (Viola sororia; Violaceae) has altered relative allo...
Context
For many organisms, responses to climate change (CC) will be affected by land-use and land-cover changes (LULCC). However, the extent to which LULCC is concurrently considered in climate change vulnerability assessments (CCVAs) is unclear.
Objectives
We identify trends in inclusion of LULCC and CC in vulnerability assessments of species an...
Local adaptation is a fundamental phenomenon in evolutionary biology, with relevance to formation of ecotypes, and ultimately new species, and application to restoration and species’ response to climate change. Reciprocal transplant gardens, a common garden in which ecotypes are planted among home and away habitats, are the gold standard to detect...
The digitization of museum collections as well as an explosion in citizen science initiatives has resulted in a wealth of data that can be useful for understanding the global distribution of biodiversity, provided that the well‐documented biases inherent in unstructured opportunistic data are accounted for. While traditionally used to model imperfe...
Premise:
A disjunct distribution, where a species' geographic range is discontinuous, can occur through vicariance or long-distance dispersal. Approximately 75 North American plant species exhibit a ~650 km disjunction between the Ozark and Appalachian regions. This disjunction is attributed to biogeographic forces including: (1) Eocene-Oligocene...
Aim
Conservation assessments frequently use occurrence records to estimate species’ geographic distributions and environmental tolerances. Typically, records with imprecise geolocality information are discarded before analysis because they cannot be matched confidently to environmental conditions. However, removing records can artificially truncate...
The digitization of museum collections as well as an explosion in citizen science initiatives has resulted in a wealth of data that can be useful for understanding the global distribution of biodiversity, provided that the well-documented biases inherent in unstructured opportunistic data are accounted for. While traditionally used to model imperfe...
Madagascar has experienced extensive deforestation and overharvesting, and anthropogenic climate change will compound these pressures. Anticipating these threats to endangered species and their ecosystems requires considering both climate change and habitat loss effects. The genus Varecia (ruffed lemurs), which is composed of two Critically Endange...
Accounting for within-species variability in the relationship between occurrence and climate is essential to forecasting species’ responses to climate change. Few climate-vulnerability assessments explicitly consider intraspecific variation, and those that do typically assume that variability is best explained by genetic affinity. Here, we evaluate...
A primary focus of historical biogeography is to understand changes in species ranges, abundance, genetic connectivity, and changes in community composition. Traditionally, biogeographic inference has relied on distinct lines of evidence, including DNA sequences, fossils, and hindcasted ecological niche models. In this review we propose that the de...
Ecological niches reflect not only adaptation to local circumstances but also the tendency of related lineages to share environmental tolerances. As a result, information on phylogenetic relationships has underappreciated potential to inform ecological niche modeling. Here we review three strategies for incorporating evolutionary information into n...
Conservation status and threat assessments evaluate species’ relative risks of extinction globally, regionally, nationally, or locally and estimate the degree to which populations of species are already safeguarded in existing conservation systems, with the aim of exposing the critical gaps in current conservation. Results of the assessments can th...
Many prior studies have uncovered evidence for local adaptation using reciprocal transplant experiments. However, these studies are rarely conducted for a long enough time to observe succession and competitive dynamics in a community context, limiting inferences for long‐lived species. Furthermore, the genetic basis of local adaptation and genetic...
The challenge of biodiversity upscaling, estimating the species richness of a large area from scattered local surveys within it, has attracted increasing interest in recent years, producing a wide range of competing approaches. Such methods, if successful, could have important applications to multi-scale biodiversity estimation and monitoring. Here...
Background
Different processes determine species’ geographic ranges, including species’ responses to changing climate, habitat, or both simultaneously. Here we ask which combination of factors best predicts shifts in the upper and lower elevation range limits and overall range of small mammal species in Yosemite National Park, California, USA acros...
The challenge of biodiversity upscaling, estimating the species richness of a large area from scattered local surveys within it, has attracted increasing interest in recent years, producing a wide range of competing approaches. Such methods, if successful, could have important applications to multi-scale biodiversity estimation and monitoring. Here...
Phenotypic variation within species can vary widely across environmental gradients but forecasts of species’ responses to environmental change often assume species respond homogenously across their ranges. We compared predictions from species and phenotype distribution models under future climate scenarios for Andropogon gerardii, a widely distribu...
Table B1: Local losses and wildlife footprints in units of occupied bird ranges (km2) and missing individual birds.
Table B2: Total and per dollar wildlife footprint for 57 global economic sectors.
Table B3: Total and per dollar wildlife footprint for 57 economic sectors within each of 129 regions.
Table B4: Global imports and exports of embodie...
Figure A1: Global estimates of (a) baseline bird ranges, in numbers of overlapping ranges, and (b) baseline individual birds, based on medium‐density estimates from Gaston et al. 2003, in individual birds/km2.
Table A1: Estimated breeding bird densities (individuals/km2) for each potential vegetation class in Ramankutty et al. 1999, drawn from ass...
Characterizing the distribution of threats facing species is a crucial, first step toward designing effective conservation strategy. The last comprehensive analysis of threats facing rare plants in the United States was conducted nearly 20 years ago. Here we systematically analyze the threats facing 2733 rare and vulnerable plants in the US using t...
Although most conservation efforts address the direct, local causes of biodiversity loss, effective long-term conservation will require complementary efforts to reduce the upstream economic pressures, such as demands for food and forest products, which ultimately drive these downstream losses. Here, we present a wildlife footprint analysis that lin...
Plants existing in small and isolated populations often depend on microclimatic refugia that create local environments buffered from macroclimatic conditions. Currently much effort is devoted toward identifying features that create refugial conditions in the expectation that they will continue to serve as refugia into the future. However, the abili...
Few strategies for conservation seed banking consider current and climate threats simultaneously and few—if any—represent uncertainty inherent in the assessment process. Here we evaluate the vulnerability of 5148 populations of 71 rare plant species in the North American Central Highlands to current threat, threat from climate change, and their com...
Aim
To provide a mechanistic and probabilistic framework for defining the species pool based on species‐specific probabilities of dispersal, environmental suitability and biotic interactions within a specific temporal extent, and to show how probabilistic species pools can help disentangle the geographical structure of different community assembly...
The forests in the Central Hardwoods Region will be affected directly and indirectly by a changing climate over the next 100 years. This assessment evaluates the vulnerability of terrestrial ecosystems in the Central Hardwoods Region of Illinois, Indiana, and Missouri to a range of future climates. We synthesized and summarized information on the c...
Phenotypic traits mediate organisms' interactions with the environment and determine how they affect and are affected by their biotic and abiotic milieu. Thus, dispersion of trait values, or functional diversity (FD) of a community can offer insights into processes driving community assembly. For example, underdispersion of FD suggests that habitat...
Species distribution models (SDMs) are commonly applied to predict species’ responses to anticipated global change, but lack of data from future time periods precludes assessment of their reliability. Instead, performance against test data in the same era is assumed to correlate with accuracy in the future. Moreover, high-confidence absence data is...
Background/Question/Methods
Assisted migration (AM), the purposeful introduction of lagging species to areas that are newly favorable as a result of climate change, is controversial because it a) has the potential to cause invasions by diseases and pests or by the introduced species itself; b) is currently practiced on an ad hoc basis; c) ignores...
Aim: Modeling the distribution of rare and invasive species often occurs in situations where reliable absences for evaluating model performance are unavailable. However, predictions at randomly located sites, or “background” sites, can stand in for true absences. The maximum value of the area under the receiver operator characteristic curve, AUC, c...
Aims
I determine the relative importance of temperature and moisture acting alone and in tandem for range contractions and expansions of mammalian species over c. 70 years.
Location
The contiguous United States west of the eastern border of the Rocky Mountains (103.77° W).
Methods
Museum records of 67 mammalian species from two time periods (1900...
We conducted detailed resurveys of a montane mammal, Urocitellus beldingi, to examine the effects of climate change on persistence along the trailing edge of its range. Of 74 California sites where U. beldingi were historically recorded (1902-1966), 42 per cent were extirpated, with no evidence for colonization of previously unoccupied sites. Incre...
Background/Question/Methods
Species’ ranges are likely limited by many factors acting alone and jointly in a spatially heterogeneous manner. The relative importance of range-limiting factors will be a function not only of the species’ niche and its orientation in environmental space, but also the spatial distribution of these factors in geographi...
Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a pla...
Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a pla...
Background/Question/Methods
Species distribution models are commonly used to project the ranges of species of concern into the future, but unlike within-era projections to the same region, their accuracy cannot be assessed because of lack of data from the future. One method for testing projections across time is to project ranges based on data col...
Conservation biologists use the species–area relationship for a variety of purposes, including upscaling diversity from small plots to regions, predicting species loss, and for identifying biodiversity hotspots and prioritizing actions to protect them. Despite its widespread use, several complications that affect the accuracy of its application are...
Ecologists have recognized for decades the importance of spatial scale in ecological processes and patterns, as well as the complications scale poses for understanding ecological mechanisms. Here we highlight the opportunity attention to scale offers experimental ecology. Despite many advantages to considering scale, a review of the literature indi...
Classic theory predicts species richness scales as the quarter-power of area, yet species-area relationships (SAR) vary widely depending on habitat, taxa, and scale range. Because power-law SAR are used to predict species loss under habitat loss, and to scale species richness from plots to biomes, insight into the wide variety of observed SAR and t...
The biodiversity scaling metrics widely studied in macroecology include the species-area relationship (SAR), the scale-dependent species-abundance distribution (SAD), the distribution of masses or metabolic energies of individuals within and across species, the abundance-energy or abundance-mass relationship across species, and the species-level oc...
As human impacts to the environment accelerate, disparities in the distribution of damages between rich and poor nations mount. Globally, environmental change is dramatically affecting the flow of ecosystem services, but the distribution of ecological damages and their driving forces has not been estimated. Here, we conservatively estimate the envi...
Host population thresholds for the invasion or persistence of infectious disease are core concepts of disease ecology and underlie disease control policies based on culling and vaccination. However, empirical evidence for these thresholds in wildlife populations has been sparse, although recent studies have begun to address this gap. Here, we revie...
A theory of spatial structure in ecological communities is presented and tested. At the core of the theory is a simple allocation rule for the assembly of species in space. The theory leads, with no adjustable parameters, to nonrandom statistical predictions for the spatial distribution of species at multiple spatial scales. The distributions are s...
A theory of spatial structure in ecological communities is presented and tested. At the core of the theory is a simple allocation rule for the assembly of species in space. The theory leads, with no adjustable parameters, to nonrandom statistical predictions for the spatial distribution of species at multiple spatial scales. The distributions are s...