William F. Fagan

William F. Fagan
University of Maryland, College Park | UMD, UMCP, University of Maryland College Park · Department of Biology

Doctor of Philosophy

About

404
Publications
109,753
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26,232
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Introduction
Current projects include: 1) Comparative movement ecology of diverse sets of mammals and birds, 2) Mathematical modeling of animal movement with a focus on memory, perception, gradient-following, and foraging success, 3) Spatial ecology and demography of the endangered Sonoran Pronghorn, and 4) Analyses of interdependencies in geyser eruptions.

Publications

Publications (404)
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Plants and their insect herbivores have been a dominant component of the terrestrial ecological landscape for the past 410 million years and feature intricate evolutionary patterns and co-dependencies. A complex systems perspective allows for both detailed resolution of these evolutionary relationships as well as comparison and synthesis across sys...
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The Upper Geyser Basin at Yellowstone National Park (Wyoming, USA) harbors the greatest concentration of geysers worldwide. Research suggests that individual geysers are not isolated but rather are hydraulically connected in the subsurface with other geysers and thermal springs. To quantify such connections, we combined techniques from machine lear...
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SignificanceFire and logging reduce the carbon stored in Amazon forests, but the long-term impact of forest degradation on animal communities remains unclear. We recorded thousands of hours of ecosystem sounds to investigate the acoustic fingerprint of the animal community in degraded Amazon forests following fire and logging. The emergent 24-h pat...
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Throughout the vector-borne disease modeling literature, there exist two general frameworks for incorporating vector management strategies (e.g. area-wide adulticide spraying and larval source reduction campaigns) into vector population models, namely, the “implicit” and “explicit” control frameworks. The more simplistic “implicit” framework facili...
Article
Trees provide critical contributions to human well-being. They sequester and store greenhouse gasses, filter air pollutants, provide wood, food, and other products, among other benefits. These benefits are threatened by climate change, fires, pests and pathogens. To quantify the current value of the flow of ecosystem services from U.S. trees, and t...
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The study of community spatial structure is central to understanding diversity patterns over space and species co‐occurrence at local scales. While most analytical approaches consider horizontal and vertical dimensions separately, in this study we introduce a three‐dimensional spatial analysis that simultaneously includes horizontal and vertical sp...
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The ability of wild animals to navigate and survive in complex and dynamic environments depends on their ability to store relevant information and place it in a spatial context. Despite the centrality of spatial memory, and given our increasing ability to observe animal movements in the wild, it is perhaps surprising how difficult it is to demonstr...
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Consumers must track and acquire resources in complex landscapes. Much discussion has focused on the concept of a ‘resource gradient’ and the mechanisms by which consumers can take advantage of such gradients as they navigate their landscapes in search of resources. However, the concept of tracking resource gradients means different things in diffe...
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Home‐range estimates are a common product of animal tracking data, as each range represents the area needed by a given individual. Population‐level inference of home‐range areas—where multiple individual home ranges are considered to be sampled from a population—is also important to evaluate changes over time, space or covariates such as habitat qu...
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Scientists often need to know whether pairs of entities tend to occur together or independently. Standard approaches to this issue use co-occurrence indices such as Jaccard, Sørensen-Dice, and Simpson. We show that these indices are sensitive to the prevalences of the entities they describe and that this invalidates their interpretability. We propo...
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Understanding noise in networks and finding the right scale to represent a system are important problems in network biology. Most research focuses on the raw, micro‐scale network from data/simulations and seldom explores the scale dependence of properties. Here, we introduce the einet package, which looks at the most informative scale in a biologic...
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The assembly and maintenance of microbial diversity in natural communities, despite the abundance of toxin-based antagonistic interactions, presents major challenges for biological understanding. A common framework for investigating such antagonistic interactions involves cyclic dominance games with pairwise interactions. The incorporation of highe...
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Modern tracking devices allow for the collection of high‐volume animal tracking data at improved sampling rates over VHF radiotelemetry. Home range estimation is a key output from these tracking datasets, but the inherent properties of animal movement can lead traditional statistical methods to under‐ or overestimate home range areas. The Autocorre...
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Comparing traits across species has been a hallmark of biological research for centuries. While inter‐specific comparisons can be highly informative, phylogenetic inertia can bias estimates if not properly accounted for in comparative analyses. In response, researchers typically treat phylogenetic inertia as a form of autocorrelation that can be de...
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Seasonal migrations are a widespread and broadly successful strategy for animals to exploit periodic and localized resources over large spatial scales. It remains an open and largely case-specific question whether long-distance migrations are resilient to environmental disruptions. High levels of mobility suggest an ability to shift ranges that can...
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Previous work involving integro-difference equations of a single species in a homogenous environment has emphasized spreading behaviour in unbounded habitats. We show that under suitable conditions, a simple scalar integro-difference equation incorporating a strong Allee effect and overcompensation can produce solutions where the population persist...
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Background: Migrating birds experience weather conditions that change with time, which affect their decision to stop or resume migration. Soaring migrants are especially sensitive to changing weather conditions because they rely on the availability of environmental updrafts to subsidize flight. The timescale that local weather conditions change ov...
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· Home-range estimates are a common product of animal tracking data, as each range informs on the area needed by a given individual. Population-level inference on home-range areas—where multiple individual home-ranges are considered to be sampled from a population—is also important to evaluate changes over time, space, or covariates, such as habita...
Preprint
Full-text available
1. Modern tracking devices allow for the collection of high-volume animal tracking data at improved sampling rates over VHF radiotelemetry. Home range estimation is a key output from these tracking datasets, but the inherent properties of animal movement can lead traditional statistical methods to under- or overestimate home range areas. 2. The Aut...
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Integrating diverse concepts from animal behavior, movement ecology, and machine learning, we develop an overview of the ecology of learning and animal movement. Learning-based movement is clearly relevant to ecological problems, but the subject is rooted firmly in psychology, including a distinct terminology. We contrast this psychological origin...
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Perception is central to the survival of an individual for many reasons, especially as it affects the ability to gather resources. Consequently, costs associated with perception are partially shaped by resource availability. Understanding the interplay of environmental factors (such as the density and distribution of resources) with species-specifi...
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Plant–insect associations have been a significant component of terrestrial ecology for more than 400 Myr. Exploring these interactions in the fossil record through novel perspectives provides a window into understanding evolutionary and ecological forces that shaped these interactions. For the past several decades, researchers have documented, desc...
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Background Even when microbial communities vary wildly in their taxonomic composition, their functional composition is often surprisingly stable. This suggests that a functional perspective could provide much deeper insight into the principles governing microbiome assembly. Much work to date analyzing the functional composition of microbial communi...
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Full-text available
Comparing traits across species has been a hallmark of biological research for centuries. While inter-specific comparisons can be highly informative, phylogenetic inertia can bias estimates if not properly accounted for in comparative analyses. In response, researchers typically treat phylogenetic inertia as a form of autocorrelation that can be de...
Preprint
Full-text available
Modularity and organizational hierarchy are important concepts in understanding the structure and evolution of interactions in complex biological systems. In this work, we introduce and use a spectral characterization measure (Spectral Entropy) to quantify modularity in protein-to-protein interaction (PPI) networks in species across the tree of lif...
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Migration of ungulates (hooved mammals) is a fundamental ecological process that promotes abundant herds, whose effects cascade up and down terrestrial food webs. Migratory ungulates provide the prey base that maintains large carnivore and scavenger populations and underpins terrestrial biodiversity (fig. S1). When ungulates move in large aggregati...
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Network inference is a major field of interest for the ecological community, especially in light of the high cost and difficulty of manual observation, and easy availability of remote, long term monitoring data. In addition, comparing across similar network structures, especially with spatial, environmental, or temporal variability and, simulating...
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Exceptionally preserved fossil sites have allowed specimen-based identification of trophic interactions to which network analyses have been applied. However, network analyses of the fossil record suffer from incomplete and indirect data, time averaging that obscures species coexistence, and biases in preservation. Here, we present a high-resolution...
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Ecologists have long been interested in linking individual behavior with higher‐level processes. For motile species, this ‘upscaling’ is governed by how well any given movement strategy maximizes encounters with positive factors, and minimizes encounters with negative factors. Despite the importance of encounter events for a broad range of ecologic...
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Full-text available
Safeguarding tropical forest biodiversity requires solutions for monitoring ecosystem composition over time. In the Amazon, logging and fire reduce forest carbon stocks and alter tree species diversity, but the long-term consequences for wildlife remain unclear, especially for lesser-known taxa. Here, we combined data from multi-day acoustic survey...
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Nomadic movements are often a consequence of unpredictable resource dynamics. However, how nomadic ungulates select dynamic resources is still understudied. Here we examined resource selection of nomadic Mongolian gazelles ( Procapra gutturosa ) in the Eastern Steppe of Mongolia. We used daily GPS locations of 33 gazelles tracked up to 3.5 years. W...
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Full-text available
The assembly and maintenance of microbial diversity in natural communities, despite the abundance of toxin-based antagonistic interactions, presents major challenges for biological understanding. A common framework for investigating such antagonistic interactions involve cyclic dominance games with pairwise interactions. The incorporation of higher...
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Full-text available
Quantifying early life movements is essential to understanding migratory pathways and habitat use that can impact individuals’ success later in life. To gauge how neonatal movements set the stage for later habitat use, we tracked neonate leatherback turtles (n= 94) with acoustic tags from Pacuare, Costa Rica, in 2016 and 2018. We analyzed movements...
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Insofar as methane was the predominant greenhouse gas of the Archean and early Proterozoic eons, its wax and wane in Earth’s atmosphere would have contributed to climate change and the relative flux of harmful UV radiation to surface environments. If correct, understanding the first-order environmental controls (e.g., O 2 or resource concentration)...
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Migrating animals are known to play an important role in nutrient transfer over short distances; however, this phenomenon has not been well studied for long-distance migrants. In this preliminary study, we focused on nitrogen (N) transfer by 44 bird species that migrate from Eurasia to two regions in sub-Saharan Africa that fall into the lowest 10%...
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Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of...
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Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of...
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Basic knowledge of species biology and ecology is essential for the assessment of species conservation status and planning for efficient conservation strategies; however, this information is not always readily available. Here we use movement behavior to understand the ecology and social biology of the poorly known southern three-banded armadillo (T...
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We propose a model for memory-based movement of an individual. The dynamics are modeled by a stochastic differential equation, coupled with an eikonal equation, whose potential depends on the individual's memory and perception. Under a simple periodic environment, we discover that both long and short-term memory with appropriate time scales are ess...
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Carbon Use Efficiency (CUE) is a popular concept for measuring the efficiency of biomass production in different biological systems and, is frequently employed to understand effects of microbial processes on soil carbon dynamics. CUE in soil microbes is often measured through respiration-based studies, especially through the addition of a labile ca...
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A classic distinction in spatial ecology is between range-residency and migration. A new study - on dozens of ungulate populations worldwide - demonstrates how the dynamics of food resources help determine which movement pattern animals will exhibit.
Preprint
Full-text available
1. Ecologists have long been interested in linking individual behavior with higher-level processes. For motile species, this 'upscaling' is governed by how well any given movement strategy maximizes encounters with positive factors, and minimizes encounters with negative factors. Despite the importance of encounter events for a broad range of ecolo...
Article
Full-text available
Management strategies for control of vector-borne diseases, for example Zika or dengue, include using larvicide and/or adulticide, either through large-scale application by truck or plane or through door-to-door efforts that require obtaining permission to access private property and spray yards. The efficacy of the latter strategy is highly depend...
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Dispersal is a fundamental ecological process that, on an individual level, is associated with intrinsic and fixed personality traits such as ‘boldness’. However, it is unknown whether personality traits or behavioural syndromes might change as a consequence of dispersal itself. We analysed 14 GPS-collared grey wolves, Canis lupus, in Finland that...
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Animal tracking data are being collected more frequently, in greater detail, and on smaller taxa than ever before. These data hold the promise to increase the relevance of animal movement for understanding ecological processes, but this potential will only be fully realized if their accompanying location error is properly addressed. Historically, c...
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Animals use different modes of movement at different times, in different locations, and on different scales. Incorporating such context dependence in mathematical models represents a substantial increase in complexity, but creates an opportunity to more fully integrate key biological features. Here, we consider the spatial dynamics of a population...
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The Cambrian Period (541-485 Mya) represents a major stage in the development of metazoan-dominated assemblages with complex community structure and species interactions. Exceptionally preserved fossil sites have allowed specimen-based identification of putative trophic interactions to which network analyses have been applied. However, network anal...
Preprint
Full-text available
Background: Multiple types of error can enter metagenomics sample analysis, including contamination during sample collection, library preparation and sequencing, as well as incorrect taxonomic assignment by bioinformatics packages. Often, such errors either go unidentified, or else are removed, ad hoc, based on user knowledge of microbial ecology....
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Accurately quantifying species’ area requirements is a prerequisite for effective area‐based conservation. This typically involves collecting tracking data on species of interest and then conducting home‐range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on previous work,...
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Encounter rates link movement strategies to intra- and inter-specific interactions, and therefore translate individual movement behavior into higher-level ecological processes. Indeed, a large body of interacting population theory rests on the law of mass action, which can be derived from assumptions of Brownian motion in an enclosed container with...
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King Penguins (Aptenodytes patagonicus) live in remote locations, in large colonies with asynchronous breeding. These three factors hinder the design and conduct of King Penguin censuses, and assessments of trend often require piecing together mismatched surveys of different demographic components. This study introduces a new method to remotely cen...
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Species range maps based on expert opinion are a critical resource for conservation planning. Expert maps are usually accompanied by species descriptions that specify sources of internal range heterogeneity, such as habitat associations, but these are rarely considered when using expert maps for analysis. Here, we develop a quantitative metric (“Ex...
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Designing an effective conservation strategy requires understanding where rare species are located. Because rare species can be difficult to find, ecologists often identify other species called conservation surrogates that can help inform the distribution of rare species. Species distribution models typically rely on environmental data when predict...
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Omnivores have long been known to play an important role in determining the stability of ecological communities. Recent theoretical studies have suggested that they may also increase the resilience of their communities to habitat destruction, one of the major drivers of species extinctions globally. However, these outcomes were obtained for minimal...
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Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research sp...
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1. Despite years of attention, the dynamics of species constrained to disperse within riverine networks are not well captured by existing metapopulation models, which often ignore local dynamics within branches. 2. We develop a modelling framework, based on traditional metapopulation theory, for patch occupancy dynamics subject to local colonisati...
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The Arctic has been warming rapidly, affecting ecological processes across the region. Caribou and reindeer (Rangifer tarandus) is a keystone Arctic species undergoing declines in many parts of its range, but definitive links between climate and populations remain elusive. The conspicuous and dramatic mass migration of many caribou populations, dur...
Preprint
Trees provide critical contributions to human well-being. They sequester and store greenhouse gasses, filter air pollutants, and provide wood, food, and other products, among other benefits. However, global change threatens these benefits. To quantify the monetary value of US trees and the threats they face, we combine macroevolutionary and economi...