Catherine Graham

Catherine Graham
Swiss Federal Institute for Forest, Snow and Landscape Research WSL | WSL · Biodiversity and Conservation Biology Research Unit

PhD

About

240
Publications
127,975
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38,487
Citations

Publications

Publications (240)
Article
Community ecologists have made great advances in understanding how natural communities can be both diverse and stable by studying communities as interaction networks. However, focus has been on interaction networks aggregated over time, neglecting the consequences of the seasonal organization of interactions (hereafter 'seasonal structure') for com...
Article
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Quaternary climate fluctuations can affect speciation in regional biodiversity assembly in two non-mutually exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation in underused adaptive zones during ice-free periods. We detected biogeographic and genetic signatures associa...
Preprint
Full-text available
Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with even greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integ...
Article
Reduction of functional diversity (FD) and phylogenetic diversity (PD) likely affects ecosystem functions and reduces the potential of communities to respond to changes, such as climate change. Mutualistic interactions are essential for maintaining diversity, but their role has largely been ignored in conservation planning. We propose using a speci...
Article
Full-text available
Species interactions are influenced by the trait structure of local multi‐trophic communities. However, it remains unclear whether mutualistic interactions in particular can drive trait patterns at the global scale, where climatic constraints and biogeographic processes gain importance. Here we evaluate global relationships between traits of frugiv...
Data
Supporting information for: Ian McFadden, Susanne Fritz, Niklaus Zimmermann, Loïc Pellissier, Daniel Kissling, Joseph Tobias, Matthias Schleuning, Catherine Graham. 2022. Global plant-frugivore trait matching is shaped by climate and biogeographic history. Ecology Letters, 25:686-696
Data
From Dryad: Modified from: McFadden et al. Global plant-frugivore trait matching is shaped by climate and biogeographic history. 2022. Ecology Letters To assemble this dataset of trait measurements for avian frugivores, we compiled a dataset of beak measurements taken from wild-caught and released individuals, as well as specimens accessed in num...
Article
Full-text available
Many endotherms use torpor, saving energy by a controlled reduction of their body temperature and metabolic rate. Some species (e.g., arctic ground squirrels, hummingbirds) enter deep torpor, dropping their body temperatures by 23-37°C, while others can only enter shallow torpor (e.g., pigeons, 3-10°C reductions). However, deep torpor in mammals ca...
Preprint
Full-text available
While aquatic (blue) and terrestrial (green) food webs are parts of the same landscape, it remains unclear whether they respond similarly to shared environmental gradients. We use empirical community data from hundreds of sites across Switzerland, and show that blue and green food webs have different structural and ecological properties along eleva...
Article
Insular biodiversity is expected to be regulated differently than continental biota, but their determinants remain to be quantified at a global scale. We evaluated the importance of physical, environmental and historical factors on mammal richness and endemism across 5592 islands worldwide. We fitted generalized linear and mixed models to accommoda...
Preprint
Full-text available
Quaternary climate fluctuations can affect biodiversity assembly through speciation in two non-mutually-exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation during ice-free periods. Here we detected biogeographic and genetic signatures associated with both mechanisms in...
Preprint
Full-text available
Species interactions are influenced by the trait structure of local multi-trophic communities. However, it remains unclear whether mutualistic interactions in particular can drive trait patterns at the global scale, where climatic constraints and biogeographic processes gain importance. Here we evaluate global relationships between traits of frugiv...
Preprint
Full-text available
Landscape dynamics and river network rearrangements are widely thought to shape the diversity of Neotropical freshwater fishes, the most species-rich continental vertebrate fauna on Earth. Yet the effects of hydrogeographic changes on fish dispersal and diversification remain poorly understood. Here we integrate an unprecedented occurrence dataset...
Article
Aim: The role of evolutionary history in shaping the patterns of species distributions is generally explored at coarse spatial extents. However, at small spatial extents, the combined effects of history and ecological processes on local diversity has received less attention. We test the relative importance of historical and ecological factors on th...
Article
Full-text available
As the pace of environmental change increases, there is an urgent need for quantitative data revealing the temporal dynamics of local communities in tropical areas. Here, we quantify the stability of avian assemblages in the highly threatened, but poorly studied, Andean biodiversity hot spot. We evaluated the temporal variation in species richness...
Preprint
Full-text available
Aim: Climate is an essential element of species' niche estimates in many current ecological applications such as species distribution models (SDMs). Climate predictors are often used in the form of long-term mean values. Yet, climate can also be described as spatial or temporal variability for variables like temperature or precipitation. Such varia...
Preprint
Full-text available
Many small endotherms use torpor, saving energy by a controlled reduction of their body temperature and metabolic rate. Some species (e.g. arctic ground squirrels, hummingbirds) enter deep torpor, dropping their body temperatures by 23-37 °C, while others can only enter shallow torpor (e.g., pigeons, 3-10 °C reductions). However, deep torpor in mam...
Article
Full-text available
Aim We aimed to dissect the spatial variation of the direct and indirect effects of climate and productivity on global species richness of terrestrial tetrapods. Location Global. Time period Present. Major taxa studied Terrestrial tetrapods. Methods We used a geographically weighted path analysis to estimate and map the direct and indirect effe...
Preprint
Full-text available
High resolution, downscaled climate model data are used in a wide variety of applications in environmental sciences. Here we present the CHELSA-TraCE21k downscaling algorithm to create global monthly climatologies for temperature and precipitation at 30 arcsec spatial resolution in 100 year time steps for the last 21,000 years. Paleo orography at h...
Article
Full-text available
Aim Separating the biotic and abiotic factors controlling species distributions has been a long‐standing challenge in ecology and biogeography. Joint species distribution models (JSDMs) have emerged as a promising statistical framework towards this objective by simultaneously modelling the environmental responses of multiple species and approximati...
Article
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Invasive species can significantly affect native species when their niches are similar. Ecological and morphological similarities between the invasive Australian palm, Archontophoenix cunninghamiana, and the native palm from the Brazilian Atlantic Forest, Euterpe edulis, suggest that they have similar environmental requirements and functional roles...
Article
Full-text available
Populations along steep environmental gradients are subject to differentiating selection that can result in local adaptation, despite countervailing gene flow and genetic drift. In montane systems, where species are often restricted to narrow ranges of elevation, it is unclear whether selection is strong enough to influence functional differentiati...
Poster
More than 200 bird and mammal species use torpor to save energy. Torpor = a controlled drop in metabolic rate and body temperature. Usually, birds are thought to either stay asleep at a high body temperature (like humans, Fig. 1a), or use deep torpor, dropping down to their minimum torpid body temperature, a drop of between 23-38 °C (e.g. hummingbi...
Preprint
Full-text available
A primary goal of biodiversity research is to uncover the processes acting in space and time to create the global distribution of species richness. However, we currently lack an understanding of how recent versus ancient biodiversity dynamics shape patterns of diversity for most groups. Here, we introduce a method to partition lineage turnover into...
Preprint
Full-text available
A primary goal of biodiversity research is to uncover the processes acting in space and time to create the global distribution of species richness. However, we currently lack an understanding of how recent versus ancient biodiversity dynamics shape patterns of diversity for most groups. Here, we introduce a method to partition lineage turnover into...
Article
1. The seasonal movement of animals has been linked to seasonal variation in ecological productivity, and it has been hypothesized that primary consumers synchronize migration with vegetation phenology. Within temperate regions of the Northern Hemisphere, herbivorous bird species often track the phenology of vegetation greenness during spring migra...
Article
Full-text available
Scientific understanding of biodiversity dynamics, resulting from past climate oscillations and projections of future changes in biodiversity, has advanced over the past decade. Little is known about how these responses, past or future, are spatially connected. Analyzing the spatial variability in biodiversity provides insight into how climate chan...
Article
Full-text available
Species distribution models (SDMs) are widely used to predict and study distributions of species. Many different modeling methods and associated algorithms are used and continue to emerge. It is important to understand how different approaches perform, particularly when applied to species occurrence records that were not gathered in struc­tured sur...
Article
Within‐clade allometric relationships represent standard laws of scaling between energy and size, and their outliers provide new avenues for physiological and ecological research. According to the metabolic level boundaries hypothesis, metabolic rates as a function of mass are expected to scale closer to 0.67 when driven by surface‐related processe...
Article
Torpor is an important energy saving strategy in some small birds, but it has rarely been studied in natural field conditions. We compared torpor use across 43 wild‐caught individuals of eight hummingbird species across sites with different natural temperature regimes. Most laboratory studies focus on the relationship between metabolic rate and tem...
Article
Full-text available
Understanding the processes that drive the dramatic changes in biodiversity along the productivity gradient remains a major challenge. Insight from simple, bivariate relationships so far has been limited. We combined >11,000 community plots in the French Alps with a molecular phylogeny and trait information for >1200 plant species to simultaneously...
Article
Explore the spatial variation of the relationships between species richness (SR), phylogenetic diversity (PD) and environmental factors to infer the possible mechanisms underlying patterns of diversity in different regions of the globe. Global. Present day. Terrestrial mammals. We used a hexagonal grid to map SR and PD of mammals and four environme...
Article
Full-text available
A key component of individual fitness is the ability to manage energy stores in response to variable resource availability, but because directly measuring energy budgets is difficult, daily energy management is rarely measured. Hummingbirds' energy management is relatively simple to model compared to other endotherms because they have high mass‐spe...
Article
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High-elevation organisms experience shared environmental challenges that include low oxygen availability, cold temperatures, and intense UV radiation. Consequently, repeated evolution of the same genetic mechanisms may occur across high-elevation taxa. To test this prediction, we investigated the extent to which the same biochemical pathways, genes...
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The probability of long-term persistence of a population is strongly determined by adult survival rates, but estimates of survival are currently lacking for most species of birds in the tropical Andes, a global biodiversity hotspot. We calculated apparent survival rates of birds in the Ecuadorian tropical Andes using a moderately long-term (11 yr)...
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Phylogenetic turnover quantifies the evolutionary distance among species assemblages and is central to understanding the main drivers shaping biodiversity. It is affected both by geographic and environmental distance between sites. Therefore, analyzing phylogenetic turnover in environmental space requires removing the effect of geographic distance....
Article
Remotely sensed data can help to identify both suitable habitat for individual species, and environmental conditions that foster species richness, which is important when predicting how biodiversity will respond to global change. The question is how to summarize remotely sensed data so that they are most relevant for biodiversity analyses, and the...
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Preserving the evolutionary history and ecological functions that different species embody, in addition to species themselves, is a growing concern for conservation. Recent studies warn that conservation priority regions identified using species diversity differ from those based on phylogenetic or functional diversity. However, spatial mismatches i...
Article
The latitudinal diversity gradient (LDG) is one of the most widely studied patterns in ecology, yet no consensus has been reached about its underlying causes. We argue that the reasons for this are the verbal nature of existing hypotheses, the failure to mechanistically link interacting ecological and evolutionary processes to the LDG, and the fact...
Article
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Read author copy here (read-only link): https://rdcu.be/9Pio. -- Many species migrate long distances annually between their breeding and wintering areas1. Although global change affects both ranges, impact assessments have generally focused on breeding ranges and ignored how environmental changes influence migrants across geographical regions and...
Preprint
Full-text available
Torpor is an important energy saving strategy in small endotherms, but it has been insufficiently studied in natural field conditions. Building on what we know from laboratory studies, we compared torpor use across hummingbird species and different natural temperature regimes to explore predominant hypotheses about torpor use and evaluate the possi...
Presentation
Comparing the beta-diversity of hummingbird-plant interactions between four sites in northwestern Pichincha, Ecuador, within the project EPHI (Ecology of plant and hummingbird interactions)
Article
Species interactions are fundamental to community dynamics and ecosystem processes. Despite significant progress in describing species interactions, we lack the ability to predict changes in interactions across space and time. We outline a Bayesian approach to separate the probability of species co‐occurrence, interaction and detectability in influ...
Article
Full-text available
Aim Seasonal migration by animals is an extensively studied, global phenomenon. Yet, we still lack a general understanding whether migrants track their niche between summer and winter ranges (following fixed environmental conditions throughout the year) and which mechanisms influence this behaviour. Here, we assessed the degree of seasonal niche tr...
Article
Full-text available
Global variation in species richness is widely recognized, but the explanation for what drives it continues to be debated. Previous efforts have focused on a subset of potential drivers, including evolutionary rate, evolutionary time (maximum clade age of species restricted to a region), dispersal (migration from one region to another), ecological...
Article
Full-text available
Many important patterns and processes vary across the phylogeny and depend on phylogenetic scale. Nonetheless, phylogenetic scale has never been formally conceptualized, and its potential remains largely unexplored. Here, we formalize the concept of phylogenetic scale, review how phylogenetic scale has been considered across multiple fields and pro...
Article
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Land use change modifies the environment at multiple spatial scales, and is a main driver of species declines and deterioration of ecosystem services. However, most of the research on the effects of land use change has focused on taxonomic diversity, while functional diversity, an important predictor of ecosystem services, is often neglected. We ex...
Presentation
Controlled nighttime hypothermia (reduction in body temperature and metabolic rate) has been described in many bird and mammal species. In hummingbirds, all past studies show exclusive use of deep torpor where body temperature drops with ambient temperature down to a minimum body temperature that seems to be species-dependent. As hummingbirds norma...
Article
Full-text available
At high temperature (greater than 40°C) endotherms experience reduced passive heat dissipation (radiation, conduction and convection) and increased reliance on evaporative heat loss. High temperatures challenge flying birds due to heat produced by wing muscles. Hummingbirds depend on flight for foraging, yet inhabit hot regions. We used infrared th...
Article
Full-text available
Identifying which species are at greatest risk, what makes them vulnerable, and where they are distributed are central goals for conservation science. While knowledge of which factors influence extinction risk is increasingly available for some taxonomic groups, a deeper understanding of extinction correlates and the geography of risk remains lacki...
Data
Variable importance plot from the random forest model. Plot shows rank order of importance of all predictors included in the model. Because we used raw (non-imputed) data to build the conditional inference forest, variables with lots of missing data were biased against in terms of their relative importance. However, two of the top three most import...