David A Spiller

David A Spiller
University of California, Davis | UCD · Department of Evolution & Ecology

Doctor of Philosophy

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74
Publications
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Publications

Publications (74)
Article
Increases in consumer abundance following a resource pulse can be driven by diet shifts, aggregation, and reproductive responses, with combined responses expected to result in faster response times and larger numerical increases. Previous work in plots on large Bahamian islands has shown that lizards (Anolis sagrei) increased in abundance following...
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Most prominent theories of food web dynamics imply the simultaneous action of bottom–up and top–down forces. However, transient bottom‐up effects resulting from resource pulses can lead to sequential shifts in the strength of top–down predator effects. We used a large‐scale field experiment (32 small islands sampled over 5 years) to probe how the f...
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Biological invasions are both a pressing environmental challenge and an opportunity to investigate fundamental ecological processes, such as the role of top predators in regulating biodiversity and food-web structure. In whole-ecosystem manipulations of small Caribbean islands on which brown anole lizards (Anolis sagrei) were the native top predato...
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Resource pulses are brief periods of unusually high resource abundance. While population and community responses to resource pulses have been relatively well studied, how individual consumers respond to resource pulses has received less attention. Local consumers are often the first to respond to a resource pulse, and the form and timing of individ...
Article
Only a handful of multi-generational experiments in natural systems of eco-evolutionary dynamics currently exist, despite Fussmann et al.'s call for more such studies nearly a decade ago. To perform such a study, in 2008 we introduced the lizard Leiocephalus carinatus, a predator (and possible food competitor) of the lizard Anolis sagrei, to seven...
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Introduced predators can have dramatic effects on island ecosystems, the magnitude of which are likely to vary with island characteristics. We investigated the influence of two important properties of islands—size and amount of resource subsidy—on the effects of an introduced predatory lizard (Anolis sagrei) on three groups of arthropod prey. Lizar...
Article
Understanding processes that may stabilize ecological systems confronted with rapidly changing environmental conditions is a key issue in ecology. We studied a system of highly fluctuating populations, the moth Achyra rantalis feeding on the plant Sesuvium portulacastrum in a group of small subtropical islands of the Bahamas. The plant is a prostra...
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AimWe ask empirically how the strength of the three major interactions – predation, competition and mutualism – changes with increasing island area. We review and expand current theory concerning these relationships.LocationData for evaluating this question come from several Bahamian archipelagos and involve both experiments and observations. The l...
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Signaling individuals must effectively capture and hold the attention of intended conspecific receivers while limiting eavesdropping by potential predators. A possible mechanism for achieving this balance is for individuals to modulate the physical properties of their signals or to alter the proportion of time spent signaling, depending upon local...
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Flows of energy and materials link ecosystems worldwide and have important consequences for the structure of ecological communities. While these resource subsidies typically enter recipient food webs through multiple channels, most previous studies focussed on a single pathway of resource input. We used path analysis to evaluate multiple pathways c...
Article
Pulsed resource subsidies can have profound effects on recipient communities. The effects of resource pulses are often mediated by increases in the density of consumer populations. Here we investigate several mechanisms linking experimental pulses of seaweed deposition to population‐level responses in the brown anole Anolis sagrei. Subsidized lizar...
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Although abiotic and biotic factors can interact to shape the spatial niche of a species, studies that explore the interactive effects of both at a local scale are rare. We demonstrate that one of the main axes (perch height) characterizing the spatial niche of a common lizard, Anolis sagrei, varies according to the interactive effects of weather a...
Conference Paper
Background/Question/Methods Founding events are a necessary component of both natural colonization and human-mediated introductions; yet, they are rarely observed in nature, thus the evolutionary significance of these events is difficult to evaluate. Whether random processes such as founder events contribute substantially to patterns of evolution...
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Traditionally, productivity and disturbance have been hypothesized as important determinants of food-chain length. More recently, growing empirical evidence suggests a strong role of ecosystem size. To theoretically explore the effects of basal productivity, disturbance, and ecosystem size on food-chain length, we develop and analyze a metacommunit...
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The extent to which random processes such as founder events contribute to evolutionary divergence is a long-standing controversy in evolutionary biology. To determine the respective contributions of founder effects and natural selection, we conducted an experiment in which brown anole (Anolis sagrei) lizard populations were established on seven sma...
Article
The effect of environmental change on ecosystems is mediated by species interactions. Environmental change may remove or add species and shift life-history events, altering which species interact at a given time. However, environmental change may also reconfigure multispecies interactions when both species composition and phenology remain intact. I...
Conference Paper
Background/Question/Methods The flow of resources from one habitat to another can significantly impact recipient food webs. Mutualisms play an underappreciated role in structuring ecological communities. We conducted a field experiment examining how seaweed subsidies from the marine environment influence the strength of a terrestrial mutualism be...
Conference Paper
Background/Question/Methods The influence of Connell's species-interactions studies on community ecology is discussed. Results/Conclusions In 1961, Joe Connell set the gold standard for species-interaction studies when he published his dissertation research in Ecology and Ecological Monographs on the effects of competition, predation and physi...
Article
The effect of resource subsidies on recipient food webs has received much recent attention. The purpose of this study was to measure the effects of significant seasonal seaweed deposition events, caused by hurricanes and other storms, on species inhabiting subtropical islands. The seaweed represents a pulsed resource subsidy that is consumed by amp...
Article
Ecologists have long struggled to explain variation in food-chain length among natural ecosystems. Food-chain length is predicted to be shorter in ecosystems subjected to greater disturbance because longer chains are theoretically less resilient to perturbation. Moreover, food-chain length is expected to be longer in larger ecosystems because incre...
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Aim To investigate species compositions, rates of species turnover, species–area and species–distance relationships and patterns of nestedness in the floras of small Bahamian islands, by comparing two groups of islands that had been differentially affected by two hurricanes. Location Small islands occurring on either side of Great Exuma near George...
Article
It is well known that for an isolated population, the probability of extinction is positively related to population size variation: more variation is associated with more extinction. What, then, is the relation of extinction to population size variation for a population embedded in a metapopulation and subjected to repeated extinction and recoloniz...
Article
We investigated how temporal variation in rainfall influences the impact of lizards on spiders inhabiting small islands in Abaco, Bahamas. Annual censuses of web spiders were conducted on nine lizard islands and on eight no-lizard islands 1994-2003. Repeated-measures ANOVA showed that annual variation in spider density (time) and in the lizard effe...
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Major abiotic disturbance can be an important factor influencing food-web dynamics, particularly in areas impacted by the recent increase in hurricane activity. We present a unique set of data on key food-web processes occurring on 10 small islands for three relatively calm years and then four subsequent years during which two hurricanes passed dir...
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As the environment changes, will species be able to adapt? By conducting experiments in natural environments, biologists can study how evolutionary processes such as natural selection operate through time. We predicted that the introduction of a terrestrial predator would first select for longer-legged lizards, which are faster, but as the lizards...
Article
We monitored spiders on 41 Bahamian islands for 4 years before and then 4 years after the catastrophic Hurricane Floyd passed directly over the site, inundating the study islands with its storm surge. The respective recoveries of major community properties after this annihilation were far from synchronous. Before the hurricane, the species-area rel...
Article
Aim To examine patterns of abundance, density, size and shell use in land hermit crabs, Coenobita clypeatus (Herbst), occurring on three groups of small islands, and to determine how these variables change among islands. Location Small islands in the Central Exuma Cays and near Great Exuma, Bahamas. Methods Land hermit crabs were captured in baited...
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Population phenomena, which provide much of the underlying basis for the theoretical structure of island biogeography, have received little direct study. We determined a key population trait—survival—in the Bahamian lizard Anolis sagrei on islands with an experimentally introduced predatory lizard and on neighboring unmanipulated islands. On unmani...
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We studied consequences of storm damage on buttonwood (Conocarpus erectus) shrubs and their herbivores in the Bahamian islands. Buttonwood is polymorphic, with green shrubs producing few leaf trichomes and silver shrubs covered in dense trichomes. We first characterize traits of green vs. silver shrubs relevant for herbivores, and then assay damage...
Article
The role of behaviour in evolutionary change has long been debated. On the one hand, behavioural changes may expose individuals to new selective pressures by altering the way that organisms interact with the environment, thus driving evolutionary divergence. Alternatively, behaviour can act to retard evolutionary change: by altering behavioural pat...
Article
Two recent hurricanes passed directly over the northern Bahamas 2 years apart, allowing a comparison of their effects on lizard populations inhabiting exactly the same islands. The hurricanes differed in two ways: one struck during the reproductive season and was relatively severe; the other struck after most reproduction had taken place and was mi...
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Studies on the lizard, Anolis sagrei, revealed that after Hurricane Floyd devastated the Bahamas in 1999, some populations consisted only of hatchlings. Because the storm surge of the hurricane completely inundated these islands, apparently for up to 6 h, survival of anole eggs in salt water for such periods is implied. To test this hypothesis dire...
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This study analyzes extinction patterns for two species of orb spiders monitored annually on 77 islands over a continuous 20-yr period. One species, Argiope argentata, has large populations sometimes crashing quickly to extinction and a much weaker relation of extinction likelihood to population size than does the other species, Metepeira datona. D...
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Following Hurricane Lili, which passed directly over the site of our ongoing study in Great Exuma, Bahamas, herbivory increased on devastated islands exposed to the storm surge, but not on protected islands. Observations suggested that foliage sprouting on severely damaged shrubs was more susceptible to herbivores than was new foliage on undamaged...
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We artificially invaded a set of small islands with the large lizard Leiocephalus carinatus to determine effects on food-web elements including an intermediate predator, the lizard Anolis sagrei; the latter was previously found to have major, mostly direct effects on web spiders, as well as detectable indirect effects on aerial arthropods (includin...
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We document the decimation and recovery of the commonest lizard species, Anolis sagrei, on 66 islands in the Bahamas that were directly hit by Hurricane Floyd in September 1999. Before the hurricane, an island's area was a better predictor of the occurrence of A. sagrei than was its altitude. Immediately after, altitude was a better predictor: Appa...
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There has been considerable research on both top-down effects and on disturbances in ecological communities; however, the interaction between the two, when the disturbance is catastrophic, has rarely been examined. Predators may increase the probability of prey extinction resulting from a catastrophic disturbance both by reducing prey population si...
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The primary objective of this study was to test the: hypothesis that lizards intensify interactions among spider species. The most abundant lizard and web-spider species (Anolis sagrei and Merepeira datona, respectively), were manipulated within field enclosures over a 30-mo period. The design was a 2 x 2 factorial: A. sagrei present and removed, c...
Article
The primary objective of this study was to test the hypothesis that lizards intensify interactions among spider species. The most abundant lizard and web-spider species (Anolis sagrei and Metepeira datona, respectively), were manipulated within field enclosures over a 30-mo period. The design was a 2 × 2 factorial: A. sagrei present and removed, cr...
Article
We used a system of neighboring small islands with and without the lizard Anolis sagrei to stage a 7-yr experimental study of the effects of an invading species. Lizard propagules were introduced to four islands, randomly selected from eight that lacked lizards naturally. Four other islands where lizards occurred naturally constituted a third treat...
Article
We used a system of neighboring small islands with and without the lizard Anolis sagrei to stage a 7‐yr experimental study of the effects of an invading species. Lizard propagules were introduced to four islands, randomly selected from eight that lacked lizards naturally. Four other islands where lizards occurred naturally constituted a third treat...
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Small islands in the Bahamas often do not contain Anolis lizards. We took an experimental approach to investigate whether absence of A. carolinensis and A. sagrei from these islands results from the inability of populations to become established and whether the presence of the other species has a negative effect on population density and probabilit...
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Lizard and spider populations were censused immediately before and after Hurricane Lili on islands differentially affected by the storm surge. The results support three general propositions. First, the larger organisms, lizards, are more resistant to the immediate impact of moderate disturbance, whereas the more prolific spiders recover faster. Sec...
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To assess the impact of lizards on species richness and properties of individual species of web spiders, we conducted a 4.5-yr field experiment on Staniel Cay, Exumas, Bahamas. Spider populations were censused at similar to 2-mo intervals in lizard-removal enclosures and in control enclosures with lizards present at natural densities. Lizards reduc...
Article
Sea grape (Coccoloba uvifera) leaf damage was measured on 11 islands with diurnal lizards (Anolis sagrei) and on 7 islands without diurnal lizards from 1986 to 1993. Two types of damage were common: scars (necrotic areas) and holes (entirely missing areas). A static measure in 1986 showed that both scar and hole damage tended to be higher on island...
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Typescript. Thesis (Ph. D.)--University of Florida, 1996. Vita. Includes bibliographical references (leaves 343-372).
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HISTORICAL ecology contains various examples of how predators introduced onto islands by man have apparently exterminated native prey species1–6. Conversely, a pioneering experiment7 showed an increase in number of species with predator presence. Subsequent experiments have shown both increases and decreases in prey diversity8–10. Here we investiga...
Article
Consider the following questions: 1) If we manipulate one species in a food web will this change the population of a species that neither eat nor are eaten by the manipulated species? 2) If removing species A in food web 1 causes a 20% in species B, can we assume that a similar decrease of B will occur if we remove species A in web 2, which contai...
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The objective of this study was to ascertain whether the impact of lizards on spiders varies temporally, and if so, whether this variability is related to rainfall. We compared annual censuses of orb-spider populations on 24 islands with diurnal lizards present, and on 20 islands with diurnal lizards absent, to rainfall over a 10-year period. A str...
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To assay the effect of area and predators on invasion success, spiders were introduced onto islands that were large, with lizard predators; large, without lizard predators; or small, without lizard predators. Short-term survival was greater on islands without than with predators; area had no effect. Spiders initially increased substantially on both...
Article
The parasitoid fraction is defined for a given set of arthropods as the number of parasitoid individuals divided by the number of all arthropod individuals. The hymenopteran parasitoid fraction was computed for arthropods caught in sticky traps on islands at two sites in the Bahamas. At Staniel, twenty islands were cross-classified by area (large,...
Article
To determine the effects of lizards and web spiders on species in lower trophic levels, we manipulated their abundances within large field enclosures on Staniel Cay, Bahamas, from May 1989 to March 1992. The experimental design (2 x 2 factorial) measured the separate effects of lizards and spiders and compensatory predation(lizard x spider interact...
Article
I studied the relationship between prey consumption and colony size in the orb spiderPhiloponella semiplumosa. Observations of unmanipulated colonies showed that prey biomass per juvenile spider was positively correlated with colony size, indicating that prey consumption was highest in the largest colonies observed. In contrast, the relationship be...
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A variety of orb-weaving spider species construct stabilimenta, patterned areas of dense silk, typically near the hub of the orb. The adaptive significance of this construction, along with associated behaviors such as shuttling and vibrating, is much debated. Arigiope argentata on small islands of the Bahamas frequently possess stabilimenta; we stu...
Article
CERTAIN ecological models1,2 predict that the impact of top predators on plants (producers) usually depends on the number of trophic levels in the food web: with three levels the impact is positive, whereas with four it is negative. These models assume that each of the nonbasal levels eats only the next level down. Indeed, freshwater pelagic system...
Article
To determine the effect of lizards on webspider populations, we conducted a long-term field experiment in the Bahamas. Numbers of spider individuals were about 3 times higher in lizard-removal enclosures than in control enclosures with natural densities of lizards. Dietary analyses showed that lizards ate spiders and that lizard and spider diets ov...
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To determine the effect of lizards on web-spider populations, we conducted an 18-mo field experiment in the Bahamas. Densities of individuals of each common spider species were about three times as high in lizard-removal enclosures as in control enclosures with lizards or in unenclosed plots with lizards; spider densities in control enclosures and...
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(1) We tested the hypothesis that grouping in the orb-weaving spider Metepeira datona functions to reduce predation by lizards. Previous studies demonstrated that lizards were major predators of M. datona. Under the hypothesis we predicted that colony size (number of individuals within a communal web) is larger where lizards are present than where...
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The concept of turnover-the repeated extinction and immigration of populations in ecological communities-has been prominent for many years 1. Here we show that a system of island orb spiders has consistently high turnover during a five-year period. This might seem to imply that most populations are ephemeral, but ~50% of the populations present in...
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Which species affect one another, how intensely, and the mechanisms of those effects are crucial data for understanding how ecological communities work. Tropical islands without lizards, the major top predators, have about ten times as dense web spider populations as those with lizards; processes responsible for this effect were experimentally simu...
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Data on feeding rates, dietary composition, and relative frequencies of food types in the environment for 2 syntopic spider species, Metepeira grinnelli and Cyclosa turbinata, were used to evaluate two consumptive-competition-coefficient formulas. The 1st formula, proposed by MacArthur and Levins (1967) and Levins (1968) , reflects only dietary ove...
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Interspecific competition between two orb-weaving spiders, Metepeira grinnelli (Coolidge) and Cyclosa turbinata (Walckenaer), was investigated by selective removal of the predators. The estimated predation rate of small prey was higher where Cyclosa was alone than where both species were present, because when Metepeira was removed the density of Cy...
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To test for inter- and intraspecific competition between two common orb-weaving spiders, Metepeira grinnelli and Cyclosa turbinata, I conducted separate field experiments in the spring and summer. During the spring experiment, the prey-consumption rate of Metepeira was reduced at higher inter- and intraspecific densities, but Cyclosa was only affec...
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To test for interspecific competition between the orb-weaving spiders Metepeira grinnelli and Cyclosa turbinata, a controlled competitor-removal experiment was conducted. Metepeira prey-consumption rate and fecundity were higher in plots where Cyclosa were removed than in control plots. Cyclosa density and vertical distribution were higher in plots...

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