Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Pseudoreplication is defined. as the use of inferential statistics to test for treatment effects with data from experiments where either treatments are not replicated (though samples may be) or replicates are not statistically independent. In ANOVA terminology, it is the testing for treatment effects with an error term inappropriate to the hypothesis being considered. Scrutiny of 176 experi- mental studies published between 1960 and the present revealed that pseudoreplication occurred in 27% of them, or 48% of all such studies that applied inferential statistics. The incidence of pseudo- replication is especially high in studies of marine benthos and small mammals. The critical features of controlled experimentation are reviewed. Nondemonic intrusion is defined as the impingement of chance events on an experiment in progress. As a safeguard against both it and preexisting gradients, interspersion of treatments is argued to be an obligatory feature of good design. Especially in small experiments, adequate interspersion can sometimes be assured only by dispensing with strict random- ization procedures. Comprehension of this conflict between interspersion and randomization is aided by distinguishing pre-layout (or conventional) and layout-specifit alpha (probability of type I error). Suggestions are offered to statisticians and editors of ecological j oumals as to how ecologists' under- standing of experimental design and statistics might be improved.

/pdf/pseudoreplication-and-the-design-of-ecological-field-44o8kzdaoi.pdf

Pseudoreplication and the Design of Ecological Field Experiments

Predation has long been implicated as a major selective force in the evolution of several morphological and behavioral characteristics of animals. The importance of predation during evolutionary ti...

Behavioral decisions made under the risk of predation: a review and prospectus

http://osenberglab.ecology.uga.edu/wp-content/uploads/2015/09/Charnov-1976-TPB.pdf

Optimal foraging, the marginal value theorem.

Qualitative surveys of 22 lakes in southern Michigan indicated that relative abundances of the northern longear sunfish (Lepomis megalotis peltastes) and pumpkinseed (L. gibbosus) depended upon amo...

Resource Partitioning in Two Coexisting Sunfish: Pumpkinseed (Lepomis gibbosus) and Northern Longear Sunfish (Lepomis megalotis peltastes)

The growth of metacommunity ecology as a subdiscipline has increased interest in how processes at different spatial scales structure communities. However, there is still a significant knowledge gap with respect to relating the action of niche- and dispersal-assembly mechanisms to observed species distributions across gradients. Surveys of the larval dragonfly community (Odonata: Anisoptera) in 57 lakes and ponds in southeast Michigan were used to evaluate hypotheses about the processes regulating community structure in this system. We considered the roles of both niche- and dispersal-assembly processes in determining patterns of species richness and composition across a habitat gradient involving changes in the extent of habitat permanence, canopy cover, area, and top predator type. We compared observed richness patterns and species distributions in this system to patterns predicted by four general community models: species sorting related to adaptive trade-offs, a developmental constraints hypothesis, dispersal assembly, and a neutral community assemblage. Our results supported neither the developmental constraints nor the neutral-assemblage models. Observed patterns of richness and species distributions were consistent with patterns expected when adaptive tradeoffs and dispersal-assembly mechanisms affect community structure. Adaptive trade-offs appeared to be important in limiting the distributions of species which segregate across the habitat gradient. However, dispersal was important in shaping the distributions of species that utilize habitats with a broad range of hydroperiods and alternative top predator types. Our results also suggest that the relative importance of these mechanisms may change across this habitat gradient and that a metacommunity perspective which incorporates both niche- and dispersal-assembly processes is necessary to understand how communities are organized.

/pdf/metacommunity-patterns-in-larval-odonates-1rp9t8ql1u.pdf

Metacommunity patterns in larval odonates

In ecological theory species interaction strengths are typically described by constants or functions that depend on the densities of the two interacting species. However, if species' traits (phenotypes) are plastic, then modifications in these traits (induced by the presence of another species) could affect interaction strengths of the focal species with a number of other species in the system. The magnitudes of such higher-order effects on interaction strengths have not been reported and are not straightforward to measure. We present a methodology to quantify changes in consumer–resource interaction coefficients (a metric of interaction strength) due to effects of predators on consumer (i.e., the prey of the predator) phenotype (e.g., nonlethal or trait-mediated effects). Application of this method to studies in diverse systems indicates that predators can strongly reduce consumer– resource interaction coefficients, often in the range of 20–80%. We use analytic and simulation models to show that effects on interaction coefficients of this magnitude can lead to trait-mediated effects that contribute more strongly than density-mediated effects to the net effects of predators on consumers and their resources, and even qualitatively change model predictions. Our results strengthen previous claims that trait-mediated effects strongly influence species interactions and suggest that recent calls to quantify interaction strengths must be broadened to include examination of the variation in interaction strengths due to their dependence on densities of other species (most notably predators) in food webs.

http://www.glerl.noaa.gov/pubs/fulltext/2004/20040023.pdf

How dependent are species-pair interaction strengths on other species in the food web?

This paper reports a laboratory study of competitive interactions between larvae of the wood frog (Rana sylvatica) and the northern leopard frog (R. pipiens). I manipulated the density of con- and heterospecifics in an additive design while keeping water volume and per capita food rations constant. Additional treatments included altering food concentration and reversing an initial size advantage of one of the species. There was no evidence of intraspecific interference competition in either species. There were strong asymmetric interspecific effects; the leopard frog depressed growth of the wood frog in mixed-species treatments whereas the wood frog had no negative effects on the leopard frog. These interspecific effects appear to be largely due to exploitative competition. Reversing initial size advantages of the species did not affect the qualitative outcome of competition, though the effect of the leopard frog on the wood frog was diminished when wood frogs were initially 30% larger. The leopard frog was consistently more active than the wood frog; I argue that this difference in activity contributes to the competitive superiority of the leopard frog in these experiments. The relation of these results to the life histories and interactions of these two species is discussed.

http://www.jstor.org/stable/pdfplus/1446532.pdf

Competitive interactions between wood frog and northern leopard frog larvae : the influence of size and activity

A fundamental goal of ecology is to understand the factors that influence community structure and, consequently, generate heterogeneity in species richness across habitats. While niche-assembly (e.g. species-sorting) and dispersal-assembly mechanisms are widely recognized as factors structuring communities, there remains substantial debate concerning the relative importance of each of these mechanisms. Using freshwater snails as a model system, we explore how abiotic and biotic factors interact with dispersal to structure local communities and generate regional patterns in species richness. Our data set consisted of 24 snail species from 43 ponds and lakes surveyed for seven years on the Univ. of Michigan’s E. S. George Reserve and Pinckney State Recreation Area near Ann Arbor, Michigan. We found that heterogeneity in habitat conditions mediated species-sorting mechanism to drive patterns in snail species richness across sites. In particular, physical environmental variables (i.e. habitat area, hydroperiod, and canopy cover), pH, and fish presence accounted for the majority of variation in the species richness across sites. We also found evidence of Gleasonian structure (i.e. significant species turnover with stochastic species loss) in the metacommunity. Turnover in snail species distributions was driven by the replacement of several pulmonate species with prosobranch species at the pond permanence transition. Turnover appeared to be driven by physiological constraints associated with differences in respiration mode between the snail orders and shell characteristics that deter molluscivorous fish. In contrast to these niche-assembly mechanisms, there was no evidence that dispersal-assembly mechanisms were structuring the communities. This suggests that niche-assembly mechanisms are more important than dispersal-assembly mechanisms for structuring local snail communities.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0587.2011.06856.x

Earl E. Werner

Papers

Resource Partitioning in Two Coexisting Sunfish: Pumpkinseed (Lepomis gibbosus) and Northern Longear Sunfish (Lepomis megalotis peltastes)

Metacommunity patterns in larval odonates

How dependent are species-pair interaction strengths on other species in the food web?

Competitive interactions between wood frog and northern leopard frog larvae : the influence of size and activity

Environmental gradients and the structure of freshwater snail communities