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

Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

■ Abstract The literature on effects of habitat fragmentation on biodiversity is huge. It is also very diverse, with different authors measuring fragmentation in different ways and, as a consequence, drawing different conclusions regarding both the magnitude and direction of its effects. Habitat fragmentation is usually defined as a landscape-scale process involving both habitat loss and the breaking apart of habitat. Results of empirical studies of habitat fragmentation are often difficult to interpret because (a) many researchers measure fragmentation at the patch scale, not the landscape scale and (b) most researchers measure fragmentation in ways that do not distinguish between habitat loss and habitat fragmentation per se, i.e., the breaking apart of habitat after controlling for habitat loss. Empirical studies to date suggest that habitat loss has large, consistently negative effects on biodiversity. Habitat fragmentation per se has much weaker effects on biodiversity that are at least as likely to be positive as negative. Therefore, to correctly interpret the influence of habitat fragmentation on biodiversity, the effects of these two components of fragmentation must be measured independently. More studies of the independent effects of habitat loss and fragmentation per se are needed to determine the factors that lead to positive versus negative effects of fragmentation per se. I suggest that the term “fragmentation” should be reserved for the breaking apart of habitat, independent of habitat loss.

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Effects of Habitat Fragmentation on Biodiversity

Body size is manifestly one of the most important attributes of an organism from an ecological and evolutionary point of view. Size has a predominant influence on an animal's energetic requirements, its potential for resource exploitation, and its susceptibility to natural enemies. A large literature now exists on how physiological, life history, and population parameters scale with body dimensions (24, 131). The ecological literature on species interactions and the structure of animal communities also stresses the importance of body size. Differences in body size are a major means by which species avoid direct overlap in resource use (153), and size-selective predation can be a primary organizing force in some communities (20, 70). Size thus imposes important constraints on the manner in which an organism interacts with its environment and influences the strength, type, and symmetry of interactions with other species (152, 207). Paradoxically, ecologists have virtually ignored the implications of these observations for interactions among species that exhibit size-distributed populations. For instance, it has been often suggested that competing species

https://www.jstor.org/stable/pdf/2096954.pdf

The ontogenetic niche and species interactions in size-structured populations

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

Part 1 Patterns: habitat structures - the evolution and diversification of a complex topic, E.D.McCoy and S.S.Bell development of habitat structure through succession in an Amazonian floodplain forest, J.Terborgh and K.Petren alternative models and tests of the interaction between habitat structure and species-area relationships, D.D.Hart and R.J.Horwitz measuring habitat structure with fractal geometry, M.Williamson and J.Lawton the effect of habitat structure on the spatial distribution of freshwater invertebrates, J.A.Downing Part 2 Responses - colonization, succession, resource use: habitat structure and morphological patterns in arboreal vertebrates, J.A.Pounds microtopography as habitat structure for mosses on rocks, P.Alpert the effects of changes in habitat structure during succession in terrestrial communities, V.K.Brown influence of patch size, vegetation texture, and host plant architecture on the diversity, abundance and life history styles of sap-feeding herbivores, R.F.Denno and G.K.Roderick habitat structure and recruitment in coral reef fishes, P.F.Sale habitat structure and community dynamics in marine benthic systems, K.P.Sebens. Part 3 Responses - predation, parasitism, disturbance: the effects of fire periodicity on habitat structure, H.R.Mushinsky and D.J.Gibson a new look at habitat structure - consequences of herbivore-modified plant architecture, S.Mopper et al habitat structure and predator-prey interactions in vegetated aquatic systems, K.L.Heck and L.B.Crowder the influence of habitat structure on the transmission of parasites, W.P.Sousa and E.D.Grosholz habitat structure and spider foraging, G.W.Uetz the influence of habitat structure and stability on the species diversity of polychaetes in vermetid reefs, U.N.Safriel and M.N.Ben-Eliahu Part 4 Applications: habitat structure and the design of nature reserves, M.B. Usher habitat structure, biogeography, and greenspace planning, E.L.Goldstein-Golding habitat structure and the design of artificial reefs, J.A.Bohnsack habitat structure - systhesis and perspectives.

Habitat structure: the physical arrangement of objects in space.

Using an index of relative importance we analyzed the stomach contents of over 300 water snakes (Nerodia spp.). Ontogenetic changes in prey consumption are most striking in Nerodia erythrogaster (number with food in gut = 44) and N. fasciata (N = 72). Prey of these two species changes from fish to frogs as the snakes exceed a snout-vent length of 50 cm. Nerodia rhombifera (N = 159) and N. cyclopion (N = 65) primarily eat fish throughout their life. However, with maturity and increased body size both species change portions of their diets. Nerodia rhombifera preys upon larger fish which occupy deeper, open-water habitats, when the snakes exceed 80 cm. Nerodia cy- clopion eats a larger proportion of centrarchid fish as its body size increases. Small prey are found in the stomachs of most size-classes of all four snake species. Regression analysis indicates that all four species eat larger prey as they mature. However, the largest individuals are females, and in two of the four species the large females eat a different array of prey than smaller nonspecific males. The size sexual dimorphism does not reduce the overlap in the diets of the two species that eat anurans as adults.

Ontogeny of water snake foraging ecology

A system of drift fences and pitfall traps was used over a 2-yr period to monitor the herpetofaunal community on four plots of land (1 ha each) maintained on different burn schedules. Experimental plots were burned every year (lE), every 2 yr (2E), or every 7 yr (7E); the control plot (CE) has not burned for 20 yr. A total of 1236 amphibians and reptiles of 27 species were captured during 1983 and 1984. Severe cold in December 1983 may have caused a large decline in herpetofauna in 1984; over two-thirds of the animals were captured in the first year of the study. Both Shannon-Weiner and Simpson's diversity indexes indicated that plot 2E had the lowest diversity each year. The greatest diversity was found on 1E or 7E. The 2-yr fire periodicity produced a dense layer of grasses and herbaceous plants that was not readily occupied by sandhill herpetofauna. The most abundant reptile was the six-lined racerunner, Cnemidophorus sexlineatus, which comprised about 33% of all captures. The highest density of racerunners was found on 1E, while lizards on 7E showed the greatest philopatric tendencies (especially in 1983, the year 7E was burned). The results indicated that burning increased diversity and abundance of amphibians and reptiles over control plots, and some fire periodicities were better than others for maintaining high diversity.

Fire and the Florida sandhill herpetofaunal community: with special attention to responses of Cnemidophorus sexlineatus

Epigenetic mechanisms impact several phenotypic traits and may be important for ecology and evolution. The introduced house sparrow (Passer domesticus) exhibits extensive phenotypic variation among and within populations. We screened methylation in populations from Kenya and Florida to determine if methylation varied among populations, varied with introduction history (Kenyan invasion <50 years old, Florida invasion ~150 years old), and could potentially compensate for decrease genetic variation with introductions. While recent literature has speculated on the importance of epigenetic effects for biological invasions, this is the first such study among wild vertebrates. Methylation was more frequent in Nairobi, and outlier loci suggest that populations may be differentiated. Methylation diversity was similar between populations, in spite of known lower genetic diversity in Nairobi, which suggests that epigenetic variation may compensate for decreased genetic diversity as a source of phenotypic variation during introduction. Our results suggest that methylation differences may be common among house sparrows, but research is needed to discern whether methylation impacts phenotypic variation.

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Epigenetic Variation May Compensate for Decreased Genetic Variation with Introductions: A Case Study Using House Sparrows ( Passer domesticus ) on Two Continents

Recent reports have suggested that a global decline in amphibian populations has taken place during the past few decades. Urban development is thought to affect the richness and abundances of species and, therefore, could be an important cause of decline. We estimated the richness and abundances of anurans in wetlands at a residential development and in similar wetlands at a nearby undeveloped park. The residential development originally was pine flatwoods habitat, as is the undeveloped park curiently. We also compared the anuran species' composition of the park in 1992 with the composition in 1974. Both richness and abundances of anurans in the residential development were different than those in the undeveloped park. Employing the same amount of sampling effort at both sites, we trapped or observed 11 species at the developement and 15 species at the park, and trapped 569 individuals at the development and 1224 individuals at the park. The anuran species richness at the undeveloped park in 1992 was nearly the same as in 1974; a single rare species apparently was not present in 1992. Of the 15 species present in both surveys, 14 showed higher abundances in 1992 than in 1974. We suggest that the current differences between the residential development and the park have resulted from degradation of both the uplands used by many species during the dry season and the temporary wetlands used by many species for reproduction. Four species especially sensitive to such degradation, Bufo quercicus, Scaphiopus h. holbrookii, Hyla femoralis, and H. gratiosa, were the species missing from the residential development. Not all species of anurans typical of pine flatwoods appeared to be affected adversely by development. Three species of ranids, Rana utricularia, R. grylio, and R. catesbeiana, were found in higher abundances at the residential development than at the park. These ranid species breed in a wide variety of aquatic systems, including the permanent bodies of water that are now abundant in the development, and probably use the uplands less than other anurans. If amphibian decline is international in scope, then the decline could be attributable either to global changes caused by humans, or to local, but widespread, environmental degradation, or to a combination of factors. While much recent popular focus has been on potential global causes of decline, we believe that this emphasis may have caused attention to be taken away from local causes that, as our study demonstrated, may be at least as important. We suggest that in many places, local environmental degradation is insidiously chipping away at amphibian diversity, and that more emphasis should be placed on these local causes than is now the case.

Henry R. Mushinsky

Papers

Habitat structure: the physical arrangement of objects in space.

Ontogeny of water snake foraging ecology

Fire and the Florida sandhill herpetofaunal community: with special attention to responses of Cnemidophorus sexlineatus

Epigenetic Variation May Compensate for Decreased Genetic Variation with Introductions: A Case Study Using House Sparrows ( Passer domesticus ) on Two Continents

Decline of Some West-Central Florida Anuran Populations in Response to Habitat Degradation