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

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

Human life histories as compared to those of other primates and mammals have at least four distinctive characteristics: an exceptionally long life span an extended period of juvenile dependence support of reproduction by older post-reproductive individuals and male support of reproduction through the provisioning of females and their offspring. Another distinctive feature of our species is a large brain with its associated psychological attributes: increased capacities for learning cognition and insight. In this paper the authors propose a theory that unites and organizes these observations and generates many theoretical and empirical predictions. The authors present some tests of those predictions and outline new predictions that can be tested in future research by comparative biologists archaeologists paleontologists biological anthropologists demographers geneticists and cultural anthropologists. (authors)

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A theory of human life history evolution: Diet, intelligence, and longevity

Fruits and Frugivory

Vertebrate responses to hunting are widely variable for target and nontarget species depending on the history of hunting and productivity of any given site and the life history traits of game species. We provide a comprehensive meta-analysis of changes in population density or other abundance estimates for 30 mid-sized to large mammal, bird and reptile species in 101 hunted and nonhunted, but otherwise undisturbed, Neotropical forest sites. The data set was analyzed using both an unnested approach, based on population density estimates, and a nested approach in which pairwise comparisons of abundance metrics were restricted to geographic groups of sites sharing similar habitat and soil conditions. This resulted in 25 geographic clusters of sites within which 1811 population abundance estimates were compared across different levels of hunting pressure. Average nested changes in abundance across increasingly greater levels of hunting pressure ranged from moderately positive to highly negative. Populations of all species combined declined across greater differences in hunting pressure by up to 74.8 percent from their numeric abundance in less intensively hunted sites, but harvest-sensitive species faired far worse. Of the 30 species examined, 22 declined significantly at high levels of hunting. Body size significantly affected the direction and magnitude of abundance changes, with large-bodied species declining faster in overhunted sites. Frugivorous species showed more marked declines in abundance in heavily hunted sites than seed predators and browsers, regardless of the effects of body size. The implications of hunting for seed dispersal are discussed in terms of community dynamics in semi-defaunated tropical forests.

Basin‐Wide Effects of Game Harvest on Vertebrate Population Densities in Amazonian Forests: Implications for Animal‐Mediated Seed Dispersal

In a continuation of our study of dietary differentiation among frugivorous primates with simple stomachs, we present the first comparison of differences in dietary macronutrient content between chimpanzees and cercopithecine monkeys Previously we have shown that chimpanzee and monkey diets differ markedly in plant part and species content We now examine whether this diet diversity is reflected in markedly different dietary macronutrient levels or the different feeding strategies yield the same macronutrient levels in their diets For each primate group we calculated the total weighted mean dietary content of 4 macronutrients: crude lipid (lipid), crude protein (CP), water-soluble carbohydrates (WSC), and total nonstructural carbohydrates (TNC) We also calculated 4 fiber fractions: neutral-detergent fiber (NDF), which includes the subfractions hemicellulose (HC), cellulose (Cs), and sulfuric acid lignin (Ls) The HC and Cs are potentially fermentable fibers and would contribute to the energy provided by plant food, depending on the hind gut fermenting capacity of the individual primate species The chimpanzee diet contained higher levels of WSC and TNC because during times of fruit abundance the chimpanzees took special advantage of ripe fruit, while the monkeys did not The monkey diets contained higher levels of CP because the monkeys consumed a constant amount of leaf throughout the year All four primate species consumed diets with similar NDF levels However, the chimpanzees also took advantage of periods of ripe fruit abundance to decrease their Ls levels and to increase their HC levels Conversely, the monkey diets maintained constant levels of the different fiber fractions thoughout the year Nevertheless, despite these differences, the diets of the 4 frugivores were surprisingly similar, considering the substantial differences in body size We conclude that the chimpanzee diet is of higher quality, particularly of lower fiber content, than expected on the basis of their body size

Dietary Response of Chimpanzees and Cercopithecines to Seasonal Variation in Fruit Abundance. II. Macronutrients

We evaluate the hardness of foods con- sumed by sympatric Cercopithecus ascanius (redtail gue- nons) and Lophocebus albigena (grey-cheeked manga- beys), and consider how selection might operate to influence foraging adaptations. Since L. albigena has among the thickest dental enamel in extant primates and is commonly referred to as a hard-object consumer, we predicted that their diet would be harder than that of the guenon. Data on diet and food hardness (as measured by resistance to puncture and crushing) were collected be- tween June-October of 1997 at Kibale National Park, Uganda, and were compared to similar data collected in Kibale between 1991-1994. Contrary to what we pre- dicted, there was no difference in dietary hardness when the puncture resistance of all fruit consumed by the two species was compared (31 tree species in both study peri- ods). However, in June-October 1997, L. albigena ex- ploited a diet more resistant to puncture and crushing than C. ascanius. This difference is largely explained by the higher percentage of bark and seeds consumed by the L. albigena during this period. We suggest that it is the difference in the mechanical properties of fallback foods during critical periods that may have served as the selec- tive pressure for thick enamel in L. albigena. Am J Phys Anthropol 125:363-368, 2004. © 2004 Wiley-Liss, Inc.

Hardness of cercopithecine foods: Implications for the critical function of enamel thickness in exploiting fallback foods

During human evolutionary history, and for many around the world, breast milk is the primary source of nutritional energy for infants. Variation in breast milk quality might logically have important effects on infant health, growth, and development, yet the sources of this variation remain largely unelucidated. We quantified nutrient and energy content of breast milk from 25 healthy, well-nourished Massachusetts mothers with infants aged 2-5 months. We examined several potential sources of variation in milk quality, particularly feeding patterns, infant sex, and maternal breast growth during pregnancy. After controlling for time since last feeding, a known correlate of milk composition, we found that mothers of male infants produced milk that had 25% greater energy content than mothers of female infants (P < 0.001). Change in maternal bra cup size during pregnancy was associated with 16.17 kcal/100 ml greater energy content of milk (P = 0.009), but was not significant after taking infant sex into account. Greater nutritional investment in sons may account for the greater observed growth rates in male compared to female infants.

Infant sex predicts breast milk energy content

Platyrrhines face a vast array of potential food resources in the Neotropics. Ecological challenges associated with finding, ingesting, masticating, and digesting foods are influenced by food availability and accessibility. Food availability is influenced by seasonal variation in forest productivity, fruiting synchrony, and crop size (e.g., Stevenson 2001; Chapman et al. 2003, but see Milton et al. 2005). Accessibility, on the other hand, is related to such factors as fruit and seed size, the ability to breach mechanically challenging tissues, to tolerate secondary chemical compounds, and to balance nutrient intake. Our goal in this chapter is to examine the diversity of platyrrhine responses to this second variable – gaining access to and processing foods. All platyrrhine genera include fruit in their diets, but the annual percentage of fruit intake ranges widely from 8% in Cebuella to 86% in Ateles (Table 11.1). A wide variety of other resources including exudates, fungi, leaves, flowers, nectar and insect or vertebrate prey make up the balance, or at times the bulk, of annual diets. Some particularly interesting feeding behaviors seen in platyrrhines signal the evolution of specific adaptations. These include the ability to extract and digest plant resources such as gums by Cebuella and Callithrix (Nash 1986; Power and Oftedal 1996), fungi by Callimico (Porter 2001; Porter and Garber 2004; Hanson et al. 2006; Rehg 2006), and seeds by the pitheciins (van Roosmalen et al. 1988; Ayres 1989; Kinzey and Norconk 1990; Kinzey 1992; Peetz 2001; Norconk and Conklin-Brittain 2004). Although gums, seeds and fungi are ingested by other primate species [especially lemurs (Nash 1989; Hemingway 1998) and colobines (Waterman and Kool 1994; Kirkpatrick 1998)], they are used very intensively by these platyrrhines, composing either a majority of their diet during a single season, a subset of the annual diet, or are routinely and extensively used throughout the year.

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Mechanical and Nutritional Properties of Food as Factors in Platyrrhine Dietary Adaptations

From a plant's perspective, the difference between a seed predator and a seed disperser should be straightforward: attract animals that will disperse seeds and defend seeds from potential predators. Unlike pulp-eating frugivores, seed predators regularly encounter diverse plant protective mechanisms. The purpose of this paper is to examine feeding constraints, morphological adaptations, and the mechanical process of seed predation. While there is evidence that some seed predators cause severe losses to seed crops, there is also evidence that seed predators enhance seed dispersal and germination. We also examine four methods by which neotropical seed predators may contribute to dispersal. 1) Seed predators examined here ingested fruit when seeds were full-sized, but not yet mature (i.e., seeds of mature fruit may be avoided by seed predators and available for dispersal by other frugivores). 2) Sympatric seed predators may ingest seeds from different plants thus reducing overall predator load on any individual plant. 3) Seed predators that manipulate seeds (e.g., remove pericarp and seed coat) may enhance germination if the prepared seeds are dropped, discarded, or buried and not ingested. 4) Small seeds may miss mastication and swallowed intact with a food bolus. The last mechanism is the most likely to contribute to seed dispersal by the widest array of vertebrate seed predators, but primate seed predators may facilitate seed dispersal using all four mechanisms. Therefore, the traditional dichotomy of seed predator vs. seed disperser oversimplifies the interactions between seed predators and plants.

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Nancy L. Conklin-Brittain

Papers

Dietary Response of Chimpanzees and Cercopithecines to Seasonal Variation in Fruit Abundance. II. Macronutrients

Hardness of cercopithecine foods: Implications for the critical function of enamel thickness in exploiting fallback foods

Infant sex predicts breast milk energy content

Mechanical and Nutritional Properties of Food as Factors in Platyrrhine Dietary Adaptations

Seed dispersal by neotropical seed predators