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

Cannibalism, defined as intraspecific predation, is a behavioral trait found in a wide variety of animals, although most references to this behavior are anecdotal or based on casual laboratory observations, The role of cannibalism in the dynamics of natural populations has been largely neglected; the most elegant and detailed analy­ ses of the population consequences of cannibalism are still provided by laboratory studies of flour beetles (Tribolium) that describe the process, examine its interac­ tions with other population processes, and attempt to derive generalities about its effects (60, 78, 88), Therefore, some authors have suggested that cannibalism is an artifact of laboratory systems (20, p, 324) or that it occurs only in cases of severe stress, especially when alternatives, such as dispersal, are not possible (I05), My purpose in this review is to show that cannibalism is a normal phenomenon in many natural populations, to evaluate its possible roles in influencing demo­ graphic structure and population processes, and to suggest conditions for, and constraints on, its occurrence, Cannibalism may be an interaction that reduces population size before acute resource shortage causes severe physiological stress, and in this sense its effects may be analogous to those of spacing behavior or dominance hierarchies in some social animals (104), I also discuss cannibalism as a limiting case of predator-prey interactions among potential competitors, This review is based mainly on field experiments and direct estimates of rates of cannibalism, but I use papers describing laboratory experiments to supplement the discussion of behavioral triggers and genetic components and to fill gaps in the field evidence, I have excluded numerous references with only casual mention of canni­ balistic events,

Cannibalism in Natural Populations

The Tropical Rain Forest

Darwin (1878) suggested in The Origin of Species (p. 230-233) that selection between families or communities had given rise to sterile castes in the social insects. He argued that sterility could not be favored directly by selection among individuals but that parents or communities might benefit, in terms of reproductive success, from the presence of sterile individuals. It is clear from his arguments that Darwin believed that selection among groups could result in a change in the types of individuals within a species. It was much later that Wright (1931) perceived intergroup selection as one of the primary forces controlling evolutionary change. He stated that the only practicable method of bringing about a rapid and non-self-terminating evolutionary advance would be through the subdivision of populations into isolated and differentiating groups, among which selection could be practiced. Haldane (1932) and Wright (1945) both considered the case of the evolution of altruistic behavior where individual selection acts against the altruist, but the altruist is favored by group selection. Group selection became a more controversial subject with the publication of Wynne-Edwards' book Animal Dispersion in Relation to Social Behavior (1962). It was Wynne-Edwards' thesis that group selection was a general phenomenon and was responsible for the evolution of mechanisms which regulated population size. Wynne-Edwards believed that population size was limited at some level below the "carrying capacity" (Errington, 1934) of the environment by means of individuals within the population withholding reproduction. To the extent that an individual withholds reproduction that individual suffers a loss of fitness, where fitness is measured by reproductive success. It was for this reason that WynneEdwards thought individual selection could not be responsible for the evolution of the mechanisms for withholding reproduction and therefore, some form of group selection was required. Territoriality, ritualized aggression, the establishment of hierarchies and other social orderings, the onset of senility, and the optimum reproductive effort were some of the regulatory mechanisms of populations that Wynne-Edwards proposed had evolved by means of group selection. The regulation of population size has been and continues to be an interesting and central problem in the field of population ecology and several authors, among them Andrewartha and Birch (1954), Williams (1964), Hamilton (1966), and Amadon (1964) have cogently discussed the evolution of the above mentioned regulatory mechanisms by means of individual selection. The focus of much of the controversy has been the question of whether or not group selection is required to explain the evolution of a particular character. In general, the viewpoint of most ecologists and theorists has been that individual selection is a faster and more efficient form of natural selection than is group selection for the following reasons: 1. In iteroparous species the generation time of the individual is short relative to the turnover time of the population and therefore selection proceeds faster when the unit of selection is the individual. 2. The numbers of individuals greatly exceed the numbers of populations. If the units of selection are numerous it is less likely that chance events will significantly influence the outcome of selection. There-

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1558-5646.1977.tb00991.x

An experimental study of group selection.

Habitat is the template against which evolutionary pressures fashion the ecological strategy of a species; the instability-stability habitat spectrum gives rise to the r-K-selection continuum. Habitat stability for any animal is conveniently expressed by τ/H (τ = generation time and H = the length of time the habitat remains suitable for food harvesting). In animals whose habitats have a value of τ/H approaching unity, one generation will not affect the resources available to the next. The strategy for these habitats can allow overshooting of the equilibrium. In animals with permanent habitats (τ/H very small), overshooting, with the consequent overexploitation of resources, will be selected against. The logistic equation cannot represent a situation that involves overshooting. A more realistic approach arises from the consideration of the difference equation (2) which includes a time delay between density-dependence acting and the subsequent population change. Its three basic parameters are the equilibri...

Ecological strategies and population parameters

Single—species populations of flour beetles, Tribolium confusum and T. castaneum, were experimentally manipulated to demonstrate that both predation by adults on pupae and predation by larvae on eggs are effective mechanisms for regulating the abundance of adult beetles. It was shown that predation by adults on pupae is the more effective of the two mechanisms, since experimental interference with the first kind of predation produces a larger increase in adult populations than does interference with the second kind. The same generalization holds for both species. See full-text article at JSTOR

Predation and Abundance in Populations of Flour Beetles

Hamadryas februa is found in lowland tropical forests in many parts of Central America. It is of particular interest for future studies on the applied entomology of neotropical regions. This paper presents new data on the natural history of this butterfly in a small patch of semi-deciduous lowland forest in the Guanacaste Province of Costa Rica. Studies included the examination of life cycle, larval host plant, adult behavior, and behavior of caterpillars. Some preliminary observations were also made on the spatial distribution of the single larval host plant species and the location of trees used for resting by adults relative to the host plant.



The development time is 33–34 days when individuals of H. februa are reared on Dalechampia heteromorpha (Euphorbiaceae) in closed plastic bags. This host plant, also used for oviposition, is a small herbaceous vine that grows in shady places primarily along forest edge, and vegetative structures attract a variety of herbivorous insects in addition to caterpillars of H. februa. But the plant occurs as small patches of one or two vines and there are considerable distances between patches. Despite an advancing dry season, the larval host plant remains lush and thus provides a resource to maintain a breeding population of H. februa throughout the year in Guanacaste.



Zusammenfassung

Zur Biologie von Hamadryas februa (Lepid.: Nymphalidae) in Guanacaste, Costa Rica



Hamadryas februa lebt in den Tieflandwaldern vieler Teile Zentralamerikas. Seine nahere Betrachtung ist insofern fur die angewandte Entomologie von Interesse, als diese Wissen-schaft in der neotropischen Region noch ganz am Anfang steht und man daher in wirt-schaftlich wichtigen Gebieten dieser Region Grundlagen-Untersuchungen uber die Lebens-weise aller haufiger auftretenden phytophagen Insektenarten durchfuhren sollte.



Die vorliegende Veroffentlichung enthalt die Ergebnisse von Untersuchungen uber den Lebenszyklus, die Fraspflanze sowie die Lebens- und Verhaltensweise der Raupen und Falter dieses Schmetterlings in den halb-laubabwerfenden Waldern der Provinz Guana-caste in Costa Rica. Auch die Verteilung der Fraspflanze und der als Rastplatze der Falter dienenden Baume wurden naher betrachtet. Die Entwicklung von H. februa (im Labor) an der Euphorbiazee Dalechampia heteromorpha betrug 33–34 Tage.



Die Eiablage und Fraspflanze ist ein rankendes Unkraut, das bevorzugt in schattigen Lagen an Waldrandern wachst. Es dient weiteren zahlreichen phytophagen Insektenarten als Nahrung und hat eine fleckenweise Verbreitung, so das zwischen den Teilpopulationen von H. februa meist erhebliche Zwischenraume bestehen. Auch in der Trockenzeit bleibt die Fraspflanze frisch und ermoglicht daher der Schmetterlingsart, das ganze Jahr uber mehrere Generationen zu bilden.

On the biology of Hamadryas februa (Lepidoptera: Nymphalidae) in Guanacaste, Costa Rica

(1975). Studies on the Natural History of Central American Butterflies in the Family Cluster Satyridae‐Brassolidae‐Morphidae (Lepidoptera: Nymphaloidea). III. Opsiphanes tamarindi and Opsiphanes cassina in Costa Rica and El Salvador. Studies on Neotropical Fauna: Vol. 10, No. 1, pp. 19-55.

Studies on the Natural History of Central American Butterflies in the Family Cluster Satyridae‐Brassolidae‐Morphidae (Lepidoptera: Nymphaloidea). III. Opsiphanes tamarindi and Opsiphanes cassina in Costa Rica and El Salvador

(1974). The demography of a confined population of the butterfly Morpho Peleides during a tropical dry season. Studies on Neotropical Fauna: Vol. 9, No. 1, pp. 1-34.

Allen M. Young

Papers

Predation and Abundance in Populations of Flour Beetles

On the biology of Hamadryas februa (Lepidoptera: Nymphalidae) in Guanacaste, Costa Rica

Studies on the Natural History of Central American Butterflies in the Family Cluster Satyridae‐Brassolidae‐Morphidae (Lepidoptera: Nymphaloidea). III. Opsiphanes tamarindi and Opsiphanes cassina in Costa Rica and El Salvador

The demography of a confined population of the butterfly Morpho Peleides during a tropical dry season

Biology of Morpho polyphemus (Lepidoptera: Morphidae) in El Salvador