H. Jane Brockmann

Kleptoparasitism in birds

Abstract Kleptoparasitism refers to the interspecific stealing of already procured food, but this paper shows that intraspecific food-stealing is effectively the same behaviour. A comprehensive review of the literature shows that certain orders of birds contain a disproportionate number of kleptoparasitic species. Birds in these orders occupy a limited range of ecological niches and are most commonly either predatory or dietary opportunists. Kleptoparasitism is particularly associated with certain ecological conditions, such as the availability of hosts feeding on large, visible food items and periods of food shortage. Birds show a wide range of socially parasitic feeding interactions of which kleptoparasitism is one extreme. The parasitic pattern of food-stealing is likely to involve frequency-dependent selection and may be an example of an evolutionarily stable strategy.

Alternative Reproductive Tactics: An Integrative Approach

Preface Rui F. Oliveira, Michael Taborsky and H. Jane Brockmann 1. The evolution of alternative mating tactics: concepts and questions Michael Taborsky, Rui F. Oliveira and H. Jane Brockmann Part I. Ultimate Causes and Origins of ARTs: 2. Alternative reproductive tactics and the evolution of alternative allocation phenotypes H. Jane Brockmann and Michael Taborsky 3. Phylogenetic analysis of alternative reproductive tactics - Problems and possibilities Vitor C. Almada and Joana I. Robalo 4. Modeling alternative mating tactics as dynamic games Jeffrey R. Lucas and Richard D. Howard Part II. Proximate Mechanisms of ARTs: 5. The roles of genes and the environment in the expression and evolution of alternative tactics Douglas J. Emlen 6. Neuroendocrine mechanisms of alternative reproductive tactics: the chemical language of reproductive and social plasticity Andrew H. Bass and Paul M. Forlano 7. Hormones and alternative reproductive tactics in vertebrates Rui F. Oliveira, Adelino V. M. Canario and Albert F. H. Ros Part III. Taxonomic Reviews of ARTs: 8. Alternative reproductive tactics in insects H. Jane Brockmann 9. The expression of crustacean mating strategies Stephen M. Shuster 10. Alternative reproductive tactics in fish Michael Taborsky 11. Alternative reproductive tactics in amphibians Kelly R. Zamudio and Lauren M. Chan 12. Alternative reproductive tactics in reptiles Ryan Calsbeek and Barry Sinervo 13. Alternative reproductive tactics in birds Oliver Kruger 14. Alternative reproductive tactics in nonprimate male mammals Jerry O. Wolff 15. Alternative reproductive tactics in primates Joanna M. Setchell Part IV. Emerging Perspectives on ARTs: 16. Communication and the evolution of alternative reproductive tactics David Goncalves, Rui F. Oliveira and Peter K. McGregor 17. Alternative mating tactics and mate choice for good genes or good care Brian Neff 18. Conflict between the sexes and alternative reproductive tactics within a sex Suzanne H. Alonzo 19. Cooperative breeding as an alternative reproductive tactic Walter D. Koenig and Janis L. Dickinson 20. Integrating mechanisms and function: prospects for future research H. Jane Brockmann, Rui Oliveira and Michael Taborsky.

The evolution of alternative strategies and tactics

Summary Discrete variation where one sex has more than one means of achieving the same functional end, such as mating or nesting (alternative strategies and tactics), requires an evolutionary explanation. Discrete differences in behavior, morphology, color, and life-history patterns are found in many contexts, such as alternative reproductive patterns, social insect castes, sex allocation, and mimicry polymorphisms. In this chapter I draw on the literature of these fields to identify similar patterns and common models that can be applied to our understanding of alternative phenotypes in general. I emphasize the invertebrate literature throughout because excellent reviews are available for vertebrates. Traditionally, the behavioral literature has separated alternative phenotypes into those due to genetic differences (e.g., polymorphisms) and those due to environmental or individual cues (e.g., conditional tactics). Such categories are impractical and they force us to dichotomize behavior as due to nature or nurture. Drawing on the well-developed sex-allocation literature, I suggest a different system for categorizing alternative phenotypes: irreversible or adult lifetime patterns (e.g., dioecy) and reversible or facultative patterns (e.g., hermaphroditism), which can be further subdivided into sequential and simultaneous. This new system for organizing alternative phenotypes allows us to see that condition dependence and frequency dependence may occur under any category. In general, alternative phenotypes can be maintained in a population when their fitness curves cross, that is, when each does better than the other under some conditions. A variety of factors can cause fitness curves to cross. Negative frequency dependence is one, which has the added advantage of explaining how patterns can be maintained at a stable frequency. Probably the most common explanation for the maintenance of discrete variants is switches in phenotype based on environmental or individual, condition-based cues. What are the circumstances that favor the evolution of irreversible phenotypes over switching? Lifetime patterns are favored when individuals that switch have lower fitness than those that do not. Lifetime patterns allow complex suites of adaptations to develop for each phenotype that are coordinated through physiological and developmental processes. When environmental conditions are predictable and correlate with fitness, selection favors the animal switching from one pattern to the other at the time that maximizes fitness. However, when the environmental conditions that favor two phenotypes are unpredictable and change frequently, selection favors animals that invest in what is necessary to perform in either role. Under most circumstances the animal will use decision rules based on information about what maximizes fitness, but if the individual does not have such information, yet must choose between exclusive alternatives, then selection will favor an arbitrary decision rule. A promising approach to studying alternative phenotypes is dynamic, state-variable modeling ( Houston and McNamara, 1999 ; Clark and Mangel, 2000 ), which is particularly good for evaluating the interacting effects of the organisms state, of environmental and social conditions, and of density and frequency dependence. When such multiple factors are evaluated together, surprising predictions about the conditions under which individuals should follow particular patterns sometimes result. An understanding of the evolution of alternative phenotypes requires a strong, integrative approach that seeks to understand the cues and mechanisms controlling behavioral decisions. When this approach is combined with dynamic, state-based models, it is possible to make predictions about the circumstances that favor the evolution of particular decision-making patterns over others.

Alternative Reproductive Tactics: The evolution of alternative reproductive tactics: concepts and questions

Here we outline the meaning of the term alternative reproductive tactics, or ARTs, and discuss why the existence of ARTs is so widespread in animals. We ask what we need to know to understand the evolution of ARTs and the importance of general principles such as frequency dependence, density dependence, and condition dependence, and what we need to know about proximate mechanisms involved in the regulation of ARTs to comprehend evolutionary patterns. We discuss current issues in the study of ARTs and list 12 questions that we think need particular attention. Throughout we shall provide representative examples of ARTs in animals to illustrate the ubiquitous nature of this phenomenon.

MATING BEHAVIOR OF HORSESHOE CRABS, LIMULUS POLYPHEMUS

Horseshoe crabs have an explosive breeding system not unlike that of some frogs and toads. They synchronize nesting to only a few hours each day at the time of the spring new and full-moon high tides. Males search for females as they come to the breeding beaches, grasp them with specially modified claws and cling to them, sometimes for weeks. Females lay several clutches of eggs in the sand and the male fertilizes them externally, the only extant arthropod with such a reproductive system. Unattached males cluster around the nesting couple, pushing on and occasionally displacing attached males. An experimental manipulation demonstrated that satellite males are capable of fertilizing eggs which suggests that sperm competition is the primary explanation for the presence of unattached males on the beach. Like other explosively breeding species, male Limulus search for females, often grabbing inappropriate objects, and satellite males compete for access to females. There is little assortative mating and attached and unattached males do not differ in size. In extreme explosively breeding species like Limulus, selection favors those males that are best able to locate and remain attached to females, and there is little opportunity for female choice or male-male competition.

Costs of sexual interactions to females in Rambur's forktail damselfly, Ischnura ramburi (Zygoptera: Coenagrionidae)

Several species of damselflies, dragonflies and butterflies are characterized by a female-limited polymorphism in which one type of female, the andromorph, looks and behaves like males whereas the other type of female, the gynomorph, looks and behaves differently. Sexual conflict has been hypothesized to play a role in the maintenance of this polymorphism in that andromorphs may have an advantage over gynomorphs by avoiding costly sexual interactions through male mimicry. We tested for costs of sexual interactions to female Ischnura ramburi damselflies by comparing the success of singly mated females maintained with no males to the success of females maintained continuously with males at a 3:1 (male to female) operational sex ratio (OSR) and a 1:1 OSR. Our findings suggest that sexual interactions affect the two morphs differently. The time spent feeding, number of eggs laid and egg-laying rate of andromorphs were lower in the 3:1 OSR treatment than in the treatment with no males. Time spent feeding and number and rate of eggs laid by gynomorphs did not differ among treatments. Sexual conflict may be occurring between males and mated andromorphs because sexual interactions are associated with net costs to mated andromorphs whereas sexual interactions with mated andromorphs are beneficial to males because there is high last-male sperm precedence. Based on this experiment, andromorphs cannot be said to have an advantage over gynomorphs by avoiding costly sexual interactions because sexual interactions were not associated with net costs to gynomorphs.

Do digger wasps commit the concorde fallacy

Abstract The Concorde fallacy is a notorious theoretical error which tempts economists and evolutionists alike. It amounts to investing further in a project simply because one has invested in it heavily in the past, rather than because of potential future return on investment. Digger waps, Sphex ichneumoneus , disconcertingly appear to behave as if following the Concorde fallacy. Pairs of females fight over jointly occupied nests, provisioned with paralysed katydids. The prior investment by each wasp in the nest is measured as the number of katydids that she has put into it. The true value of the nest is approximated by the total number of katydids there. The evidence suggests that the wasp with the least prior investment is the one most likely to surrender. In a post-hoc attempt at rationalizing this Concordian result, we uncover some of the pitfalls of naive optimality speculations, and recommend analysis in terms of evolutionarily stable strategies.

Alternative reproductive tactics and life history phenotypes

Alternative reproductive tactics (ARTs) coexisting within a population are found in many organisms. Their existence has been an enduring puzzle in evolutionary biology. Why should selection produce distinctly different alternatives to reach the same goal? How can such alternative solutions coexist in a population? What determines their evolutionary stability? Here we outline ultimate and proximate mechanisms responsible for the origin, coexistence and stability of ARTs. We argue that behavioural and reproductive polymorphisms often reflect different allocation decisions in response to trade-offs in reproduction or life-history optima that may involve heritable threshold responses to environmental variation. Alternative tactics may either be fixed for life or plastic, with simultaneous or sequential switches between tactics. General principles include disruptive selection, negative frequency dependence, density dependence, and an interaction between genetic and environmental components to generate alternative tactics. ARTs are found often where individuals invest heavily in reproduction in a way that can be circumvented and exploited by competitors, which reflects disruptive selection on reproductive investment. This often coincides with consistent size variation between individuals pursuing bourgeois and parasitic tactics.

Male mating tactics in the horseshoe crab, Limulus polyphemus

Abstract Horseshoe crabs nest on beaches of the eastern U.S. at the new and full moon high tides during spring and summer. Some males arrive attached to females, whereas others arrive unattached. The unattached males crowd around the nesting couples where they are thought to gain fertilizations (fertilization is external). Because males return to the beach more frequently than females (and most females arrive attached), the operational sex ratio during one tide can be strongly male biased. Attached and unattached males did not differ in size but attached males were less likely to have their prosomas and eyes encrusted with epibionts, and they were lighter in colour, suggesting that they were on average either younger than unattached males or that they had moulted more recently. When attached males were experimentally detached from females, they were more likely to return with a female on the following tide than males that had arrived on the beach unattached. When detached males and unattached males were allowed to pair with females in wading pools and were then released at sea while still attached, the detached males were more likely to return the next day with the same partner than the unattached males. Although detached and unattached males were equally likely to attach while in the pools if given enough time, unattached males took longer to attach and were more likely to let go of the female during the release process than the detached males. These results suggest that attached and unattached male mating tactics are the result of condition-dependent differences.

Island Colonization by Lesser Antillean Birds

-We present an analysis of bird distribution in small islands in the northern Lesser Antilles colonized principally from Guadeloupe. In spite of great differences among the islands in soils, rainfall, and vegetation, their avifaunas are strikingly uniform. We found that species inhabiting coastal scrub on the source island performed better as colonists than inhabitants of interior rainforest, suggesting that humid forests in the target islands would hold drastically impoverished bird communities. This proved not to be the case. Diversities in the small-island rainforest communities were compensated by the substitution of coastal scrub species for missing forest counterparts and the expansion of vertical foraging zones. In progressing from species-poor to species-rich communities in equivalent habitat, the number of trophic guilds remains constant, while the number of species per guild and the tightness of species packing increase. We conclude that the faunal uniformity of islands colonized from Guadeloupe results from nonuniform dispersal abilities coupled with ordering ecological constraints: versatility in habitat occupancy, trophic status and size in relation to guild neighbors.-Department of Biology, Princeton University, Princeton, New Jersey 08540; Division of Biological Sciences, University of Missouri, Columbia, Missouri 60521; and Department of Zoology, University of Florida, Gainesville, Florida 32601. Accepted 2 August 1976. MODERN biogeography has enjoyed considerable success in accounting for the numbers of species of birds, lizards, and other taxa found on the islands of various archipelagoes. Nearly all the interisland variation in bird species numbers in the southwest Pacific, for example, can be explained by a simple empirical formula that takes into account each islands area, elevation, and distance from New Guinea, the ultimate source of colonists in that region (Diamond 1973). Equilibrium theory (MacArthur and Wilson 1963) maintains that insular faunas are stabilized by a dynamic balance of colonizations and extinctions, and suggests the statistical limits within which the number of species should vary on any given island. However, equilibrium theory tells us nothing about how different or how alike the faunas of two nearby islands should be. If they were totally different we should be surprised. We should also be surprised if they were totally alike, for the equilibrium model rests on random processes, limited to be sure by certain statistical constraints. To phrase the question in general terms, we ask whether the interaction of colonization and extinction leads to chaos, a rigidly ordered community structure, or to some more perplexing intermediate condition. In at least one group of islands, the Lesser Antilles, the answer is clearly that the composition of insular avifaunas is highly deterministic. In a previous publication one of us (Terborgh 1973) showed by regression analysis that the species lists of both the smaller ( 300 but < 1,600 kM2) islands were approximately 90% determined by their locations. Another result of this analysis was that interisland differences in habitat in the Lesser Antilles exert such a minor influence on species composition that it is scarcely detectable. This was particularly astonishing in the case of the northern Lesser Antilles, a group of 10 islands lying to the north and northwest of Guadeloupe, and to the east of the Virgins (Fig. 1). These islands comprise 2 natural groups, an inner chain of 5 high, wet volcanic peaks covered with rainforest, and an outer chain of 5 low, dry coral platforms covered with xeromorphic scrub. Though the islands of the two chains are of very nearly the same size and within sight of one another, it is hard 59 The Auk 95: 59-72. January 1978 This content downloaded from 157.55.39.212 on Sun, 09 Oct 2016 05:49:50 UTC All use subject to http://about.jstor.org/terms 60 TERBORGH ET AL. [Auk, Vol. 95 PUERTO RICO ANOUILLA ST. MARTIN MONA S D CDS T. BARTHELE MY o ) Y VIRGIN 19S. SABA ZIBARBUDA ST. EUSTATIUS SE o ANTlGUA ST. KITTS/ ST. KITTSZ 4MONTSERRAT GUADELOUPE \ NEVIS XS \?U0()GUADELOUPE /E GRANDE TERRE O