Sex allocation

Abstract: This book is the first comprehensive treatment of sex allocation from the standpoint of modern evolutionary theory It shows how the determination of sex ratio, resource allocation to sperm versus egg within simultaneous hermaphroditism, and the evolution of sex reversal can he explained as examples of a single process The genetical theory, developed mostly with graphical arguments, also specifies when hermaphroditism and dioecy are themselves evolutionary stable The work balances theory with field and laboratory research, providing critical tests of the theory by empirical studies of sex ratio in parasitoid wasps and mites, sex reversal in shrimp and coral reef fish, and allocation of resources to pollen versus seeds in higher plants In addition, the author oilers an encyclopedic review of the field and laboratory work of other scientists, reviews many as yet untested hypotheses in sex allocation, and points toward numerous plant and animal systems that hold promise for future tests

Abstract: Halminton (1) was apparently the first to appreciate that the synthesis of Mendelian genetics with Darwin's theory of natural selection had profound implications for social theory. In particular, insofar as almost all social behavior is either selfish or altruistic (or has such effects), genetical reasoning suggests that an individual's social behavior should be adjusted to his or her degree of relatedness, r, to all individuals affected by the behavior. We call this theory kinship theory. The social insects provide a critical test of Hamilton's kinship theory. When such theory is combined with the sex ratio theory of Fisher (9), a body of consistent predictions emerges regarding the haplodiploid Hymenoptera. The evolution of female workers helping their mother reproduce is more likely in the Hymenoptera than in diploid groups, provided that such workers lay some of the male-producing eggs or bias the ratio of investment toward reproductive females. Once eusocial colonies appear, certain biases by sex in these colonies are expected to evolve. In general, but especially in eusocial ants, the ratio of investment should be biased in favor of females, and in it is expected to equilibrate at 1 : 3 (male to female). We present evidence from 20 species that the ratio of investment in monogynous ants is, indeed, about 1 : 3, and we subject this discovery to a series of tests. As expected, the slave-making ants produce a ratio of investment of 1 : 1, polygynoys ants produce many more males than expected on the basis of relative dry weight alone, solitary bees and wasps produce a ratio of investment near 1 : 1 (and no greater than 1 : 2), and the social bumblebees produce ratios of investment between 1 : 1 and 1 : 3. In addition, sex ratios in monogynous ants and in trapnested wasps are, as predicted by Fisher, inversely related to the relative cost in these species of producing a male instead of a female. Taken together, these data provide quantitative evidence in support of kinship theory, sex ratio theory, the assumption that the offspring is capable of acting counter to its parents' best interests, and the supposition that haplodiploidy has played a unique role in the evolution of the social insects. Finally, we outline a theory for the evolution of worker-queen conflict, a theory which explains the queen's advantage in competition over male-producing workers and the workers' advantage regarding the ratio of investment. The theory uses the asymmetries of haplodiploidy to explain how the evolved outcome of parent-offspring conflict in the social Hymenoptera is expected to be a function of certain social and life history parameters.

Abstract: Part 1 Introduction - invariants imply deeper symmetries: introduction (with examples) population dynamics fitness and life history evolution inheritance and sex allocation relative timing (and body size) variables life history theory for the aM number allometry philogenetic methods book layout - a short summary Part 2 Sex allocation: introduction and overview sex allocation under the Fisher inheritance symmetry simultaneous hermaphroditism sex reversal - breeding sex ratio dioecy - population sex ratio with environmental sex determination Part 3 Alternative life histories - mostly about males: bluegill sunfish salmon ESS theory - symmetric beginnings ESS theory - asymmetric beginnings one non-intuitive prediction Part 4 Indeterminate growth: fish aquatic invertebrates reptiles a life history theory for the Beverton-Holt invariants Part 5 Determinate growth - mostly about mammals: empirical patterns for female mammals theory - the basic 25 scaling theoretical interpretations one special invariant - aM a mortality cost of reproduction? sexual dimorphism in adult body size Part 6 Population dynamics: rmax allometry Fowler's rules Part 7 Senescence (ageing): determinate versus indeterminate growth sex-changing fish pollen grains alternative male life histories