Steven A. Frank

Learn More
Several evolutionary processes influence virulence, the amount of damage a parasite causes to its host. For example, parasites are favored to exploit their hosts prudently to prolong infection and avoid killing the host. Parasites also need to use some host resources to reproduce and transmit infections to new hosts. Thus parasites face a tradeoff between(More)
Kin selection arguments, based on Hamilton's (1964) concept of inclusive fitness, provide a powerful heuristic and can therefore give us valuable insights into the different pathways through which natural selection acts. But their formulation can be quite tricky, requiring as they do, a close accounting of all the fitness effects of a particular item of(More)
Evolutionary theory has not explained how competition among lower level units is suppressed in the formation of higher-level evolutionary units. For example, the key problem of early evolution is small, individual replicators formed cooperative groups of sufficient complexity to allow accurate copying of the genetic material. The puzzle is why parasites did(More)
A general framework is presented to unify diverse models of natural selection. This framework is based on the Price Equation, with two additional steps. First, characters are described by their multiple regression on a set of predictor variables. The most common predictors in genetics are alleles and their interactions, but any predictor may be used. The(More)
Models of sex-ratio evolution in structured populations are derived with G.R. Price's covariance form for the hierarchical analysis of natural selection (1970, Nature 227, 520-521). Previous work on competition among related males for mates (local mate competition), competition among related females for a limiting resource (local resource competition),(More)
Conditions are analyzed under which natural selection favors an individual to help another species at a cost to its own reproduction. Traditional models for the evolution of altruism between species focus on the genetic relatedness between the original donor and the recipients of return benefits from the mutualistic partner species. A more general model is(More)
Predictions from the theory of sex ratios in subdivided populations are tested by studying fig wasps (Agaonidae). Observations strongly support the qualitative prediction that fig wasp sex ratios (males/total) decrease with increasing amounts of both inbreeding and competition among male relatives for access to mates (local mate competition). However, the(More)
George Price studied evolutionary genetics for approximately seven years between 1967 and 1974. During that brief period Price made three lasting contributions to evolutionary theory; these were: (i) the Price Equation, a profound insight into the nature of selection and the basis for the modern theories of kin and group selection; (ii) the theory of games(More)
The transition from competing individuals to cooperative groups has occurred several times in evolutionary history. The puzzle is why selfish individuals did not subvert cohesive group behaviour by taking resources without contributing to the group’s overall success. Kin selection and reciprocal altruism are the two standard explanations for group cohesion.(More)
Bulmer (1986) has recently studied sex ratio evolu= tion under the island migration model. His study was motivated by my statement that as genetic differentiation among isolated patches increases, _the predicted proportion of males declines linearly with Pdt, Wright's (1969) measure for differentiation among demes (Frank, 1985, 1986). Bulmer's results show,(More)