Showing papers in "Theoretical Population Biology in 1976"

TL;DR: This paper will develop a model for the use of a “patchy habitat” by an optimal predator and depresses the availability of food to itself so that the amount of food gained for time spent in a patch of type i is hi(T), where the function rises to an asymptote.

TL;DR: These coevolutionary principles, applied to a model for resource partitioning, entail that the niche separation between species relative to given niche widths, increases with the variety of available resources and decreases with the number of competing populations.

TL;DR: A discrete (difference) single age-class model for two-species competition is presented and its stability properties discussed, which resembles the Lotka-Volterra model in having linear zero growth isoclines but differs in allowing the populations to show damped oscillations, stable cycles or even apparent “chaos” if competition is sufficiently severe.

TL;DR: The values obtained show that gynodioecy is not a single breeding system, but merges into hermaphroditism and dioecY at opposite extremes, and in most species, seed counts overestimate the ovule contributions of males.

TL;DR: A mathematical model in which any number of competing species can coexist on four resources which regenerate according to an algebraic relationship is developed and it is concluded that the competitive exclusion principle should be considered to apply only to coexistence at fixed densities.

TL;DR: The usual equilibrium for heterozygote advantage is found to depend, in the present case, on the parameters of the learning process, and Oscillatory equilibria and more than one stable equilibrium can exist in certain circumstances.

TL;DR: A family of one-level differential-equation competition models in which two populations are limited by the energy flowing into the system generates the following results: either one species wins or the species coexist, depending on initial values.

TL;DR: There appears to be an upper limit in heterozygosity for protein loci as measured by electrophoresis and the excess of rare alleles is more pronounced in Drosophila than in man.

TL;DR: A model of population structure is discussed which under certain circumstances allows for evolution of altruistic traits, beyond the classical restrictions imposed by kin selection theory and related concepts such as reciprocal altruism.

TL;DR: Populations that obey differential-delay equations, and those that obey ordinary first-order difference equations, may be understood within a common general framework, wherein excessive time lags lead to stable limit cycle behavior.

TL;DR: The term altruist is adopted here in its biological meaning for any inherited trait which reduces the fitness of its individual carrier but which is beneficial to the neighboring population of this carrier.

TL;DR: The ways by which a chromosome mutation can increase in a random mating population, despite the mutation's deleterious effect on the fertility of heterozygotes are reviewed.

TL;DR: In this article, the authors examined selection at the colony level in social Hymenoptera with colonies containing single, once-mated queens under a simple two-allele model.

TL;DR: The probability distribution of H is found in panmictic populations where three selectively neutral alleles mutate to each other and formulas for the variance are obtained for any given number of alleles and for all moments when the mutations are non recurrent.

TL;DR: A population of constant size is subjected to mutation, such that each mutant is of a new allelic type, and the age of an allele, whose present frequency is known, is a random variable with distribution independent of the frequencies of other alleles.

TL;DR: Using the island model of finite size, the distributions as well as the means and variances of dw and db are obtained and it is shown that the actual genic variation in a colony may be much larger than that revealed by the heterozygosity in the colony.

TL;DR: A nonlinear version of the Lotka-Sharpe model of population growth is considered in which the age specific fertility is a function of the population size, and the stability of an equilibrium population distribution is investigated with respect to both global and local perturbations.

TL;DR: If a deterministic model ecosystem has a good Lyapunov function, it may be possible to derive simple and useful tests for the system to be nonvulnerable, if the smallest eigenvalue of a certain matrix is not only positive, but is greater than a positive number.

TL;DR: A general prey-predator model is formulated and the conditions for the occurrence of limit cycles are discussed and the effects of random environmental fluctuations on a stable equilibrium and on a limit cycle are investigated.

TL;DR: It is shown that a polymorphism based on Mendelian segregation is never stable for any recombination frequencies between 0 and 1 2, and that, for tight linkage between the main locus and the modifiers locus, the modifier locus tends towards heterozygosity.

TL;DR: The loss of genetic variability in two dimensions is so slow that evolutionary forces not considered in this model would supervene long before a two-dimensional natural population became completely homogeneous.

TL;DR: Schoener (1973) has recently discussed a simple model of growth and competition, fitted to data on interspecies competition between Drosophila willistoni and D. pseudoobscura, and this note treats Schoener’s model in the spirit of earlier work.

TL;DR: Compared with the use of cytoplasmically incompatible males for control, the former is to be chosen since the release rates of males necessary for population suppression would cause population replacement due to the unavoidable escape of even a very few females.

TL;DR: It is shown that up to three polymorphic equilibria may exist, two of which are in linkage disequilibrium and one in linkage equilibrium, which exhibit behavior qualitatively opposite to what is widely accepted as the usual for two locus systems.

TL;DR: A hybrid model is established for the transmission of schistosomiasis in a community that allows for latency and differential mortality in the snail population and gives conditions under which the infection will be eradicated.

TL;DR: It is shown that this mode of eradication of schistosomiasis from an isolated community is facilitated by a control program that is directed at such changes of the biological-environmental parameters that reduce the parasite population.

TL;DR: The findings of the initial experiments are that a sequence of products of human population projection matrices converges towards the sequence defined by its positive, or Perron-Frobenius, eigenstructure, and that, when appropriately defined, sequences both of left and of right eigenvectors converge to constant vectors.

TL;DR: A phenotypically determined nonrandom mating model is specified for a continuous trait controlled by a major gene, and conditions for equilibria, polymorphic and degenerate, are given for a series of analytical and numerical cases.

TL;DR: Models of population structure analyzed include: the uniform model and the multiuniform model, which is of interest in situations of population radiation and of centripetal migration.

TL;DR: It is shown how the genetic structure of a population can initiate bifurcations to periodic and chaotic trajectories and the dependence of this phenomenon on the strength of assortative mating, the level of heterozygosity, and the intensity of selection is investigated.