Bertram G. Murray

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Despite a long history, the term “density dependence” lacks a generally accepted definition. A definition is offered that seems consistent with most other definitions and general usage, that is, a density-dependent factor is any component of the environment whose intensity is correlated with population density and whose action affects survival and(More)
New Zealand pohutukawa (Metrosideros excelsa), a member of the Myrtaceae, is a large, mass-flowering tree endemic to northern New Zealand coastlines. Mainland populations have been reduced to fragmented stands, and the original suite of bird pollinators has been largely replaced by introduced species. The native pollinator fauna on several offshore islands(More)
Closely-related, sympatric species differ in one or more characters that have been identified as premating isolating mechanisms. These may be morphological, behavioral, physiological, or ecological. Theoretically, premating isolating mechanisms evolve as divergent characters in allopatric populations or as specific adaptations that reduce the frequency of(More)
Scientists observe nature, search for generalizations, and provide explanations for why the world is as it is. Generalizations are of two kinds. The first are descriptive and inductive, such as Boyle's Law. They are derived from observations and therefore refer to observables (in this case, pressure and volume). The second are often imaginative and form the(More)
We test the Murray-Nolan equation for calculating clutch sizes of birds with demographic data from a long-term study of the Florida Scrub Jay (Aphelocoma c. coerulescens). The predicted value, 3.43, is very close to the observed clutch size, 3.33. This result provides further support for the equation's being an adequate description of the relationship among(More)
We derive an equation for calculating the clutch sizes of birds and other long-lived animals from Murray's (1979) theory on the evolution of clutch size. For the Prairie Warbler (Dendroica discolor) in Indiana, this equation predicts an average clutch size of 3.49, less than half an egg smaller than the recorded average clutch size of 3.89. We attribute the(More)
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