The Editor wishes to thank all the referees of published articles in Volume 44, as well as those ... more The Editor wishes to thank all the referees of published articles in Volume 44, as well as those who gave of their knowledge and time but upon whose judgement rejections had to be made (superscript gives the number of manuscripts reviewed for this volume if more than one).
In a previous paper (Roff, 1974) a simulation model was presented demonstrating the importance of... more In a previous paper (Roff, 1974) a simulation model was presented demonstrating the importance of dispersal in a spatially heterogeneous environment. In the present paper this model is analysed in detail. It is shown that the qualitative properties of the model can be ...
The hypothesis that dispersal in a heterogeneous environment can be an important factor in popula... more The hypothesis that dispersal in a heterogeneous environment can be an important factor in population stability is examined. It is shown that dispersal may increase the persistence time of a population by several orders of magnitude.
Many cryptic species have been discovered in various taxonomic groups based on molecular phylogen... more Many cryptic species have been discovered in various taxonomic groups based on molecular phylogenetic analyses and mating experiments. Some sympatric cryptic species share equivalent resources, which contradicts the competitive exclusion principle. Two major theories have been proposed to explain the apparent lack of competitive exclusion, i.e. niche-based coexistence and neutral model, but a conclusive explanation is lacking. Here, we report the co-occurrence of cryptic spider wasp species appearing to be ecologically equivalent. Molecular phylogenetic analyses and mating experiments revealed that three phylogenetically closely related species are found sympatrically in Japan. These species share the same resources for larval food, and two of the species have the same niche for nesting sites, indicating a lack of competitive exclusion. This evidence may suggest that ecologically equivalent species can co-occur stably if their shared resources are sufficiently abundant that they can...
... arguments are commonly advanced for homeotherms (Hamilton 1961; Kendeigh 1970, 1976; James 19... more ... arguments are commonly advanced for homeotherms (Hamilton 1961; Kendeigh 1970, 1976; James 1970; Brown and Lasiewski 1972; Tracy 1977) though ... is followed in the tropics where population growth is interrupted by the seasonal change in food supplies (Pipkin 1965). ...
The Editor wishes to thank all the referees of published articles in Volume 44, as well as those ... more The Editor wishes to thank all the referees of published articles in Volume 44, as well as those who gave of their knowledge and time but upon whose judgement rejections had to be made (superscript gives the number of manuscripts reviewed for this volume if more than one).
In a previous paper (Roff, 1974) a simulation model was presented demonstrating the importance of... more In a previous paper (Roff, 1974) a simulation model was presented demonstrating the importance of dispersal in a spatially heterogeneous environment. In the present paper this model is analysed in detail. It is shown that the qualitative properties of the model can be ...
The hypothesis that dispersal in a heterogeneous environment can be an important factor in popula... more The hypothesis that dispersal in a heterogeneous environment can be an important factor in population stability is examined. It is shown that dispersal may increase the persistence time of a population by several orders of magnitude.
Many cryptic species have been discovered in various taxonomic groups based on molecular phylogen... more Many cryptic species have been discovered in various taxonomic groups based on molecular phylogenetic analyses and mating experiments. Some sympatric cryptic species share equivalent resources, which contradicts the competitive exclusion principle. Two major theories have been proposed to explain the apparent lack of competitive exclusion, i.e. niche-based coexistence and neutral model, but a conclusive explanation is lacking. Here, we report the co-occurrence of cryptic spider wasp species appearing to be ecologically equivalent. Molecular phylogenetic analyses and mating experiments revealed that three phylogenetically closely related species are found sympatrically in Japan. These species share the same resources for larval food, and two of the species have the same niche for nesting sites, indicating a lack of competitive exclusion. This evidence may suggest that ecologically equivalent species can co-occur stably if their shared resources are sufficiently abundant that they can...
... arguments are commonly advanced for homeotherms (Hamilton 1961; Kendeigh 1970, 1976; James 19... more ... arguments are commonly advanced for homeotherms (Hamilton 1961; Kendeigh 1970, 1976; James 1970; Brown and Lasiewski 1972; Tracy 1977) though ... is followed in the tropics where population growth is interrupted by the seasonal change in food supplies (Pipkin 1965). ...
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Papers by Derek Roff