Toshiyuki Namba | Osaka Prefecture University (original) (raw)
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Papers by Toshiyuki Namba
Theoretical population biology, 2004
Models of metapopulations have often ignored local community dynamics and spatial heterogeneity a... more Models of metapopulations have often ignored local community dynamics and spatial heterogeneity among patches. However, persistence of a community as a whole depends both on the local interactions and the rates of dispersal between patches. We study a mathematical model of a metacommunity with two consumers exploiting a resource in a habitat of two different patches. They are the exploitative competitors or the competing predators indirectly competing through depletion of the shared resource. We show that they can potentially coexist, even if one species is sufficiently inferior to be driven extinct in both patches in isolation, when these patches are connected through diffusive dispersal. Thus, dispersal can mediate coexistence of competitors, even if both patches are local sinks for one species because of the interactions with the other species. The spatial asynchrony and the competitioncolonization trade-off are usual mechanisms to facilitate regional coexistence. However, in our case, two consumers can coexist either in synchronous oscillation between patches or in equilibrium. The higher dispersal rate of the superior prompts rather than suppresses the inferior. Since differences in the carrying capacity between two patches generate flows from the more productive patch to the less productive, loss of the superior by emigration relaxes competition in the former, and depletion of the resource by subsidized consumers decouples the local community in the latter.
Ecological Issues in a Changing World, 2004
One of the basic questions in ecology is to understand how the ecological communities and ecosyst... more One of the basic questions in ecology is to understand how the ecological communities and ecosystems are organized. It has gained the greater importance because of the growing concern about the conservation of biodiversity and restoration of damaged ecosystems in a changing world. Species interactions and spatio-temporal variability are the key factors influencing ecological processes. Since many problems interconnect across
Theoretical population biology, 2004
Models of metapopulations have often ignored local community dynamics and spatial heterogeneity a... more Models of metapopulations have often ignored local community dynamics and spatial heterogeneity among patches. However, persistence of a community as a whole depends both on the local interactions and the rates of dispersal between patches. We study a mathematical model of a metacommunity with two consumers exploiting a resource in a habitat of two different patches. They are the exploitative competitors or the competing predators indirectly competing through depletion of the shared resource. We show that they can potentially coexist, even if one species is sufficiently inferior to be driven extinct in both patches in isolation, when these patches are connected through diffusive dispersal. Thus, dispersal can mediate coexistence of competitors, even if both patches are local sinks for one species because of the interactions with the other species. The spatial asynchrony and the competitioncolonization trade-off are usual mechanisms to facilitate regional coexistence. However, in our case, two consumers can coexist either in synchronous oscillation between patches or in equilibrium. The higher dispersal rate of the superior prompts rather than suppresses the inferior. Since differences in the carrying capacity between two patches generate flows from the more productive patch to the less productive, loss of the superior by emigration relaxes competition in the former, and depletion of the resource by subsidized consumers decouples the local community in the latter.
Ecological Issues in a Changing World, 2004
One of the basic questions in ecology is to understand how the ecological communities and ecosyst... more One of the basic questions in ecology is to understand how the ecological communities and ecosystems are organized. It has gained the greater importance because of the growing concern about the conservation of biodiversity and restoration of damaged ecosystems in a changing world. Species interactions and spatio-temporal variability are the key factors influencing ecological processes. Since many problems interconnect across