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1976 Evolution of resource partitioning
CHAPTER FORTY
1976 Evolution of resource partitioning The concept The theory of density-dependent natural selection had been applied to the evolution of single populations (Chapter 27). In 1976 Roughgarden expanded this theory to the coevolution of competing species to produce the first comprehensive theory of community evolution.
The explanation The evolution of parameters of the logistic equation via densitydependent natural selection was reviewed in Chapter 27. Roughgarden (1976) sought to expand this evolutionary model by looking at a community of interacting species. These interacting species might be a predator and prey or it might be a collection of species that compete for a common resource. In either case, the fact that each species may affect the growth of another complicates the evolutionary dynamics. Roughgarden makes some general conclusions about these coevolutionary models before looking at some specific cases. The example that Roughgarden spends the most time developing is the case of competing species. In the case of two species the per-capita growth rate of species 1 is given by the Lotka-Volterra competition equations as, 1 þ a12 rN2 1 r rN K K , where a12 is the competition coefficient which measures the impact of species-2 on the growth of species-1. Competition is for a single resource which can be measured on a single axis, like the length of a seed. The carrying capacity for each species can then be a function (say Gaussian) on the resource axis. Each species has a different location on the resource axis where its carrying capacities is at a maximum. Likewise, competition is assumed to be proportional to the overlap of each species utilization of the resource. With some assumptions, the level of competition between two species may then be a simple function of the distance between the two on the resource axis. Conceptual Breakthroughs in Evolutionary Ecology ISBN: 978-0-12-816013-8 https://doi.org/10.1016/B978-0-12-816013-8.00040-5
© 2020 Elsevier Inc. All rights reserved.
95
j
96
Conceptual Breakthroughs in Evolutionary Ecology
Roughgarden’s model then shows that the evolution of resource use will be a balance between the evolutionary force to reduce competition and the disadvantage to shifting to a new resource type. Roughgarden reaches some general conclusions. If species diversity is not correlated with resource diversity then increasing the number of species in a community will result in neighboring competitors having greater niches overlap. This relationship is not expected if there is a correlation between species and resource diversity.
Impact: 9 Roughgarden’s paper was a significant advance in the theory of community evolution. It showed how species interactions, like competition, could affect the evolution of important community properties such as the level of niche overlap.
Reference Roughgarden, J., 1976. Resource partitioning among competing species-a coevolutionary approach. Theor. Popul. Biol. 9, 388e424.
1976 Evolution of resource partitioning The concept The theory of density-dependent natural selection had been applied to the evolution of single populations (Chapter 27). In 1976 Roughgarden expanded this theory to the coevolution of competing species to produce the first comprehensive theory of community evolution.
The explanation The evolution of parameters of the logistic equation via densitydependent natural selection was reviewed in Chapter 27. Roughgarden (1976) sought to expand this evolutionary model by looking at a community of interacting species. These interacting species might be a predator and prey or it might be a collection of species that compete for a common resource. In either case, the fact that each species may affect the growth of another complicates the evolutionary dynamics. Roughgarden makes some general conclusions about these coevolutionary models before looking at some specific cases. The example that Roughgarden spends the most time developing is the case of competing species. In the case of two species the per-capita growth rate of species 1 is given by the Lotka-Volterra competition equations as, 1 þ a12 rN2 1 r rN K K , where a12 is the competition coefficient which measures the impact of species-2 on the growth of species-1. Competition is for a single resource which can be measured on a single axis, like the length of a seed. The carrying capacity for each species can then be a function (say Gaussian) on the resource axis. Each species has a different location on the resource axis where its carrying capacities is at a maximum. Likewise, competition is assumed to be proportional to the overlap of each species utilization of the resource. With some assumptions, the level of competition between two species may then be a simple function of the distance between the two on the resource axis. Conceptual Breakthroughs in Evolutionary Ecology ISBN: 978-0-12-816013-8 https://doi.org/10.1016/B978-0-12-816013-8.00040-5
© 2020 Elsevier Inc. All rights reserved.
95
j
96
Conceptual Breakthroughs in Evolutionary Ecology
Roughgarden’s model then shows that the evolution of resource use will be a balance between the evolutionary force to reduce competition and the disadvantage to shifting to a new resource type. Roughgarden reaches some general conclusions. If species diversity is not correlated with resource diversity then increasing the number of species in a community will result in neighboring competitors having greater niches overlap. This relationship is not expected if there is a correlation between species and resource diversity.
Impact: 9 Roughgarden’s paper was a significant advance in the theory of community evolution. It showed how species interactions, like competition, could affect the evolution of important community properties such as the level of niche overlap.
Reference Roughgarden, J., 1976. Resource partitioning among competing species-a coevolutionary approach. Theor. Popul. Biol. 9, 388e424.