An evolutionary explanation of the aggregation model of species coexistence

In ecology, the 'aggregation model of coexistence' provides a powerful concept to explain the unexpectedly high species richness of insects on ephemeral resources like dung pats, fruits, etc. It suggests that females aggregate their eggs across resource patches, which leads to an increased...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2003-08, Vol.270 (Suppl 1), p.S33-S35
Main Authors: Rohlfs, Marko, Hoffmeister, Thomas S.
Format: Article
Language:English
Subjects:
Aggregation
Allee Effect
Animals
Biological Evolution
Competition
Density Dependence
Drosophila
Drosophila - classification
Drosophila - physiology
Ecological competition
Ecological modeling
Ecosystem
Egg-To-Adult Survival
Eggs
Female
Insect communities
Insect larvae
Larval development
Models, Biological
Natural resources
Oviposition - physiology
Population Density
Species
Species Specificity
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Summary:In ecology, the 'aggregation model of coexistence' provides a powerful concept to explain the unexpectedly high species richness of insects on ephemeral resources like dung pats, fruits, etc. It suggests that females aggregate their eggs across resource patches, which leads to an increased intraspecific competition within occupied patches and a relatively large number of patches that remain unoccupied. This provides competitor-free patches for heterospecifics, facilitating species coexistence. At first glance, deliberately causing competition among the females' own offspring and leaving resources to heterospecific competitors seems altruistic and incompatible with individual fitness maximization, raising the question of how natural selection operates in favour of egg aggregation on ephemeral resource patches. Allee effects that lead to fitness maxima at intermediate egg densities have been suggested, but not yet detected. Using drosophilid flies on decaying fruits as a study system, we demonstrate a hump-shaped relationship between egg density and individual survival probability, with maximum survivorship at intermediate densities. This pattern clearly selects for egg aggregation and resolves the possible conflict between the ecological concept of species coexistence on ephemeral resources and evolutionary theory.
ISSN:0962-8452
1471-2954
DOI:10.1098/rsbl.2003.0002