Editing Competitive exclusion principle (section)

==Redefinition==

Recent studies addressing some of the assumptions made for the models predicting competitive exclusion have shown these assumptions need to be reconsidered. For example, a slight modification of the assumption of how growth and body size are related leads to a different conclusion, namely that, for a given ecosystem, a certain range of species may coexist while others become outcompeted.<ref>{{Cite journal |last1=Rastetter |first1=E.B. |last2=Ågren |first2=G.I. |year=2002 |title=Changes in individual allometry can lead to coexistence without niche separation |journal=Ecosystems |volume=5 |pages=789–801 |doi=10.1007/s10021-002-0188-3 |s2cid=30089349}}</ref><ref>{{Cite journal |last1=Moll |first1=J.D. |last2=Brown |first2=J.S. |year=2008 |title=Competition and Coexistence with Multiple Life-History Stages |journal=American Naturalist |volume=171 |issue=6 |pages=839–843 |doi=10.1086/587517 |pmid=18462131 |bibcode=2008ANat..171..839M |s2cid=26151311}}</ref>

One of the primary ways niche-sharing species can coexist is the [[competition-colonization trade-off]]. In other words, species that are better competitors will be specialists, whereas species that are better colonizers are more likely to be generalists. Host-parasite models are effective ways of examining this relationship, using host transfer events. There seem to be two places where the ability to colonize differs in ecologically closely related species. In feather lice, Bush and Clayton<ref>{{Cite journal |last1=Clayton |first1=D.H. |last2=Bush |first2=S.E. |year=2006 |title=The role of body size in host specificity: Reciprocal transfer experiments with feather lice |journal=Evolution |volume=60 |issue=10 |pages=2158–2167 |doi=10.1111/j.0014-3820.2006.tb01853.x |pmid=17133872 |s2cid=221734637}}</ref> provided some verification of this by showing two closely related genera of lice are nearly equal in their ability to colonize new host pigeons once transferred. Harbison<ref>{{Cite journal |last=Harbison |first=C.W. |year=2008 |title=Comparative transmission dynamics of competing parasite species |journal=Ecology |volume=89 |issue=11 |pages=3186–3194 |bibcode=2008Ecol...89.3186H |doi=10.1890/07-1745.1 |pmid=31766819}}</ref> continued this line of thought by investigating whether the two genera differed in their ability to transfer. This research focused primarily on determining how colonization occurs and why wing lice are better colonizers than body lice. Vertical transfer is the most common occurrence, between parent and offspring, and is much-studied and well understood. Horizontal transfer is difficult to measure, but in lice seems to occur via phoresis or the "hitchhiking" of one species on another. Harbison found that body lice are less adept at phoresis and excel competitively, whereas wing lice excel in colonization.

Support for a model of [[competition-colonization trade-off]] is also found in small mammals related to fire disturbances. In a project focused on the long-term impacts of the [[Yellowstone fires of 1988|1988 Yellowstone Fires]] Allen et al.<ref>{{Cite journal |last1=Allen |first1=A.G. |last2=Roehrs |first2=Z.P. |last3=Seville |first3=R.S. |last4=Lanier |first4=H.C. |year=2022 |title=Competitive release during fire succession influences ecological turnover in a small mammal community |journal=Ecology |volume=103 |issue=8 |pages=1–12 |bibcode=2022Ecol..103E3733A |doi=10.1002/ecy.3733 |pmc=9891167 |pmid=35430726}}</ref> used stable isotopes and spatial mark-recapture data to show that [[Southern red-backed vole|Southern red-backed voles (''Clethrionomys gapperi'')]]), a specialist, are excluding [[Eastern deer mouse|deer mice (''Peromyscus maniculatus'')]], a generalist, from food resources in old-growth forests. However, after wildfire disturbance deer mice are more effective colonizers, and able to take advantage of the release from competitive pressure from voles. This dynamic of establishes a pattern of ecological succession in these ecosystems, with competitive exclusion from voles shaping the amount and quality of resources deer mice can access.