The Species-Rank abundance curve for Run (Figure 1.) and Riffle (Figure 2.) treatment shows similar relationship between rank abundance and log10 abundance for dominance preemption and the observed data. Since the data in both treatments resembled the Dominance preemption model, species assemblages are unstable.
The dominance preemption model supposes that the first species to invade the communities of relatively few species where a single environmental factor is of dominating importance. Only a few species are fit to survive in such a habitat so they are numerically dominant. Both cold-temperature communities and polluted communities fit this profile, so we are not surprised to see limited species richness in such situations. Fits of data …show more content…
The T-Test of the two treatments of Sorensen coefficient fails to reject the null hypothesis that there is no difference in the average assemblage similarity between the two habitat types.
Here assemblage similarities are used as a measure of assemblage stress. In a non-stressed system replicate within a treatment should host habitat generalists, intermediates, and specialists. But as the replicate is limited in size, each replicate is likely to host a different subset of specialist species, that is, replicate to replicate although the generalists and intermediates are likely to be similar, the collection of specialist species should change. As there are more specialist species than generalist species, assemblage similarity between replicates of the same habitat type should on average be low. By comparison, because individual specialist species are comparatively rare these specialist species are normally lost first in a stressed system. Thus through comparing assemblage similarities between replicates in a stressed system, the average similarity are higher due to the loss of diversity and greater influence of the remaining habitat generalists and intermediates (Cao and Epifanio
The dominance preemption model supposes that the first species to invade the communities of relatively few species where a single environmental factor is of dominating importance. Only a few species are fit to survive in such a habitat so they are numerically dominant. Both cold-temperature communities and polluted communities fit this profile, so we are not surprised to see limited species richness in such situations. Fits of data …show more content…
The T-Test of the two treatments of Sorensen coefficient fails to reject the null hypothesis that there is no difference in the average assemblage similarity between the two habitat types.
Here assemblage similarities are used as a measure of assemblage stress. In a non-stressed system replicate within a treatment should host habitat generalists, intermediates, and specialists. But as the replicate is limited in size, each replicate is likely to host a different subset of specialist species, that is, replicate to replicate although the generalists and intermediates are likely to be similar, the collection of specialist species should change. As there are more specialist species than generalist species, assemblage similarity between replicates of the same habitat type should on average be low. By comparison, because individual specialist species are comparatively rare these specialist species are normally lost first in a stressed system. Thus through comparing assemblage similarities between replicates in a stressed system, the average similarity are higher due to the loss of diversity and greater influence of the remaining habitat generalists and intermediates (Cao and Epifanio