NEU Ecology Fall 2013 Lec set 8

This is also called scramble or exploitative competition and features organisms that utilize the same resources that are in short supply

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Resource competition

This is also called contest competition and features organisms that seek a resource and, by doing so, harm one another in the process

Interference competition

What is one critical parameter that determines competition amongst plant species?

Spacing of individuals

What are the Lotka-Volterra equations bringing into account?

They are accounting for the fact that two given species use the same resource to grow and reproduce

(alpha)N2 = the equivalent number of species one individuals which means that alpha is the conversion factor for expressing species two in units of species one. What does this all mean?

Alpha is the effect of species 2 on species 1

What does it mean when the alpha value for competition between two species is higher than 1?

The per capita effect of interspecific competition is more important than the per capita effect of intraspecific competition

What are the three potential outcomes in the case of competition?

1: Both species coexist 2: Species 1 becomes extinct 3: Species 2 becomes extinct

What were the two key conclusions drawn from Tilman’s model?

1: You can predict the outcome of competition if you know the limiting nutrient concentration for each species and 2: superior competitors consume limiting resources to low levels, thereby eliminating competitors

What was actually found to be the limiting factor in yeast growth between two species from Gause’s (1932) experiments?

Ethyl alcohol was preventing new yeast buds from growing

What did Hutchinson (1958) define the fundamental niche of a species as?

It is the set of resources of a species that can be utilized in the absence of competition and other biotic factors

What two key problems has the fundamental niche idea run into?

1: Given the potentially infinite number of dimensions, we will have trouble defining or measuring the niche of any organism and 2: this model refers to a singular point in time whereas competition is a dynamic process

What is a realized niche?

It is the observed resource use of a species in the presence of competition