Bio 51: Lab 2 (Population Growth and competition)

fundamental niche of a species

theoretical habitat in which interspecific competition is absent: species can theoretically sustain a viable population in a range of habitats that possess suitable environmental conditions and resources

realized niche

actual habitat a species occupies; interspecific competition the fundamental niche of a species into realized niche

Gause

russian ecologist that explored niche concept. he are two protozoan species (Paramecium aurelia and Paramecium caudatum) by themselves in a jar of liquid medium

describe the graph when two protozoan species are cultured alone

logistic growth curve describing the growth of a population. the carrying capacity (K) is equal to 1000 individuals

Describe the logistic growth when the protozoan species were cultured alone

In the beg. of the experiment when there were few individuals, the resources (bacteria and yeast) were abundant and most of individuals had high reproductive success. The population size increase exponentially until they were more individuals than the resources in the jar could support. This leads to reduction of the total number of protozoa in the population until the resources were able to rebound or replenish. With replenished resources the protozoa again increased in number until they again overexploited their resources. The population size dipped again, and increased in number once the resources were again replenished. The final, stable number of protozoa in a jar fluctuated in a cyclic manner above and below the carrying capacity (K) of that environment.

Carrying capacity (K)

the maximum number of individuals a set of resources can support in a given environment

What happened when Gause grew P. aurelia and P. caudatum together in a jar of medium?

P. aurelia always survived and P. caudatum always declined to the point of extinction. Thus, P. aurelia=superior competitor

Competitive exclusion principle

two species competing for the same, limiting resources cannot coexist in the same niche indefinitely. One species will always use the resources more efficiently and cause the other species to become extinct locally

Paramecium digitus

using dominant hand to capture food

paramecium utensilius

using fork in your non-dominant hand to retrieve food

evolution

changes in populations through time individuals interact and exchange genes in populations to shape properties of species

ecology

# of individuals=abundance, changes through time (=pop. growth)

conservation

factors impacting birth/death rates (=pop. growth)

disease transmission

# of individuals and their spatial distribution, dynamics can predict outbreaks

a major agent of natural selection leading to the adaptations we see in populations of plants and animals

competition

population growth can be modeled in what two ways?

logistic and exponential

what was the result of lab?

when P. Utensilius and P. Digitus population trials were run together, the P. Utensilius population almost became extinct. there were a lot of P. Digitus individuals remaining, suggesting the theory of competitive exclusion.