BIOL 1001 Learning Outcomes Final.docx

Mutualism will increase the numbers of both species

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Mutualism will increase the numbers of both species and will increase the frequency of these species being found together Parasitism will cause a cycle between the numbers of the parasitic species and prey species. Parasitic species will limit the number of prey species from becoming too large and if the prey species numbers become too low, the parasitic organism will also become low. o Species act as agents of natural selection. This can be seen in the arms race between predators and prey. If a prey species’ population has a new trait that increases in frequency that provides a resistance or protection from being preyed on, individuals with this trait will increase in numbers. Individuals of the predator species with another trait that would work against this newly-obtained prey trait would be at a higher fitness and spread this trait to offspring, causing the trait to be at a greater frequency in time. This will occur back and forth. o Interactions among species are dynamic and conditional. For example with mutualism, although both species are benefiting, sometimes one species will try to “trick” the other. This can be seen with flowers and pollinators. Both have a mutualistic relationship – the pollinator gets a flower’s nectar and the flower gets to have its pollen dispersed by the pollinator. Sometimes, however, flowers can evolve to have no nectar, and so the pollinator does not receive any benefit but the flower does.
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Niche overlap is when two species occupy the same niche. The competitive exclusion principle is said to result from niche overlap. It states that when two species occupy the same niche, both will compete until one species outcompetes the other, forcing the other into extinction. This can be seen with two different species of paramecium. When placed in the same petri dish, it was seen that one paramecium species’ numbers increased while the other species’ numbers drastically declined. Niche differentiation is when there is a change in the traits of a species that is involved in a niche overlap with another species. This allows one of the species to occupy other resources of the niche that do not cause competition with another species. This can be seen with two different species of barnacles. Both species occupy the same niche and exploit similar resources, but one species is found in above tidal zones, which puts them at a disadvantage, whereas others are found below tide zones. The reason for this is because barnacles occupying the same niche causes the species that lives above tide to fall significantly in numbers. o Fitness trade-offs in interspecific competition can benefit competing species. Often times, the trade-off is between reproduction and lifespan. If a species is prone to predation when it is young and small, it will likely have short and fast somatic development, causing its lifespan to be short, and reproduce at an earlier age, having a lot of offspring at once. If a species is prone to predation when it is older and larger, it will have a slower and longer rate of somatic development, causing its lifespan to be long, and will have only a few offspring.
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