Lecture 3: Species Interactions

Classify population interactions in terms of the positive and negative effects that the interactions have on the interacting populations.

Mutualism +/+

Commensalism +/0

Competition -/-

Predation +/-

Explain how population interactions are often the product of coevolution and why non-native species can wreak havoc on native populations.

Species evolve traits that benefit others (mutualism), predators and prey develop a relationship that keeps the other in check, and species competing for the same resource often adapt different niches or traits. They have no predators can outcompete natives for resources.

Discuss adaptations of prey for avoiding capture by predators.

Camouflage, mimicry, enhance senses, physical defenses, and aposematic coloring

Describe countermeasures that predators evolved to cope with prey defenses.

Toxin tolerance, avoidance, pack hunting, specialized anatomy

Distinguish between Batesian and Mullerian mimicry.

Batesian: Harmless

Mullerian: harmful

Categorize parasites into different life histories (direct, vector-borne, complex)

Direct: only need one host and transfer directly from one to another (lice)

Vector-borne: a vector transports the parasite between hosts (malaria via mosquitos)

Complex: Requires 2+ hosts for development and sexual reproduction

Give examples of common mutualisms and identify conditions under which mutualisms can break down.

Bees get nectar, plants get pollen dispersed for reproduction

Ants get food and shelter, Acacia tree gets protection from herbivores

Explain the ecological "niche” concept.

An organisms unique role and lifestyle within their ecosystem to avoid direct competition.

Distinguish the fundamental and realized niches of Chthalamus and Balanus.

The Chtalamus’ fundamental niche covers the whole intertidal zone, but its realize niche is resticted to the upper zone. The balanus lives in the lower zone as it would outcompete the Chtamalus.

Describe how interspecific competition, under conditions of resource limitation, can lead to character displacement.

Similar species evolve different traits to minimize niche overlap, allowing them to coexist