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9/8/16In the exponential growth model, the realized per-capita growth rate equals rwhen population density is near zero.What is the equilibrium point for the logistic growth model? Kor
Polar bear and its cub and bottom is wolf spider. 2 different looking species possess one life history trait that they share in common, parental care. Differ in how many offspring they produce, possess different life history strategies even though some of the traits that make up these strategies are the same. Orchid lady slipper. Long life span, around 50 years. They produce a single flower and reproduce every several years. Other plant in bottom, completes its life cycle in 3 weeks. Arabid opsis plant. 2 species of birds. First glance look similar but possess different life history strategies. MacArthur and Wilson Came up with theory to explain variation in life strategies. Theory based on the logistic model. What determines life history strategy is whetheror not maximizing little r or maximizing k benefits them most. r and k are driving force. r-k selection theory. Situation where resources are unlimited. Where species are growing in an exponential way, only use little r. Species A has higher intrinsic rate of increases (r). Growth will be steeper. Species A will grow faster. The difference in population size will vary greater over time. Higher density for A. At any time, species a is doing better. One way to maximize fitness is to produce more offspring so species a is producing more than b. Species b will become proportionately more rare. Relative extinction event, it becomes less abundant, not extinct though. Species in a resource unlimited environment, the species with higher little r will have higher fitness. Natural selection should favor species that grows fastest with little r, over time for both species, should have higher values for little r. Circumstances where r-selection expected? Species invade a new habitat like collared dove. Expect r to be favored for species invading new habitats. Population crash, black noddies. Cats were introduced and killed these birds that nested on the ground and the populations recovered. Following crashes where populations are plentiful bc of their low density, they will grow well. Plentiful resources following disturbance, scotch pine. Fires burn understory and free up resources for weeds to grow and populations grow exponentially for a while. Little r selected species to be successful under these circumstances. Weeds; They will take over an area bc there are plentiful resources created by these disturbed habitats. High little r species will leave the most offspring. K selection for species that are resource limited. Lynx and bobcat. 2 species that looksimilar. They overlap with one another, share the same resources, both hunt small mammals. Live in similar areas. Likely compete with one another for resources. Each