BIOL-1106 - Lesson XX - Notes Outline PDF

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This is a hybrid course. Corresponds with video lecture 20 for all BIOL-1106 sections....

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Daniel T. Eisert Lesson XX: Ecology of Individuals & Populations BIOL-1106: Principles of Biology QUIZ: August 7, 2017 _________________________________________________________________________________________________ Opening Remarks 1-Ecology is all about relationships. 2-Environmentalism refers to the concern about and action aimed at protecting the environment.

Ecology - The study of how organisms react with one another and their abiotic environment. - Focuses on individuals, populations, communities, and ecosystems. Adaptation - A helpful change. - Phenotypic plasticity (individual adaptation) : a helpful change within an individual; the ability to change one’s phenotype. - Evolutionary adaptation: an inherited trait that helps or improves the ability of individuals to survive and reproduce.

Population Ecology -

Subpopulation: a subset of a larger population. Metapopulation: a group or population that has limited exchange (i.e. pollenating different mountain tops) ~ linked local populations. - Subspecies: individuals of a species with a distinguishing characteristic/regional variability. - Species: individuals capable of interbreeding and producing fertile offspring. - Population : a group of individuals of a single species that are separate from other groups of that species. - Fitness: the number of offspring that survive to reproductive age. Distribution - Uniform occurs when there is competition for resources that are somewhat evenly dispersed. - Random - Clumped Density - Density typically decreases as organism size increases. Demographics - The quantitative study of population. - Sex ratio - Age structure (cohort) - Fecundity (birthrate) - Mortality - Generation time : the average interval between the birth of an individual and the birth of an offspring. Population Growth r=b+i−d −e - Let r represent the population growth rate. Daniel T. Eisert

Principles of Biology

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- Let b represent the birth rate. - Let i represent the immigration rate. - Let d represent the death rate. - Let e represent the emigration rate. Geometric/Exponential Growth Model dN =r i N dt dN represent a change in population per unit of time. dt - Let ri represent the maximum population growth rate. - Let N represent the number of individuals in the population. - Conditions: no net immigration or emigration and no population limit. Logistic Growth Model - Population growth with limits dN =rN K −N dt K - Carrying capacity, K, is added to the equation. The factor slows down growth as the multiplier gets closer to carrying capacity. Population Limitation & Regulation - Population limitation: a factor that stops growth (i.e. carrying capacity). - Population regulation: factors that keep the population dynamically stable. - Density-independent factors: exert the same force on a population regardless of the population density (i.e. weather, natural catastrophes). - Density-dependent factors: exert greater force on a population that is denser (i.e. food, predators, territory). - This is typically negative feedback; as the density of the population increases, the competition for food increases. - Positive feedback can occur too; Allee effect: where an increase in population density corresponds to an increase in birth rate (this only occurs in very small populations). -

Let

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r- and K-Selection -

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K-selection: individuals are good survivors and competitors (i.e. humans, elephants). r-selection: individuals are good reproducers (i.e. short-lived species—mice, cockroaches)  densityindependent factors. Most species fall somewhere along a continuum between the two selection types.

Daniel T. Eisert

Principles of Biology

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