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5 Cards in this Set
- Front
- Back
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Population
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• Potential interbreeding population
• continuity over time • Species • Characteristics -Size (numbers) -Density (numbers per unit area or host) -Distribution (clumped, random, uniform) -Variation (size, density, distribution) -Social Behavior (interaction) -Genes (genotype-genetic makeup, phenotype- interaction between genotype in environment) -evolution (isolate=speciation) -extinction |
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Population Dynamics
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• Changes in population size over time (density)
• Exponential Growth Curve (no limits in population size) housefly -two flies lay 100 eggs (male:50, female:50) -Ideal situation: 25 generations -No mortality until old age • Logistic Growth Model -competition for food, space, and resources -carrying capacity (K) – maximum population size for food, space, needs amount |
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Darwin and Natural Selection
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• Reproduction form new generation
• Overproduction cause except fecundity • Heredity • Genetic diversity • Variation in fitness • Selection pressure- external factors favors a certain adaptation • Fitness: probability that an individual will survive and produce |
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Demography (Natality and Mortality)
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• Type I- most live to old age (humans, starved fruit fly)
• Type II-Constant morality (butterfly adults, hydra) • Type III-High infant mortality (most insect, oysters) • Only females will continue the generation • (refer to handout graph) • Net reproductive rate- average number of female offspring over adult female’s lifetime • Balance of births and deaths -Natality > mortality (growth) -Natality = mortality (stable) -Natliaty < mortality (decine) -refer to graph (works well with insects with one generation, not with multi-generation/year) |
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Limits to Population Size
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• Natural control –all factors cause population to change in size
• Population fluctuate between upper and lower limit by actions of abiotic and biotic factors • Density-dependent (DD) factors -severe increase to population as it increases in density 1. Intraspecific Competition (food, space)-decrease reproduction, reduce development rate, emigration 2. Natural Enemies (predators, parasitoids, pathogens)- lag effect with predator; numerical vs function response (graph) • Density Independent (DI) Factors -do not change in intensity with population density (whether if population is big or small) -weather, chemical pesticides, mowing, floods |
