Hierarchical Life History Axes Training of maturity Frequency of Reproduction Effort per Reproductive Bout Distribution of Effort Life History Variation Across all life Across major phylogenetic scales Across major linages mammals molluscs angionsperms Across genera sunflowers Within single species Enviornment r species Produce many offspring Reproduce early in life Small body size Rapid development Grow from low population to high very quickly Boom bust cycle opportunistic Unpredictable environment Develop fast k Species Produce few offspring Reproduce later in life Competitive Large body size Develop slowly Constant population Constant environment Do life history strategies evolve With trade offs Natural selection Semelparous r species Only reproduce once Die after reproduction Iteroparous Reproduces more than once Put energy into survival and growth Darwinian Demon Harvests large amounts of energy Lives forever Always reproduces No such organism Offspring always big and survive Ontogenies of resource allocation Description of development How much energy is being put into growth Census Actual count of all organisms Population density Number of individuals per unit area Population growth rate Change of number of individuals at a given time Distribution Size shape and location of the area it occupies and the spacing of the individuals in the area Abundance Total number of individuals biomass Density Number of individuals per unit area Malthus Equation There is a limit to how many people earth can support Food supply can t keep up with growth Limit population growth Discrete Time Model Geometric Growth Not continuous Nt 1 Nt Count individuals at two times is the slope What population will be after t generations in closed system Continuous Time Models Exponential Growth Model dN dt B D B bN D dN dN dt rN Continuous births and deaths Assume resources unlimited random mating no immigration Predict what population will be after t Size after t generations continuous growth Density Dependent Logistics Growth Models dN dt rN K N K N K r N K r 0 N K r Population will initially increase K is constant o Is likely to change over both space and time o All individuals equal o Each 1 Kth Continuous vs Discrete Continuous any number distance Discrete limited whole number Number of kids
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