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41 Cards in this Set
- Front
- Back
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Characteristics that define the life history of an organsim
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Age and size at sexual maturity
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life history strategy
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overall pattern in the average timing and nature of life history events
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how is life history strategy determined
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the way the organism divides its time and energy between growth, reproduction, and survival
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life history traits influenced by genetic traits are more (similar or different) within families than between them
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more similar
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what kind of life history traits does natural selection favor
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those that result in the organism having a better chance of surviving and reproducing
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phenotypic plasticity
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one genotype may produce different phenotypes under different environmental conditions
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what does phenotypic plasticity produce
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morphs
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allometry
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different body parts grow at different rates, resulting in differences in shape or proportion
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asexual reproduction
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simple cell division'
all prokaryotes and many protist |
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sexual reproduction benefits
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recombination promotes genetic variation
may provide protection against disease |
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sexual reproduction disadvantages
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an individual transmits only half of its genome to the next generation
growth rate of populations is slower |
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isogamy
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when gametes are of equal size
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anisogamy
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gametes of different sizes
usually the egg is much larger and contains more nutritional material |
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complex life cycles
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involves at least two distinct stages that may have different body forms and live in different habitats
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metamorphosis
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abrupt transition in form from the larval to the juvenile stage
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why complex life cycles
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small offspring may experience the environment very differently than larger parents
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direct development
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go from fertilized egg to juvenile without passing through a larval stage
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alternation of generations
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a multicellular diploid sporophyte alternates with a multicellular haploid gametophyte
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semelparous
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species that reproduce only once
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iteroparous
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species can reproduce multiple times
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r-selection
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selected for high population growth rates; in uncrowded environment; newly disturbed habitats etc.
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K-selection
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selection for slower growth rates; populations that are at/near carrying capacity; efficient reproduction is favored
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trade-offs
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organisms allocate limited energy or resources to one structure or function at the expense of another
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senescence
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decline in fitness of an organism with age and physiological deteriortation
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endosperm
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nutrient-rich material that sustains the embryo during germination
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diapause
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state of suspended animation
organisms can survive unfavorable conditons |
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paedomorphic
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becoming sexually mature while retaining larval morphologies and habitat
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sequential hemaphroditism
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change in sex during the course of the life cycle
timed to take advantage of the high reproductive potential of different sexes at different sizes |
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distribution
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geographic area over which individuals of a species
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abundance
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number of individuals in a specific area
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population
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group of individuals of the same species that live within a particular area and interact with one another
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how do populations exists in patches
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linked by dispersal
*often fragmented by human activity |
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genet
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one individual
the product of a single fertilization |
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ramets
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members of a genet
may be independent physiologically |
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abiotic features of the environment
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moisture, temperature, pH, sunlight, nutrients, etc.
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disturbance
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events that kill or damage some individuals, creating opportunities for other individuals to grow and reproduce
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dispersal limitation
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things that prevent species from reaching areas of suitable habitat
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geographic ranges
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the entire geographic region over which a species is found
includes areas a species occupies during all life stages |
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patchy distribution
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results because not all habitat within a the range is suitable
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dispersion
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spatial arrangement of individuals within a populations
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types of dispersion
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regular - individuals are evenly spaced
random - individuals scattered randomly clumped - the most common pattern |
