15-19 study - Chapter 15: Strategies -Strategy -Long-term...

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Chapter 15: Strategies - Strategy -Long-term plan of action for achieving certain goal -molded by natural selection -Winning judged by fitness (measure of contribution of given genotype to subsequent generation, relative to that of other genotype) -Can be spotted bc response to “why” questions -Why is species rare or common, specialized/generalized, fecund/not, etc Ex: Plant defense -Terrestrial plants 2 basic goups based on appearance to herbivore - Apparent : Long lifespan, likely to be found by herbivores -Ex: woody perennial - Unapparent : Short lifespan, can escape from most herbivores in time and Space -Ex: Herbaceous annual -Strategies - Apparent : must defend against wide variety of possible parasites, need defense that’s uneasy to overcome -Quantitative defenses (ie, terpenes, tannins, thick leaves) -Expensive -Over time, effective but may need supplement of qualitative against the few herbivores that overcome them - Unapparent : must defend mainly against formerly wide-ranging generalist herbivores that have keyed in on them -Qualitative defenses (toxins) -Inexpensive -Effective but over time break down by coevolution of detoxification mechanisms by some herbivores -Result: host-specific herbivores -Plant response: stronger toxins -Five Principles -balance, context, constraints, imprudence, selfishness 1) Balance -Multiple simultaneous limitations -organism faces variety of potential limitations -ecologists track by using niche concept - niche : place where organism lives and what it does there -Ex: Oaks -Live in oak woodlands w/ specific soil conditions, rainfall, temperature, elevation -Absorb sunlight by photosynthesis -Absorb water & mineral salts from soil -Provide shelter
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-Act as support for creeping plants -Source of food -Cover ground w/ dead leaves 2) Context -Games organisms play -Two strategies: Hawk & Dove -Hawk: Always fight for resource, hawk-hawk symmetrical, conflicts brutal and end in injury to one hawk -Dove: Never fight for resource, dove-dove asymmetrical, conflicts just displays, never injured -Fitness reduced by increasing frequency of either strategy relative to other strategy -A strategy that is best possible in relation to given set limitations won’t surely “win” 3) Constraints (Ex: Over time, humans have increased survival rates, decreased longevity) -Increase in longevity -only worth it (by fitness) if leads to greater lifetime production of offspring -human eggs limited, with females undergoing reproductive senescence (aging) -lifespan correlated w/ delayed reproduction in human females -trade-off? -Body size
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This test prep was uploaded on 04/19/2008 for the course PCB 3043 taught by Professor Mccoy during the Fall '07 term at University of South Florida.

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15-19 study - Chapter 15: Strategies -Strategy -Long-term...

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