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Reproductive Strategies

Reproductive Strategies. Objective: I will evaluate the effects of reproductive strategies and compare them to carrying capacity. Factors that Influence Population Size. Density-dependent factors- the size of the population will influence an individual ’ s probability of survival.

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Reproductive Strategies

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  1. Reproductive Strategies Objective: I will evaluate the effects of reproductive strategies and compare them to carrying capacity.

  2. Factors that Influence Population Size • Density-dependent factors- the size of the population will influence an individual’s probability of survival. • Density-independent factors- the size of the population has no effect on the individual’s probability of survival.

  3. Exponential Growth Model • Growth rate- the number of offspring an individual can produce in a given time period, minus the deaths of the individual or offspring during the same period. • Intrinsic growth rate- under ideal conditions, with unlimited resources, the maximum potential for growth.

  4. Exponential Growth Model • J-shaped curve- when graphed the exponential growth model looks like this.

  5. Logistic Growth Model • Logistic growth- when a population whose growth is initially exponential, but slows as the population approaches the carrying capacity. • S-shaped curve- when graphed the logistic growth model produces an “S”.

  6. Variations of the Logistic Model • If food becomes scarce, the population will experience an overshoot by becoming larger than the spring carrying capacity and will result in a die-off, or population crash.

  7. Sexual Reproduction: Courtship • Courtship rituals consume time and energy, can transmit disease, and can inflict injury on males of some species as they compete for sexual partners. Figure 8-8

  8. Reproductive Strategies • K-selected species- the population of a species that grows slowly until it reaches the carrying capacity. Ex. elephants, whales, and humans. • R-selected species- the population of a species that grows quickly and is often followed by overshoots and die-offs. Ex. mosquitoes and dandelions

  9. Reproductive Patterns:Opportunists and Competitors • Large number of smaller offspring with little parental care (r-selected species). • Fewer, larger offspring with higher invested parental care (K-selected species). Figure 8-9

  10. Types of Population Change Curves in Nature • Population sizes may stay the same, increase, decrease, vary in regular cycles, or change erratically. • Stable: fluctuates slightly above and below carrying capacity. • Irruptive: populations explode and then crash to a more stable level. • Cyclic: populations fluctuate and regular cyclic or boom-and-bust cycles. • Irregular: erratic changes possibly due to chaos or drastic change.

  11. PREDATION • Some prey escape their predators or have outer protection, some are camouflaged, and some use chemicals to repel predators. Figure 7-8

  12. Camouflage (a) Span worm Fig. 7-8a, p. 153

  13. Camouflage (b) Wandering leaf insect Fig. 7-8b, p. 153

  14. Chemical Warfare (c) Bombardier beetle Fig. 7-8c, p. 153

  15. Chemical Warfare (d) Foul-tasting monarch butterfly Fig. 7-8d, p. 153

  16. Warning Coloration (e) Poison dart frog Fig. 7-8e, p. 153

  17. Mimicry (f) Viceroy butterfly mimics monarch butterfly Fig. 7-8f, p. 153

  18. (g) Hind wings of Io moth resemble eyes of a much larger animal. Deceptive Looks Fig. 7-8g, p. 153

  19. Deceptive Behavior (h) When touched, snake caterpillar changes shape to look like head of snake. Fig. 7-8h, p. 153

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