# Ecology Chapter 9 ECU

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1. Life tables describe how
survival and reproductive rates vary with age, body size, or life cycle stage
2. Nx =
Number of individuals alive at age x.
3. Sx =
Survival rate; (Nx+1/Nx); proportion of individuals of age x that survive to age x + 1
4. lx =
Survivorship; Nx/N0; proportion of individuals that survive from birth (age 0) to age x
5. Fx =
Fecundity; average number of offspring born to a female while she is of age x
6. Static Life Table
• Provides a snapshot of all cohorts at one time
• Provides data on: Survivorship (lx) Fecundity (Fx)
• No Survival Rate (Sx)
7. Survivorship curves
A plot of the number of individuals from a cohort (actual or estimated) that will survive to reach different ages.
8. Three types of survivorship curves
• Type I: Most individuals survive until old age
• Type II: Constant chance of dying
• Type III: Most individuals die young
9. Age structure:
The proportions of the population in each age class (e.g., 20/100, 30/100, 50/100)
10. Age class:
All individuals within a population that fall in a range of ages (e.g., 0-1, 1-2, 2-3).
11. Age structure can influence
how rapidly populations grow
12. ------ and ------ do not change in life tables
fixed age-specific survivorship and fecundity
13. When lambda is below one, population is
decreasing. When above one, increasing
14. Understanding population growth requires knowing when -------- and ----- occur
births and deaths occur.
15. Life tables describe how survival and reproductive rates vary with (3)
age, body size, or life cycle stage
16. Fixed age-specific survival and fecundity produce (2)
unchanging population growth or decline (λ) and a stable age distribution
17. Changing age-specific survival and fecundity alters ---------------and ----------------
population growth and stable age distributions
18. λ can stand for
• 1)the proportional change in population size between generations
• 2)the geometric population growth rate (finite rate of increase)
19. Geometric population growth:
• Reproduction occurs at discrete intervals.
• Example: Organisms that breed once a year.
20. λ formula
(Nt +1)/Nt
21. dN/dt =
rate of change in the population at each instant of time
22. (dN/dt)=rN what does each part stand for?
• dN/dt = rate of change in the population at each instant of time
• r = The intrinsic rate of natural increase; indicates how rapidly the population is growing
• N = the current population size
23. Populations growing exponentially are represented with a ------------
continuous line
24. t
doubling time, of a population is the number of years it will take the population to double in size
25. doubling time formula
 Author: zzto ID: 173241 Card Set: Ecology Chapter 9 ECU Updated: 2012-09-27 13:19:41 Tags: Ecology Chapter ECU Folders: Description: Ecology Chapter 9 ECU Show Answers: