Ecology&Evolution - Ecology 1. A population is a group of...

Ecology
1. A population is a group of individuals from the same species that live in the same
area at the same time.
2. Population ecology is the study of how and why the number of individuals in a
population changes over time.
3. The mathematical and analytical tools used in population ecology help biologists
predict changes in population size and design management strategies to save
threatened species.
4. Demography- study of factors that determines the size & structure of a population
a. Birth, death, immigration (move in), and emigration(move out) are leading
processes that determine demography
5. Study demography to make predictions about future of population
6. Also need to know generation age- the average time between a mom’s first
offspring and daughters first offspring
7. Population with healthy young individuals, population should increase over time
8. Population that are old and have low survival rate, then decline over time
9. A life table summarizes the probability that an individual will survive and
reproduce in any given time interval over the course of its lifetime.
10. Survivorship- proportion of offspring produced that survive, on average, to a
particular age
11. The survivorship curve is a plot of the logarithm of the number of survivors
versus age.
a. In a type I curve, survivorship throughout life is high, and most
individuals approach the maximum life span of the species; humans show
this type of survivorship curve. (humans)
b. In a type II curve, most individuals experience relatively constant
survivorship over their lifetimes; songbirds have this curve. (song birds)
c. Type III curves result from high death rates early in life, with high
survivorship after maturity; many plants have type III curves. (plants)

12. Fecundity is also a key part of a life table; it is defined as the number of (female)
offspring produced by each female in the population…reproductive success
13. Age-specific fecundity is the average number of female offspring produced by a
female in a given age class—a group of individuals of a specific age.
14. Fitness trade-offs occur because every individual has a restricted amount of time
and energy at its disposal―its resources are limited.
15. Less offspring means you can give more time to individuals so they have better
chance to survive
16. life history describes how an organism allocates its resources to growth,
reproduction, and activities or structures related to survival.
a. Traits such as survivorship, age-specific fecundity, age at first
reproduction, and growth rate are all aspects of an organism’s life history.
17. Understanding variation in life-history is all about understanding
18. In general, organisms with high fecundity tend to grow quickly, reach sexual
maturity at a young age, and produce many small eggs or seeds.