Lecture 19

Question 1

Define population

Answer 1

a group of individuals of the same species living in the same locations

• rely on the same resources
• influenced by same environmental conditions
• interact w each other

Question 2

Boundary e.g. for a population

Answer 2

• might be natural (lake, island, gut)
• arbitrary - natural park
• match to the PURPOSE of the study + BIOLOGY of the organism

Question 3

Properties of a population

Answer 3

• size
• boundary
• distribution (clumped, uniform, random)
• structure (sex ratio, age structure)

Question 4

How is size of a population dynamic?

Answer 4

birth, death, immigration, emigration

Question 5

Population ecology

Answer 5

the scientific study of populations in relation to environment + resources

• how biotic & abiotic factors influence abundance, distribution, and composition of populations

applications:
- threatened species management
- pest control
- harvested populations

Question 6

Estimating population size

Answer 6

• COUNTING; in some cases it works
• SAMPLING; locate plots across a portion of the population’s range (prevision depends on # plots + variation in counts b/w plots)

IMPERFECT DETECTION IS A PROBLEM (e.g. esp when animals can camouflage - leads us to underestimate the size)

Question 7

Mark-recapture

Answer 7

1. catch individuals in a population & mark them
2. return them to the population, let them re-mix, then catch again

can use artificial or natural marks

also genetic methods (feces or hair)

signs as indices

Question 8

Some key assumptions of mark-recapture

Answer 8

• marks remain for the length of the study
• marking is benign
  (marks don’t harm individuals)
  (probability of recapture is not affected, trap happy, trap shy)
• closed population (no births, death, immigration, or emigration)
• violation of assumptions will lead to bias (systematic over-estimation or underestimation may be necessary) – (or modify analysis to account for violations)

Question 9

What describes lifecycle?

Answer 9

• length of generations (several per year, one per year - annuals, one generation over several years - perennials )
• reproductive events per generation (iteroparous vs semelparous)

Question 10

Define demography

Answer 10

the study of the birth and death rates of populations and how they change over time

life-tables: useful summary of demographic info for a population