Lecture 15: Survey Methods and Population Structure

Question 1

How do we estimate population size?

Answer 1

Either by it’s absolute population or size, or to save time there are methods you can use to measure their relative abundance.

Question 2

Explain the four methods you can use to measure the relative size of a species.

Answer 2

Mark-recapture: marking and recapturing mobile species

Quadrat-based: sampling a portion of an area to measure the size of immobile organisms - plants

Line-transect: observing individuals from a transect line - bird surveying

Species distribution: predicts a species’ distribution based on their habitat and niche

Question 3

Patterns of survival: define life table

Answer 3

Tracks birth and death rates in a population

Question 4

Patterns of survival: define survivorship curve

Answer 4

Graphic summary of a life table

Question 5

Patterns of survival: define cohort life table

Answer 5

Identifying and keeping record of individuals born at the same time

Question 6

Patterns of survival: define static life table

Answer 6

Recording age at death of a large number of individuals over a short period of time

Question 7

Patterns of survival: define age distribution

Answer 7

Calculating differences in proportion of individuals in each age class. Simplest method, but there are assumptions of static population size and no dispersal.

Question 8

Explain the arithmetic scale in a survivorship curve

Answer 8

Constant rate of mortality is a concave line - type III

Question 9

Explain the logarithmic scale in a survivorship curve

Answer 9

Constant rate of mortality is a straight line - type II

Question 10

Why are sex ratios usually equal?

Answer 10

Fitness of a genotype depends on its frequency - only one male gets to reproduce with one female, assuming monogamy