properties of populations pt 3 (age structure->active dispersal)

age structure 

proportion of individuals in different age classes

what is age structure influenced by?

reproduction + mortality

→ these influence the rate of population growth

what are the 3 categories of reproductive growth in a population?

1) pre-reproductive

2) reproductive

3) post-reproductive

what are the ways that we age animals to figure out what stage of reproductive growth they are in?

• marking young organisms + following their survival

• study a representative sample

• tooth wear

• plumage changes/patterns

• growth rings in teeth, horns, ear bones, etc.

what are the ways we age plants to figure out what stage of reproductive growth they are in?

• mark individual seedlings + follow them through their lifetimes

• diameter at breast height (dbh)—trees and shrubs

• counting annual rings—trees and shrubs

age pyramid

represents the age structure of a population at some period in time

why is the distribution of age classes in plants skewed?

mature forests block light from reaching the floor, inhibiting seedling growth

sex ratio

ratio of male to female

what is the primary sex ratio at conception?

1:1

what can alter the sex ratio in a population?

differences in life expectancy caused by male rivalry + predation

would random deaths of organisms in a population cause a deviation from a 1:1 sex ratio?

no

→ if the deaths are random, they would be distributed equally on average which would not change the sex ratio

dispersal

movement of individuals in a space

what directly influences local density of a population?

dispersal

what maintains gene flow between subpopulations?

dispersal

what are the one-way movements of individuals?

emigation + immigration

emigration

when an individuals moves out of a subpopulation

immigration

when an individual moves into a subpopulation

dispersal is a key process in _________ dynamics

metapopulation

passive dispersal

relying on another event to disperse an organism

(gravity, wind, water, animals)

→ the dispersal distance depends on the agents of dispersal

active dispersal

movement of an organism using its own energy to travel from one location to another