Flashcards in Lecture 17 and 18- population ecology Deck (120)
All the individuals of a species in a given area.
What does population structure describe?
The age distribution of individuals in a population and how they are spread over the environment
Why is population structure studied?
Spatial distribution influences population stability
What is the number of individuals of a population per unit area called?
What changes the structure of a population?
What are some demographic events?
Birth, death, immigration, emigration
What is the study of population dynamics called?
What do most field studies of animals require?
Tagging or marking the animal
How are birds typically tagged?
Colored bands on the leg
How are butterflies typically tagged?
Placing colored spots on their wing
How are bees marked?
By placing numbered tags on their bodies
How are mammals marked?
Tags or dyeing their fur
How is information about an animals physiology, feeding behavior and socialization recorded?
Microchips and other types of electronic tagging
How else can the movement of individuals across long distances be tracked?
The chemical composition of feathers of what bird can be tracked as they migrate south?
What does the chemical composition of american redstart feathers tell scientists?
Where they molted
Strong latitudinal gradient of hydrogen isotopes in precipitation
How are population densities estimated?
Counting the number of individuals in a representative habitat and extrapolating the counts to the entire ecosystem
Why is it harder to count mobile organisms?
They move into and out of the census area- instead they are captured, marked and then released
What equation is used to calculate the number of organisms after capture, mark, release?
m2= no.marked in 2nd sample
n2=total number of individuals in 2nd sample
n1= no.marked in 1st sample
N= estimated population size
What do ecologists use estimates of population densities to estimtate?
The rate at which births, deaths and movements take place, how these rates are influenced by the environment, life histories and pop.densities.
How can information about birth and death rates in a population be displayed?
In a life table
What is the group of individuals born at the same time called?
What is a life table constructed with?
Cohort, survivorship (the numbers still alive)
What else do life tables sometimes contain?
offspring produced by cohort- fecundity
What can life tables be used for?
To predict future trends in populations
What life table is used in the book?
1978 cohort of the Cactus Finch on isla daphne (galapagos archipelago)
How many cactus finch were in the cohort?
How many of the cohort were alive in 1991 when the cohort stopped being followed?
What were the general patterns in the cactus finch cohort?
High mortality in 1st year
Dropped dramatically for several years
General increase in later years