Bio 1215- Chapter 16
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Bio 1215- Chapter 16
what does population ecology describe?
describes population density, dispersion, and demography
define density. what does it usually require?
number/ unit area
usually requires sampling
what are some example of sampling? (3)
(counting nests, droppings)
for animals mark and recapture
what is the equation for the mark and recapture method?
N= (# marked)(total # caught second time)/ (# of marked 2nd time)
what are some problems with the mark and recapture method? (3)
migration of animals
animals being preyed because of tag or labelling
animals avoid traps more/ go into traps more for free food
pattern of spacing
list the 3 types of dispersion.
what is an example of
and what does it facilitate?
food, nesting sites maybe clumped
mating, social behaviour
what does uniform dispersion indicate? what is an example?
ex. territoriality; plant allelochemicals
(inhibit growth of other plants)
what does random dispersions indicate?
indicates no interactions
ex. some trees and ferns
study of vital statistics that affect population size
what are some vital statistics? (2)
birth and immigration rates=increase population
death and emigration= decrease population
(can vary for gender and diff age classes)
what is a life table? what does is measure?
summarizes vital statistics of a population by following a cohort from birth to death
mortality, survivorship, births
what are survivorship curves?
plot proportion of cohort still alive vs. age
what is type 1 species? (3)
have small # of well-cared offspring
many survive to old age
greatest mortality later in life
what is type 3 species? (3)
have many offspring with no parental care
few survive for long until old age
greatest mortality early in life
what is type 2 species? (2)
intermediate between type 1 and type 3
roughly constant mortality rate experienced regardless of age
Natural selection should favour strategies that maximize ______________________________.
lifetime reproductive success (fitness)
lifetime reproductive success is affect by what 3 things? what does all of these features involve?
# of reproductions/ lifetime
age at first reproduction
all involves trade-offs (limited energy budget)
what is clutch size? what is the correlation between clutch size and offspring?
# of offspring/ event
smaller clutch <----> bigger offspring
bigger clutch <----> smaller offspring
how does age at first reproduction relate to lifetime reproductive success?
early breeding females may be smaller which lead to:
produce smaller clutches
less energy for later clutches
leads to lower lifetime reproductive success
Population growth can be modelled __________________.
what is the exponential growth model?
maximum rate of growth
(maximum birth rate; minimum deaths)
what is r
maximum rate of growth
what is the downside of exponential growth model?
such growth (r
) cant be maintained forever
what is the logistic population growth model?
population limited by carrying capacity (K) of the environment
Life histories can be related to the _____________.
define "r-selected" species?
evolved to maximize r
what are some characteristics of "r-selected" species? (6)
population size can increase quickly
many small offspring
no parental care
type 3 survivorship curves
(most die young)
define "k-selected" species.
evolved in populations that were near carrying capacity
what are some characteristics of "k-selected" species? (4) what is an example?
few big offspring
many have long life
type 1 survivorship curves
ex. elephants and humans
what 2 things regulate population size?
combination of density dependent and independent factors
In density dependent population regulation,
effects increase as population size __________.
how would less resources/individuals affect population?
less resources--> less food, territories, nest sites--> lower survival, less offspring
what density dependent factors will tend to keep populations near K? (3)
As a density dependent factor, how does crowding change behaviour or physiology?
delayed maturity, lower offspring
what are the 2 density independent factors?
know back population size , no matter how big population
Some species show regular population cycles. "regular" cycles maybe due to?
time lags of density-dependent factors (ex. predation, epidemics and intrinsic changes)
why has the human population increased so? (5)
antibiotics and vaccines
growth rate not the same in all countries. what is it influenced by?
growth rates influenced by age structure
lots of kids now= increasing population later
what is the fertility rate in Canada?
so what is the carrying capacity for us? what is he good news in this?
estimates average 10-15 billion
good news= growth is slowing
what is an ecological footprint?
land and water area needed by a nation or person to get all of its resources and dispose of its wastes.
are resources evenly distributed in the world?
resources are limited and not evenly distributed
human population increase is decreasing ___________________.
carrying capacity for other species