Download - Population ecology ch 53
Population Ecology
Chapter 53 Campbell & Reece
Population group of a single species
in the same area
Density
Dispersion
Video of GYE bears
Density
• Dynamic (immigration, emigration, birth death)
• Mark-recapture method
• Index of population size (scat, burrows,etc “sign surveys”)– Glacier NP DNA study podcast or MSNBC
Patterns of Dispersion
• Clustered– Environmental factors unevenly distributed– Mating– Defense/predation
• Uniform– Territoriality– Absence of strong attraction/repulsion– Key environmental factors evenly distributed
• Random – not that common
• Image from Wikipedia, http://en.wikipedia.org/wiki/File:Population_distribution.svg
Table 53.1 Belding's Ground Squirrel Survivorship
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7 8 9 10
Age (years) at end of year
Pro
po
rtio
n a
live
female proportion alive
male proportion alive
Table 53.1 Belding's Ground Squirrel Survivorship
0.001
0.01
0.1
1
1 2 3 4 5 6 7 8 9 10
Age (years) at end of year
Pro
po
rtio
n a
live
female proportion alive
male proportion alive
Survivorship Curves
http://www.bio.miami.edu/dana/pix/survivorship.gif
Tioga Pass, California (3,031m)home of the Belding’s ground
squirrel• _3,031 m
Reproductive Output
• “Big-bang” reproduction – “semelparity”– Reproduce 1x in life
then die– Favored with poor
survival of either parent or offspring
– Often occur with highly variable, unpredictable environments
Image from scienceblogs.com
Repeat reproduction (iteroparity) –
* common in more dependable, predictable environments
High parental care, low numbers of offspring, high survival
Tasmanian Devil, from http://news.mongabay.com/2008/0714-hance_devils.html
Trade-offs
• Ideal = many offspring, well-cared for, repeatedly over lifespan
• This does not exist
• Reproduction is costly (increased maternal mortality)
Growth Curves
• Exponential growth (geometric)– Ideal, limitless growth– Must be temporary– J-shaped curve– Exponential Growth Simulator
http://nortonbooks.com/college/biology/animations/ch34a01.htm
• Logistic GrowthCarrying capacity – There are limits to
growth!– S-curve (sigmoid)– Logistic Growth Simulator:
http://nortonbooks.com/college/biology/animations/ch34a02.htm
Limiting Factors Carrying Capacity
• FWARPS
• Carrying Capacity (K) = max # of individuals of a species that can occupy a certain habitat
• Lag time, Boom & bust (rough transition)
Kaibab Plateau, Arizona
http://depts.alverno.edu/nsmt/youngcc/research/kaibab/story3.html
Rule of 70
• 70 / growth rate = doubling time!
• Learn this, avoid massive debt
K-selection
• Sensitive to population density
• More successful in crowded environments
• Often iteroparous
http://z.about.com/d/healing/1/0/7/N/gtotem_koala.jpg
R-selection
• Maximize reproductive success in uncrowded environments
• Density-independent
• Often semelparous
• Disturbed habitats
http://www.hot-screensaver.com/wp-myimages/cockroach.jpg
Reproductive Strategies• r- Selected (maximum
growth rate, below carrying capacity)– Early reproduction
– Short life span– High mortality rate– Little or no parental care– Large investment in
producing large numbers of offspring
– Below carrying capacity– Examples:
• Bony fish• Grasshoppers
• K-Selected (maximizes population size near carrying capacity)– Late reproduction– Long life span– Low mortality rate– Extensive parental care– Greater investment in
maintenance and survival of adults
– At or near carrying capacity
– Examples:• Sharks• Elephants
BioEd Online
Slide adapted from BioEd Online
Limits on Population Growth
• Density Dependent Limits– Food– Water– Shelter– Disease
• Density Independent Limits– Weather – Climate
Water and shelter are critical limiting factors in
the desert.
Fire is an example of a
Density independent
Limiting factor.BioEd Online Slide adapted from BioEd Online
Limiting Factors
• Density Independent– Fires, floods, drought, etc– Can be exacerbated by density
Density Dependent
Disease, territoriality, competition, predation, toxic waste, intrinsic factors (physiological)
Population Dynamics
• Isle Royale Moose and Wolves
Human Population• Look at 53.22…seriously look at it
http://economicedge.blogspot.com/2009_05_17_archive.html
Demographic Transition
• HIGH birth rate, HIGH Death Rate
• HIGH Birth Rate, Low Death Rate
• Low Birth Rate, Low Death Rate
Age Structure Pyramids
http://www.census.gov/ipc/www/idb/country.php
Ecological Footprint
• footprint as homework