1. Rate of increase reveals much more about a population than the speed with which it grows. It measures a population’s general well-being, describing the average reaction of all members of the population to the collective action of all environmental influences. No other statistic summarizes so concisely the demographic vigour of a population.
G. Caughley

2. Population Ecology: The Basics
How do births, deaths, immigration, & emigration affect wildlife populations?
What affects births, deaths, immigration, & emigration?
What are demographic characteristics?
What is the difference between exponential & logistic population growth?

3. Population Ecology: The Basics
What is Aldo’s model?
What is carrying capacity?
What are patterns of abundance and what controls them?
What is metapopulation and how does it relate to wildlife population dynamics?
Who cares?

4. Population Ecology: The Basics
What is a population?
Why not deal with individuals?
(U.S Fish & Wildlife Service)
(U.S Fish & Wildlife Service)

5. Population Ecology: The Basics
N = B + I – D – E (demographic characteristics)
Nt+1 = Nt + Bt + It – Dt – Et N
Population Size
Births
Deaths
Immigration
Emigration
♂:♀
Juvenile:Adult
Effects of:
Harvest
Restocking
Habitat
Weather
Other organisms

6. Population Ecology: The Basics
Population growth without resource limitation
Exponential
Nt = N0ert
dN/dt = N/t = rN
Assumes no I & E or I = E
Assumes no structure r
Instantaneous rate of increase, intrinsic rate of increase, Malthusian parameter, or per capita rate of increase
b - d
Units: ind/(ind*time)
Based on 0 N
Time A B C
Biotic Potential N
dN/dt A B

7. Population Ecology: The Basics
Population growth with resource limitation (in relation to conditions)
Logistic growth
Nt = K/(1 + [{K - N0}/N0]e-rt)
dN/dt = rN(1 - [N/K])
Assumes no I & E or I = E
Assumes no structure
K = carrying capacity
Max. # the environment can support
Assumes constant K
Can change with time & space
K = N?
K > N?
K < N?
K = ∞?
Density-dependence N
dN/dt
Time
Accelerating Phase K
Inflection Point (½ K)
Decelerating
Phase

8. Population Ecology: The Basics
Population growth with resource limitation (in relation to conditions)
Logistic growth
Nt = K/(1 + [{K - N0}/N0]e-rt)
dN/dt = rN(1 - [N/K])
r v. dN/dt
Unused portion of carrying capacity
(1 - [N/K])
N = 2, K = 100 → 0.98
N = 98, K = 100 → 0.02 N
dN/dt
Time
Accelerating Phase K
Inflection Point (½ K)
Decelerating
Phase

9. Population Ecology: The Basics
What is this thing called Carrying Capacity?
Ecologically-based
K-carrying capacity (KCC)
Socio-economically-based
I-carrying capacity (ICC)
Optimum carrying capacity (OCC)
Minimum-impact carrying capacity (MCC)
Animals must be removed N
Time
MCC
KCC
ICC (½ K)
OCC

10. Population Ecology: The Basics
Aldo Leopold’s Population Model
Decimating factors
Welfare factors
Other possibilities?
Exposure
Space
Harvest = removal
The limiting factor (link)?
Influences
Land-uses
Weather
Fire N
Time K
Inflection Point (½ K)
Hunting (Harvest)
Diseases & Parasites
Accidents
Starvation
Food
Cover
Water
Special Factors
Welfare
Factors
Predation
Environmental Resistance
Decimating
Biotic Potential

11. Population Ecology: The Basics
Other patterns of abundance
Density-dependent v. density-independent factors
Causes? N
Time A N
Time B K N
Time C N
Time D K K

12. Population Ecology: The Basics
Metapopulations
Groups of local populations
Subpopulations or demes
Size, quality, connectivity, & distance (I & E are important)
Island Biogeography & Conservation Biology
Matrix

13. Population Ecology: The Basics
Minimum viable populations (MVP)
National Forest Management Act of 1976
Species- & site-specific
50/500 rule
USDA photo by: Bob Nichols

14. Population Ecology: The Basics
Minimum viable populations (MVP)
Shaffer (1981)
Need for performance criteria
99% chance of surviving for 1000 years despite stochastic events
Genetic stochasticity
Environmental stochasticity
Natural catastrophes
Demographic stochasticity
BBDBBD v. DDBBBB
Importance of individuals
Florida panther
(U.S Fish & Wildlife Service)

15. Population Ecology: The Basics
Effects of sex & age structure on population growth?
Population Size
Births
Deaths
Immigration
Emigration
♂:♀
Juvenile:Adult

16. Population Ecology: The Basics
So what!