population ecology. dynamics of species’ populations interaction of populations with environment...
TRANSCRIPT
Population Ecology
• Dynamics of species’ populations• Interaction of populations with
environment
Population Ecology
• Most species live in groups
Groups
• Probability that a species will persist
Population Viability
Population Viability
Increased (+)• Favorable environment
(light, temp, nutrients)• Few competitors• Suitable defense
mechanisms• Able to migrate• Resistance to disease• Sufficient food• Generalized niche• Satisfactory habitat
Decreased (-)• Unfavorable
environment• Many competitors• Unsuitable defenses• Cannot migrate• Not resistant• Insufficient• Specialized niche• Unsatisfactory
habitat
• Number of organisms that an environment can support
Carrying Capacity (K)
• Below K, population increases• Above K, population decreases
Carrying Capacity (K)
• Keep populations in balance with environment
• Density dependent
• Density independent
Limiting Factors
• Max rate at which a population can grow
– When?
• Influences:
Biotic Potential
• Exponential Growth
• Logistic Growth
Growth Patterns
http://www.allamericanpatriots.com/photos/salmonella-bacteria
Growth Patterns
• Adaptations– Maximize growth rate when lacking limiting
factors• r-strategists • r = growth rate (births-deaths)
– Maintain population size near K• K-strategists• K = carrying capacity
Reproductive Strategies
Reproductive Strategies
r-strategists • Mature rapidly• Short lived• Tend to be prey• Many offspring
(overproduction)• Low parental care• most pest species are
r-selected
K-strategies• Mature slowly• Long lived• Tend to be predators• Few offspring
• High parental care• Most endangered
species are K-species
Reproductive Strategies
r-strategists • Wide fluctuations in
population• Usually small• Limited by
independent factors
K-strategies• Stabilized population
• Larger• Limited by dependent
factors
• K or r?
Reproductive Strategies
• At what point during an organism’s life does it die?
• Curves show age distribution characteristics, reproductive strategies, and life history
• Curves represent balance between resource limitations and competition
Survivorship Curves
Survivorship Curves
Type Description
I. Late Loss Reproduction occurs fairly early in life. Low mortality at birth. High probability of surviving until old age
II. Constant Loss All ages have fairly uniform death rate. Death usually due to predation
III. Early Loss Large numbers of offspring. High death rate for young, declines with age.
Survivorship Curves