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Population Ecology. Population Ecology. Dynamics of species’ populations Interaction of populations with environment. Groups. Most species live in groups. Population Viability. Probability that a species will persist. Population Viability. Increased (+). Decreased (-).
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Population Ecology • Dynamics of species’ populations • Interaction of populations with environment
Groups • Most species live in groups
Population Viability • Probability that a species will persist
Population Viability Increased (+) Decreased (-) Unfavorable environment Many competitors Unsuitable defenses Cannot migrate Not resistant Insufficient Specialized niche Unsatisfactory habitat • Favorable environment(light, temp, nutrients) • Few competitors • Suitable defense mechanisms • Able to migrate • Resistance to disease • Sufficient food • Generalized niche • Satisfactory habitat
Carrying Capacity (K) • Number of organisms that an environment can support
Carrying Capacity (K) • Below K, population increases • Above K, population decreases
Limiting Factors • Keep populations in balance with environment • Density dependent • Density independent
Biotic Potential • Max rate at which a population can grow • When? • Influences:
Growth Patterns • Exponential Growth • Logistic Growth http://www.allamericanpatriots.com/photos/salmonella-bacteria
Reproductive Strategies • 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 r-strategists K-strategies Mature slowly Long lived Tend to be predators Few offspring High parental care Most endangered species are K-species • Mature rapidly • Short lived • Tend to be prey • Many offspring (overproduction) • Low parental care • most pest species are r-selected
Reproductive Strategies r-strategists K-strategies Stabilized population Larger Limited by dependent factors • Wide fluctuations in population • Usually small • Limited by independent factors
Reproductive Strategies • K or r?
Survivorship Curves • 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