Chapter 53 Flashcards
Population
Group of con-specific individuals, living in the same area, relying on the same resources, influenced by the same environment, and interacting/breeding with one another
Community
Group of interacting populations of different species
Population Dynamics
- all populations experience birth and death
- immigration and emigration are not universal
Growth
If organisms can freely acquire energy/resources, grow and reproduce
Change in population (N)
- ^N/^t = B-D
- If B>D the population is growing
- If B
Exponential Growth
Reproduce at physiological limit (r Max)
Carrying capacity
Maximum population that can be supported by available resources
Allee Effect
If population size is too small reproduction is reduced
Infant Mortality and Life Expectancy
- parental reproductive choices change -> high IM = parent more likely to have more children
- carrying capacity of Earth is dependent on energy use and ecological footprint
Communities - Interactions
- Predation (+/-)
- Herbivory (+/-)
- Competition (+/-)
- Symbiosis (direct contact): parasitism, mutualism, commensalism
- Facilitation (not in direct contact): interactions influence structure of communities
Primary characteristics of community
diversity and trophic structure
Diversity
- Species composition: number and variety of organisms
- Richness: absolute number of species
- Relative abundance: proportional representation of each species
Disturbance
- Event that removes organisms or alters resource availability
- frequency and intensity influence species diversity and composition
What is a good predictor of diversity?
Water
- Evapotranspiration: evaporation of water from soil plus transpiration from plants
- Function of solar radiation, temperature (and water availability)
Trophic Structure
Feeding Relationships - Food Chain
- Food Web:
- more realistically represents relationships
- chains embedded in web
- Energy restrictions and stability requirements
