Population: Population Biology Concepts
Population - A group of individuals of the same species that live in the same geographic area at the same time.
Population ecology - The branch of biology that deals with the numbers of a particular species found in an area and how and why those numbers change over time.
Population density - The numbers of individuals of a species per unit of area or volume at a given time.
Birth rate - The number of births per 1000 people per year.
Death rate - The number of deaths per 1000 people per year.
Growth rate - The rate of change of a population's size, expressed in persent per year.
Population ecology - The branch of biology that deals with the numbers of a particular species found in an area and how and why those numbers change over time.
Population density - The numbers of individuals of a species per unit of area or volume at a given time.
Birth rate - The number of births per 1000 people per year.
Death rate - The number of deaths per 1000 people per year.
Growth rate - The rate of change of a population's size, expressed in persent per year.
Characteristics of populations:
- Population density
- Birth and death rates
- Growth rates
- Age structure
*Ecologists study how a population responds to its environment and how predation, disease, and other evironmental pressures affect the population. A population won't increase indefinitely because of environmental pressures.*
Important aspects
- Their reproductive success or failure.
- How populations affect the normal functioning of communities and ecosystems
Four types of population cycles:
1. Stable (slight up and down)
2. Irregular (up and down and all over)
3. Cyclic (wide up and downs)
4. Irruptive (slight up and down and then big change, then goes back to slight up and down)
1. Stable (slight up and down)
2. Irregular (up and down and all over)
3. Cyclic (wide up and downs)
4. Irruptive (slight up and down and then big change, then goes back to slight up and down)
Intrinsic rate of increase - The exponential growth of a population that occurs under ideal conditions.
Exponential population growth - The accelearating population growth that occurs when optimal conditions allow a constant reproductive rate over a period of time.
Carrying capacity - The maximum number of individuals of a given species that a particular environment can support for an indefinite period, assuming no changes in the environment.
Environmental resistance - How the environment sets limits that ultimately inables organisms to reproduced indefinitely at their intrinsic rates of increase.
Exponential population growth - The accelearating population growth that occurs when optimal conditions allow a constant reproductive rate over a period of time.
Carrying capacity - The maximum number of individuals of a given species that a particular environment can support for an indefinite period, assuming no changes in the environment.
Environmental resistance - How the environment sets limits that ultimately inables organisms to reproduced indefinitely at their intrinsic rates of increase.
Carrying capacity changes in response to environmental changes.
A J curve population growth is when a population grows exponentially.
An s curve (logistical growth) population growth is when a population increases and levels off.
A J curve population growth is when a population grows exponentially.
An s curve (logistical growth) population growth is when a population increases and levels off.
R selection - Populations that have traits that contribute to a high population growth rate.
K selection - Populations that have traits that maximize the chance of surviving in an environment where the number of individuals is near the carrying capacity of the environment.
K selection - Populations that have traits that maximize the chance of surviving in an environment where the number of individuals is near the carrying capacity of the environment.