Glossary
Abiotic Factors
Non-living physical and chemical components of an ecosystem that influence living organisms.
Example:
The amount of sunlight a plant receives or the temperature of a pond are abiotic factors affecting organisms.
Biotic Factors
Living components of an ecosystem that affect other organisms or the environment.
Example:
The presence of predators like wolves or the availability of prey like elk are biotic factors influencing a population.
Birth Rate (B)
The number of births per unit of time within a population, contributing to its growth.
Example:
If 100 new chicks hatch in a bird colony over a year, that contributes to the population's birth rate.
Carrying Capacity (K)
The maximum population size that a particular environment can sustain indefinitely, given the available resources.
Example:
A small pond might only have enough oxygen and food to support a carrying capacity of 100 fish.
Climate
The long-term prevailing weather conditions in a particular area, including temperature, precipitation, and humidity, which significantly influence ecosystems.
Example:
The desert climate with its high temperatures and low rainfall dictates the types of plants and animals that can survive there.
Competition
An interaction between organisms or species in which the fitness of one is lowered by the presence of another, often due to limited resources.
Example:
Two different species of birds vying for the same limited nesting sites in a tree is an example of competition.
Death Rate (D)
The number of deaths per unit of time within a population, contributing to its decline.
Example:
If 50 fish in a pond die due to a sudden cold snap, this contributes to the population's death rate.
Density-Dependent Factors
Limiting factors whose impact on a population intensifies as the population density increases, such as competition, predation, and disease.
Example:
As a deer population grows, the spread of a disease among them becomes more rapid, making it a density-dependent factor.
Density-Independent Factors
Limiting factors whose impact on a population is not related to the population's density, such as natural disasters or extreme weather events.
Example:
A sudden wildfire destroying a forest affects all populations within it, regardless of their size, making it a density-independent factor.
Disease
A condition that impairs the normal functioning of an organism, often caused by pathogens, and can significantly impact population size.
Example:
A widespread viral infection among a population of bats can lead to a drastic reduction in their numbers.
Exponential Growth
Population growth that occurs under ideal conditions with unlimited resources, resulting in a J-shaped curve where the population increases at a constant per capita rate.
Example:
A bacterial colony in a petri dish with abundant nutrients will initially exhibit exponential growth, doubling rapidly.
Habitat
The natural environment in which an organism lives, providing all the necessary resources for its survival and reproduction.
Example:
A coral reef serves as the habitat for numerous marine species, offering food and shelter.
Limiting Factors
Environmental conditions that restrict the growth, abundance, or distribution of a population.
Example:
For a plant, insufficient sunlight or lack of nutrients in the soil can act as limiting factors.
Logistic Growth
Population growth that slows down as it approaches the carrying capacity of the environment, resulting in an S-shaped curve.
Example:
A population of rabbits introduced to an island will initially grow exponentially but then slow down as food becomes scarce, showing logistic growth.
Population
A group of individuals of the same species living in the same geographical area at the same time.
Example:
A herd of white-tailed deer living in a specific forest constitutes a population.
Population Ecology
The study of how populations interact with their environment, focusing on factors that affect population size, density, distribution, and age structure.
Example:
Studying the decline of a specific fish species in a lake due to pollution is an application of population ecology.
Predation
An interaction where one organism, the predator, kills and consumes another organism, its prey.
Example:
A lion hunting and eating a zebra demonstrates a classic predator-prey relationship.
Resources
Anything an organism needs to survive and reproduce, such as food, water, shelter, and mates.
Example:
For a plant, access to sufficient water and sunlight are crucial resources for its growth.
dN/dt (Population Change)
Represents the change in population size over a specific period of time, calculated as the difference between birth rate and death rate.
Example:
If a population of squirrels has 50 births and 30 deaths in a month, the dN/dt would be +20, indicating population growth.
r max (Maximum Per Capita Growth Rate)
The intrinsic rate of natural increase, representing the maximum potential growth rate of a population under ideal conditions with no limiting factors.
Example:
A species with a high r max, like insects, can reproduce very quickly when conditions are favorable.