56 terms

AP Biology Test Prep Chapter 18: Ecology in Further Detail

Term used to describe all the biotic and abiotic resources used by the organism.
Population Density
The number of individuals per unit area in a given population.
Clumped Dispersion
Dispersion pattern that occurs when the individuals live in packs that are spaced out from each other.
Uniform Dispersion
Dispersion pattern that occurs when the individuals are evenly spaced out across a geographic area.
Random Dispersion
Dispersion pattern that occurs when the species are randomly distributed across a geographic area.
Birth Rate
The number of births in a population in a certain amount of time.
Death Rate
The ratio of deaths in an area to the population over a certain amount of time.
Sex Ratio
The number of males per 100 females in the population.
Generation Time
The period between the birth of one generation and the birth of the next generation.
Age Structure
The distribution of individuals among different ages in a population.
Biotic Potential
The maximum reproductive rate of an organism, given unlimited resources and ideal environmental conditions.
Carrying Capacity
Largest number of individuals of a population that a environment can support.
Limiting Factors
Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms.
Density-Dependent Factors
A limiting factor of a population wherein large, dense populations are more strongly affected than small, less crowded ones.
Density-Independent Factors
Limiting factor that affects all populations in similiar ways, regardless of population size.
Exponential Growth
Population growth that is unhindered because of the abundance of resources for an ever-increasing population.
Logistic Growth
Growth rates regulated by internal and external factors that establish an equilibrium with environmental resources.
Population Cycle
An increase in predators might cause a crash of the prey population, which may result in a decline in the predator population, out of phase.
K-selected Populations
Likely to live at density near limit from resources. long maturation time. long lifespan. low death rate. few offspring per reproductive episode. several reproductions per lifetime. late first reproduction. large offspring or eggs. extensive parental care.
R-selected Populations
Individuals reproduce at an early age, semelparous, have large clutch sizes. selection for life history traits that maximize reproductive success in uncrowded environments.
Opportunistic Populations
R selected organisms that tend to appear when space in the region opens up due to some environmental change, they grow, reproduce, and die quickly.
Survivorship Curves
They show the likelihood of survival at different ages throughout the lifetime of the organism.
Type I
These individuals live a long life until an age reached where the death rate in the population increases rapidly, causing the steep downward end of these curves.
Type II
These individuals have a death rate that is reasonably constant across the age spectrum.
Type III
These individuals have a steep downward curve for those of young age, representing a death rate that flattens out once a certain age is reached.
Intraspecific Competition
Competition among members of the same species.
Interspecific Competition
Competition for resources between members of different species.
Aposematic Coloration
The bright coloration of animals with effective physical or chemical defenses that acts as a warning to predators.
Batesian Mimicry
A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators.
Cryptic Coloration
Coloring that conceals or disguises an animal's shape.
Deceptive Markings
Patterns that cause an animal to appear larger or more dangerous than it really is.
Mullerian Mimicry
The evolution of two species, both of which are unpalatable and, have poisonous stingers or some other defense mechanism, to resemble each other.
The process in which species exert selective pressure on each other and gradually evolve new features or behaviors as a result of those pressures.
Climax Community
A relatively stable long-lasting community reached in a successional series.
Primary Succession
An ecological succession that begins in a an area where no biotic community previously existed.
Bare-rock Succession
Involves the attachment of lichen to rocks, followed by the step-by-step arrival of replacement species up to the climax community.
Pond Succession
The process of succession by which sediment and organic material gradually replace the water volume of a pond ultimately resulting in the area becoming dry land.
Secondary Succession
Succession on a site where an existing community has been disrupted.
Biomass Pyramid
Represents the amount of living organic matter at each trophic level.
Pyramid of Numbers
Representation of the number of individual organisms in each trophic level of an ecosystem.
Food Chains
Energy links between different organisms in an ecosystem based on feeding habits.
Food Webs
A complex diagram representing the many energy pathways in an ecosystem.
A broad, regional type of ecosystem characterized by distinctive climate and soil conditions and a distinctive kind of biological community adapted to those conditions.
A barren region with little or no rainfall, usually sandy and without trees.
Grassland with scattered trees; found in tropical regions of Africa, Australia, and South America.
Biome in which the winters are cold but summers are mild enough to allow the ground to thaw.
Temperate Deciduous Forests
Types of forests that grow in areas with moderate average temperatures that change significantly with the season. These ares have long, warm summers, cold but not too severe winters, and abundant precipitation, often spread fairly evenly throughout the year.
Temperate Grasslands
Dominated by grasses; trees and large shrubs are absent. Temperatures vary more from summer to winter, and the amount of rainfall is less than in savannas. This biome has hot summers and cold winters and occurs in South Africa, Hungary, Argentina, the steppes of the former Soviet Union, and the plains and prairies of central North America.
Tropical Forests
Characterized by the greatest diversity of species, believed to include many undiscovered species. Occur near the equator. Soils tend to be low in nutrients. Distinct seasonality: winter is absent, and only two seasons are present (rainy and dry).
Biome, subject to very cold winters; during summer, the upper soil thaws, but the deeper soil, the permafrost, remains permanently frozen, grasses, and plants tolerant of soggy soils.
Layer of permanently frozen subsoil in the tundra.
Carbon Cycle
Begins when carbon is released into the atmosphere from volcanoes, aerobic respiration and the burning of fossil fuels. Most of the carbon in the atmosphere is present in the form CO2. Plants contribute to this biogeochemical cycle by taking carbon and using it to perform photosynthetic reactions, and then incorporating it into their sugars. The carbon is ingested by animals, who send the carbon back to the atmosphere when they die.
Nitrogen Cycle
In this biogeochemical cycle, plants have nitrogen to consume thanks to the existence of organisms that perform nitrogen fixation, the conversion of N2 into NH3 (Ammonia). The only source of nitrogen for animals is the plants they consume. When these organism die, their remains become a source of nitrogen for the remaining members of the environment. Bacteria and fungi (decomposers) chomp at these organisms and break down any nitrogen remains. The NH3 in the environment is converted by bacteria into NO3 (Nitrate), and this NO3 is taken up by plants and then eventually by animals to complete this biogeochemical cycle.
Nitrogen Fixation
Process by which certain bacteria convert nitrogen gas into ammonia.
Process in which fixed nitrogen compounds are converted back into nitrogen gas and returned to the atmosphere.
Water Cycle
The continuous movement of water from the ocean to the atmosphere to the land and back to the ocean.