Chapter 3 Flashcards
Evolution, Biodiversity, and Population Ecology
Species
Classification of organism whose members can interbreed and produce fertile offspring.
Population
Group of individuals within a species that live in one geographic area.
Evolution
Genetic changes alter physical characteristics and behaviour of a population over generations.
Natural selection
Process that favors certain inherited characteristics, causing them to be passed on more frequently.
Adaptation
Evolution of genes that lead to better reproductive success in a population.
Mutations
Accidental changes to DNA, which cause genetic variation among individuals (separate from mixing through sexual reproduction).
Convergent evolution
Unrelated species in similar environments independently acquire similar traits (sometimes due to selective pressures).
Artificial selection
Selection caused by humans, such as domesticating dogs, cats, and livestock.
Biodiversity/biological diversity
Variety of life across levels (species, genes, populations, communities).
Speciation
Process by which new species are generated.
Allopatric speciation
Populations become physically separated over geographic distances. Populations eventually grow so different they can no longer mate.
Phylogenetic trees
Tables analyzing genes and external traits to represent the history of divergence.
Genus
Grouping of related species. Related genera are grouped into families.
Fossil
Imprint in stone of a dead organism.
Fossil record
Body of fossils worldwide.
Extinction
Most species that once lived have disappeared. Extinction occurs when the environment changes faster than species can adapt.
Background extinction rate
Rate of gradual extinctions (most extinctions).
Mass extinction events
Events that wiped out 50-95% of Earth’s species (e.g. Permian extinction).
Ecology
Study of interactions among organisms and with their environments on different levels.
Organism
Single living thing.
Population
Group of individuals of the same species in the same area.
Community
All populations of species that live and interact in an area.
Community ecology
Studies interactions of species in an area.
Ecosystems
Communities and all abiotic/nonliving parts of the environment.
Ecosystem ecology
Studies flow of energy and nutrients between living and nonliving parts.
Biosphere
Total of all living things/habitats on Earth.
Landscape ecology
Studies how ecosystems/communities/populations are distributed across Earth.
Habitat
Environment an organism lives in (including rock, soil, leaf litter, plant life), which varies by size.
Habitat use
Patterns created by the ability of organisms to survive in some habitats but not others.
Habitat selection
Mobile organisms can choose where they live.
Niche
Organism’s role in its community (resource use, interaction with other organisms).
Specialists
Species with narrow niches.
Generalists
Species with wider niches.
Population size
Number of organisms in an area at a time.
Population density
Number of individuals per unit area.
Population distribution
Spatial arrangement of organisms in an area.
Random population distribution
Population distribution with no particular pattern.
Uniform population distribution
Population distribution where individuals are spaced evenly.
Clumped population distribution
Population distribution where individuals concentrate in certain areas.
Sex ratio
Proportion of males to females.
Monogamous species
Sex ration of 1:1.
Age structure
Number of individuals of different ages within a population.
Natality
Births in a population.
Mortality
Deaths in a population.
Immigration
Arrival of outside individuals to a population.
Emigration
Departure of individuals from a population.
Rate of natural increase
Birth rate - death rate.
Exponential growth
Population increased by a fixed percentage each year.
Limiting factors
Physical, chemical, and biological constraints to a population.
Carrying capacity
Maximum population size an environment can sustain.
Logistic growth
Slowing of population growth as a population reaches its carrying capacity.
Density-dependent factors
Factors that rise and fall with population density (e.g. Predation, disease).
Density-independent factors
Factors unaffected by population density (e.g. Temperature, natural disasters).
Ecotourism
Tourism of natural areas (which is increased by efforts of organizations to protect land, remove alien species, and restore native habitats).
