Unit 3 Flashcards
Interspecific competition
Competition between different species
Intraspecific competition
Competition a among members of the same species
Competitive exclusion principle
• If in two species are in direct competition with each other, one must win outright, adapt by resource partitioning or character displacement, migrate, or die out
• Also called Gause’s law
Resource partitioning
The evolution of specialized traits by different species to reduce competition between species for similar scarce resources
Predation
A member of one species (predator) feeds on all or part of another species (prey)
Coevolution
The natural selection process in which changes in the gene pool of one species leads to changes in the gene pool of another species
Parasitism
A species interaction in which one species (the parasite) lives in or on and preys on another species (the host)
Mutualism
A species interaction in which both species benefit
Commensalism
A species interaction in which one species benefits and the other is unaffected
Symbiosis
A mutually beneficial relationship between two species
Population
A group of interbreeding individuals of the same species
Limiting factors
• A factor that limits the growth of a population
• Also called environmental resistence
Carrying capacity
The maximum number of individuals that an environment can sustain for an indefinite time
R-selected species
• A species with a high capacity for growth
• Gives birth to many offspring which mostly die in early early life
• Also called r-strategists
K-selected species
• A species with a low capacity for population growth
• Gives birth to few offspring and care for them, many reach adulthood
• Also called k-strategists
Survivorship curve
• Illustrates different life expectancies of species by showing percentages of members of different ages
• Three types: late loss (k-strategists), early loss (r-strategists), constant loss (constant death rate at all ages)
Cultural carrying capacity
The maximum number of people who could live in a reasonable freedom and comfort indefinitely, without decreasing the ability of the earth to sustain future generations
Crude birth rate
The number of live births per 1000 people in a population in a given year
Crude death rate
The number of death per 1000 people in a population in a given year
Total Fertility Rate (TFR)
The average number of children born to women of childbearing age in a population
Infant mortality rate
The number of babies out of every 1000 born who die before their first birthday
Migration
The movement of people into (immigration) and out of (emigration) specific geographic areas
Age structure
The distribution of individuals among various age groups in a population
Demographic transition
• The theory that as a country industrializes and population grows, the crude birth and crude death rate decrease, slowing population growth
• Takes place in four stages: preindustrial, transitional, industrial, postindustrial
Habitat
A general physical place of residence in an environment
Niche
The functional role of an organism in a community
Ecological equivilants
• Two species from different taxonomic categories that have comparable niches and habitats in different places
• The outcome of convergent evolution
• The Australian Tasmanian wolf and the Ethiopian lion are ecological equivalents because they are both running carnivorous mammals (the same niche)
Size of an population
• Increases with births and immigration
• Decreases with deaths and emigration
Estimation methods for population size
• Extrapolation based in a few points
• Mark, release, recapture (used for hard to count, mobile organisms)
• Mark, release, recapture uses the Lincoln-Peterson index
Population density
Low density populations are territorial or widely dispersed species (may be apex predators) and high density populations are social species or overpopulated
Population dispersion
Three kinds: uniform, clumped, and random dispersion
Age structure
The distribution of individuals
among various age groups in a
population
Factors that effect population growth
• Age at which reproduction begins
• Number of offspring per reproduction
• How often reproduction occurs (semelparous or iteroparous)
• Reproductive timespan
• Changes of survival until age of reproduction
• Immigration and emigration
Semelparous
Reproduction occurs only once in a lifetime
Iteroparous
Reproduction occurs 2+ times in a lifetime
Biotic potential
The maximum number of organisms that can live in an environment
Density independent factors
- Not related to concentration of organisms
- Organisms have no control over them
- Will affect over or under populated populations
- Inclement weather, man-made disasters, natural disasters
Density dependent factors
- Effects depend on abundance of the population
- These are evolutionary in nature
- Resources, predators, competition, invasive species
Predator strategies
Speed, agility, venom and weapons, trapping and attracting
Prey countermeasures
- Constant vigilance, bluff
- Physical defenses (porcupine spines, cactus spines)
- Chemical deterrents (bombardier beetles spray acid)
- Speed and agility
- Camouflage or cryptic coloration (leaf bugs, orchid mantis)
- Aposematic (warning) coloration (bright reds, yellows, etc.)
- Startle coloration (butterflies with eye patterns)
Batesian mimicry
Once species is poisonous and the other is harmless (monarch and viceroy)
Mullerian mimicry
Both species are dangerous and enforce each others’ threat to predators (most wasps and yellow-black striped insects)
Invasive species
- Any species that is not native to a given area
- Compete with native animals over the same niche
- May not have natural predators
- Zebra mussels, Anacondas
