Biology 30: Unit D Vocabulary

genetic variation

variation in population lies in the differences in genes carried by chromosomes

gene pool

all the genes found in a population

Hardy-Weinberg Principle

Without any outside forces, the frequency of each allele in a population will not change as generations pass. It is useful for predicting allele frequencies in a population that is not evolving. The conditions for this are no population in or out (gene flow), no net mutations, random mating, natural selection does not occur, and the population is large enough that the errors (such as no mating or mutations) do not affect the frequencies (genetic drift).

genetic equilibrium

when frequency of allele in population does not change as generations pass

evolution

changes of allele frequencies within a population over time

allele frequencies

the proportion of a gene copies in a population of a given allele

genetic drift

changes to allele frequency as a result of chance

founder effect

genetic drift that results when a smaller number if individuals seperate from their original population and fina a new population

bottleneck effect

When a species is separated by climate, such as roads or fires, causing a huge genetic drift as the species has shrunk. This is only due to chance.

gene flow

the movement of alleles from one population to another through movement of individuals or gametes.

mutation

a change in the DNA sequence in a chromosome

non-random mating

mates are picked based upon favoured traits

natural selection

the result of differential reproductive success of individuals caused by variations in their inherited characteristics

sexual selection

favours the selection of any trait that influences the mating success of an individual

speciation

the formation of a new species

selective pressures

cause each population to evolve in different ways

geographic barriers

include water, mountains, canyons, ect.

reproductive barriers

incompatibility of the chromosomes or different mating rituals or seasons

symbiotic relationships

are close relationship between two different species

predator-prey relationships

Relationship between predator and prey. Predators control the population of prey while the prey control the predator’s population. They co-evolve and improve the gene pool.

competition

A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites. It may be intraspecific or interspecific.

interspecific competition

competition between individuals of different species

intraspecific competition

an ecological interaction in which individuals of the same species compete for resources in their habitats

Gause's principle

states that no two species can occupy the same niche at the same time, and that the species that is less fit to live in the environment will either relocate, die out, or occupy a smaller niche

parasitism

a symbiotic relationship in which one organism (the parasite) benefits at the expense of another organism ( the host), which is often harmed but usually not killed (+/-)

commensalism

a symbiotic relationship in which one organism benefits and the other organism is unaffected (+/0)

mutualism

a symbiotic relationship in which both organisms benefit (+/+)

obligatory

each depends on the other exclusively

predation

an ecological interaction in which a predator ( a member of one species) kills and consumes prey (usually a member of another species)

camoflage

coloration that allows an organism to blend in with its surroundings

mimicry

Ability of an animal to look like another more harmful animal

primary succession

Starts without soil, so rock. It usually occurs during volcanic eruptions, avalanches, or ocean level changes. The pionner species are often lichen

secondary succession

Starts from the soil. It will occur if a fire, tornado, or in an old farm house with soil in it. IN cooler environments, the pioneer species is moss, while in warmer environments it’s grass.

pioneer organisms

the first species to appear during succession

transition communities

takes over and continues the process

climax community

A stable, mature community that undergoes little or no change in species over time

Chaos Theory

states that "since randomness is a basic feature of many complex systems, long term predictions may well be difficult to impossible."

population size

the number of individuals of a specific species occupying a given area/volume at a given time

population density

the number of individuals of the same species that occur per unit or volume

rate of change

the rate at which change occurs

natality

the number of births per unit of time

mortality

the number of deaths per unit of time

immigration

the number of individuals that move into an existing population per unit of time

emigration

the number of individuals that move away from an existing population per unit of time

open populations

a population in which change in number and density is determined by births, dealths, immigration, and emigration.

closed population

a population in which change in size and density is determined by births and deaths alone

clumped dispersion

the pattern in which individuals in a population are more concentrated in certain parts of a habitat

random dispersion

the pattern in which individuals are spread throughout a habitat in an unpredicatable and patternless manner

uniform dispersion

the pattern in which individuals are equally spaced throughout a habitat

per capita growth

the change in population size relative to the initial size of the population, per unit of time

biotic potential

the maximum number of offspring that a species could provide with unlimited resources

carrying capacity

the maximum number of individuals of a species that can be suppported by an ecosystem

density-dependent factor

a factor in an ecosystem that affects members of a population because of the population density

density-independent factor

a factor in an ecosystem that affects members of a population regardless of population density

J-shaped curve

Curve with a shape similar to that of the letter J; can represent prolonged exponential growth.

S-shaped curve

Leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow.

K-selected

Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.

r-selected

Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period.