Bio: Evolution and Ecology

homologous

similar; NOT same

directional selection

when an extreme phenotype is preferred and the average phenotype becomes the extreme. For example, as the horse started moving from forests to grasslands, its weight started to increase.

disruptive selection

when two or more extreme phenotypes are preferred over the intermediate phenotype. For example, British land snails live in areas with low and high vegetation. In the areas with low vegetation areas, the lighter colored snails survive, and in the high vegetation areas, the darker colored snails survive.

stabilizing selection

when an intermediate phenotype is the best for the current environment. For example, infants born with an intermediate weight have a better chance of surviving than those who were born at an extreme.

carrying capacity

the largest a population can get

primary succession

rock, soil, plants

secondary succession

soil, plants

symbiosis

unrelated species living together

limiting factor

anything that constrains a population's size and slows or stops it from growing

ecosystem

a biological community of interacting organisms and their physical environment

biome

an area classified according to the species that live in that location

niche

a position or role taken by a particular kind of organism within its community. Such a position may be occupied by different organisms in different localities, e.g., antelopes in Africa and kangaroos in Australia

community

a group of interdependent organisms of different species growing or living together in a specified habitat

biomagnification/bioaccumulation/bioconcentration

(10x rule) Bioconcentration and bioaccumulation happen within an organism, but biomagnification occurs across levels of the food chain

nitrogen cycle

a repeating cycle of processes during which nitrogen moves through both living and non-living things: the atmosphere, soil, water, plants, animals and bacteria


1. nitrogen fixing bacteria
2. nitrifying bacteria
3. bacteria of decay
4. dentrifying bacteria

nitrogen fixing bacteria

Atmospheric N2 to ammonia(NH3) (on roots of legumes)

prokaryotic microorganisms that are capable of transforming nitrogen gas from the atmosphere into “fixed nitrogen” compounds, such as ammonia, that are usable by plants

nitrifying bacteria

convert ammonia (NH3) to nitrites (NO2) and nitrates (NO3). NItrates make good fertilizer

bacteria of decay

convert plant and animal protein to ammonia

dentrifying bacteria

convert nitrates to atmospheric N2

lightning converts atmospheric N2 to nitrates

evolution

change over time; a change in an allele frequency over time

adaptive radiation

the diversification of a group of organisms into forms filling different ecological niches

start from one group and radiate out

convergent evolution

the process where distantly related organisms independently evolve similar traits to adapt to similar necessities

Lamarck

acquired characteristics during your lifetime are inheritable


1. theory of need
2. theory of use and disuse
3. theory of acquired characteristics

comparative anatomy

The comparison of the structure (anatomy) of one animal or plant with the structure of a different animal or plant

embryology

the study of the formation and development of an embryo and fetus

biochemistry

explores chemical processes related to living organisms

vestigial structures

things we inherited but no longer function

microevolution

an evolutionary change within a population over a short period of time

gene pool

the alleles of every gene of every individual in a population

allele frequency

the percentage of an allele in a gene pool

mutation

a change in a DNA sequence

gene flow

the movement of alleles amongst populations

genetic drift

the change of an allele frequency in a gene pool resulting from a chance event

bottleneck effect

a genetic drift in which natural disasters, disease, habitat loss, overhunting, or overharvesting cause a loss of genetic diversity

founder effect

a genetic drift in which individuals leave the population to create a new population, causing a loss of genetic diversity

Coevolution

when two species adapt as a response to selective pressure from the other species

pioneer species

the first producers that live in a community after a disturbance

climax community

the community after succession