GENERAL BIOLOGY 2

Evolution

Change in the inherited characteristics of biological populations over successive generations.

Population

Group of individuals of the same species that mate and produce offspring.

Mutations

Any heritable change of the base-pair sequence of genetic material.

Natural Selection

Individual organisms/phenotypes that possess favorable traits are more likely to survive and reproduce.

Genetic Drift

Overall shift of allele distribution in an isolated population.

Genetic Hitchhiking

Phenomenon in which a gene increases in a population because it lies near genes on the same chromosome.

Gene Flow

Transfer of alleles/genes from one population to another.

Micro Evolution

involves the change in allele frequencies that occur over time within a population.

Macro Evolution

change among species over a long time span with some species dying out and new species emerging.

Aristotle

recognized that all organisms are related in a hierarchy of simple to complex form, but he believed that all members of a species were created identical to one another.

George Louis Buffon

One of the first to openly suggest that closely related species arose from a common ancestor & were changing.

Jean Baptiste de Lamarck

he reasoned that organisms that used one part of their body repeatedly would increase their abilities. Conversely, disuse would waste the organ until it disappeared.

Perpetual Change

the world is constantly changing.

Common Descent

states that all forms of life descended from a common ancestor.

Multiplication Species

species divide and split into diff. species which can no longer interbreed.

Gradualism

large differences actually originate from an accumulation of many smaller differences.

Natural Selection

explains the selective processes of the environment through a phenomenon called adaptation.

Directional Selection

one phenotype is more favorable; allele frequency shifts in one direction.

Disruptive Selection

two or more extreme phenotypes are fitter than the intermediate phenotype.

Stabilizing Selection

occurs when extreme phenotypes are less fit than the optimal intermediate phenotype.

Geologic Time Scale

divides Earth's history into segments defined by major events.

Paleontology

study of past life.

Fossil

any evidence of an organism from more than 10,000 years ago.

Biogeography

study of the distribution of species across the planet.

Homologous Structure

structures that are derived from the same common ancestors but may not have same functions.

Analogous Structure

different structure, some function.

Vestigial Structure

a body structure in a present day organism that no longer serves its original purpose.

Convergent Evolution

organisms that are not related independently develop similar traits.

Divergent Evolution

describes evolution toward different traits in closely related species.

Molecular Biology

DNA and protein sequences are similar between related organisms.

Comparative Embryology

similar embryo logical development in closely related species.

Biological Species

group of organisms that can potentially interbreed and produce fertile offspring.

Speciation

formation of new species.

Gene Pool

a population's entire collection of genes and alleles.

Reproductive Barrier

mechanism that prevents group of organisms from sharing a gene pool.

Extinction

death of all individual of a species.

Prezygotic Barriers

block fertilization from happening.

Postzygotic Barriers

occur after zygote is formed.

Behavioral Isolation

absence of cross-attraction between individuals of separate species inhibiting any courtship initiation/individual behavior during copulation does not allow normal fertilization to occur.

Ecological Isolation

variations in the ecology of species give rise to barriers.

Habitat Isolation

species occupy diverse habitats in different biological or genetic tendencies then limiting gene flow during breeding seasons.

Temporal Isolation

species living in the same area have different breeding seasons preventing gene flow.

Pollinator Isolation

flowering plants have varying interactions with pollinators thereby preventing gene flow.

Mechanical Isolation

reproductive structures are incompatible between species inhibiting copulation/ pollination.

Gametic isolation

gametes that are transferred during copulation/pollination are ineffectual for fertilization due to problems with storage/transfer of gametes.

Allopatric Speciation

gene flow interrupted when population is divided into geographically isolated sub populations.

Parapatric Speciation

occurs when part of a population enters a new habitat bordering the range of the parent species.

Peripatric Speciation

new species is formed from a peripheral population.

Sympatric Speciation

new species arises while living in the same physical area as its parents.

Gradualism

one species gradually transforming into another through a series of intermediate forms.

Punctuated Equilibrium

relatively burst of rapid evolution interrupting long periods of little change.

Adaptive Radiation

rapid diversification of one species into several different species.

Background Extinction

results from the steady, gradual loss of species due to normal evolutionary processes.

Mass Extinction

many number of species disappeared over a relatively short period of time.

Biome

group of land ecosystems with similar climates and organisms.

Temperate Rain Forests

having moderate temperatures.

Tropical Rain Forests

found in regions close to the equator, warm and humid all year long.

Canopy

a leafy roof formed by the tallest trees.

Understory

a second layer of shorter trees and vines.

Deserts

an area that receives less than 25 cm of rain per year.

Namib

cools rapidly after the sun goes down.

Grasslands

An area that is populated mostly by grasses and other non-woody plants.

Savanna

located closer to the equator.

Deciduous Forest

have trees that shed their leaves and grow new ones each year.

Boreal Forest

Mostly contain coniferous trees.

Tundra

Extremely cold and dry area.

Ponds and Lakes

bodies of standing/still freshwater.

Estuary

river meets saltwater of the ocean.

Intertidal Zone

area between the highest high tide line and the lowest low tide line.

Surface Zone

first few hundred meters deep.

Deep Zone

below the surface.