Evolution

adaptive radiation (divergent evolution)

process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms

analogous structures

is a trait or an organ that appears similar in two unrelated organisms

anatomical homology

similar body structures among different species from a common ancestor

biogeography

is the study of the distribution of species and ecosystems in geographic space and through geological time

Charles Darwin

was an English naturalist that established that all species of life have descended over time from common ancestors and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection

cladogram

diagram that shows the evolutionary relationships among a group of organisms

common ancestry (common ancestor)

a group of organisms share common descent if they have a common ancestor thus all living organisms on Earth are descended from a common ancestor.

convergent evolution

process by which unrelated organisms independently evolve similarities when adapting to similar environments

decent with modification

principle that each living species has descended, with changes, from other species over time

derived characteristics

characteristic that appears in recent parts of a lineage, but not in its older members

developmental homology

similarities in the development of embryos between different species that share a common ancestor

diversity vs. unity

how different things are vs. how similar things are

embryo

organism in its early stage of development

embryology

the study of embryos

evolution

change in a kind of organism over time; process by which modern organisms have descended from ancient organisms (decent with modification)

fossil record

the geological record of organisms on earth that have been preserved in the rock in a chronological order (oldest on bottom layers and youngest on top layers)

homologous structures

structures that have different mature forms in different organisms but develop from the same embryonic tissues

homology

similar structure among different species from a common ancestor

interbreed

to be paired for reproducing, or mate, with a closely related individual

molecular homology

similar DNA (amino acid sequences) among different species from a common ancestor

speciation

formation of new species

species

group of similar organisms capable of interbreeding and producing fertile offspring

theory

a well-tested, well-established, and highly reliable explanation, but may be subject to change as new areas of science and technologies are developed

Theory of Evolution

the best scientific explanation for both the unity and diversity of life; proposed by Charles Darwin

vestigial structure

a structure that an organism has that is no longer useful to it, but that they have this structure because a common ancestor to that organism found it useful (Ex: Hip bones in whales)

extinction

disappearance of a species from all parts of its geographical range

gradualism

when speciation occurs over long periods of time rather than by sudden major changes

Law of Superposition

a general law stating that in any sequence of sediments or rocks that has not been overturned, the youngest sediments or rocks are at the top of the sequence and the oldest are at the bottom

punctuated equilibrium

pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change

stasis

the condition of the constant state of being of organism on earth

directional selection

a form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

disruptive selection

a form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

fitness

ability of an organism to survive and reproduce in its environment

gene pool

is the set of all genes, or genetic information, in any population, usually of a particular species.

natural selection

process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest

polygenic trait

trait controlled by two or more genes (ex: height of humans)

relative allele frequency

number of times an allele occurs in a gene pool compared with the number of times other alleles occur

single-gene trait

trait controlled by a single gene (ex: attached or unattached earlobes)

stabilizing selection

a form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end

survival of the fittest

process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection

differential reproductive success

another way of saying "survival of the fittest"; some organisms will leave more young behind them, as they have an advantage, compared to organisms that do not have an advantage - therefore "differential"

finite supply of resources

limited environmental resources such as food or shelter

inherited variations

hereditary traits that can affect natural selection, and therefore affect the individual's ability to compete, survive, and reproduce

variations

the differences within a species

adaptation

inherited characteristic that increases an organism's chance of survival

adaptive radiation (divergent evolution)

process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms

behavioral isolation

form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding.

convergent evolution

process by which unrelated organisms independently evolve similarities when adapting to similar environments

coevolution

the evolution of two or more interdependent species, each adapting to changes in the other (Ex: between insects and the flowers that they pollinate)

diversity

the fact or quality of being diverse; difference

diversity among species

the differences between two or more species (1.7 million species on Earth discovered and named so far)

diversity in species

the differences in a single species (Ex: tall vs. short in humans)

genetic equilibrium

situation in which allele frequencies remain constant

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

inherited vs. acquired traits

characteristics passed on via genetic material vs. characteristics that are NOT passed on genetically

natural selection

process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest

migration

ex: immagration is moving in and emigration is moving out

natural resistance

ex: bacterial resistance to antibiotics or insects resistant to pesticides/insecticides

non-random mating

mating that can cause evolution to occur because it causes the allele frequencies in the population to either increase or decrease (Ex: bird mating rituals)

random mating

mating that is associated with maintaining genetic equilibrium and therefore a lack of natural selection and speciation

reproductive isolation

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences

temporal isolation

form of reproductive isolation that occurs when members of two species occupy similar habitats, but breed at different times

crossing over (gene shuffling)

is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes

gene flow

is the transfer of alleles or genes from one population to another

gene pool

is the set of all genes, or genetic information, in any population, usually of a particular species.

genetic drift

the process of change in the genetic composition of a population due to chance or random events rather than by natural selection, resulting in changes in allele frequencies over time

bottleneck effect

a type of genetic drift where there is a reduction of genetic diversity in a population that has just seen a significant reduction in size due to a random event such as a natural disaster

genetic variation

variation in alleles of genes, occurs both within and among populations; it provides the genetic material for natural selection; brought about by mutation and/or genetic recombination

mutation

a random change in the DNA that can possibly produce a beneficial effect and increase an organisms chance for reproductive success; and therefor passing on the mutated gene and producing variation in a species

natural selection

process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest

genetic recombination

also called crossing over or gene shuffling; occurs during meiosis to produce variation in a species

Endosymbiotic Theory

theory that helps explain the complexity of eukaryotic cells; it states that a photosynthetic prokaryote (bacteria) & an aerobic heterotrophic prokaryote (bacteria) were engulfed by an ancestral host cell; eventually becoming a chloroplast and mitochondria respectively; so some features of eukaryotic organelles are similar to prokaryotes

"Primordial Soup" Hypothesis

hypothesis proposed in the 1920's separately by scientists Oparin & Haldane about how the first simple organic molecules (amino acids) were formed; inorganic elements such as hydrogen, ammonia, methane, and water + a primative Earth environment without oxygen + a primer such as heat or lightening to trigger the reaction = first organic molecules called amino acids (the building blocks of proteins)

catalytic RNA

an RNA segment that has the ability to self-replicate and synthesize proteins without additional enzymes

hypothesis

a tentative and testable statement that must be capable of being supported or not supported by observational evidence

Miller-Urey Experiment

concidered to be the classic experiment on the origin of life; this experiment performed in the 1950's tested and confirmed Oparin & Haldane's "Primordial Soup" hypothesis that conditions on the primitive Earth favored chemical reactions that synthesized organic molecules from inorganic precursors

organic molecule

substances containing carbon found in living things; the four main classes are carbohydrates, proteins (chain of amino acids), lipids, and nucleic acids

RNA World Hypothesis

contraversial hypothesis proposed in the 1980's by a variety of scientists that RNA, not DNA, was the first genetic material because catalytic RNA can self-replicate without additional enzymes; this is only one of several alternative hypothesis on the evolution and formation of long complex biomolecules for self-replicating life (you can research and analyze others on your own, but will not be tested on them in this course)