bio final exam

Carolus Linnaeus (1707-1778)

Specialized in taxonomy, developed a binomial system of naming organisms according to genus and species that is still used today. Also adopted a system for grouping similar species into a hierarchy of increasingly general categories.

James Hutton (1726-1797)

Gradualism, the idea that earth is continuously, slowly modified by the accumulation of many small geological changes such as erosion, wind, sedimentation, etc.

Uniformatarianism, the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes.

Comte de Buffon (1707-1788)

Recognized the dynamic relationship between the external environment and living forms. Also recognized vestigial structures.

Jean-Baptiste Lamarck (1744-1829)

The first modern European thinker to develop a comprehensive theory of evolutionary change.

Idea that characteristics are acquired during an individual organism's lifetime and could be inherited

Georges Cuvier (1769-1832)

Founded comparative anatomy and paleontology; demonstrated the fact of organic extinction.

Realized that extinction was a common occurence, advocated catastrophism even though he was against evolution.

Alfred Russel Wallace (1823-1913)

English naturalist who proposed, independently of Charles Darwin, the concept of natural selection as a mechanism for evolution and as a way to explain the great variety of living things

Charles Darwin (1809-1882)

Theory of natural selection, a plausible mechanism for biological evolution

Argued that all the organisms that have ever lived arose through descent with modification, the evolutionary alteration and diversification of ancestral species

Gregor Mendel (1822-1884)

Investigated inheritance in pea plants by observing differences in various traits of the plants from generation to generation, leading to the idea that information needed to build an organism is packaged into units associated with specific traits

Gradualism

The view that Earth and its living systems changed slowly over its history

Essentialism

a belief that things have a set of characteristics that make them what they are, and that the task of science and philosophy is their discovery and expression; the doctrine that essence is prior to existence.

Scala Naturae

all living organisms arranged in a linear order from simple to complex

Catastrophism

The theory that Earth has been affected by sudden, violent events that were sometimes worldwide in scope

natural selection

The evolutionary process by which alleles that increase the likelihood of survival and the reproductive output of the individuals that carry them become more common in subsequent generations.

Homology

Similarity in characteristics resulting from a shared ancestry.

homologous structures

Characteristics that are similar in two species because they inherited the genetic basis of the trait from their common ancestor

transitional forms

fossils that connect ancestral species with their descendants through a series of tiny steps

Archeopteryx

Famous bird-like fossil that links birds and reptiles

Tiktaalik

"missing link" thought to be a transitional form between lobefin fish and tetrapods

Pakicetus

52 million year old whale ancestor

Dorudon

An extinct species that had a vestigial pelvis and is related to whales

law of succession

fossil species are strikingly similar to living species in the same geographic areas

genetic structure

frequency of different alleles and genotypes in a population

gene pool

The sum of all alleles at all gene loci in all individuals in a population

gene locus

The particular site on a chromosome at which a gene is located.

phenotypic frequency

The percentage of individuals in a population possessing a particular phenotype

genotypic frequency

The percentage of individuals in a population possessing a particular genotype

allele frequency

The abundance of one allele relative to others at the same gene locus in individuals of a population.

Microevolution

Small-scale genetic changes within populations, often in response to shifting environmental circumstances or chance events.

Macroevolution

Large-scale evolutionary patterns in the history of life, producing major changes in species and higher taxonomic groups

Hardy-Weinberg Principle

An evolutionary rule of thumb that specifies the conditions under which a population of diploid organisms achieves genetic equilibrium

Hardy-Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time

genetic drift

Random fluctuations in allele frequencies as a result of chance events; usually reduces genetic variation in a population.

bottleneck effect

An evolutionary event that occurs when a stressful factor reduces population size greatly and eliminates some alleles from a population.

founder effect

An evolutionary phenomenon in which a population that was established by just a few colonizing individuals has only a fraction of the genetic diversity seen in the population from which it was derived.

gene flow

The transfer of genes from one population to another through the movement of individuals or their gametes.

nonrandom mating

changes in a population's gene pool due to mate choice or other forces that cause individuals to mate with certain phenotypes more than others

Inbreeding

A special form of nonrandom mating in which genetically related individuals mate with each other.

assortive mating

Mating of individuals with similar phenotypes

Polymorphism

The existence of discrete variants of a character among individuals in a population.

morph

The form or shape of an organism, or of a part of an organism.

gel electrophoresis

Technique by which DNA, RNA, or protein molecules are separated in an agarose gel subjected to an electric field.

geographical variation

differences in the phenotypic variation between populations that are separated geographically

cline

A pattern of smooth variation in a characteristic along a geographical gradient.

balanced polymorphism

The maintenance of two or more phenotypes in fairly stable proportions over many generations.

frequency-dependent selection

A form of natural selection in which rare phenotypes have a selective advantage simply because they are rare.

Darwininan Fitness

Relative contribution an individual makes to the gene pool of the next generation compared to contribution by other individuals

relative fitness

The number of surviving offspring that an individual produces compared with the number left by others in the population.

stabilizing selection

A type of natural selection in which individuals expressing intermediate phenotypes have the highest relative fitness.

directional selection

A type of natural selection in which individuals near one end of the phenotypic spectrum have the highest relative fitness.

diversifying (disruptive) selection

A type of natural selection in which extreme phenotypes have higher relative fitness than intermediate phenotypes

sexual selection

A form of natural selection established by male competition for access to females and by the females' choice of mates.

sexual dimorphism

Differences in the size or appearance of males and females.

Macroevolution

Large-scale evolutionary patterns in the history of life, producing major changes in species and higher taxonomic groups over long periods of time

Anagenesis

The slow accumulation of evolutionary changes in a lineage that continues to exist as an interbreeding population

Cladogenesis

Branching evolution that occurs when one or more new species branches out from a parent species

morphological species concept

The concept that all individuals of a species share measurable traits that distinguish them from individuals of other species

biological species concept

The definition of species based on the ability of populations to interbreed and produce fertile offspring

Ernst Mayr

Fused Charles Darwin's theory of natural selection with the modern science of genetics; coined the "biological species" concept, altering understanding of the nature of a species

geographic isolation

physical separation of a group of individuals from others of the same species

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring

prezygotic barriers

A reproductive isolating mechanism that acts before the production of a zygote, or fertilized egg

habitat (ecological) isolation

A prezygotic reproductive isolating mechanism in which species that live in the same geographical region occupy different habitats

behavioral isolation

A prezygotic reproductive isolating mechanism in which two species do not mate because of differences in courtship behavior; also known as ethological isolation.

temporal isolation

A prezygotic reproductive isolating mechanism in which species live in the same habitat but breed at different times of day or different times of year.

mechanical isolation

A prezygotic reproductive isolating mechanism caused by differences in the structure of reproductive organs or other body parts.

gametic isolation

A prezygotic reproductive isolating mechanism caused by incompatibility between the sperm of one species and the eggs of another; may prevent fertilization.

postzygotic barriers

A reproductive isolating mechanism that acts after zygote formation

reduced hybrid viability

A postzygotic reproductive isolating mechanism in which a hybrid individual has a low probability of survival to reproductive age

reduced hybrid fertility

A postzygotic reproductive isolating mechanism in which hybrid offspring cannot form functional gametes

hybrid breakdown

A postzygotic reproductive isolating mechanism in which hybrids are capable of reproducing, but their offspring have either reduced fertility or reduced viability

Reinforcement

The enhancement of reproductive isolation that had begun to develop while populations were geographically separated

allopatric speciation

The evolution of reproductive isolating mechanisms between two populations that are geographically separated.

sympatric speciation

Speciation that occurs without the geographical isolation of populations.

peripheral isolates

relatively small isolated or semi-isolated populations distributed on the periphery of a larger, central population; conditions favor allopatric speciation

adaptive radiation

A cluster of closely related species from a common ancestor that are each adaptively specialized to a specific habitat, food source, or ecological niche; very common in "island-like" situations

allopolyploidy

The genetic condition of having two or more complete sets of chromosomes from different parent species; may occur when two closely related species hybridize and produce polyploid offspring (may be initially sterile)

Autopolyploidy

The genetic condition of having more than two sets of chromosomes from the same parent species; may occur when gametes spontaneously receive the same number of chromosomes as a somatic cell during meiosis

parapatric speciation

when a species is spread out over a large geographic area but only reproduces with local species, resulting in the development of a new species

Phylogeny

Evolutionary history of a species or group of species.

Clade

A monophyletic group of organisms that share homologous features derived from a common ancestor.

monophyletic

a grouping consisting of a clade that includes a most recent common ancestor and ALL of its descendents

paraphyletic

grouping consisting of a clade that includes a most recent common ancestor and most but not all of its descendants

polyphyletic

a grouping consisting of species that does not include their most recent common ancestor and also not including all the descendants of that ancestor

Homology

Similarity due to descent from common ancestor; may serve different function in descendants

Analogy

Similarity due to same function/evolutionary need

convergent evolution

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

Synapomorphy

shared derived character; evidence of recent relationship

Symplesiomorphy

shared ancestral character; evidence of more distant evolutionary relationship

character

A heritable feature that varies among individuals

character state

One of two or more distinguishable variants of a character

ingroup

a group of closely related taxa that is investigated for evolutionary relationships

outgroup

a reference group or a taxon outside the group of interest and more distantly related to the ingroup

parsimony

A particular trait is less likely to evolve independently in separate evolutionary lineages rather than as a result of shared ancestry; hence, all other things being equal, the best hypothesis is the one that requires the fewest evolutionary changes

Reducing atmosphere

A popular view about the early atmosphere that suggests that the atmosphere was mainly composed of CH4, NH3, hydrogen, water vapor and very little oxygen. These chemicals act as reducing agents where electrons are donated and allow chemical synthesis (electron bonding).

Stanley Miller

An American Scientist who experimented in Harold Urey's laboratory at the University of Chicago in 1953 to see if the gases hypothesized to exist on early earth could really create organic compounds. Simulated the water cycle on early earth, isolating amino acids and nitrogenous bases in the process which can form polymers under certain conditions

Fossils

The preserved remains or traces of organisms that once lived on Earth.