Anthro Exam 2

Front 1

Traits *

Back 1

Characteristics of organisms.

Front 2

Balanced Polymorphism

Back 2

Maintenance in a population of different alleles of a particular gene in proportion to the advantages offered by each.

Front 3

Biological Species Concept

Back 3

A species is a group of interbreeding organsims that are reproductively isolated from other organisms.

Front 4

Ecological Species Concept

Back 4

Natural selection, not reproductive isolation, plays the important role in maintaining differences between species.

Front 5

Allopatric Speciation

Back 5

Speciation that occurs when two or more populations of a single species are geographically isolated from each other and then diverge to from two or more new species.

Front 6

Character Displacement

Back 6

Members of different species become morphologically or behaviorally more differnt from each other as the result of competition over limited resources.

Front 7

Reinforcement

Back 7

The process in which selection acts against the likelihood of hybrids occurring between members of two phenotypically distinctive populations leading to the evolution of mechanisms that prevent interbreeding.

Front 8

Parapatric Speciation

Back 8

A two-step process of speciation that occurs when (1) selection causes teh differentiation of geographically separate, partially isolated populations of a species, and (2) then subsequently the populations become reprouctively isolated as a result of reinforcement.

Front 9

Sympatric Speciation

Back 9

A hypothesis that speciation can result from selective pressures favoring different phenotypes within a population, without positing geographical isolation as a factor.

Front 10

Phylogeny

Back 10

The evolutionary relationships among a group of species descended from a common ancestor.

Front 11

Taxonomy

Back 11

Branch of biology concerned with the use of phylogenies for naming and classifying organisms.

Front 12

Comparitive Method

Back 12

A method for establishing the function of a phentoypic trait by comparing different species.

Front 13

Systematics

Back 13

A branch of biology that is concerned with the procedures for constructing phylogenies.

Front 14

Analogous Traits

Back 14

Traits that are similar because of convergent evolution, not common descent.

Front 15

Homologous Traits

Back 15

Traits that are similar because of common ancestry, not convergence.

Front 16

Ancestral Trait

Back 16

A trait that appears earlier in the evolution of a lineage or clade, one that characterizes a common ancestor.

Front 17

Derived Trait

Back 17

A trait that appears later in the evolution of a lineage or clade, one that has evolved since th etime of the last common ancestor.

Front 18

Outgroups

Back 18

Taxonomic groups that are related to the group of interest and can be used to determine which traits are ancestral and which are derived.

Front 19

Cladistic Systematics

Back 19

A system for classifying organisms in which patterns of descent are the only criteria used in classification.

Front 20

Evolutionary Systematics

Back 20

A system for classifying organisms in which both patterns of descent and patterns of overall similarity are used in classification.

Front 21

Pleiotropic Effects

Back 21

Phenotypic effects created by genes that influence multiple characters (traits).

Front 22

Correlated Characters

Back 22

Traits that are statistically associated in a population, e.g., beak depth and width are both controlled by genes that influence overall size.

Front 23

Point Mutation

Back 23

A common type of mutation in a single codon, causing the substitution of one amino acid for another in a protein sequence.

Front 24

Balanced Polymorphism

Back 24

Maintenance in a population of different alleles of a particular gene in proportion to the advantages offered by each.

Front 25

Fitness *

Back 25

A measure of an individual's genetic contribution to subsequent generations.

Front 26

Blending Inheritance

Back 26

A widely-held nineteenth-century theory that a child is an intermediate between maternal and paternal characteristics, as the result of the mixing of their bloods.

Front 27

Genes

Back 27

A unit of inheritance carried on a chromosome, transmitted from generation to generation by the sex cells, and controlling some trait or character.

Front 28

Alleles

Back 28

Alternative forms of a gene.

Front 29

Genotype

Back 29

The genetic makeup of an organism, its total genetic material.

Front 30

Phenotype

Back 30

The observable characteristics of an organism.

Front 31

Segregation

Back 31

Genes exist on paired chromosomes; at meiosis the pairs are segregated so that a gamete has only one of the pair.

Front 32

Independent Assortment

Back 32

Genes on one chromosome do not influence the distribution of genes on other chromosomes; they separate independently from one another during meiosis and are randomly asorted in the gametes.

Front 33

Independent Assortment

Back 33

Genes on one chromosome do not influence the distribution of genes on other chromosomes; they separate independently from one another during meiosis and are randomly asorted in the gametes.

Front 34

Recombination

Back 34

The creation of novel genotypes as a result of the random segregation of chromosomes and of crossing over.

Front 35

Mutation

Back 35

A spontaneous change in the chemical structure of DNA.

Front 36

Polygenic

Back 36

Determined by more than one gene.

Front 37

Genome

Back 37

All of the genetic information carried by the organism.

Front 38

Population Genetics

Back 38

The branch of biology dealing with the processes that change the genetic composition of populations through time.

Front 39

Population

Back 39

A community of potentially interbreeding individuals, usually at a given locality or within a limited geographical region.

Front 40

Gene Pool

Back 40

All of the genes found in the members of a population.

Front 41

Evolution

Back 41

Change in a population's gene pool from generation to generation.

Front 42

Microevolution

Back 42

Small-scale changes in gene frequencies within a population over a short period of time.

Front 43

Macroevolution

Back 43

Large-scale, long-term changes in gene frequencies resulting ni the formation of new species.

Front 44

Environmental Variation

Back 44

Phenotypic differences between individuals that exist because individuals developed in different environments.

Front 45

Gene Flow

Back 45

The movement of genes from one population to another, as the result of interbreeding.

Front 46

Mate Guarding

Back 46

A form of mating in which the male defends his mate after copulation to prevent other males from mating with her.

Front 47

Plastic

Back 47

Describes traits that are very sensitive to environmental conditions during development, so that different phenotypes are produced in different environments.

Front 48

Canalized

Back 48

Describes a trait that is very insensitive to environmental conditions during development, resulting in similar phenotypes in a wide range of environments.

Front 49

Genetic Drift

Back 49

Random change in gene frequencies due to sampling variation that occurs in any finite population.

Front 50

Fixation

Back 50

A state that occurs when all of the individuals in a population are homozygous for the same allele at a particular locus.

Front 51

Development

Back 51

The process of growth and differentiaion from zygote to adult.

Front 52

Convergence

Back 52

The evolution of similar adaptations in unrelated species.

Front 53

Equilibrium *

Back 53

A steady state in which either gene or genotype frequencies do not change.

Front 54

Stabilizing Selection

Back 54

Selection pressures in a stable habitat that favor average traits by eliminating the extreme variations in a continuous distribution.

Front 55

Directional Selection

Back 55

Selection pressures in a changing habitat that favor one extreme variation in the distrubution of a trait.