BISC 120 Midterm 1 @ USC

Genotype

an organism's genetic makeup

Phenotype

observable traits of an organism

Allele

an alternate version of a gene

Gene

a unit of heredity information made of a specific nucleotide sequence

Character

an observable, heritable trait

Trait

a variant of a character

Dihybrid

an individual that is heterozygous for 2 genes of interest

True breeding

organisms that produce offspring of the same variety over many generations of self-pollination

Testcross

breeding an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Eugenics movement

a social movement that claimed that the human race could be improved through selective breeding

Gregor Mendel

Austrian monk who developed laws of inheritance

cross-fertilization

the fertilization of an organism by the fusion of an egg from one individual with a sperm or male gamete from a different individual

self-fertilization

fertilization that occurs when male and female gametes produced by the same organism unite

addition rule

when calculating the probability of either event A or B occurring, add their individual probabilities together

dominant allele

an allele that is fully expressed in the phenotype of a heterozygote

recessive allele

an allele whose phenotypic effect is not observed in a heterozygote

Law of Segregation

two alleles segregate (separate) during gamete formation and end up in different gametes

Law of Independent Assortment

each pair of alleles assorts (segregates) independently of each other pair during gamete formation

multiplication rule

when calculating the probability of events A and B occurring, multiply their individual probabilities together

complete dominance

Homozygous dominant individuals are indistinguishable from heterozygotes (ex. Widow's peak, earlobe attachment)

codominance

both alleles affect the phenotype in separate, distinguishable ways (ex. RBC surface proteins)

incomplete dominance

heterozygotes display a phenotype that is an intermediate between the two homozygotes (Ex. snapdragon flower coloration)

Thomas Hunt Morgan

This scientist's fruit fly experiments provided the first strong evidence that genes are on chromosomes.

sex-linked genes

a gene located on either sex chromosome

Frederick Griffith

This scientist discovered bacterial transformation by mixing pathogenic and nonpathogenic strands of pneumonia.

Oswald Avery

This scientist built on Frederick Griffith's work and showed that transforming substance was DNA, not protein.

Rosalind Franklin and Maurice Wilkins

These scientists made X-ray diffraction images of DNA.

Alfred Hershey and Martha Chase

These scientists used a bacteriophage (a kind of virus) to determine that hereditary material is DNA.

James Watson and Francis Crick -- 1953

These scientists resolved 3D structure of DNA

Aristotle

He believed that life forms were fixed, but his Scala Naturae inspired future evolutionary theories.

Carolus Linnaeus

Regarded as "the father of taxonomy," he developed a classification system to reveal the divine order of life

Georges Cuvier

This person created catastrophism and believed boundaries between strata were due to catastophes.

Hutton and Lyell

These people advocated for gradualism and believed that earth's features could be explained by processes currently operating. They implied that the earth was older than 6000 years.

Erasmus Darwin

This person was Charles Darwin's grandfather and he wrote prose and poetry discussing origins of life from a single ancestor, as well as transmutation of one species into another.

Jean-Baptiste LaMarck

He developed the theory of inheritance by acquired characters.

What year was Darwin's "The Origin of Species" published?

1859

Thomas Malthus

This theorist proposed that population growth would exceed resource growth, and there would be a catastrophic check on overpopulation.

Irreducible complexity

The first steps toward complex adaptations could not have been favored

Homologous characters

similarities due to common ancestry (includes both anatomical and molecular homologies)

Vestigial traits

historical remnants of traits important for ancestors

Point mutations

Single-base substitutions caused by DNA polymerase errors (Ex. sickle-cell anemia)

Indel mutations

a mutation involving the addition or subtraction of one more nucleotide pairs in a gene (can cause addition/loss of amino acids, frameshifts, or truncated proteins)

Gene duplications

duplication of a short stretch of DNA (caused by unequal crossovers during meiosis or strand slippage during DNA replication)

Chromosome inversions

a mutation where the gene order is switched

Polyploidization

a mutation where the organism possesses more than two complete chromosome sets, as a result of an accident of cell division

Natural selection

differential survival and/or reproduction results in certain alleles being passed to the next generation in greater proportions

Maladaptive evolution

Evolution in which the average fitness of the population declines over time

Stabilizing selection

Selection against both extremes, towards the mean (Ex. birth weight)

Directional selection

selection against an extreme, towards the other extreme (ex. industrial melanism in moths)

Disruptive selection

selection against the mean, towards both extremes (ex. seedcracker finches in Cameroon)

sexual selection

natural selection for mating success, which can result in sexual dimorphism and increased risk of extinction (ex. Irish Elk)

Phylogenetic species concept

defines a species as the smallest group of individuals that share a common ancestor

Ecological species concept

views a species in terms of its ecological niche

Morphological species concept

Defines a species by structural features

Biological species concept

Defines a species as a group that is actually or potentially capable of interbreeding

Habitat isolation

Prezygotic barrier in which two species are in the wrong place (Ex. marine vs land iguanas)

Temporal isolation

Prezygotic barrier in which species breed at different times (Ex. 13 vs 17 year old cicadas)

Behavioral isolation

Prezygotic barrier in which courtship rituals unique to a species are effective barriers (Ex. albatross courtship)

Mechanical isolation

Prezygotic barrier in which morphological differences prevent successful mating (Ex. flowers specifically shaped for pollinators)

Gametic isolation

Prezygotic barrier in which sperm cannot fertilize in a particular egg (Ex. broadcast spawning marine invertebrates)

Reduced hybrid viability

Postzygotic barrier in which genes of the different parent species may interact and impair the hybrid's development (Ex. Rana pipiens x Rana sylvatica)

Reduced hybrid fertility

Postzygotic barrier in which even if hybrids are vigorous, they may be sterile due to problems at meiosis (Ex. ligers)

Hybrid breakdown

Postzygotic barrier in which some first-generation (F1) hybrids are sterile, but offspring of the next generation are feeble or sterile (Ex. copepod Tigriopus californicus)

"Evo-devo"

a field of biology which studies the evolution of genes controlling development

heterochrony

changes in rate and timing

allometry

changes in the relative growth rates of different body parts (Ex. human vs. chimp adults)

paedomorphosis

sexually mature adults with juvenile morphology (Ex. domesticated dogs)

Homeotic genes

control body plans by controlling the developmental fate of groups of cells

Exaptation

structure that evolved for purposes other than those for which it is currently used

Binomial nomenclature

two-part format for scientific names (Ex. Homo sapiens)

Hierarchical classification system

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Phylogeny

the evolutionary history of a species or groups of related species

Taxonomy

the science of naming and classifying organisms

Systematics

scientific system for classifying organisms

Phylogenetic systematics

classification of organisms by their order of branching on an evolutionary tree

PhyloCode

a proposed classification system in which traditional taxonomic ranks would no longer exist and only monophyletic groups would be recognized

Branch point/node

where lineages diverge

Polytony

an unresolved point of divergence

Maximum parsimony

the best tree requires the fewest changes

Maximum likelihood

the best tree is the tree with the highest likelihood given certain rules about how DNA changes over time

Cladistics

an approach to reconstructing phylogeny organisms are placed into groups called clades

Clade

ancestor and all of its descendants

Ethology

the study of behavior, especially under natural conditions

orthologous genes

genes found in different species as a result of speciation

paralogous genes

genes found in the same species as a result of gene duplication

Molecular clock

yardstick for measuring absolute time of evolutionary change

Motoo Kimura

This scientist developed Neutral theory.

Fixed action patterns

sequence of unlearned behaviors that are largely unchangeable

Ecosystem services

a function performed by an ecosystem that directly or indirectly benefits humans