Structure and Funct. of Organisms Exam 1

Hardy Weinberg

Provides baseline for populations, Deviations = evolution.

Hardy Wienberg Equation

P ^2 + 2 P Q + Q ^2 = 1

Phenotype variation

a difference in DNA and environment

Mutations

random errors in DNA replication, create new alleles but too slow to shift allele frequency fast.

Germ-line mutations

heritable, drives evolution

Somatic mutations

do not pass down, effects individuals

Recombination

shuffles alleles into new combos

Deleterious mutation effects

reduce fitness and are harmful

Advantageous mutation effects

increase fitness and are rare

Neutral mutation effects

no effect

Most mutations are _____

neutral

Fitness is

the ability to survive, reproduce, and pass down genes

Gel electrophoresis

reviews band patterns of enzyme coding genes

DNA sequencing

the most genetic variation revealed

Natural selection

best traits survive and reproduce

Alleles that increase fitness

increase frequency

Alleles that decrease fitness

decrease in frequency.

Balancing selection

maintains 2 alleles

Artificial selection

Humans choose which individuals reproduce

Sexual selection

selecting favorable traits leading to phenotype change, not adaptation

Intrasexual selection

individuals of the same sex compete for mates

Intersexual selection

members of one sex choose their mates, usually based on physical traits

Genetic drift

a population drifts from the original and creates random allele frequency changes, having a large impact on small cell populations.

Founder Effect

New populations form from few individuals.

Bottleneck effect

Population crashes. Few individuals are left and may not represent the original gene pool.

Gene Flow

individuals "flow” through populations; homogenies (similarities) created or introduced new alleles.

Nonrandom mating

changes genotype frequency, not allele frequency

Only natural selection produces

adaptation

Molecular clocks operate:

mutations accumulate at a constant rate (More differences mean more time)

Fast molecular clock

mitochondrial DNA leading to recent diversion.

Slow molecular clock

rRNA leading to a deep split

Molecular clock calibrated by

fossil records of known age of divergent event

Biological Species Concept

interbreeding leads to viable fertile offspring

Hybrids

complicated (some sterile offspring)

Biological Species Concept doesnt apply to

asexual organisms, fossils, geographically separated pop.

Morphology

reflect genetic difference

Morphospecies

defined by physical appearance

Ecological

defined by ecological niche

Phylogenetic

defined by smallest monophyletic group

Prezygotic reproductive isolation

before fertilization

Postzygotic reproductive isolation

doesnt prevent mating, produces non-viable offspring

Habitat isolation

prezygotic, different areas

Temporal isolation

prezygotic, different breeding times/seasons

Behavioral isolation

prezygotic, different courtship signals

Mechanical isolation

prezygotic, incompatible reproductive structures

Gamete isolation

prezygotic, gametes don't fuse

Hybrid inviability

postzygotic, hybrid embryo fails to develop

Hybrid sterility

postzygotic, hybrid lives but is sterile

Hybrid breakdown

postzygotic, F1 fertile, F2 was sterile

Allopatric speciation

geographic separation. Population splits by barrier and over time develops 2 separate species and leads to reproductive isolation

Vicariance barrier

barrier splits population

Dispersal barrier

individuals colonize new area

Sympatric speciation

same geographical area

Disruptive selection

2 extreme phenotypes favored

Hybridization + polyploidy (has 2 sets of chromosomes)

alloploidy can create reproductively isolated new species

Peripatric speciation

small founder population splits off, rapid divergence

Adaptive radiation

1 lineage rapidly diversifies into many niches

Monophyletic (clade)

ancestors and ALL decedents

Paraphyletic

ancestors and SOME decedents

Polyphyletic

no common ancestors

Character matrix

taxa and derived characters

Synomorphies

shared derived characters unite clades

Homologous

same structure, same ancestors, USEFUL for trees

Analogous (convergent)

similar appearance, different ancestry

Molecular data

many characters (traits), less homoplasy (similar features)

Parsimony

prefer trees with fewest evolutionary changes

Fossil types

Body, cast, trace, chemical

Relative dating

rock strata position, deeper = older

Absolute dating

radiometric decay, ratio parent to daughter isotope

Archaeopteryx transitional fossils

dino features + feathers -> dinos to birds

Tiktaalik transitional fossils

fish features + limb-like fins -> fish to tetrapod

End of Permian

Largest extinction (96% of marine life), Volcanic activity, climate change, acidic oceans , Cleared niches, Made way for dinosaurs

End of Cretaceous

75% loss of non-avian dinosaurs , Asteroid and volcanic activity, Rapid mammalian diversification, Avian dinos (birds) survived