CSU BZ 220 Exam 1

Evolution

changes in allele frequency in a population from one generation to the next

Microevolution

small scale changes within populations - describes the process that explains patterns

Macroevolution

large scale changes observed above the species level - describes a pattern

Scientific Theory

a broad explanation for a wide range of phenomena, based on a set of principles

Scientific Hypothesis

is a proposed explanation to describe a limited set of phenomena

Macroevolution subfields

phylogenetics (evolutionary relationships)

systematics/taxonomy

comparative analysis

Microevolution subfields

population genetics

natural selection

genetic drift

strong inference

a prescribed method for conducting a scientific inquiry that consists of repeatedly disproving hypotheses -- alternative hypothesis

alternative hypothesis

the hypothesis that a proposed result is true for the population

Biology Questions

how did the diversity of life arise?

what is the history of life?

why are some organisms so similar?

why are some organisms so different?

4 alternative hypotheses before evolution

no change

extinction occurs

extinction occurs and lineages change over time

complex tree of life with extinction, lineage changes, and common descent

Clade

a group of species that shares a common ancestor

Fossil Record

the worldwide collection of fossils

Extinction

Principal of Faunal Succession

fossils are more similar to other fossils in adjacent rock layers and living organisms in same geographic location

indicates that organisms in a given location are related, changing over time

Transitional Forms

intermediate characteristics between ancestral and descendant groups

found between major groups of organisms

Law of Superposition

in sedimentary rock layers, the older layers are at the bottom

enables relative dating with principles of stratigraphy

Stratigraphy

the study of rock layers and the sequence of events they reflect

Homology

characters that are shared due to common ancestry

Radiometric Dating

absolute dating based on rate of atomic decay

Relative Dating

method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock

Absolute Dating

any method of measuring the age of an event or object in years

Vestigial Traits

functionless/reduced trait that is similar to functional trait in closely related species

Evidence rejecting alternative hypotheses

evidence from fossil record, homology, age of earth, and direct observation of change supports that there is a complex tree of life with extinction, lineage changes, and common descent

Tips

represent extant species (living species of a class of animals)

Nodes

represent ancestral species that lived in the past

Branches

internal branches represent the passage of time

extinct animals represented by shortened branches

Mary Anning (1799-1847)

greatest fossilist the worlds ever known

discovered many Jurassic fossils

contributed evidence that supported extinction events

George Cuvier (1769-1832)

paleontologist and comparative anatomist

established fossil record

Dinosaur-Bird transitional forms

feathers (and other traits) allow us to form hypotheses about evolutionary relationships among extant and extinct lineages

examples of homology

forelimbs of a frog, bird, rabbit, and lizard look different because they have evolved under different pressures

Molecular Homology

DNA sequences are nearly identical but can be different due to mutations. Some animals share same mutation

vestigial traits

provide evidence for evolution because they offer clues about the ancestors of organisms, because they are remnants of structures.

Artificial Selection

breeding of plants and animals to produce favorable traits

Gradualness

differences among organisms evolve by innumerable small steps

Uniformitarianism

geological processes shaped earth gradually and constantly over a long time scale, not through catastrophism

Taxonomy

naming organisms

Catastrophism

sharp inconsistencies in geological record are evidence of environmental catastrophe

Carl Linnaeus

father of modern systematics (classifying organisms)

invented taxonomy (naming organisms)

Comte De Buffon

father of biogeography (geographical distribution of plants and animals)

Buffon's law (despite similar environments, different regions have unique species)

species variation exists

George Cuvier

fossil resemblance to modern species

stablished extinction as fact

Charles Darwin

defined evolution, common descent, gradualness, population speciation, and natural selection

Charles Lyell

principles of geology

contemporary of Darwin

changes of rock layers only appear sudden when viewed on a timescale that is too short

uniformitarianism

Thomas Malthus

essay on principle of population (gave Darwin idea for mechanism of evolution, natural selection)

rate of population growth > rate increase in food

unchecked growth leads to famine and struggle for survival

Jean-Baptiste Lamarck

argued fossil records shows changes within lineages

evolution due to changes in individuals during their life time, this mechanism was incorrect but got people thinking

Alfred Russel Wallace

also discovered idea of natural selection while collecting insects in Malaysia

Galapagos Mockingbirds

large impact on his evolutionary thinking because they were all so similar yet still had differences between inhabitants of the different islands

"species are not immutable"

meant that new species can arise

artificial selection - Darwin

Darwin was able to see that some traits are more favorable than others and will be kept among generations

Origin of Species

1. EVOLUTION AS SUCH: characteristics of lineages change

2. COMMON DESCENT: species diverged from a single common ancestor.

3. GRADUALNESS: differences among organisms evolve by innumerable small steps.

4. POPULATION SPECIATION: evolution occurs by changes in the proportions of individuals within a population

5. NATURAL SELECTION: competition causes proportions of variant individuals within populations to change.

Pangenesis

all parts contribute to sex cells

Germ Plasm

only gonad's cells contribute to sex cells

Gene

a sequence of DNA that codes for a particular protein or RNA molecule

Locus

the position a gene occupies on a chromosome

Allele

one of the alternative forms of a single gene

Homozygous

in a diploid organism, an individual with the same allele on both chromosomes

ex. YY or yy

Heterozygous

in diploid organisms, an individual with different alleles on each chromosome

Genotype

genetic makeup of an organism

Phenotype

the physical, chemical, or behavioral expression of the genotype

Dominance

a characteristic in which an allele that expresses its phenotype even in the presence of a recessive allele

Dominant Allele

expressed whenever it is part of the genotype, even in heterozygous genotype

Recessive Allele

expressed only in the homozygous genotype

Diploid

have 2 of each chromosome

Haploid

has 1 of each chromosome

Discrete Variation

variation in a qualitative trait that falls in distinct categories

ex. hitchhikers thumb, attached/detached earlobes

Continuous Variation

variation in a quantitative trait that falls long numerical continuum

ex. height, weight, age

Epistasis

the interaction of 2+ genes to control a single phenotype

ex. color/intensity

Modern Synthesis

gradualism supported; same heredity for continuous and discrete traits

microevolution leads to macroevolution

mutation is raw material for selection

Gametes

sex cells

Incomplete Dominance

heterozygotes exhibit an intermediate phenotype compared to the homozygotes

ex. medium height

blending inheritance

parents traits blend to make offsprings traits

Laws of Inheritance

Principle of Dominance

Law of Segregation: during meiosis, alternate alleles of a single gene separate to different gametes

Law of Independent Assortment: during meiosis, alleles of two unlinked genes are inherently independent of each other

Mendel's pea plants

amenable to controlled crosses

hermaphroditic and self-compatible

short generation time

true-breeding lines

large number of progeny

easily distinguishable discrete traits when a yellow and a green pea were crossed, the offspring were all yellow but then their offspring was both green AND yellow(3:1 ratio)

Continuous variation causes

Environmental effects: Salt of soil

Incomplete dominance: Heterosygotes have an intermediate phenotype

Polygenic traits (phenotype influenced by more than one gene): skin color

Epistasis: Interactions of 2+ genes to control a single phenotype (intensity and color)

Gregor Mendel

father of genetics

pea experiment

Hugo De Vries

experiments in heredity

mechanism for evolution: MUTATION!

Sewall Wright

one of the founders of population genetics

studied guniea pigs (crossbreeding vs inbreeding) and genetic drift

Ronald Fisher

statistician who combined Mendelian inheritance with population genetics

J.B.S Haldane

combined Mendelian inheritance with population genetics separately from Fisher

Nucleotide Substitution

a point mutation that results from replacement of one nucleotide in DNA with another nucleotide

Transition

nucleotide changes but protein stays the same

Transversion

nucleotide changes and protein changes

Frameshift

one nucleotide deleted and whole sequence shifts over one

Mis-sense Mutation

change in amino acid

Non-sense Mutation

change to stop codon

Chromosome Mutation

inversion, deletion, duplication, translocation

Deletion, Duplication, Inversion, Translocation

Fitness

a measure of an organisms reproductive success

Nucleotide

single letter

Codon

group of 3 letters

Sequence

string of codons

Synonymous

no change in protein

Non-synonymous mutation

alters amino acid sequence of a protein

Genome Duplication

polyploidy

Polyploidy

multiple sets of chromosomes

error during meiosis, no segregation

gametes

where mutation must occur to be heritable

Most mutations are

neutral because they are most likely not in a protein-coding region, redundancy in genetic code, amino acid changes but functions the same

mutation rates in humans

1 in 10k to 1 in 100k

measure mutation rates

calculate new # of phenotypes per gene per generation; identify nucleotide changes from DNA sequences

Number v rate of mutations

mutation rate is frequency of new mutations over time