GEOSCI110 Midterm

Darwin 2 main discoveries

1) all living things share common ancestry

2) species on earth evolve through natural processes

In order for natural selection to occur:

a. Populations are variable

b. Variants that are successful leave more offspring

c. Generation by generation species change

Evidence of Evolution

- fossil record

- classification and biogeography

- morphology & development

- DNA/

Fossil record

Demonstrates evolution through temporal succession

Faunal Succession

Relative age and correlation of strata

Fossil organisms follow one another in a definite and irreversible order. Simple forms proceeding to invertebrates then vertebrates

Linnaean Hierarchy

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species ; nested groups... more closely related look most similar

Immortal genes

500; shared amongst all living species

Neoplatonism: view on fossils

Fossils produced in rocks by molding forces (Vis plastica)

Aristotelianism; view on fossils

Fossils are the product of spontaneous generation from non-living material

Middle Ages; view on fossils

Fossils regarded as works of the devil

Da vinci

Discovered that fossils start from organic matter & lie in positions that resemble living communities; fossils also to fragile to be carries great distances

Law of Superposition

oldest rocks at the bottom, youngest at the top

Stensen

Used tongue stones and real shark teeth to discover that they were not products of visplastica but actually remains of past sharks teeth

Paley

Eighteenth century English philosopher who proposed the idea of a conscious celestial designer of all life on earth

Evolution

Species undergo genetic change over time

Is evolution constant amongst species

NO: evolution does not predict constant evolution or speed at which it occurs

DEPENDS ON: evolutionary pressure each individual species experiences

Gradualism

Takes generations to produce a substantial evolutionary change

Strong natural selection

When evolutionary change can be fast

I.e.: animal or plant colonizes a new environment

Weak natural selection

Evolution often slows down

I.e.: When a species becomes well adapted to a stable habitat

Fundamental traits

- biochemical pathways we use to produce energy

- standard four-letter DNA code

- how code is read and translated into proteins

Speciation

Common ancestor x is the missing link between each species that evolved from it

Every pair of species shares a common ancestor sometime in the past; closely related species had a common ancestor that lived more recently

nested hierarchy

Big groups of species whose members share a few traits are subdivided into smaller groups of species whose members share a few traits are subdivided into smaller groups of species sharing more traits and so on down to species that share nearly all their traits

Diluvialism

Fossils as "proof" of biblical flood

Principle of original horizontality

Everything is layered horizontally

Principle of Lateral Continuity

layers are continuous until encountering an obstruction

Robert Hooke (1635-1703)

Suggested that fossils were remains of extinct organisms and that species have a limited lifespan

- fossils could be used to correlate strata

William Strata Smith

Published first series of high quality geologic maps of Britain correlating strata with the use of fossils

Faunal Succession

Fossils layer in rocks are older than the rock they rest in

Properties of good index fossils

- easy to identify

- geographically and environmentally widespread

- geologically short lived

Biological evolution

Organisms that change over time typically due to natural selection

Georges Cuvier & Alexandre brongniart

Generated maps for the Paris basin (1811) using faunal Succession

Erosional surfaces

Represent missing time & catastrophic events that happened earlier in earths history

Cuvier

Examined jaws of fossils found to modern day elephants and saw that they bone structure was the same

- believed life's moved progressively towards its "perfect" modern state

Catastrophism

The principle that events of the past occur suddenly and wildly

James Hutton

"No vestige of a beginning no prospect of an end"

Father of modern geology & uniformitarianism

-Used present processes to understand the past recorded in rocks (uniformitarianism)

-realized the temporal implications of the rock cycle (antiquity of earth)

Plutonism

Origin of igneous rocks is molten magma forcibly intruded upward into the earths crust due to subterranean heat

Enclosing relations

Intruding magma encloses older pre-existing rocks into its magma

Cross-cutting relations

Magma cuts through older existing rock

Principle of inclusion

Any rock represented by eroded fragments that are included in another rock must be older than the enclosing one

Uncomformity

Surface of erosion and or non-deposition separating two rock bodies; represents missing time

angular uncomformity

tilted rocks are overlain by flat-lying rocks

Nonconformity

metamorphic or igneous rocks in contact with sedimentary strata

Disconformity

A type of unconformity in which the beds above and below are parallel and sedimentary

Lyell uniformity of law

Natural laws are invariant in space and time

Lyell uniformity of process

Only processes operating today operated in the past

Wallace line

Between Asian islands and Australia

Placentals on one half & marsupials on the other half

Central tenents

Heritability

Variability

Differential reproduction

Excess

Divergence

Heritability

Offspring inherit a combination of traits from parents

Variability

Offspring not exact copies

Differential reproduction

Slight adaptive advantage greater chance of producing offspring

Excess

Many more offspring by everything that can possibly survive and be sustained

Divergence

Branching process

Hypothesis

A proposed explanation for an observed phenomenon...MUST be testable

Theory

A hypothesis that has withstood extensive testing by a variety of methods and in which a higher degree of certainty may be placed

Evolutionary predictions

1. Able to find some evidence for evolutionary change within the fossil record

2. Able to find some cases of speciation in the fossil record, with one line of descent dividing into two or more

3. Find examples of species that link together major groups suspected to have common ancestry

4. Species show genetic variation for many traits

5. Cases of imperfect adaptation

6. See natural selection acting in the wild

Darwin observations while on voyage

1) fossil animals are now extinct

2) distinction between species and varieties of species were sometimes unclear

3) geographic variation and species replacement

4) different varieties on different islands

5) South American affinities of Galapagos island populations

Stabilizing selection

Selects against extremes in a population (end members of populations)

- results in maintenance of the status quo around optimum

-can decrease variability in population

Directional selection

A type of natural selection where a single phenotype is favored, causing the allele frequency in the population to shift in one direction over time; One extreme selected against

TYPE OR INTENSITY OR DIRECTION OF SELECTION MAY CHANGE

Fitness

Relative ability to contribute offspring to next generation

disruptive selection

Natural selection where extreme forms are favored over intermediate forms

Selection for extremes in a population

- results in divergence away from existing mode

Drift

No selection present

- no differential reproduction, all forms equally successful

- expectation is no change in mean morphology of population

- typically results in an increase in the variability of a population

Mutations

Copying errors that randomly occur during DNA replication as cells grow and divide

Natural selection and randomness

Natural selection involves the nonrandom survival of randomly generated variants

Bacteria

Do not reproduce sexually; evolve quickly due to;

Cell-cell transfer genes

Large population sizes

Rapid generation times

Biological species concept

Group of inter-breeding natural populations that are reproductively isolated from other such groups

Artificial selection

The process by which a species is modified via human actions that encourage the breeding of individuals with certain traits

Human intervention

Controlled, selective breeding of domestic animals

Why did Darwin need artificial selection as an analogy to natural selection

Because natural selection is often too slow for us to observe in a lifetime

Because artificial selection has resulted in dramatic changes

Because artificial selection demonstrates inheritance

Gregor Mendel

Father of genetics

Raised > 29000 pea plants between 1856-1863 &a closely controlled reproduction and kept careful notes on plant traits generation by generation

Bending inheritance

Each hereditary factor is permanently diluted in a hybrid (WRONG!!!)

Mitosis

Normal cell division

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

Locus

A given site on the chromosome

Alleles

Alternative forms of the same gene

Homozygous

2 alleles are identical

Heterozygous

2 different alleles

dominant allele

Is expressed even when heterozygous

Recessive allele

Is only expressed when homozygous

Mendelian Genetics

- phenotype traits are determined by units of heredity called genes

- each parent contributes one randomly chosen allele of each gene to each offspring (principle of segregation)

Wrong aspects of Mendelian genetics

-One gene codes for one trait

-Some alleles are dominant others are recessive

-Each pair of alleles (gene) behaves independently of other allele pairs (principle of independent assortment)

incomplete dominance of alleles; what is it and what is it an example of?

A condition in which neither allele for a gene completely conceals the presence of the other; results in intermediate expression of trait I.e flower color

EXAMPLE OF NONMENDELIAN CHARACTERISTICS

Con-dominance of alleles; what is it and what is it an example of?

Both alleles fully expressed i.e AB blood type

EXAMPLE OF NONMENDELIAN CHARACTERISTICS

Many alleles for one gene ( in a population)

Non Mendelian characteristic

One gene may have multiple effects

I.e allele for albinism

Non Mendelian characteristic

One trait may result from the input of many genes

I.e cow milk production & human skin color

Non Mendelian characteristic

Genes may influence each other

I.e hello lab fur

Non Mendelian characteristic

DNA

Deoxyribonucleic Acid

4 basic bio molecules of life

1. Carbohydrates (CHO): fast energy

2. Lipids (CHO- glycerol, fatty acids): long term energy storage, cell membranes

3. Proteins (CHON, made of amino acids): builds tissues, muscles, immune systems and enzymes

4. Nucleus acids (CHONP): DNA, RNA

DNA structure

Ladder twisted into a double helix

- holds information to build proteins and direct development

DNA sides

Sugar-phosphate backbone

DNA rungs

Base pairs

Base pairing rules

Adenine pairs with Thymine

Gaunine pairs with Cytosine

Nucleotides

Basic units (building blocks) of DNA molecule, composed of a five carbon sugar, a phosphate group, and one of 4 DNA (nitrogenous) bases

Anti parallel strands

DNA strands run in opposite directions

Why study DNA

- is the fundamental basis of variation and change

- DNA operates the same way in ALL living things

- many current issues involve an understanding of DNA

DNA replication process:

- Begins by unzipping the molecule

- a complimentary base hooks up to each unpaired base

- result is two daughter DNA molecules; each is half old half new

Helicase

An enzyme that untwists the double helix of DNA at the replication forks.

DNA polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule

Gene

Segment of DNA molecule that codes for an amino acid chain to build a protein

Where does DNA replication occur:

Inside the nuclear and before an individual cell divides