BIO200C Evolution

Precambrian

first appearance of hard-shelled animals, better preserved in the fossil record

protoplanetary disk

A rotating disk of gas and dust grains surrounding a newly formed star. Over time, can form protoplanets

formation of Earth

gravity outside of the sun caused matter to condense around the protoplanets

Late Hadean eon

Earth surface cooled quickly. 4-3.8 bya, heavy asteroid bombardment the steam and gases created atmosphere, still volanic

Gases around during late Hadean eon

ammonia, CO2, no free oxygen

First life

end of the Hadean eon, between 4.2 and 3.8 bya

time period: Precambrian supereon

4.6 bya- 543 mya

time period: Paleozoic era

543 mya - 250 mya

time period: Mesozoic era

250 mya- 65 mya

time period: Cenozoic era

65 mya to now

What is the Cenozoic era split into?

Paleogene, Neogene, Quaternary

Stromatolites

single cells, some of the first life to evolve, mats of cyanobacteria

Multicellular life

arose late in the Precambrian, 1 bya

Paleozoic era

first land plants and animals

Cambrian explosion

rapid diversification of most major animal groups marking the start of the Paleozoic era

Permain extinction

"the great dying", 96% of marine life, 70% of land animals went extinct, only known mass extinction of insects

Mesozoic Era

Age of reptiles, dramatic lowering of the number of animals, first mammals

K-Pg Extinction

Cretaceous-Paleogene extinction event 65 million years ago. Killed off the dinosaurs, possible caused by a meteor, made room for mammals to become dominant

Cenozoic era

age of mammals

Hadean eon

no oceans, no free oxygen, only hydrogen and helium gas, no protective atmosphere

Two characteristics of life

organization, replicates itself

Earth 3.8 bya

molten rock, no free oxygen and high energy

Four steps to life on early Earth

1. Abiotic synthesis of organic material

2. Formation of polymers

3. Forming protobionts

4. Origin of hereditary material

Miller-Urey Experiment

Experiment that found that organic molecules can form in a strongly reducing atmosphere.

Products after one week of the Miller-Urey experiment

amino acids, nucleotides, sugars, lipids, ATP

What is the importance of clay?

clay is rich in minerals like iron and zinc which can attract monomers leading to the formation of polymers

protobionts

collections of abiotically produced molecules surrounded by a membrane-like structure

protocells

precursor of a living cell that had a membrane-like structure and that maintained an internal chemistry different from that of its surroundings

RNA world

easily forms abiotically (more easily than DNA), can replicate itself, has hereditary information and has catalytic properties

Beginning of time

most people thought that life was created by a supernatural power

Tenants of the history of the theory of evolution

supreme being placed organism on Earth, the organisms were designed by the supreme being, species do not change

Anaximander

Greek philosopher who suggested that humans evolved from fish that had moved onto land, theory of common descent and transmutation of species

Carolus Linnaeus

founder of taxonomy, the branch of biology concerned with naming and classifying organisms, binomial nomenclature, hierarchical classification

James Hutton

father of modern geology, natural processes gradually shaped rock formations, first person to contradict the young Earth hypothesis

Gradualism

James Hutton's theory that evolution occurs slowly but steadily

Sedimentation

the action or process of forming or depositing sediment and being compressed to form stone

Adam Smith

Economist who was known for Laissez-faire economics, chaos governed by invisible hand and believed in the benefits of competition

Jean-Baptiste Lamarck

This man developed the first cohesive theory of evolution after his studies of biology, inheritance of acquired characteristics "use and disuse"

Thomas Malthus

Known for an essay about the Principle of Population, said human population can outgrow food supply; result will be war, famine, disease

Georges Cuvier

developed paleontology, the study of fossils and comparative anatomy, advocated for catastrophism

Catastrophism

A principle that states that geologic change occurs suddenly

Charles Lyell

effectively discredited the long-standing view that the earth's surface had been formed by short-lived events, his theory was uniformitarianism: same geological processes that are at work today slowly formed the earth's surface over a long time

Uniformitarianism

Charles Lyell's idea that geologic processes have not changed throughout Earth's history.

Charles Darwin

English natural scientist who formulated a theory of evolution by natural selection, species evolved from common ancestor

Alfred Russel Wallace

British naturalist who developed a hypothesis of natural selection similar to Darwin's

Gregor Mendel

Augustinian monk and botanist whose experiments in breeding garden peas led to his eventual recognition as founder of the science of genetics, discovered that traits are inherited by predictable laws

James Watson and Francis Crick

discovered the structure of DNA, means for heritable information to be stored and passed on

Darwin's hypothesis

there must be variation in the population, variation must lead to difference in reproductive success, variation must be transmitted to the next generation

Darwin's hypothesis: 5 parts

individuals vary, populations tend to overbred leading to survival struggles, survival of the fittest, survivors will reproduce, traits leading to better survival must be heritable

Grant and Grant

discover that better variation for a particular environment have higher survival rates, find this by studying the finches

1977

La Nina, extreme drought and population decline, withered vegetation, mostly large, hard seeds remain--larger beaked finches survive

1984/85

El Nino, wet, abundant vegetation, high concentration of small softer seeds--finches with small beaks survive

Grant and Grant II

also help to prove that survivors have more offspring and that the traits that are heritable (like beak size) are passed down to their offspring

Implications of Darwin's Theory

Earth must be old enough for evolution to occur, fossils would show the change with older rock having fewer modern fossils, the gradual small changes through time indicates that there should be intermediates

Is the Earth old enough for evolution to have occurred?

Yes, illustrated by depth of canyons and thickness of rock strata which can be dated back billions of years

"Missing Links"

intermediate fossils between groups of organisms that must exist if evolutionary theory is true

Archaeopteryx

An intermediate fossil that shows both reptile and bird characteristics.

Tiktaalik

"missing link" thought to be a transitional form between fish and amphibians

Problem with "missing link"

every time a "missing link" is found it created two more new missing links

Thomas Hunt Morgan

Bred fruit flies, and supported the the theory of chromosomal inheritance by finding that a specific gene is carried on a specific chromosome

Theodosius Dobzhansky

"Nothing in biology makes sense except in the light of evolution"

Sewall Wright, Ronald Fisher, J.B.S. Haldane

funders of populations genetics, mathematical models of evolution, statistical genetics

true-breeding plant

a plant that will always produce offspring with the same form of a trait when it self-pollinates

Non-true breeding plants

plants that produce some offspring that look different than the parent plants

The basic cross

between two trouble breeding plants resulting in hybrid offspring

P generation

Parental generation, the first two individuals that mate in a genetic cross

Cross fertilize

fertilization of one plant by pollen from a different plant

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms, (offspring of the P generation)

Self Cross

crossing organism to itself (mostly just plants)

F2 generation

Offspring resulting from interbreeding of the hybrid F1 generation.

Mendel's five element model

1.) Parents transmit information about traits to their offspring

2.) Each individual receives one copy of each gene from each parent. (2 copies total)

3.) Not all copies of genes are identical

4.) The two alleles remain discrete, they do not blend

5.) The presence of a particular allele does not ensure that the trait it encodes will be expressed

Mendel's 1st Law of Segregation

two alleles segregate during gamete formation to be rejoined at random during fertilization

Mendel's 2nd Law of Heredity

In a dihybrid cross the alleles of each gene assort independently

Exceptions: factors assort independently

gene linkage

Exceptions: each trait is controlled by a single factor

polygenic inheritance

Exceptions: factors do not interact

Epistasis

Exceptions: each factor only controls one trait

Pleiotropy

Exceptions: factors only have two alternative outcomes

Incomplete dominance and codominance

Exceptions: factors are unaffected by the environment they are expressed in

environmental effects on expression

Polygenic inheritance

combined effect of two or more genes on a single character

Polygenic inheritance examples

height

Epistasis

A type of gene interaction in which a trait can be affected by more than one gene

Epistasis example

coat color in dogs

Pleiotropy

The ability of a single gene to have multiple effects

Pleiotropy example

sickle cell anemia

Incomplete dominance

parental phenotypes blend in the heterozygote

Codominance

heterozygotes show both parental phenotypes unblended

Environmental affects

can affect gene expression and influence genetically determined traits

Chromosomes

discovered in 1879, come in pairs, chromosomal theory of inheritance

Karyotype

A picture of all the chromosomes in a cell arranged in pairs

Chromatid

one half of a duplicated chromosome

Sister chromatids

Replicated forms of a chromosome joined together by the centromere

Centromere

Area where the chromatids of a chromosome are attached

Homologous pair

a pair of chromosomes, one from each parent

Ploidy

the number of copies of chromosomes

Haploid

a cell with one copy of a chromosome

Diploid

a cell with two copies of a chromosome

Polyploid

a cell with multiple copies of a chromosome (more than 2)

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis, highly variable

Gene linkage

Traits that tend to be inherited together as a consequence location on the chromosome (genes close together get linked together)