Evolution Exam 1 Study Guide

Descent with modification

1. Earth and life are OLD 2. New life-forms derive from older forms = macroevolution 3. All life-forms are related = Shared Ancestry 4. Lineages split and diverge = speciation 5. Species change over time = microevolution

Types of mutation

1. Point mutation 2. Insertion 3. Gene duplication 4. Deletion 5. Genome duplication 6. Inversion 7. Chromosome fusion

Synapomorphies

A derived form of a trait that is shared by a group of related species (i.e. one that evolved in the immediate common ancestor of the group and was inherited by all of its descendants)

Phylogram

A phylogenetic tree with branch lengths proportional to the amount of character change

Dendogram

A picture of evolutionary relationships No time scale, no weighting of characteristics, not based on empirical data A primitive hypothesis of evolutionary descent E.x. Darwin's first phylogeny

Evolutionary reversal

A reversion of a derived character state to a form resembling its ancestral state

Gene duplication

A segment of DNA is copied a second time A small duplication can produced an extra copy of a region inside a gene, or a copy of an entire gene

Inversion

A segment of DNA is flipped around and inserted backwards into its original position

Insertion

A segment of DNA is inserted into the middle of an existing sequence This insertion may be as short as a single base or as long as thousands of bases

Deletion

A segment of DNA may be deleted accidentally A small portion of a gene may disappear, or an entire set of genes may be removed

Morphogen

A signaling molecule that flows between nearby cells and acts directly to alter expression of target genes

Synapsids

A skull with one hole in it for jaw musculature Found in mammals Evolved later than diapsids

Diapisids

A skull with two holes in it for jaw musculature Found in reptiles Allows for strong bites

Polyphenism

A trait for which multiple, discrete phenotypes can arise from a single genotype depending on environmental circumstances

Analogous trait

A trait that has a similar function in two species because they both independently evolved it (convergent evolution) NOT due to a common ancestor

Exaptation

A trait that initially carries out one function and is later co-opted for a new function. The original function may or may not be retained E.x. Dinosaur feathers were originally used for coloration, became co-opted for flight

Genome duplication

All the nuclear DNA in a cell is copied

Dominant allele

Allele that exerts itself over the other allele, is always expressed In heterozygotes, will express itself over the recessive allele to determine the phenotype

Biological evolution

Any change in the inherited traits of a population that occurs from one generation to the next (i.e., over a time period longer than the lifetime of an individual in the population) Change has to be passed down Encoded in genes

Mutation

Any change to the genomic sequence of an organism Multiple types of mutations

Lord Kelvin

Argued that the earth couldn't be hundreds of millions of years old Proposed that the earth was formed as molten rock which space then cooled into the crust. The heat left inside the planet flowed to the surface. Thus if a rock cools at a steady rate (and rocks deep underground are still warm), the earth has not cooled enough to be super old. He estimated the earth to be 20 million years old at most This was wrong b/c his calculations were based on earth as a rigid sphere

Nucleotide

Basic unit of DNA Has a nitrogenous base 4 types Guanine pairs with cytosine Thymine pairs with adenine

Amino Acids

Basic unit of proteins 20 different types Have primary - Quaternary structure Each amino acid is determined by codons (3 bases) on DNA

Homologous trait

Characteristics which are similar in two or more species because they are inherited from a common ancestor

Alfred Russel Wallace

Corresponded closely with Darwin Wallace effect - Two different populations separate and speciate. If they meet again, hybrids selected against, speciation occurs again (now called reinforcement) Also proposed that life had evolved Agreed with the idea of natural selection His letters to Darwin were read at the Linnean society

Recombination

Crossing over during meiosis Creates genetic variation

Transposable element

DNA sequence that can change position within the genome, at times creating or reversing mutations and altering the cells genome size Discovered by Barabara McClintock

Radioactive isotopes

Decay at a steady rate and have a half life Half life = the amount of time it takes for half of the isotope's atoms to decay Parent isotope decays into more stable daughter isotopes Used for radiometric dating = using the half-lifes of atoms in rocks to estimate their age

Homoplasy

Describes a character state similarity not due to shared descent (e.g produced by convergent evolution or evolutionary reversal)

Monophyletic

Describes a group of organisms that form a clade Most recent common ancestor with all of its descendants

Paraphyletic

Describes a group of organisms that share a common ancestor although the group does not include all the descendants of that common ancestor

Polyphyletic

Describes a taxon that does not include the common ancestor of all members of the taxon A grouping of two species without a common ancestor included

Marie Curie

Discovered radioactive isotope decay Instrumental in development of radiometric dating (carbon dating)

William Smith

Discovered that different rock layers contained distinct fossils (old fossils in old rocks, new fossils in newer rocks) Thus the different strata of rocks were set apart by time E.x. A dinosaur that lived 100 million years ago would be found in the layer of rock that was set down around that time

Barbara McClintock

Discovered transposable elements Studied Maize corn

Thomas Malthus

Economists who thought that population growth would outstrip food production Humans would reach their carrying capacity on earth due to lack of natural resources

Charles Darwin

English naturalist Trained at medical school Traveled on the HMS beagle in 1931 Collected many fossils, living organisms Studied geology Developed the theory of evolution (descent with modification) Published "On the Origin of Species" Influenced by many who came before him Believed in common ancestry, natural selection

Mary Annig

English woman who discovered many marine fossils on the English coast These fossils provided evidence for the concept of evolution

Artificial selection

Evidence of microevolution (species change over time) When humans select for certain traits in a population, breeding animals so that those traits become more common or exaggerated

Macroevolution

Evolution occurring above the species level, including the origination, diversification, and extinction of species over long periods of evolutionary time

Microevolution

Evolution occurring within populations, including adaptive and neutral changes in allele frequencies from one generation to the next

Speciation

Evolutionary process by which new species arise Speciation causes one evolutionary lineage to split into two or more lineages

Nicolas Steno

Father of geology and stratigraphy (study of layering in rock) Believed "tongue stones" were actually fossilized shark teeth Two critical ideas 1. Life and earth had a history of change 2. Earth itself kept a record of that history Didn't believe in evolution Catholic Bishop

Carl Linnaeus

Father of modern taxonomy Classified animals into a system and hierarchy Organized life into species, genus, phylum, etc Believed God had created life's diversity in the beginning (i.e. all species have been present from the beginning of creation)

Georges Cuvier

French naturalist who pioneered the study of paleontology Compared elephant fossils to modern skeletons and discovered key differences Proposed these fossils (called mammoths) were species that had gone extinct Believed species had gone extinct and others rose up to take their place Rejected evolution

Point mutation

Gene mutation in which a single base pair in DNA has been changed

Genotype

Genetic make up of an individual Also applies to specific alleles for any gene of interest

Clade

Group of related organisms Organism and all of its descendants

How are whales related to hippos?

Have many homologous structures - earbone structure, presence of a pelvic girdle, presence of anklebones

Independent assortment

How homologous chromosomes align at meiosis Also creates genetic variation

Adaptations

Inherited traits of an individual that allow it to outcompete other members of the same population that lack the trait Adaptations are traits that have evolved through the mechanism of natural selection

Jean-Baptiste Lamarck

Life driven from simple to complex Complex species had descended from microbes Believed animals could adapt to their environment (Giraffe stretching his neck to eat) - this adaptation would then be passed down to its offspring (this was incorrect b/c somatic mutations cant be passed down) First proponent of evolution

Panspermia Hypothesis

Life originated elsewhere in the universe and traveled here on asteroids and meteorites The primitive cells then colonized earth

Oparin-Haldane model

Life started on earth from a chemical "soup" Eventually DNA, proteins, lipids were found in the soup These gave rise to eventual organisms

Natural Selection

Mechanism that can lead to evolution, whereby differential survival and reproduction of individuals cause some genetic types to out-compete others NOT survival of the fittest ( only true if fittest means producing more offspring) Started by random mutation which is helpful in the habitat Passing these genes on is the MOST important thing

Biomarker

Molecule produced only through biological activity Include fragments of DNA, lipids, etc Molecular evidence of life in the fossil record

Recessive allele

Must be homozygous in order to be expressed Will not be expressed in a heterozygote

Germ-line mutations

Mutations in gametes (eggs, sperm) of an individual that can be transmitted to offspring Because they can be passed on, germ-line mutations create the heritable genetic variation that is relevant to evolution

Somatic mutations

Mutations that occur in body cells and are passed down to all daughter cells produced by the mutated cell Can affect the phenotype of the individual Not passed down to offspring

Ockham's razor/ The principle of Parsimony

Notion that the simplest explanation of a phenomenon is the one that is most likely to be correct. Parsimony = the phylogenetic tree with the least amount of changes is probably correct

Phenotype

Observable, measurable characteristics of an organism Determined by genotype and environment

Viral reassortment

Occurs when genetic material from different strains gets mixed into new combinations within a single individual Several strains of a virus come together, become more potent, can then attack humans

Chronogram

Phylogenetic tree that shows time of evolution through its branch length Most common in publications

Georges Buffon

Proposed that the earth formed according to laws of physics and chemistry and from debris of the Sun Believed earth to be old (70,000 years) Proposed that life started from organic particles in the ocean Believed life had distinct types when it first emerged, BUT also thought populations could change over time Argued life had changed over time

Taxon

Refers to groups of organisms that a taxonomist judges to be cohesive units, such as a species or order Group of organisms put together as a unit (phylum, etc)

Ploidy

Refers to the number of copies of unique chromosomes in a cell (n) Haploid = n Diploid = 2n Triploid = 3n

Extinction

Refers to the permanent loss of a species Marked by the death or failure to breed of the last individual

James Hutton

Scottish chemist and geologist Recognized that change is gradual on earth - processes (like sediment deposition) accumulate over time Thus thought that the earth was very old

Polyphenic trait

Single genotype produces multiple phenotypes depending on environment

Phenotypic plasticity

The ability of one genotype to produce more than one phenotype when exposed to different environments

Random fertilization

The combination of each unique sperm with each unique egg increases genetic variability Not all sperm reach every egg

Reaction Norm

The pattern of phenotypic expression of a single genotype across a range of environments

Gene expression

The process by which information from a gene is transformed into a product

Zoonosis

The process of infectious disease transmission between species When a disease jumps from an animal to a human

Taxonomy

The science of describing, naming, and classifying species of living or fossil organisms

Paleontology

The study of prehistoric life

Cladogram

Tree with branching pattern that shows relationships between organisms Groups similar organisms together Doesn't show time or ancestral relationships thus it is not an evolutionary tree

Chromosome fusion

Two chromosomes are joined together as one

Phylogeny

Visual representation of the evolutionary history of populations, genes, or species Always a hypothesis of the evolutionary relationships b/w species

Heterozygotic state

When a trait has both the dominant and recessive allele The dominant allele is expressed over the recessive

Homozygous state

When a trait has the both of the same type of allele Can either be both dominant or both recessive

Shared Ancestry

When two species share a common ancestor All life can be traced back to one ancestor The more two species share an ancestry, the closer related they are

Convergent evolution

the independent origin of similar traits in separate evolutionary lineages Similar environments lead to similar adaptations in unrelated species E.x. Both birds and bats evolved to fly but aren't closely related