BIO 1B MIDTERM 1

rules of evolution

• Evolution is a fact

• Pattern of change

  • How organisms adapt over time

• Mechanism that causes change

what is uniformitarianism?

the same natural laws that occur have always occurred

Charles Darwin facts

• Voyaged and collected specimens for his research 

  • Age 22 - 27

  • Wrote “The Transmutation of Species” (1838) notebook on his voyage

the origin of species (1859) chapter 1

• CH 1: Variation Under Domestication

  • Variation traits

  • Heritable traits

    • Variation is heritable 

  • Select for desirable traits

    • Selective breeding possible

the origin of species (1859) chapter 2

• CH 2: Variation in Wild

  • Mimics variation in domesticated animals/plants

the origin of species (1859) chapter 3

• CH 3: Struggle for Existence

  • Natural theology

    • “every organism is harmonious in nature”

  • Thomas Malthus

    • Human growth is exponential

the origin of species (1859) chapter 4

• CH 4: Natural Selection

  • Traits to allow a population to survive better in their environment

    • A species evolves, not the individuals within

      • Beneficial to the individual population, not the species

    • Causes adaptation

    • Lots of time required

the origin of species (1859) chapter 5

• CH 5: Potential Objections:

  • Transitional forms exist in past not present

    • ex: fossil documents of ancestors

  • Large transitions

the origin of species (1859) chapter 6

• CH 6: Explanatory Power:

  • Ability for a theory to explain a biological phenomenon

  • Similar organisms live in one area since ancestors did

what are Darwins four observations?

• Oceanic islands have low diversity

  • Due to lack of accessibility

• There is a bias of presence of certain kinds

• Most similar kind to oceanic forms are on nearest continent

• There is a bias in the type of species found on oceanic islands

  • Plants, insects, birds, etc. (things that can withstand the salt water)

what does homologous mean?

similarities between ancestors and common day relatives

what does pseudogene mean?

•  non-functional gene that was copied but is not expressed

  • Ruined by mutations

what is a homeotic mutation?

 a body part develops into another (extra/displaced body parts)

what is a X1Hbox mutation?

causes antierios parts to look like posterior parts

what is a hox gene?

group of genes that regulate the development of body parts in animals

what is population genetics?

the study of Mendialian genes in populations

what is a population?

group of individuals of same species that can interbreed and is isolated from other populations of same species

what is the hardy Weinberg equation?

•  p^2 +2pq + q^2

  • If equation = 1, in equilibrium

  • If expected matches observed, in HWE

  • Phenotype: the observable

  • Genotype: the physical genetic makeup

what changes allele frequency?

mutation, genetic drift, gene flow, and natural selection

what is a mutation?

• Random error in DNA replication

  • Point mutation: change from coding DNA (ex: A to G)

    • Four bases: A, C, T, G

    • 20 amino acids

    • Codon is first three bases

    • Transitions: C to T, A to G

    • Transversions: A to T, C to G

  • Insertions or deletions of DNA

  • Inversions

  • Duplications of segments 

• They are rare, frequency of 1/2N

• All variation in a population is created by mutation

what is genetic drift?

• Changes in allele frequencies caused by finite population size

• More powerfun, causes larger fluctuations in allele frequency from one generation to the next

• Will eventually cause an allele to be lost and other to be fixed in population (frequency of 1.0)

• Chance that allele is fixed is 1/2N

• Bottleneck Effect: population size is reduced for the species

• Founder Event: a population separates and makes its own population

• A substitution is a fixed difference between two species

  • Kimura is the rate of substitution calculated: k = u x 2N x 1/2N = u

    • u x 2N: number of neutral mutations introduced to the population every generation

    • 1/2N: probability of the mutations being fixed

what is the bottleneck effect?

• population size is reduced for the species

what is a founder event?

• a population separates and makes its own population

what is natural selection?

• Favors big allele 

• Directional selection: overtime the big allele will become fixed (1.0)

• Purifying selection: removes harmful alleles from the population

  • Ensures bad mutations do not take over 

• Balancing selection: maintains genetic diversity by preserving multiple alleles

what is directional selection?

•  overtime the big allele will become fixed (1.0)

what is purifying selection?

•  removes harmful alleles from the population

  • Ensures bad mutations do not take over 

what is balancing selection?

• maintains genetic diversity by preserving multiple alleles

what is gene flow?

• Gene flow: movement of individuals and the alleles they carry from one population to another

• Increasing gene flow causes the groups to become similar to each other

• Decreasing gene flow causes diversity to become limited

what is senescence?

•  process of aging

  • Cells stop dividing but do not die

what is neutral mutation?

• change in DNA sequence that does not benefit the organism for survival or reproduction

what is a deleterious mutation?

• harmful change in the DNA sequence that can negatively impact an organism's health, survival, or reproduction

what is adaptive color polymorphism

• genetic trait that allows organisms to have multiple colors

what is an outgroup species?

• species that is closely related to a group of interest, but is not part of the group

what is a homologous gene?

gene that is shared by two or more species after being inherited from a common ancestor

what is homology?

similarity in form caused by common ancestry

what is lineage sorting?

process where multiple populations are descended from common ancestor but cannot reproduce

What is synapomorphy?

a shared derived characteristic

What is homoplasy?

a character that evolves more than once on a tree

what does sex do genetically?

gamete formation (eggs and sperm), spread of chromosomes, and independent assortment (genes separate during formation)

what is isogamy?

gametes are same size

what is anisogamy?

gametes can be different sizes

what is an hermaphrodite?

a being that has both male and female reproductive organs, can change genders

what is protandry?

male first then transitioned to female

what is protogyny?

female first, transitioned to male

name for both asexual reproduction in plants and animals

apomixis in plants, parthenogenesis in animals

what is the two-fold cost of sex?

• Asexual species:

  • Produce copies of themselves, if one female start they will all be female

• Sexual species:

  • Produces on average one female and one male

fishers model for evolution

sexually reproducing species adapt more rapidly to a changing environment

mullers model of evolution

sexually reproducing species can more easily purge deleterious mutations

two types of sexual selection

male to male competition vs. male choice

what is the morphological species concept?

a species is a group of organisms that share physical characteristics but are distinct from others with physical characteristics

what is the biological species concept?

a species is a group of organisms that can reproduce with each other and produce fertile offspring

what is species formation?

• First step is the restriction or elimination of gene flow

• Allopatric: separated by geography, gene flow restricted

• Sympatric: same area, gene flow restricted

what is allopatric?

separated by geography, gene flow restricted

what is sympatric?

same area, gene flow restricted

two classes of isolating mechanisms

• Pre-zygotic: mechanics that prevent the egg from being formed in the first placed

  • Examples:

    • Courtship dances

    • Sexual parts do not fit each other

• Post-zygotic: mechanics that prevent the normal development after the zygote has been formed

  • Examples:

    • Infertility

what is pre-zygotic?

• mechanics that prevent the egg from being formed in the first placed

what is post-zygotic?

• mechanics that prevent the normal development after the zygote has been formed

what is adaptive radiations?

rapid diversification of a species into many new forms

what is viviparity?

gives live birth

what is a hominid?

lineage from common ancestor

parts of chromosomes

• Telomeres: ends of chromosomes

• Centromeres: where the spindle is, place of joining together

who was adripithecus?

• extinct hominid that was discovered in Ethiopia

  • Walked bipedally: walked upright

  • Evidence that Ardi walked bipedally:

    • Shape of upper pelvis

    • Shape of lateral foot

    • Shortened cranial base

what are traits of homo?

• larger brain, smaller/flatter face, smaller teeth/jaws, greater height, longer legs