Midterm 1 Flashcards
Anthropology
study of humans
cultural, archaeology, linguistic, biological
biological anthropology
what makes us humans?
Great Ape Phylogeny
phylogeny of apes - shows last common ancestor is 5 million years ago
phylogeny: evolutionary tree - closer they are, closer related
comparative approach
compare humans to other species
Why do humans smile (SBT)?
in despotic: SBT when there is a threat
in egalitarian: SBT in many contexts
power emancipation hypothesis
power emancipation hypothesis
human smiling indicated egalitarian hierarchy in evolution
our approach
observe, question, hypothesize, predict, test
convergent evolution
same trait evolves seperately
properties of science
data driven, things aren’t proven, constantly updating/self correcting, not authoritative
facts = laws, big ideas = theories
evolution
change over time
homology
similar structure due to common descent
anatomical evidence for evolution
Genetic Evidence for Evolution
DNA/RNA is universal
vestigal organs
structures from past ancestor that is unused
ex: goosbumps: reaction to being aroused
ex: whale skeletons: hip bones
Fossil Evidence for Evolution
find traces/fossils of species that used to exist; ancestors of species w/ different features suggests change
fossils of humans: sahelanthropus tehadensis, transitional fossils
mistakes and imperfections
show built on pre-existing structure
jury rigged design
ex: baggage of bipedalism, appendix, impacted moalrs
jury rigged design
animals aren’t machines - work w/ what’s available
Evolution is Predictive
origin of tetrapods - able to find when it should have lived (375 mil) - found tiktaalik
Carl Linnaeus
systema nautrae (1735) - organized life into categories
insisted humans are primates & shared simmilarities; taxonmic system
natural theology
18th century belief of human origin; special creation from God & perfectly adapted
18th century biology
branch of theology
had to swear on 39 articles and study religion
William Paley
life is well adapted, so God must be the designer
more detailed science - greater glory to creator (humans = best)
how happened
Lamark
evolution via the inhertiance of acquired characteristics
big mistake is acquired!
what happened
Charles Lyell
uniformitarianism: idea that world changes slowly and constantly
what happened
18th century evidence of evolution
fossils existed
Charles Darwin
wealthy; went on a voyage (Beagle) and developed the theory of evolution
Alfred Russel Wallace
malaria inspired letter with same idea of the theory of evolution
Natural Selection
process by which traits become more or less common in a population
mechanism for evolution
4 postulates of natural selection
competition, variation, reproduction, inheritance
competition
resources are limited, not everyone survives to reproduce + overreproduction is a threat
variation
individuals are different - affects ability to compete & survive
reproduction & inheritance
traits are passed from parent to offspring
galapogos finches example
Peter + Rosemary Grant:
study finches - beak shape correlate to fallback food
in a drought, change in beak style to process harder seeds
adaptive variation
change in response to habitat
cross-foster
switch offspring to determine that it is genetic and not learned
fitness
ability of organism to survive & transmit gene
adaptation
feature shaped by natural selection (survival + reproduction)
homology
traits shared by a common ancestor
go back to common link
homoplasy
traits shared due to convergent evolution
many species can share w/o common ancestor that had trait
Non-Adaptive Traits
mutations & incidental by-products
mutations
small effect @ population level (most rare and don’t work)
more effect when selection relaxed
Incidental by-product
have because of adaptation, but isn’t an adaptation
example: water birds have penises due to underwater fertilization
females have clitoris as a by-product (same developmental tissue)
only mechanism that produces adaptation
natural selection
does not always lead to evolution
behavioral ecology
apply evolutionary theory to behavior
What Darwin couldn’t explain
why are there showy traits?
why are traits not blended away?
where did new variation come from?
why do we help eachother?
he did not know genetics
Gregor Mendel (mid to late 1800s)
monk who experimented in garden
Garden Pea experiment
father of modern genetics
Garden Pea experiment
characteristics had discreet physical forms
seeds: smooth/wrinked, yellow/green
when crossed found that in the first generation (f1), all yellow and round; in the second (f2), mixed
lead to the idea of genes
Dihybrid crosses
cross looking @ two traits
principle of segregation
inheritance of traits determined by genes passed on - one from mother one from father
genes don’t necessarily show
principle of independent assortment
genes for different traits assort independently
Mendellian traits in humans
dimples, freckles, earwax
Cell Theory (1665-1855)
all organisms are made of cells, the most baseic unit of life
all cells are produced from other cells
Rediscovering Mendel (1900)
people did his experiments again and then realized he already existed
Chromosomes
small linear body in nucleus
replicated during cell division & creation of gametes
Chromosome Inheritance Theory (1902)
sea urchins: sperm + egg have 1/2 of chromosoms of a somatic cell
wrong number of chromosomes leads to improper development
sperm + eggs experiment
when frogs had sex in “taffeta pants” - no tadpoles
confirm that sperm was used in sexual reproduction
ploidy
number of chromosmes in a cell (do they have pairs)
diploid, haploid, triploid
2, 1 (gametes), 3 - respectively
Non Mendellian
linkage, pleiotropy, incomplete dom, co-dom, sex linked, trisomy
somatic cells
all cells other than gametes
mitosis
diploid parent cell
chromosomes replicated
divide into diploid identical daughter cells
mitosis
meiosis
diploid parent cell
replication (involving crossing over)
divide into haploid gametes
Principle of Segregation (genetics)
1 copy of chromosome from each parent
Individual Assortment (genetics)
different chromosomes have different genes - independent (esp. bc cross over)
allele
gene variants
homozygous
AA or aa
the alleles are the smae
heterozygous
Aa
the alleles are different
why not blended???
Genotype
combination of alleles in individual
Phenotype
observable characteristics (based on dominant and recessive)
What happens when you breed two heterozygous
Genotype ratio: 1:2:1
Phenotype ratio: 3:1
Crossing over/Recombination
swap info on chromosomes during replication so the two gametes are recombinant types
Linkage
some traits on chromosomes ARE linked - greater the closer they are together
Non-Mendellian Inheritance
Pleiotropy
single gene affects multiple traits
non-mendellian inheritance
Incomplete Dominance
two traits “combine”
ex: straight hair + curly hair = wavy hair
non-mendellian inheritance
Co-Dominance
traits are both dominant and both appear
ex: black and white feathers
ex: AB blood type
non-mendellian inheritance
Sex-Linked
Y-chromosome is small - cannot trump recessive trait on the X-chromosome
ex: colorblindness: allele on X
in XY, Y cannot overpower, but in XX, other X overpowers (carrier)
therefore, more likely to be a trait in people with XY chromosomes
non-mendellian inheritance
Trisomy
chromosomes don’t split in meiosis
ex: extra chromosome in 21 - down sydrome
non-mendellian inheritance
Environmental Implications on Traits
environment can change traits
ex: hydrangea flowers of same genotype have different colors based on soil
non-mendellian inheritance
Polygenic
multiple genes code for trait (ex: skin color)
non-mendellian inheritance
genome
all of the genetic material in a cell, including the DNA.
double helix
structure of DNA
huge sections are non-coding
allows for replication and inheritance
made of base-pairs: Adenine - Thymine, Cytosine - Guanine
Who discovered DNA?
Watson, Crick, and Franklin
DNA replication
“unzips” - now has a template due to pairs, and can copy
Importance of Proteins
structural: muscle, collagen, keratin
enzymes: affect & allow chemical reactions in the body
regulatory proteins
structure of proteins
amino acids into peptides
20 amino acids that go into differnt sequences depending on the code
how does DNA code?
DNA is transcipted into RNA which is translated into a protein
the bases combine into 3 letter codons, each of which code for amino acids
DNA transcribed into mRNA (which has U instead of T), which attaches to the ribosome
tRNA brings the amino acids - makes a protein
Why are codons repetitive?
reduces the likelihood of a mutation changing something
non-synonomous mutation
something changes
synonymous mutation
nothing changes
gene regulation
some DNA is regulatory
ex:
repressor regions (prevent)
activator regions (turn on)
enhancers (increase rate)
Explain Lactase persistence
lactase decreases after waining to conserve energy at a cellular level - sometimes persists
neolithic revolution (12000-6000 ya) - farm + conserve dairy
biocultural coevolution theory
convergent evolution in Europe and Asia
pastoralism
cultural practice of milking livestock
biocultural coevolution theory
pastoralism coevolved with lactase persistence
both changes reinforced eachother
What is the mutation for Lactase persistence?
SNP - change in regulation of lactase
biometrics
getting data on human characteristics
racist undertones/history
continuous variation
work of many genes - almost impossible for single gene to control
in many cases, will have a bell curve - show mendellian for each individual gene
Population Genetics
change in population over time
natural sellection acts on phenotype but changes frequencies of alleles in the population
Evolution causes
natural selection, mutation, migration, genetic drift
Population
group of individuals of same species that can interbreed with eachother (big locations or small)
Gene Pool
all genes and alleles in a population
look for changes of frequencies in alleles in gene pool - indicator of evolution
Genotype Frequency
number with a particular genotype/number of individuals in a population
Allele Frequency
copy of alleles/total number of alleles for the gene
Hardy-Weinberg Principle
allele proportions constant if no evolution
p = frequency of A
q = frequency of a
p+q = 1
q = frequency of (aa) + 0.5(frequency A)
q^2 +2pq + p^2 = 1
if alleles stay consistent, genotype will reach equilibrium
When does the Hardy-Weinberg Principle hold?
- large population size
- random mating
- no mutation
- no alleles transferring in or out
- no selection
Agents of Evolutionary Change
natural selection, mutation, gene flow, non-random mating, genetic drift
direct fitness
number of genomes passed directly to next generation
indirect fitness
number of genomes passed via relatives
inclusive fitness
number of direct + number of indirect
natural selection favors
inheritance of acquired characteristics
epigenetics
ex: rat licking
methylation stops genes from being transcribed
when not licked, methylated, and don’t lick
when licked, non methylated, and lick
not tied to genes
how is variation maintained?
mutations and hidden variation
microevolution
allele frequency changes within population
macroevolution
origin of new taxonomic groups above level of species
Peppered Moth
example of microevolution: dark color blended in with soot covered trees in industrial revolution
how to connect macro + micro evolution
microevolutions put togeter make macro
species
darwin: rhetorical
clustered by genotypic and phenotypic traits
(sometimes can only tell through chromosomal analysis)
Biological Species Concept (BSC)
species: can breed and reproductively isolated
Barriers to reproduction
- ecological (space)
- temporal (time)
- behavioral (preference)
- mechanical (physically impossible)
- gametic incompatibility
Behavioral Barrier
green lacewings: song differences
Mechanical Barrier
Drosophila: genital arches differ
Snail shells swirl in same direction
Post Zygotic Barriers to Reproduction
- instability (miscarriage)
- hybrid inviability (die before reproduce)
- hybrid stability (offspring cannot reproduce)
- hybrid breakdown (over few generations, die off)
Problems with BSC
doesn’t apply to fossils, cannot apply to asexual species
Ecological Species Concept
reproductive isolation is not necessary
natural selection keeps species distant from onee another (hybrids can’t compete as welll)
Humans and the BSC
- 7 mil YA: humans and chimps split; 500000 YA: Neanderthals split; 70000 YA: emigrate out of Africa and encounter Neaderthals
- interbreed (modern 2%)
- selection acted against hybrids
Speciation
when 2 populations genetically diverge (on node of phylogenic tree)
allopatric and parapatric and sympatic
Allopatric Speciation
geographical isolation + natural selection
character displacement pushes traits to both ends
Parapatric Speciation
selection + partial geographic isolation
hybrid zones, but natural selection keeps seperate
Sympatic Speciation
populations in same place; instantaneous speciation
taxonomy
groupings of organisms based on shared characteristics
phylogeny
evolutionary relations between species
phylogenic tree
branches that show species based on shared morphology
if go to top, share trait
if don’t go to the top, extinct
distance: take all the lines and lay flat
Why Reconstruct Phylogeny
explains why certain adaptations evolved
ancestral trait
present in common ancestor
derived trait
arose since common ancestor
molecular clock
average rate at which species genome accumulates mutations
