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Lecture 2

BIOLOGY 1M03 Lecture 2: Bio-Notes (Podcasts)


Department
Biology
Course Code
BIOLOGY 1M03
Professor
Jon Stone
Lecture
2

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BIOLOGY 1M03 REVIEW
PODCAST 1- CHAPTER 13-oct 28
-evolution determines the characteristics of organisms
ALL OF EVOLUTION- CHANGES OF GENES OVER TIME
BEHAVIOUR- characteristic of an organism
-evolution has therefore determined human behaviour
-not every characteristic of human behaviour can be explained because it is adaptively favoured
in our current environment.
-stopped working so figure something out :)))srrryy
PODCAST 2-same chapter
-long distance exchange- we go somewhere dig up some site and find some rocks there that
don't exist in that neighbourhood so this tells us humans were trading
-they were moving stuff around
-more beads-people are producing more objects
-the point:: if you want to know about behaviour; when did behaviour evolve; maybe if its
walking and u can look at a skeleton and figure out when that individual was doing that by
looking at there bones;
the EXTENDED PHENOTYPE; physical manifestation of our genes, but how about a birds
nest;? its a behaviour that is coded by genes, different species of spiders make diff types of
webs
-all of our material culture; stuff we make; are encoded by our genes. extended phenotype;
means that even the physical stuff we make is encoded
-images and artwork- drawing representational art (thats not a buffalo but everyone in your tribe
knows its a buffalo) its a symbolic representation
-GENETIC EVIDENCE FOR HUMAN PREHISTORY;
-populations left africa sometime around 60kya and we have physical evidence that these
people were overlapping with neanderthals
-homoflorensis- small human species from Philippines
-we have evidence of interbreeding between modern human population populations and
neaderthals and denisovans
-genetic marker- any genetic variation that were trying to use to figure something out
-there are different kinds:
AUTOSOME-chromosomes inherited from mother and father- nonsex chromosomes
Y CHROMOSOME- from father, parts of the non-recombining region NRY combine with the x
and get passed on to u (nuclear dna)
MITOCHONDRIAL- have their own DNA, there unicellular organelles there from your mother,
and it tends to evolve faster than nuclear DNA (there outside the nucleus)
MARKER- variation in genes
SINGLE NUCLEOTIDE POLYMORPHISMS-a base pair in some part of your genome thats
changed, different people in different populations have different base pairs. variable means its
polymorphic
MICROSATELLITE- repetitive DNA, small unit, so a small chunk that says GTC GTC GTC, its
not actually making a protein or coding for DNA, this is a variation we can look at as a marker
HAPLOTYPES- unit of NON RECOMBINING DNA. it makes life easier when trying to trace
lineages back. its inherited as a unit because of this we can use it to trace the history
-mitochondria are haplotypes
-the non recombining part of the y are haplotypes

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BIOLOGY 1M03 REVIEW
-SIGNATURES OF BOTTLENECKS;
-if a population doesn't have much genetic variation it means the population has gone through
a population bottleneck recently
-humans have very low genetic variation in relation to chimps
-this suggests that the entire human population went through a population bottleneck
WHY- because at a constant population size you get a lot of mutations, this increases genetic
variability, less variability through selection, given enough time and no mutation we would get to
a good similar genotype this is MUTATION SELECTION BALANCE
-WHEN the population size gets small the variation is lost
-humans went though one of about 10 thousand so at about one point we are essentially from
all these 10 thousand
CHIMP CHIMP AND HUMAN HUMAN DIVERGENCES
!
-THIS IS SAYING; take two individuals, left (humans ) right (chimps), sample there genes
sequence there mitochondria and see how many differences there are with their mitochondrial
genomes, small numbers here mean that the two samplers are similar and large numbers are
huge differences
BOTTLENECKS
-gene frequencies change because your taking a random sample but you do get less variations
-in the second sample you loose a colour and as the population grows up and the same thing
happens again in the final time: each one is less variable than the last one
-there isn't not enough time in those migrations for the populations to build up again
INFERENCE FROM TREES
-we can build gene trees and find the most common recent ancestor (MRCA) for a haplotype
lineage
-the population is constant
-this is a coalescent process because you look at it backwards in time
-and says if we go back one generation for two people we come from the same
ancestry- a coalescent event
-mitochondrial eve- looking at mitochondria
-Y chromosome adam- u look at non recombining
dna from the y chromosome

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BIOLOGY 1M03 REVIEW
COALESCENT TREES-
-the smaller the population the more chance two people are from the same ancestor
-when was the branching rapid or slow
small pop- more branching
big pop- less branching
HUMAN SPREAD
-first thing that happened was migration out of EAST AFRICA
-quite late they spread from asia to north asia
-middle east to europe
-we can look at climates, 30-50kya the climate got warmer
TWO-MIGRATION THEORY
-it might be that the first was southern asia- australia and much later to europe
-climate was prob more suitable for this
HOMININ CONTEXT
-what kinds of interbreeding happened between modern humans??
-homo sapiens was either nearly or at the same time as other hominid species
know: modern humans coexisted with other hominids particularly neanderthals
and denisovans
-about the graph::: need to know that we can reconstruct past population histories and
that the genetic data backs up what we think about when the bottlenecks were in human
lineages; the africans didn’t go through bottleneck just as much as everybody else
FOSSIL EVIDENCE OF OVERLAP
-we can find anatomically human fossils in AFRICA middle east and asia
-indication #1 that neanderthals and humans overlapped are the fossils in middle east of
anatomically modern humans and neanderthals
PODCAST 3-
NON-CONSISTENT GENE TREES
-one big ancestral population splitting up into 3/4 branches essentially 3/4 species
-the split between hemoglobin a and b is before chimps split
-introgression- the gene moved from one species to another after those species split up
so - someone from one species mated with someone from a different species
INTROGRESSION
NON AFRICAN HUMANS have about 2% neanderthals genome in their genes
ASIAN/ NATIVE AMERICAN have 0.2 % from DENISOVANS
OCEANIAN have 5% from DENOSIVANS
-DENISOVANS were hybridizing with neanderthals
-iclicker:: genetic data indicate that modern humans and neanderthals
DENOSIVANS ARE MORE CLOSLEY RELATED TO NEANDERTHALS THAN EITHER IS TO
MODERN NUMANS
-archaic hominins: someone who is older than the groups we are talking about
-THE ANSWER IS THAT THE MODERN HUMANS AND NEANDERTHALS INTERBRED IN
EUROPE; WHICH MAKES SENSE BECAUSE THEY ALL CAME FROM AFRICA AND
NEANDERTHALS GENES ARE ONLY FOUND IN PEOPLE WITH NON AFRICAN
ANCESTRY
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