Mon, Jan 30

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Mon, Jan 30 Teaching Assistant Lindsey
West email lindwest_at_gmail.com office hours
(M-3-551) Monday 3-4 Tuesday 11-12 or by
appt. Professor Jane Adams, Ph.D. Office
hours (M-2-270 M and F after class until
100 Parts of lecture adapted from
http//evolution.berkeley.edu
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• Evolution
• descent with modification
• central idea all life forms share a common
  ancestor
• process that results in heritable changes in a
  population from one generation to the next.
• Process acts on individuals, but this changes
  the composition/ characteristics of groups
• well-established theory (scientific fact
  equivalent to fact of gravity)

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Phylogeny the evolutionary history of a group
of organisms Often represented by a family
tree. The root of the tree represents the
ancestral lineage. Branching represents the
formation of a new species. The tips of the
branches represent the descendents of that
ancestor. As you move from the root to the tips,
you are moving forward in time.
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• Evolution produces a pattern of relationships
  among ancestral lineages that is tree-like, not
  ladder-like.

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• Just because we tend to read phylogenies from
  left to right, there is no correlation with level
  of "advancement."

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• For any speciation event on a phylogeny, the
  choice of which lineage goes to the right and
  which goes to the left is arbitrary. The
  following phylogenies are equivalent

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• It is important to remember that
• Humans did not evolve from chimpanzees. Humans
  and chimpanzees are evolutionary cousins and
  share a recent common ancestor that was neither
  chimpanzee nor human.
• Humans are not "higher" or "more evolved" than
  other living lineages. Since our lineages split,
  humans and chimpanzees have each evolved traits
  unique to our own lineages.

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• Ancestral histories (Phylogenies) are
  constructed by placing pieces of evidence
  together.
• Heritable traits (things passed down
  through genetics) are compared across organisms -
  physical characteristics (morphology), genetic
  sequences, and behavioral traits.
• Data used to build hypotheses about the
  relationships between species phylogenetic
  histories.

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• Evolution
• I. Darwin (1859)
• summarized all of the evidence in favor of idea
  that all organisms have descended with
  modification from a common ancestor
• proposed natural selection as the mechanism
• Natural selection - mechanism through which a
  differential production of offspring occurs by
  selected members of a species

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• Natural selection depends on
• presence of many individuals with variable
  characteristics
• environment determines who has right
  characteristics to survive and leave offspring
• selection acts on the individual but determines
  characteristics of the next generation

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• Modern theory of evolution
• recognizes that characteristics are inherited as
  discrete entities called genes
• recognizes other mechanisms of evolution
  (mutation, random genetic drift)
• postulates that species can be created gradually
  over long periods of time or due to punctuated
  changes

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Human Phylogeny Kingdom - Animal Phylum -
Chordate Subphylum - Vertebrate Class -
Mammals Order - Primates Family -
Hominidae Genus - Homo Species - Sapiens
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• Basis of Heredity
• Chromosomes (23 pairs) - long thin structures in
  the nucleus of each cell.
• Each chromosome is a double-stranded molecule of
  DNA. DNA consists of a sequence of nucleotide
  bases this is the genetic code.
• DNA - blueprint for life instruction set for
  creating and sustaining life (and death).
• Humans have 23 pairs of chromosomes one member
  of each pair (and the corresponding set of genes)
  comes from the father and the other from the
  mother.

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Basis of Heredity 2. Genes units of
inheritance the sections of a chromosome (the
segment of base pairs on DNA) that controls the
synthesis of one protein responsible for one
trait. For each trait, we have one gene from
Dad and one from Mom The 2 genes that control the
same trait known as alleles.
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Two genes code for one expressed trait. When both
are the same - homozygous When the 2 are
different - heterozygous When different, 1
dominant gene determines the trait. For moth
color brown is dominant over white. If one
parent contributes a brown gene and other a white
baby moth is brown. If both contribute a white
gene moth is white (a recessive trait)
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Genotype - genetic makeup all genes (half from
Dad, half from Mom) Phenotype - the traits that
are expressed. Natural selection acts on the
phenotype the individuals traits.
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Dark color Light color 2 genes
2 genes DD or Dl
ll Dark (D) is dominant Light (ll)
is recessive and is
expressed only when 2 l
recessive genes are inherited. Moth
color a phenotypic trait. Genotype may vary for
the same dark phenotype.
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Examples of Natural Selection acting on the
Phenotype 1. An English moth - light (98) and
dark (2) types --gt a few years passed --gt 95
dark type present. Why? - industrial revolution
presence of soot made it easier for birds to see
the light moths - ate them. Dark survived and
passed on genes to next generation.
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2. Humans with sickle cell genes Red blood cells
- round or sickle shaped. 2 genes for round -
healthiest normally (carry oxygen well). 2 genes
for sickle - unhealthy anemic (cannot carry
oxygen well enough). 1 round and 1 sickle -
provides resistance to malaria. Shape makes it
harder for malaria organism to enter
cell Malaria present - best survival by sickle
cell heterozygotes. Sickle gene at high frequency
in Africa, India, parts of Middle East where
malaria was/is a problem.