SECTION 2- Only the most AWESOMEST SECTION EVER!!!!

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SECTION 2-Only the most AWESOMEST
SECTION EVER!!!!

• (this is where you burst into applause and dance)

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Darwin-Hes the man

• Darwin was born in 1809 and the world was bathed
  in sunshine and angels!
• Darwin was not very good in school( that sounds
  really familiar, Einstein?)
• He came from a pretty famous family
• Erasmus Darwin(1731-1802) was his granddaddy
• Josiah Wedgewood(1730-1795) was his other
  grandaddy who made fine pottery

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Darwins boring family

• Robert Darwin and Susannah Wedgewood were his
  parents, and they raised their children in the
  Anglican Church
• Darwin loved the great outdoors, which was fine,
  except that upper-class gentleman had to have
  some real profession.

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Darwins Education

• Edinburgh University 1825 for medicine..and he
  soon discovered it wasnt for the faint of heart
• Christs College in Cambridge (by his dad) to
  study for the clergy

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• While there, he became really fascinated with
  beetles, and nature stuff
• Became really good friends with Botany professor
  John Henslow and Geology professor Adam Sedgewick

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Darwins Two Epiphanies

• 1- I guess he was bored one day and picked up a
  copy of Zoonomia by Erasmus Darwin
• He notes that perhaps many characteristics of
  species had changed throughout the course of
  history and even came from a single filament

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Darwins Two Epiphanies

• Darwin was with Professor Sedgewick when a local
  workman discovered a fossil of a tropical mollusk
• It annoyed Sedgewick because Wales was not a
  tropical place, so where did it come from? (this
  is a rhetorical question, cuz I know you cant
  answer itYET!)

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Darwin Gets a Break Onto the Beagle

• Captain FitzRoy was leading an expedition to
  South America about his ship the HMS Beagle
• Henslow recommended Darwin, who got a job as
  naturalist on the Beagle

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• To prepare, he read Principles of Geology by
  Charles Lyell
• Lyell claimed that the extinct species that
  appeared in the fossil record were a result of
  Earths gradual changes that modified the
  conditions the creatures lived in

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And here it comes.

• Darwin makes an inference!
• If species are always dying, but there are plenty
  of other species on earth, new ones must have
  arisenwhich means they could still be doing it.
• So blah blah blahpreparationstechnical
  detailsreading. And then they SET SAIL!

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What happens in South America, Stays in South
America.

• They get to SA and near the Straits of Magellan,
  Darwin experiences an Earthquake
• The earthquake exposes fossilized seashells, and
  he later discovers a petrified forest higher up
  and a fossilized horse tooth
• BUT WAIT
• Horses didnt come to South America until the
  Spanish came in the 16th centurycurious

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• IN 1835 the Beagle finally makes it to the
  Galapagos!
• He makes a great observation the animals and
  plants were unique to every island
• After this stunning observation, the packet
  rudely breaks off and talks about the journey
  back, so I suppose we have to move onsigh

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Home Sweet Home

• On the way home, the Beagle stops by the Cape
  Verde Islands.
• Well thats weird says Darwin, The animals in
  Africa look an awful lot like the ones in South
  AmericaCaptain, are you sure were near Africa?

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And now, passages of the most boring book ever
written, The Voyage of the Beagle

• The only good thing about it is that it will put
  you to sleep several times in the course of a
  minutefor those of you who are tormented by
  thoughts of natural selection every night

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A reluctant summary

• Darwin stops on the Galapagos Islands, all of
  them, and makes long, frivolously detailed notes
• Note all of these islands were caused by
  volcanic activity
• Chatham Island- Parched surface, little
  vegetation, lots of craters. Darwin meets two
  large tortoises
• Charles Island- Small colony of Ecuadorians who
  hunt turtles. Darwin observes their numbers have
  fallen significantly.
• Albemarle-Found a salt lake and big black lizards

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Summary continued

• James Island- Stays with the natives and eats
  some of their delicacy (the tortoise) . He
  follows some Spaniards to a salt lake where he
  sees the skull of an unfortunate captain.
  Observes more similarities
• Both in space and time, we seem to be brought
  somewhat near to that great-that mystery of
  mysteries-the first appearance of new beings on
  this earth.
• Observes rat species This rat is merely a
  variety produced by the new and peculiar climate,
  food, and soil, to which it has been subjected

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• Darwin makes boring observations of the different
  bird beaks on the island, especially of Totanusgt
• He describes some interesting reptiles native to
  the Galapagos, Amblyrhynchus
• Notes the absence of frogs May this difference
  not be caused, by the greater facility with which
  the eggs of lizards, protected by calcareous
  shells might be transported through salt water,
  than could the slimy spawn of frogs?

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Darwins tortoises

• They are amazingly large, over 200 pounds!
• They travel long distances for water, in line
  formation!
• Hypothesizes that tortoises bladders help them
  consume large quantities of water and that they
  are native to the Galapagos
• As part of his naturalist role, Darwin takes a
  ride on one of the tortoises!!!

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Amblyrhynchus (lizards)

• There are two species-
• A. cristatus (aquatic)
• hideous, black color, stupid and sluggish
• Sun themselves on rocks
• Limbs adapted for crawling over masses of lava
• Eat seaweed
• BUT, when its scared, it will not enter the
  water!!!
• Darwin tested this out, read page 40!

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Amblyrhynchus (lizards)

• The second species A. Demarlii, is terrestrial
• Confined to central part of Galapagos islands
• Yellow-orange on belly and brownish on top
• from their low facial angle they have a
  singularly stupid appearance
• They inhabit burrows and they cannot move very
  fast because of the lateral position of their
  legs
• The lizard lives well with other animalsit
  allowed a bird to ride on its back

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More zoological observationsas if we havent had
enough

• Darwin basically takes inventory on page 42, and
  notes that the species of everything he collects
  is unique to the islands
• But its still not nearly as impressive as St.
  Helena or Hawaii

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I never thought Id be so happy to talk about
plants

• Look at the table on page 44 for a summary of
  Darwins plant collections
• These species, having the same general habits,
  occupying analogous situations, and obviously
  filling the same place in the natural economy of
  this archipelago, that strikes me with wonder

• Darwin calls it a creative force

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On the tameness of those lame birds

• The birds appear unafraid of humans
• Darwin thinks it is not acquired by individual
  birds in a short time, even when much persecuted
  but that in the course of successive generations
  it becomes hereditary
• How is this different from Lamarck?

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Congratulations! You made it through a passage
that most biologists shudder to even think about
reading!

• And now, I will hand over the explanation of
  adaptive radiation to our beautiful little bird
  Fincha!

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Tweet Tweet

• Tweet tweet tweet tweet tweet
• tweet tweet
• Trill
• tweet tweet tweet tweet tweet
• Trill
• tweet tweet tweet
• Tweet
• Tweet
• Tweet
• Did you get all that?

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ADAPTIVE RADIATION!

• All about how cute little birds became cuter, or
  uglier, it depends

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The tree of life
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Four important questions all biologists think
about at night

1. Origins Where did the ancestors come from, when
   and how?
2. Speciation How and why are new species formed?
3. Diversity Why are there x number of species?
4. Disparity Why are these species as different or
   as similar as they are?

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Talk to me Bird!

• Finches arose in SA, but traveled 1000km to the
  Galapagos
• The only living relative of the finches we know
  of are grassquit genus Tiaris
• The finches must have reproduced fast and often,
  because their doubling time is 750, 000 years

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One speciesTwo species?

• The allopatric model of speciation developed by
  Leopold von Buch in 1825 can explain that.
• And, just to throw a Russian name in here,
  Theodosius Dobzhansky elaborated on it
• The basic idea of allopatric model is that
  GEOGRAPHIC SEPARATION is needed for new species
  to form

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There are three steps to allopatric speciation

1. A species from the mainland colonizes an island
   and the population adapts to the environment by
   natural selection (remember, those who are most
   fit for that environment survive and reproduce,
   creating a population that is better fit!!)

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• 2. A few members of the population colonize a
  second island and adapt to the conditions on that
  islandafter a few generations, this species has
  become so different that they have diverged from
  the mother species.
• 3. the two species meet up againand crazy things
  start to happen!!! There are three possible
  outcomes

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Three possible outcomes

• the members of the populations will interbreed
  without loss of fitness
• the members of the population will interbreed BUT
  they will lose fitness
• the members of the populations will not
  interbreed at all

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Sound cool doesnt it? WRONG!

• Except that this model makes a few wrong
  assumptions

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Wrong assumption 1

• The two species were separated for a long time
  and then came to live on the same island
• We now know that it doesnt matter how far apart
  a population is from another, something called
  sympatric speciation
• The populations could overlap, but for different
  reasons, evolve separately depending on
  ecological niche

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Wrong assumption 2

• The islands all existed at the time of
  speciation.
• Biologists have traced back to three million
  years ago, which is when the speciation started,
  and found as the number of islands increased, so
  did the number of finch species
• So they have hypothesized that the finches
  arrived on the Galapagos at the start of the Ice
  AgeTHIS IS A FREAKIN OLD SPECIES

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The authors of this article have something to
doother than stimulate us with their exciting
information

• They study seed-eating ground finches on Daphne
  Major
• It all started in the drought of 1977 that
  prevented seed-producing plants from growing
• small beaked birds disappeared from the
  population at a faster rate
• This is because the only seeds available were
  larger, so big beaksfood

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Ten years later

• They repeat the experiment when another drought
  occurred
• But plants with larger seeds suffered and small
  seeds dominated the food supply
• So natural selection favored or in other words,
  who was better adapted to this environment

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Okay that was a major tangent..back to speciation

• We can conclude that speciation does not
  necessarily need geographical isolation, it needs
  reproductive isolation
• This can happen through mating songs and visual
  features that would attract mates
• Birds find mates by responding to the song type
  of their fathers when its time for them to mate
• But there are limitationssongs are learned, not
  controlled by genetics

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So there are along of ways bird songs can aid
speciation

• The individuals that populate an island have
  fragments of the songs they need
• Sons can make errors in copying the song of
  their fathers
• If it is transmitted better in the new
  environment, then it can repel males and attract
  more females.
• Changes in body size and sound box can change
  the frequency of the songs

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What to do when you cant understand the organism
you are about to mate with.

• You dont mate. The chemistry just isnt there.
  So everyone goes their separate ways, to their
  own branch of the evolutionary tree.

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Theres some hope though

• Unless the song is extremely different from the
  native song, females will recognize the song
• So what female finches dont know wont kill
  themthen again

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A term you need to know

• Ecological niche- the function of a species
  within its environment
• Almost like a position in their environment, how
  they fit in.
• It gets really competitive keeping these niches

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So, what should you take away from section 2?

• Darwin is awesome but
• He writes too much, so
• His book isnt so awesomebut were glad he wrote
  it because
• Thats how we learned about adaptive radiation
  of
• Very cute finches!
• The end of section 2!!!!

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Congratulate yourselves for not
having anything better to do than learn
evolutionnot like I do, but just putting it out
there.