Darwinian Evolution The change of populations over time. Genetic variation

So why is there such a variety of life?

Evolution  When Populations of living things slowly adapt and change over time  Does not explain origin of life

Evolution theory is a way to show the connection of all life forms

Evolution also explains the variety within a kind  Ex. Types of cats

Origin of Species Where did all the species come from?

Macroevolution  The formation of new taxonomic groups  Kingdoms to species

Microevolution Variations within a Variations within a “type”genus or group “type”genus or group

Speciation  Formation of a new species  A species is a population of similar organisms that can reproduce and produce fertile offspring

Historical context

Carolus Linnaeus   Father of modern taxonomy (classification)  Binomial nomenclature  genus species  Canis Lupus

James Hutton  Gradualism – Profound change is the product of slow, continuous processes  “The present is the key to the past”  Ex. Mountains grow slowly now so they always grew slowly! so they always grew slowly!

Jean Baptiste Lamarck  Evolution through acquired traits  Based on fossils, relics or impressions of dead organisms  Sedimentary rock, ice, tar, amber

Charles Darwin  Evolution by natural selection  Also cited fossil evidence  Anticipated that intermediates would be found  Travelled extensively to observe diversity of life Published “origin of species” In 1859

Evolutionary theories Lamarck VS Darwin Lamarck VS Darwin

Lamarck  Individual organisms change. These changes are passed on to offspring  Ex Giraffes – stretched their necks to get food and passed longer necks on to offspring

Darwin  Said species change by Natural Selection. Survival of the fittest. Natural Selection. Survival of the fittest.  The ones best naturally adapted to survive, have more offspring and pass on the traits to those offspring

Darwin’s version of giraffes  Some giraffes were born with longer necks and better able to get food. These ones survived and passed longer necks to their offspring

Darwin’s big adventure! He sailed around the world

He sailed on the Beagle  No, Not that beagle!!!!!!!

HMS Beagle  This one

Darwin observed  There was a change in diversity as he sailed. There was more diversity close to equator which became less as he sailed toward poles

Galapagos islands  Darwin’s most famous observations

He studied lots of interesting creatures in Galapagos  seals, tortoises, iguanas and blue footed boobies

Especially finches

Darwin’s Finches  Finches on different islands developed type beaks due to type beaks due to natural selection natural selection according to type of food available. better beaks survived better

Finches  Ground finch – Seed eater  Small tree finch – Insect eater  Woodpecker finch – Tool user

Lamarck and finches  What would he say?  Individual finches beaks grew differently to adapt to the food source, this trait was passed on

Comparison summary  Lamarck – individual changes to adapt to environment. Passes changes to offspring  Darwin – Certain individuals born with advantages, and passes them to offspring Changes due to random variation and mutation

Darwin or Lamarck?  A sea turtle that has more webbing on its feet can swim better and catch more food and survives to have lots of offspring  Darwin

Darwin or Lamarck?  A rabbit living in arctic has a lighter color coat and hides better from the wolf, survives to have offspring better  Darwin

Darwin or Lamarck?  A squirrel grows longer claws to grab tree branches better to keep from falling and when it has offspring, they are born with longer claws to grab branches  Lamarck

Darwin or Lamarck? 

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Similarities of Darwin and Lamarck  Both Darwin and Lamarck believed changes were due to environmental pressure and changes (lack of food, shelter, mates etc)

Geographic isolation  When 2 groups are separated they can have different environments causing natural selection  Ex. The flying lizards (genus Draco) of Southeast Asia. Differ in size according to location

Darwins “Origin of Species”  2 main points 1) Descent with modification 2) Natural selection –

Descent with modification  Slight changes can occur from one generation to the next  Called gradualism  Punctuated equilibrium – Changes occur suddenly (an alternate model that explains lacking fossil evidence)

Natural selection  A differential success in reproduction caused by an interaction between the environment and the phenotypes of a population  Environment selects for favorable traits for favorable traits

Artificial selection  The breeding of domestic plants and animals  Traits are SELECTED by scientists

Examples of natural selection  1) Evolution of drug resistance in HIV virus and bacteria  Antibiotics “select” for resistant mutations

2) Peppered moth  Moths adapt to pollution on tree bark better camouflaged (dark moths) survive  Problem: peppered moths do not rest on tree trunks!

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Evidence for evolution

1) Homologies – Homologous structures  Structural resemblance that indicates possible evolutionary relationship of species  Ex. Bat wing, cat leg

Analogies- Analogous  Structures that are similar function but not related species. Do NOT indicate evolutionary relationship.  Called Convergent evolution  Ex. insect wing, bird wing and bat wing

Analogies or homologies Analogies or homologies  Analogy

Analogies or homologies Analogies or homologies  Homology  Cauliflower and broccoli are genetically engineered mustard flowers

Analogies or homologies Analogies or homologies  Homology (distant)

Analogies or homologies Analogies or homologies  Analogy

Analogies or homologies Analogies or homologies  Homology

Analogies or homologies Analogies or homologies

2) Vestigial structures  Structures that have little or no use in an organism. (historical remnants)  Ex. Whales and snakes with vestigial hip bones

3) Embryological Homologies  Haeckel (1874) all vertebrate classes pass through an identical evolutionarily conserved "phylotypic" stage

Proved NOT true  Actual photographs

4) Molecular Homologies  Similar DNA and Proteins  DNA is used more now to determine evolutionary relatedness

Convergent evolution  When two non related species develop the same structure  Fish – The most simple of vertebrates  Orca – a mammal. Thought to have evolved from land mammals

Divergent evolution  When two species have a common ancestor and therefore have common structures  Ex. Polar Bear and grizzly bear both had a bear type ancestor