Descent With Modification: A Darwinian View of Life

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Descent With Modification A Darwinian View of
Life

• Darwins formulation of evolution is as follows
  
• descent from a common ancestor modified by the
  mechanism of natural selection, resulting in the
  evolution of species adapted to their
  environments. The scientific and philosophical
  climate of Darwins day was quite inhospitable to
  the implications of evolution but most biologists
  accepted the theory of evolution quite rapidly.
  Only later was natural selection recognized as a
  mechanism of evolution. Evidence for evolution
  is drawn from biogeography, the fossil record,
  comparative anatomy, comparative embryology, and
  molecular biology.

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The Historical Context for Evolutionary Theory

• The concept of natural selection states that a
  population can change over the course of time if
  individuals with certain heritable traits produce
  more viable offspring than the other individuals
  do.
• Evolutionary adaptation, the result of natural
  selection, is the tendency of characteristics of
  a species to change over generations to enable
  that species to better fit the environment.

• http//faculty.knox.edu/fmcandre/guards.jpg

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The Historical Context for Evolutionary Theory

• Taxonomy - sector of biology dedicated to the
  naming and classification of all forms of life.
• Species are named using a two part system
  binomial nomenclature

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The Historical Context for Evolutionary Theory
http//www.calstatela.edu/faculty/acolvil/sediment
/assorted_fossils.jpg

• Fossils
• found in sedimentary rock
• - impressions of organisms that are no longer
  living
• have given proof to the theory of evolution
• Paleontology is the study of fossils

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The Historical Context for Evolutionary Theory

• Gradualism geologic theory states that profound
  changes in the earths features over the course
  of geologic time is the result of slow,
  continuous processes
• Uniformitarianism geologic processes that have
  shaped the planet have not changed over the
  course of the earths history

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The Historical Context for Evolutionary Theory
http//www.museumonline.at/1999/schools/classic/st
ernberk/lamarck.jpg

• Jean Baptiste Lamarck
• Early theory of evolution
• Characteristics acquired during an organisms
  lifetime could be passed on to the next
  generation

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Lamark

• Evolution is Goal Driven, and involves two
  theories
• Use and Disuse
• The inheritance of acquired traits

http//www.instoneinc.com/gallery/De20Lamark-O.jp
g
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Goal Driven Evolution

• Feels the need to stretch neck and get food

http//www.princessleia.com/images/MyImages/essays
/giraffe_lamark.jpg
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Use and Disuse

• If you use it, you keep it, if you dont use it
  you lose it.
• Giraffes that used their longs necks keep them,
  those that dont develop shorter necks.

http//img.sparknotes.com/figures/1/1534327ece5d34
7f8fe2828c8fdb7677/giraffe.gif
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The inheritance of acquired traits

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jpg
http//www.dontclickme.com/media/arnold-schwarzene
gger-big_muscle.jpg
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The Darwinian Revolution
http//bio.univet.hu/SALVE/00gallery/people/Darwin
_Ch_1849_lg.jpg

• Charles Darwins voyage on the HMS Beagle in 1831
  was the impetus for the development of his theory
  of evolution
• Descent with modification all living organisms
  are related by descent from an unknown common
  ancestor

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Darwins Discovery

• Introduction to the History of Life

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The Journey of the BEAGLE

• In 1831, the BEAGLE a British warship was sent to
  complete a survey of the Galapagos Islands
  coastline and create longitudinal measurement.

• Many English ships were traveling the Beagle was
  special because of 1 naturalist who was
  extremely fond of geology and indeed al branches
  of natural history

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Located in the Pacific Ocean about 600 miles, or
970 kilometers, west of Ecuador.

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Animals of the Galapagos

• Blue Footed Booby courtship displays

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Giant Tortoise
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Reptiles

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Birds

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Darwins Journey

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Darwin's
Finches
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Darwins Finches

• OBSERVATION
• Darwin noticed there were many many finches on
  the Galapagos.
• QUESTION
• How did so many finches survive if they were all
  eating the same types of food and living in the
  same habitat?
• Wasnt there too much competition to survive?
• ANALYSIS
• Same Tree Different Parts of Tree
• All ate insects different insects
• CONCLUSION
• Each finch had a different niche or adapted
  different traits to survive
• EACH FINCH HAD ORIGINATED FROM THE SAME
  ANCESTRIAL SPECIES

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Features of Finches
http//www.people.fas.harvard.edu/gfeldman/birds.
html.
http//www.rit.edu/rhrsbi/GalapagosPages/DarwinFi
nch.html
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Large Ground Finch

• Habitat ground
• Beak type Strong, Heavy
• Food Thick Shelled seeds

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Medium Ground Finch

• Habitat ground
• Beak type Short, Heavy
• Food Medium sized seeds

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Small Ground Finch

• Habitat ground
• Beak type short, delicate
• Food small seeds

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Sharp Beak Ground Finch

• Habitat ground
• Beak type curved, sharp
• Food flesh of insects

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Large Cactus Finch

• Habitat cactus
• Beak type Tough beak
• Food Cactus and nectar

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Small Tree Finch

• Habitat Tree
• Beak type small, pointed
• Food probes cracks in bark for insects

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Natural Selection

• 1. Trait is genetic
• 2. Animals with the
• best adapted traits survive
• 3. Animals survive to reproduce and give trait to
  offspring

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Observation

• Darwin noticed there were many many finches on
  the Galapagos.

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Questions

• How did so many finches survive if they were all
  eating the same types of food and living in the
  same habitat?
• Wasnt there too much competition to survive?

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Analysis

• Same Tree Different Parts of Tree
• All ate insects different insects

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Conclusions

• Each finch had a different niche or adapted
  different traits to survive
• EACH FINCH HAD ORIGINATED FROM THE SAME
  ANCESTRIAL SPECIES

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Peppered Moths
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More Examples Evolution
http//www.micro.utexas.edu/courses/levin/bio304/e
volution/horseevol.gif
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The Darwinian Revolution

• Darwins Theory
• Natural selection is the result of differing
  reproductive success that is due to the unequal
  ability of individuals to survive and reproduce
• The process of natural selection occurs through
  interactions between the environment and
  organisms that vary in their genotype in a
  population.
• The result of natural selection is the adaptation
  of a population to its environment.

http//guru.gmxhome.de/bilder/darwin.jpg
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The Darwinian Revolution

• Artificial selection
• The process by which species are modified by
  humans
• Plants and animals are specifically chosen to
  breed with the desired goal of producing
  offspring with specific characteristics

http//www.anselm.edu/homepage/jpitocch/genbios/22
-11b-ArtificalSelection.jpg
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Artificial Selection

• Traits are selected by humans

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Examples Natural Selection

• Who survives on an island fast or slow twitch
  muscles?
• After a volcano eruption, who survives?

http//www.southeastmissourihospital.com/mainstree
t/IMAGES/runners-art.jpg
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The Darwinian Revolution

• Population
• a group of interbreeding individuals that live in
  a certain geographic area
• the smallest unit that can evolve (individuals
  cannot evolve)
• Natural selection can only work on heritable
  traits

http//tidepool.st.usm.edu/pix/population.gif
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Evidence of Evolution The Darwinian Revolution

• Biogeography
• The geographic distribution of species
• Species that live closer together tend to be more
  closely related
• Endemic species are found in a certain geographic
  location and nowhere else.

http//www.boltzmanninc.com/wildvistas/biogeograph
y/Biogeography-map-copy_05.jpg
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Evidence of Evolution The Darwinian Revolution

• Homology
• - Species that share common ancestry should have
  similarities
• - Homologous structures are anatomical signs of
  evolution (see right)
• Vestigial organs are historical remnants of
  structures that were functional in ancestors
• (appendix, molars, little toe)

• http//itech.pjc.cc.fl.us/astabler/BSC2010Chapter2
  2/Homologous20structures.jpg

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More Homologous and Vestigial Traits
Scutes
www.amonline.net.au
www.dinosauria.com
http//museum.gov.ns.ca/mnh/nature/snakes/img0015.
jpg
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More Homologous and Vestigial Traits
Coccyx
www.thechirowc.com
Splint Bones
www.wonderquest.com
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Evidence of Evolution The Darwinian Revolution
http//www.chsweb.lr.k12.nj.us/mstanley/outlines/e
volution/evidence/image199.gif

• Embryological homologies are prominent during
  developmental stages
• Molecular homologies are shared characteristics
  on the molecular level, such as using the same
  method for reproducing DNA

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The Historical Context for Evolutionary Theory

• Ontology recapitulates phylogeny
  development evolutionary
  history

http//www.chsweb.lr.k12.nj.us/mstanley/outlines/e
volution/evidence/image199.gif
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The Darwinian Revolution Human Evolution