Earth History GEOL 2110

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Earth History GEOL 2110 Lecture 5 EVOLUTION Part I

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Earth History GEOL 2110. Lecture 5 EVOLUTION Part I. Major Concepts. In the late 1700/early 1800’s, a number of natural scientists had proposed that evolution of life was likely, however, without a mechanism to explain evolution, the idea was generally dismissed. - PowerPoint PPT Presentation

Transcript of Earth History GEOL 2110

Page 1: Earth History  GEOL 2110

Earth History GEOL 2110

Lecture 5EVOLUTION

Part I

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Major Concepts• In the late 1700/early 1800’s, a number of natural scientists

had proposed that evolution of life was likely, however, without a mechanism to explain evolution, the idea was generally dismissed.

• Darwin’s Origin of Species (1859) not only provided multiple lines of emperical evidence for evolution, but moreover, proposed a plausible cause (natural selection).

• With the discovery of genetic theory in the early 1900’s providing a mechanism for evolution, it became overwhelmingly accepted as a “fact” of science.

• The genetics within isolated, small populations provided the triggers for the “origin” of new species

• The mechanisms of evolution are still being figured out, but not the concept of evolution is not in doubt and has achieved the status of a paradigm of science.

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Early Ideas about Evolution

• To the early Greeks and Romans, the notion that nature changes/evolves was well accepted

• Christian teachings required that all organisms were created together, at once, and unchanged for all of time

• The notion that God would let organisms go extinct (as proposed by Cuvier and Smith) was antithetical to genesis and heretical

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Early Ideas about EvolutionGeorges de Buffon

Histoire Naturelle (1847)• defined the concept of species

(the ability to interbreed)• was the first to emphasize the

importance of environment causingechanges (evolution) within fixed species

• recognized that organism seek to adapt to their environment but did not offer an explanation how this might occur

• noted evidence for inheritance of traits, but again did not offer an explanation.

• Enough time for Evolution was a major sticking point

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Early Ideas about Evolution

Erasmus Darwin (1731–1802)Charles’s Grandfather

• as an animal breeder, recognized the subtle changes from generation to generation

• argued that the fitness of an organism to feed itself, protect itself against predators, and its ability to succeed in mating were important factors controlling its survival and thereby its ability to pass on these characteristics to its offspring.

•Still the question remains - how does inheritance work?

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Early Ideas about EvolutionDefined “biology” as a study of the plant and animal world• Ideas about evolution published in 1809, where he argued that the fundamental course of nature is change and this change was controlled by environment• Did not ascribe to Buffon’s fixed species concept, but rather believed that organism represent a continuum of change.•Did not believe in extinction, but rather the “loss” of an organism was due to it’s changing into or replacement by another simpler form.

Jean Baptiste de Monet – Chevalier de LAMARCK

(1744–1829)

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Inheritance of Acquired CharacteristicsLamarck’s Giraffes

But again, how are these acquired characteristics passed on?

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Darwinian Evolution• Born in the year that Lamarck published

his ideas about evolution• Embarked on a 5-year voyage (1832-

1835) around the world on the HMS Beagle where he was charged with documenting the diversity of flora and fauna in the tropics and Southern hemisphere.

• Struck by: • Variety of species• Number and diversity of individuals per

species• The importance of competition for food,

safety from predators, and shelter as his grandfather pointed out

Charles Darwin (1809-1882)

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Darwin’s Epiphany

Darwin

Captain FitzroyHMS Beagle

Ship-side ReadingMalthus (1798) Principles of PopulationLyell (1830) Principles of Geology

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Natural Selection

• Natural environments change• Individuals within a population of

organisms change• Individual changes that are best fitted

(adapted) to the changes in the environment are the most likely to survive

• “survival of the fittest”

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Radiation into Environmental NichesThe Finches of the Galapagos

• Only birds on the islands – no competition

• 4 different genera

• 15 different species

• Each adapted a different beak type reflecting their dietary preference

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On the Origin of Species• First draft completed in 1839, but

not published until 1859

• Fearful of backlash from British scholars and clergy

• For 20 years, compiled supporting data

• Primary goals of the book:• Document evidence for

Evolution• Propose a mechanism

(Natural Selection)

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Evidence of EvolutionBranching Organization of Life

Early classifications of the animal and plant kingdom show groups within groups within groups based on anatomical features

Best portrayed by a branching family tree implies related lineages

Today, genetic coding affirms that grouping

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Evidence of EvolutionHomologous Elements

Diverse organisms share similar organs and features

For example, the bones of appendages in a variety of vertebrates

Green –humerusRed – radiusBlue – ulnaTan – wrist and phalanges

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Evidence of EvolutionVestigal Structures and Imperfections

Unnecessary body parts

Why would such things be “created”?

HumansTail bonesAppendicies

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Evidence of EvolutionEmbryonic History

All vertebrate embryos go through similar early stages of development

“Ontogeny recapitulates Phylogeny” Hackel (1866)

(i.e. embryonic development repeats evolutionary history)

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Evidence of EvolutionPaleogeography

On unconnected continents, unrelated animals have evolve to occupy similar environmental niches

For example – Marsupials of Australia

“Ecological Convergence”

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Next Lecture

EVOLUTION IIGenetics and the Origin of Species

Quiz #2Chapter 3