bsc 2008 chapter17 lecture

7/27/2019 BSC 2008 Chapter17 lecture

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21.1 How Do Scientists Date Ancient Events?Chapter 17:Life on Earth


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21.1 How Do Scientists Date Ancient Events?

Each time period is characterized by the appearance of new species.

Some persist, some eventually go extinct.


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There are millions of species on Earth right nowand this is only a tinyfraction of everything that ever lived.

How many living species?


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Video: (select Continental Drift) http://science.discovery.com/videos/greatest-discoveries-earth-science/

A lot of lifes diversity was affected by the moving continents.Plate tectonics is the study of this movement.Upheavals of the earths crust changed weather patterns and climates.

Sea levels shifted as epicontinental seas filled and drained.Continents crashed into each other and moved apart.
http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/http://science.discovery.com/videos/greatest-discoveries-earth-science/


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Distribution of species = biogeography

Biogeography is the study of how organisms are distributed ingeographical space.Wallace is generally considered the Father of Biogeography for his workmapping patterns of faunal distribution.

A map from The Malay Archipelagoshows the physical geography of the archipelago andWallace's travels around the area. The thin black lines indicate where Wallace travelled;red lines indicate chains of volcanoes.

A portrait of Alfred Russel Wallaceon the frontispiece ofDarwinism(1889).
http://en.wikipedia.org/wiki/The_Malay_Archipelagohttp://en.wikipedia.org/wiki/The_Malay_Archipelago


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Sometimes taxa are in a specific place because that is where theirancestors were.


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Historical context

Diversity is affected by competition andselective pressures (predator/prey, whichanimals already occupy a given niche).

This is one of the reasons the informationin the fossil record is so very important tounderstanding current diversity.

Mammals didnt diversify significantly until

dinosaurs went extinct

http://www.flickr.com/photos/praivio/2467981021/Copyright Perttu Raivio 2007

http://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlCopyright Brittany Gunther

http://evolution.berkeley.edu/evosite/evo101/VIIB1aAdaptiveRadiations
http://www.flickr.com/photos/praivio/2467981021/http://www.flickr.com/photos/praivio/2467981021/http://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.hyaenidae.org/the-hyaenidae/spotted-hyena-crocuta-crocuta/crocuta-association-with-other-species.htmlhttp://www.flickr.com/photos/praivio/2467981021/http://www.flickr.com/photos/praivio/2467981021/


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Adaptive radiation

An adaptive radiation is when a species or group of species adapt and diversify to fillopen niches, producing many daughter species.This may be due to the extinction of another group (like the extinction of the

dinosaurs), exploiting an unoccupied niche, or because of a new innovation (birdsand flight).

Darwins finches are an example of adaptiveradiation on the Galapagos islands theydiversified from the founding species to occupy

lots of different niches.

Lake Tanganyika is a very large, very deep African Lake. It has ~ 200species of cichlids which vary in body form, color, position in the water

column and diet. All of these species have diversified from a commonancestor in less than 2 million years.

http://www.cichlid-forum.com/articles/lake_tanganyika_diverse.php
http://www.cichlid-forum.com/articles/lake_tanganyika_diverse.phphttp://www.cichlid-forum.com/articles/lake_tanganyika_diverse.phphttp://www.cichlid-forum.com/articles/lake_tanganyika_diverse.phphttp://www.cichlid-forum.com/articles/lake_tanganyika_diverse.php


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Punctuated equilibrium vs. gradualism

There has been a lot of argument about how species change over time.

Does it happen gradually, over the entire period of a species existence?

Or does it happen all at once (punctuated), only at speciation?

There was debate on both sides for many years everyone had an opinion.Current consensus is that there is evidence for both, depending on the

circumstances.


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Organizing lifes diversity

Carolus

Linnaeus

TAXONOMY is the science of identifying organisms, naming

them, and classifying them into groups.

Video: Linnaeushttp://science.discovery.com/videos/100-greatest-discoveries-evolution/
http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/http://science.discovery.com/videos/100-greatest-discoveries-evolution/


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Linnaean Hierarchy of Classification

Most inclusive

(largest category)

Least inclusive(very specific)


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Binomial nomenclature

Always italicized, always in Latin

genus species name

Homo sapienslower casecapitalized


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Taxonomy vs. systematics.

TAXONOMY identifies, classifies and categorizes.

SYSTEMATICS goes further it is intended to reflect relatedness and evolutionaryhistory. Systematics is based on the idea that shared characteristics (morphology,DNA, developmental traits) are inherited from a common ancestor.

So the more closely related animals are, the more characteristics they will share.

A phylogeny is used to show that those relationships (the family tree)

Phylogeny: Tree of Life

http://tolweb.org/tree/
http://tolweb.org/tree/http://tolweb.org/tree/


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DNA - the genetic code. BehaviorDevelopmental patterns

Phylogenies can be built using many differentkinds of traits.

In all cases, the more shared characters, the morelikely they are to be related.

Building phylogenies (trees)

Morphology


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DNA sequences have become the most widely used data for constructingphylogenetic trees.

Can obtain thousands and thousands of characters rapidly (other methodsonly produce a few hundred).

Drawbacks: expensive, cant use on fossils, some taxa not available.

Molecular data


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Count the differences and similaritieswho is more closely related?Most distant?

DNA

Human/chimp

mouse


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Regardless of data type, systematics is based on the idea that shared characteristicsbetween two organisms are inherited from a common ancestor.

The more closely related they are, the more characteristics they will share.

Features that arose earlier in evolutionary history will be shared by more taxa.

Features that arose later will be shared by fewer taxa.

Nested sets of characters

Coelom


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25.4 How Does Phylogeny Relate to Classification?How to read a tree

25 4 H D Ph l R l t t Cl ifi ti ?


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The root of a tree is the original common ancestor for that group.Branches are the lineages leading from an ancestor.A CLADE is an ancestor and all its descendants.

Sister groups share a common ancestor.

A CB D E GF H

= node = common ancestor. root

branches = lineages


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How to read a tree

A CB D E GF H

A clade is an ancestor and all descendants.It can be big or small.All the groups circled are clades.


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Sister groups SHARE a common ancestor.

A and B are sister taxa (common ancestor 4)C and D are sister taxa (common ancestor 5)E and F are sister taxa (common ancestor 6)G and H are sister taxa (common ancestor 7)

Clade (A + B) is sister to (C + D) because theyshare a common ancestor at node 2

Clade (E + F) is sister to (G + H) because theyshare a common ancestor at node 3

Clade (A+B+C+D) is sister to (E+F+G+H)because they share a common ancestor atnode 1.

A

CB

DE

GF

H

1

3

2

5

4

7

6


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Coelom

Characteristics that are shared between members of a group are given the namesynapomorphy. They define a particular group.

Characteristics that evolved very early so that all of the taxa share them are given

the name symplesiomorphy = shared primitive characteristic

Nested sets of characters

synapomorphy

synapomorphy

synapomorphy

(symplesiomorphy)

H l


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Homology

Owen: Homology is the same structure (organ) under every variety ofform and function

But limb homologies go back even before tetrapods had limbs.

Homology

http://bytesizebio.net/wp-content/uploads/2009/07/homology-limbs.jpg


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Homology


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An analogous structure looks the same and performs the same function but was NOTpresent in the ancestor.

Another term for analogy is convergent evolution because the similar function ledto a similar structure.

The different taxa converged on the same solution.

Analogy and convergent evolution

Insect wingsBat wings Bird wingshttp://birdspic.blogspot.com/2011/04/bird.htmlhttp://www.wired.com/wiredscience/2010/04/bat-flight-evolution/

http://homepage.mac.com/iain_sommerville/iblog/C1026094055/E20070104140031/index.htmlhttp://mobarrett.net/shadows/index.php?showimage=66

Torpedo shape sharkTorpedo shape dolphin
http://www.wired.com/wiredscience/2010/04/bat-flight-evolution/http://homepage.mac.com/iain_sommerville/iblog/C1026094055/E20070104140031/index.htmlhttp://homepage.mac.com/iain_sommerville/iblog/C1026094055/E20070104140031/index.htmlhttp://mobarrett.net/shadows/index.php?showimage=66http://mobarrett.net/shadows/index.php?showimage=66http://homepage.mac.com/iain_sommerville/iblog/C1026094055/E20070104140031/index.htmlhttp://homepage.mac.com/iain_sommerville/iblog/C1026094055/E20070104140031/index.htmlhttp://www.wired.com/wiredscience/2010/04/bat-flight-evolution/http://www.wired.com/wiredscience/2010/04/bat-flight-evolution/http://www.wired.com/wiredscience/2010/04/bat-flight-evolution/http://www.wired.com/wiredscience/2010/04/bat-flight-evolution/http://www.wired.com/wiredscience/2010/04/bat-flight-evolution/

bsc 2008 chapter17 lecture

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