Evolution

Evidence of change

The fossil

record

Similarities in body

structure

Similarities in early

development

Similarities in chemical

composition

Distribution of species

PaleontologyStudy of prehistoric life

Fossils • preserved remains or traces of organisms; • evidence of past life http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_03

http://www.nap.edu/openbook.php?record_id=6024&page=12

The Fossil RecordFossils and their placement in rock formations and sedimentary strata

Paleontology

How fossils are formed

http://www.wwnorton.com/college/anthro/our-origins2/img/AskClarkFAQs/Figure-8.4.jpg

Paleontology

Geology• Estimate of

fossil’s age in comparison with other fossils

• Layers may not have been deposited horizontally or may have been overturned

Radiochemistry• Age of the

sample is calculated based on the amount of radioactive elements contained

• C14 N14 upon an animal’s death

• C14>C12 = older organisms

• K40 for older samples

http://evolution.berkeley.edu/evosite/lines/IIIAchronology.shtml

Paleontology

Fossils link the present with the past

• Baleonoptera musculus (blue whale)• Modern marine mammal

• Basilosaurus• “king lizard”• w/ 0.5m hind legs, w/ some

bones similar to those of land mammals

• Ambulocetus natans• “walking whale that swims”• Skeletons found in Pakistan• Has a long, low body w/ short,

powerful limbs• Descended from land-living

carnivorous hoofed animals http://www.whale-info.com/bluewhale.html, http://www.bbc.co.uk

Paleontology

Problems with the fossil record

1. Fossils form by chance

2. Quality of fossils varies

3. Fossil reconstruction requires thorough knowledge of anatomy

4. Dating of fossils is achieved through various methods

http://eweb.furman.edu

Paleontology

Comparative EmbryologySimilarities in early development

Closely-related organisms have similar stages in embryonic development

1. Tail

2. Pharyngeal slits/pouches/arches

http://www.nature.com/nrg/journal/v7/n11/fig_tab/nrg1918_F2.html

Similar genes at

work

Similarities in early

development

Shared heritage from a common ancestor!

Comparative AnatomySimilarities in body structures

http://hippie.nu/~unicorn/tut/img/basics/animalanatomy/wing-feathers.jpeg, http://www.uksafari.com/jpeg2/batwing2.jpg, , http://www.bugshop.com.au/images/Butterfly%20Wing.jpg

Similar structures

Homologous

Similar structure, different function

Due to common ancestry

Analogous

Similar appearance and function

Different origins

Similarities in body structures and evolution

Divergent evolution or adaptive radiation• Common origin• Descendants appear different externally but are similar internally

Convergent evolution• Different origins• Descendants independently evolve similarities when adapting to similar environments

Comparative Anatomy

http://itc.gsw.edu/faculty/bcarter/histgeol/paleo2/limbs.jpg

Comparative Anatomy

http://www.evolution-textbook.org/content/free/figures/22_EVOW_Art/07_EVOW_CH22.jpg, http://www.carolinabeachtoday.com

Comparative Anatomy

Vestigial structures• structures that are of

marginal or little use to an organism

• e.g. coccyx and wisdom teeth in humans, hipbones and pelvis in whales, anal spurs in pythons and boas

• evolution is a remodelling process: ancestral structures may be modified as they take on new roles

http://3.bp.blogspot.com/-KAdBIaT796A/Ta-KqBdscqI/AAAAAAAAABQ/KWFe8Ks8Oic/s1600/whale-vestigial-structure.jpg

, http://en.wikipedia.org/wiki/Anal_spur

Comparative Anatomy

Biochemistry and Molecular BiologySimilarities in chemical compounds

Species pairs % difference in nucleotide sequences

& chimpanzee A 2.5& gibbon B 5.1& old world monkey C 9.0& new world monkey D 15.8& lemur E 42.0

A B C

D E

• Similarity of DNA b/w individuals of a species:related individuals > unrelated individuals

• Two spp. judged to be closely related by other criteria have a proportion of their DNA in common than more distantly related spp.

http://web.scc.losrios.edu/evanst/, http://andfinally.tv/2009/06/baby-gibbon-mothered-247-by-human/, http://www.datensklaven.de/?tag=animals, http://eco-stride.blogspot.com/2007/10/monkey-mobilized-in-columbia.html,

http://www.naturalphotos.com/sekercioglu/madagascar/pages/MG8-TnZoo-RTLE.htm

,

***Hemoglobin: protein that transports O2 in blood

Central dogma of mol bio:

DNA RNA proteinsStructure of proteins dictated by DNA sequence Similar proteins ~ similar DNA sequence

***

Biochemistry and Molecular Biology

Similarity of chemical compounds• sequences

copied from a common ancestor

• common genetic code passed on along all the branches of evolution

Degree of relatedness

Biochemistry and Molecular Biology

BiogeographyDistribution of species in space and through time

Gondwana broke up around 160 MYA eventually forming modern Antarctica, South America, Africa, Madagascar, Australia-New Guinea, and New Zealand, as well as Arabia and the Indian subcontinent

http://planet.uwc.ac.za/nisl/biodiversity/loe/images/pic231.gif

Modern species present on a land mass evolved from ancestors that inhabited those regions.• species are not

distributed only according to where they can survive

http://evolution.berkeley.edu/evolibrary/article/history_16, http://faculty.scf.edu/odaffej/WasDarwinWrong.3/WasDarwinWrongEDIT6.html

Islands have many endemic species that are closely related to species of the nearest mainland or neighboring island.

http://myweb.rollins.edu/jsiry/c1x17b-finches.jpg, http://www.galapagosisland.net/galapagos_islands/map.html

Islands have many endemic species that are closely related to species of the nearest mainland or neighboring island.

http://bonvito.files.wordpress.com/2010/11/carlito.png

Islands have many endemic species that are closely related to species of the nearest mainland or neighboring island.

http://people.eku.edu/ritchisong/birdbiogeography1.htm

http://people.eku.edu/ritchisong/wallacesline2.gif

Wallace Line - imaginary line separating ecozones of Asia and Wallacea. West of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origin is present.

http://people.eku.edu/ritchisong/554images/Zoogeographical_regions.jpg

http://worldpress.org/images/maps/world_600w.jpg