EvolutionPart 2

BIOL 1407

Evolutionary Fitness

• Darwin’s concept: An organism is more “fit” if it has more offspring that successfully reproduce compared to others in the population

Photo Credit: Eigenes Werk, 2008, Wikimedia Commons

Evolutionary Fitness

• More fertile offspring = Higher Fitness

Photo Credit: Larry Ridenhour, Bureau of Land Management, 2005

Evolutionary Fitness

• Fitness ≠ Survival

• Fitness ≠ Stronger

• Fitness ≠ Healthier

• Fitness ≠ Smarter

• Fitness ≠ Better • Photo Credit: Jeff Kubina, 2004, Wikimedia Commons

Evolutionary Fitness

FITNESS = MORE OFFSPRING!

Photo Credit: B.navez, 2007, Wikimedia Commons

Evolutionary Fitness

• Fitness comes down to leaving more copies of your genes in future generations than others

• Photo Credit: Harlequeen, 2007, Wikimedia Commons

Inclusive Fitness

• Inclusive fitness = your fitness + fitness of family members

• Directly and indirectly leaving copies of your genes

• Photo Credit: Ltshears, 2006, Wikimedia Commons

Florida Scrub Jays

• Young jays help their parents raise siblings • May forego reproducing for up to five years • Some never get to reproduce• Photo Credit: VvAndromedavV, 2008, Wikimedia Commons

Florida Scrub Jays

• Still have fitness their genes are present in the siblings they helped raise

Adaptations

• Characteristics that increase fitness in a particular environment

• Can be:– Structures– Biochemical reactions– Behaviors– Anything under genetic control that provides some

sort of advantage

Adaptations

• A successful adaptation in one environment may not be successful in a different environment.

• Photo Credit for desert: Jörn Napp, 2007, Wikimedia Commons

• Photo Credit for Prairie: Katy Prairie Conservancy, 2008, Wikimedia Commons

Walrus Adaptation

• Thick blubber is an adaptation for cold Arctic ocean conditions.

• In warmer waters, they overheat and die

• Photo Credit: NOAA, 2005, Wikimedia Commons

Adaptation Example: Railroad Vine

• Often seen on Texas beaches

• Live on sand dunes– Constantly

shifting sand– Little water – High salt levels.

• Photo Credit: South Siesta Key Beach Restoration

Railroad Vine

• Long runners stabilize sand

• Soil accumulates around roots

• Stabilizes dune

• Photo Credit: UNK Vieques Field Trip 2008

Example: Railroad Vine

• Other plants move onto stable dunes

• Railroad vines cannot compete successfully in other environments.

• Photo Credit: National Park Service, Padre Island, http://www.nps.gov/archive/pais/pphtml/photogallery.html

The Great Potoo

• Night: Fly and catch insects

• Day: sleep on branches

• Camouflage used for protection

• Video: http://www.youtube.com/watch?v=MK6nlsOZpuU

• Photo Credit: Tom Davis

The Great Potoo

• Adaptations:– Plumage

coloration– Body

position– Eyelids

• Photo Credit: Tom Davis

Evidences of Evolution

• Fossil Record

• Biogeography

• Comparative Anatomy

• Comparative Embryology

• Molecular Evidence

Fossils• A window into

evolutionary history • Only way to see

what some organisms looked like in the past

• Photo Credit: Doyle Cross at Texas Memorial Museum, UT Austin

Pterosaur FossilPhoto Credit: Doyle Cross at Texas Memorial Museum, UT Austin

Pterosaur Wing DetailsPhoto Credit: Doyle Cross at Texas Memorial Museum, UT Austin

Fossil Record

• Gaps in fossil record

• In cases of major structural changes:– Evolve in step-by-step fashion?– Evolve suddenly (one step)?

• With gaps, you can’t be sure

Transitional Fossils

• Demonstrate a step-by-step transition from an ancestral form to modern forms

• Photo Credit for Tiktaalik rosae: ArthurWeasley, 2007, Wikimedia Commons• Building Tiktaalik Video: http://www.youtube.com/watch?v=MkOy1XU0cbY• And, for fun, enjoy the music video: http://www.youtube.com/watch?v=B9h1tR42QYA

Whale Transition

• Fossils: Pakistan, Egypt, North America

• Four-legged terrestrial ancestors Whales

• Hind limbs: Legs Vestigial bones

• Front limbs: Legs Flippers

• Ankle bones: Similar to hippos & relatives

Biogeography• Study of distribution of organisms:

– Where are they located?– Why are they there?

Horseshoe Crabs Distribution Map Credit: University of Delaware College of Marine and Earth Studies and the Sea Grant College Program http://

www.ocean.udel.edu/horseshoecrab/history/pastpresent.html

An Example: Ratites

• Large, flightless birds

• Southern Hemisphere

• Photo Credit: Richard001, 2007, Wikimedia Commons

Living Ratites

• Ostrich (Africa)• Rheas (South

America)• Emus (Australia)• Cassowaries

(Australia and Papua New Guinea),

• Kiwis (New Zealand)• Photo Credit: Paul IJsendoorn, 2007,

Wikimedia Commons

Extinct Ratites

• Moas (New Zealand)

• Elephant Bird (Madagascar)

• Photo Credit for Moa drawing: Frederick William Frohawk, 1907, Wikimedia Commons

Evolution of Ratites

• Common ancestor evolved on Gondwana

• Gondwana Southern Continents

• Picture Credit: USGS image from Wikimedia Commons

Comparative Anatomy

• Similarities and differences in structure

Photo Credits: Vassil (2007, Crocodile eye) and Rainer Zenz (2006, Cuttlefish eye), Wikimedia Commons

Homologous Structures

• Similar due to shared ancestry

Analagous Structures

• Similar lifestyles but different ancestry

Comparative Embryology

• Similarities and differences in development

Comparative Embryology• Some similarities only visible during early development • Completely obscured in later stages

Photo Credits: Fir0002, 2008, Wikimedia Commons (Chick); Michele Cross, 2007 (Human baby)

Comparative Embryology

• Click on this link and play the video: http://www.pbs.org/wgbh/evolution/library/04/2/l_042_02.html

Photo Credit: Dr. Katharine Lewis, University of Cambridge, School of the Biological Sciences, http://www.pdn.cam.ac.uk/staff/lewis/

Molecular Evidence

• Comparisons of protein or DNA sequences • Can show evolutionary relationships among

widely divergent organisms

Protein Sequence Credit: Miguel Andrade, 2006, Wikimedia Commons

Molecular Evidence

• Distinguish homologous from analogous structures

• Read about Giant Pandas at: http://www.giantpandaonline.org/naturalhistory/phylogen

• Photo Credit: Jeff Kubina, 2004, Wikimedia Commons

Molecular Evidence

The End

Unless otherwise specified, all images in this presentation came from:

Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.