Evolution
Part 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=M
K6nlsOZpuU
•
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 Fossil
Photo Credit: Doyle Cross at Texas Memorial Museum, UT Austin
Pterosaur Wing Details
Photo 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.