Biology 1112

1
Lecture 2

• Biology 1112
• Chapter 13 How Populations Evolve

2
Learning Objectives

• List
• Evolutionary adaptations of the Blue-footed booby
• Examples of artificial selection, natural
  selection
• Recite
• 4 lines of evidence supporting evolution
• Contrast
• Artificial vs. natural selection
• Discuss
• How Charles Darwin developed evolutionary theory
• A strategy to combat insecticide resistance
• Sickle cell

3
What is an Evolutionary Adaptation?

• An inherited trait
• Increases likelihood of survival

4
Adaptations of the Blue-footed Booby

• Lives on Galapagos Islands
• Big feet
• Yes, they look silly
• But good for swimming
• Nostrils close during diving
• Prevents water from getting into lungs
• Oil gland in tail for waterproofing feathers
• Salt gland excretes excess salt

5
Voyage of the Beagle

• A ship of the British Royal Navy
• Mission to map parts of the Southern Hemisphere
• Charles Darwin aboard as naturalist

6
Things Darwin Saw

• In Andes, marine snail fossils high in mountains!
• Clearly, mountains were once under ocean
• On Galapagos Islands, marine iguanas
• Resembled South American iguanas, but different
  species
• Had unique salt gland

7
Things Darwin Read

• Charles Lyells Principles of Geology
• Concept of Earth changing over millions of years
• Darwin reasoned life could change too
• Thomas Malthus essay
• Concerned with human population increase, with
  limited natural resources
• Darwin felt this could apply to other species too

8
Major Darwininan Concepts

• Environment can support limited individuals
• In nature, more are born than can survive
• Survival and reproduction differ among
  individuals
• Traits, inherited from parents, affect survival
  reproduction

9
After the Voyage

• 1840s Darwin had written long essay on
  revolutionary concepts
• Did not publish feared social backlash
• 1850s Alfred Russell Wallace communicates
  similar ideas
• Darwin felt scooped
• Happy ending mutual friends presented Darwin and
  Wallaces works to scientific community

10
Evolution Defined

• Evolution is inherited change in organisms over
  time
• A population and species level process
• Does not occur within an individual
• Key concepts
• Survival AND reproduction of the fittest
• Form follows function
• Fitness of a trait depends upon environment

11
4 lines of Evidence for Evolution

• Biogeography
• Comparative anatomy
• Comparative embryology
• Molecular biology

12
Biogeography

• Literally, the study of where things live
• Ex Galapagos iguanas resemble those in South
  America
• Suggests common ancestors

13
Comparative Anatomy

• Studies body structure of closely-related
  organisms
• Especially vertebrates

14
Comparative Embryology

• Studies early development of closely-related
  organisms
• Ex all vertebrate embryos have gill slits
• In fish, become gills
• In humans, become bones supporting voicebox

15
Molecular Biology

• Nucleotides can be sequenced in RNA, DNA
• Amino acids sequenced in proteins or polypeptides
• Sequences more similar if
• Individuals related
• Species are more closely related
• Ex human-monkey hemoglobin 8 amino acids
  different

16
(No Transcript)
17
Whales are Related to Cows!

• Fossil whales have leg bones!
• DNA evidence supports

18
7th Inning Stretch
19
Artificial Selection

• Done by humans to many organisms
• The many breeds of dogs all just modified wolves
• Many veggies from single species of wild mustard

20
Natural Selection Defined

• Done by nature, rather than people
• Can lead to
• Variation in species
• New species (ex many species in dog family)

21
Examples of Natural Selection Observed

• Individuals with certain traits may be favored
• Depends upon the environment
• Examples
• Peppered Moth in England
• Beak size of Galapagos finches
• Insecticide resistance

22
Peppered Moth

• Lichens grow on trees
• Light in color, grow in patches
• Require clean air
• Die if exposed to air pollution
• Peppered moth has 2 forms
• Light (common before 1900)
• Dark (rare before 1900)
• Moths rest on trees

23
Peppered Moth (Contd)

• Industrial Revolution
• Lots of air pollution
• Lichens die
• Tree trunks become dark
• By 1900, light form rare
• Birds could now see light moths
• Present day
• Good news! Less pollution
• Lichens returning
• Light morph increasing

24
Peppered Moth (Contd)

• Good evidence for evolution
• A change in a species over time
• Demonstrates that fitness depends on the
  particular environment
• When environment changes, fitness of the 2 moth
  color morphs changed

25
Beak Size Galapagos Finches

• Larger beaks
• Stronger, can break larger seeds
• During dry spells
• Small seeds rare
• birds with larger beaks have higher reproductive
  success
• Smaller beaks
• More efficient for eating many small seeds

26
Insecticide Resistance
27
Thinking About Selection

• What environmental pressure favors sickle cell
  anemia?