Evolution

1
Evolution
2
Theory of Evolution

• Basic Idea
• Life forms have changed (evolved) over time

3
Lamarcks Theory

• Jean-Baptiste Lamarcks theory had two basic
  ideas
• structures grow by use, die with non-use
• acquired characteristics are then given to
  offspring (no proof)

4
CHARLES DARWIN

Voyage of the Beagle, 1831-1836
5
Darwins theory of Evolution

• Historical Influences
• Sailed on HMS Beagle, studying plants and animals
  of the South Pacific and Galapagos Islands
• Collected many specimens from island
• Island resident story
• Studied Lyell, a geologist, who said face of
  earth is constantly being changed by rivers,
  wind, etc. (therefore organisms must have to
  change)
• Believed Malthus, an economist

6
MALTHUS PREDICTION

• Populations are kept in check by the food
  supply.

7
Darwins Theory

• Collected and analyzed finches.
• 14 species, differing in size and shape of their
  beaks.
• Why did finches differ so much from one island to
  the next?

8
Darwins Finches
9
Darwins Natural Selection

• Survival of the Fittest
• Characteristics that enhance survival and
  reproduction are continued and eventually replace
  ones that arent.
• Adaptations- characteristics that allow a species
  to survive
• VIDEO (5 mins)

10
(No Transcript)
11
Lamarck vs. Darwin

12
Descent with Modification

• Life has a history of change
• Descendents of the earliest organisms spread into
  various habitats over millions of years
• Accumulated adaptations to diverse ways of life

13
Darwins Theory Changed Biology

• Alfred Wallace- 1858
• Theory supported Darwins
• Darwin published his book On the Origin of
  Species in 1859

14
Homework

• 1) Why would Lamarck say that giraffes have long
  necks? Darwin?
• According to this article, why do giraffes really
  have long necks?
• Is this thought more related to Darwin or
  Lamarcks theory? Explain.

15
Plier Birds

• Walnut Almond
• Pecan Brazil Nut

16
Plier Birds

• Needle Nose Lineman
• Regular Channel Lock

17
Evidence for Evolution

• Evolution- Life has existed for billions of
  years and has changed over time

18
Evidence for Evolution

• Fossils- preserved remains or markings left by
  organisms that lived in the past
• Shows life is old and has changed over time.
• BEST EVIDENCE FOR EVOLUTION

19
(No Transcript)
20
Paleontologists

• Study fossils
• Video

21
Homologous Structures

• Similar structures in species sharing a common
  ancestor

22
Vestigial Structures

• Remnants of structures that may have important
  functions in an ancestral species, but have no
  clear function in some modern descendants.

23
Similarities in Development

• Bird vs. human embryo

24
Molecular Biology

• DNA of many species is very similar, showing that
  they are closely related.

25
Darwins Theory of Evolution

• Natural Selection
• Only the best suited for the environment will
  survive!

26
Evidence to Darwins Theory

• Peppered Moth (Biston betularia)

27
Evidence to Darwins Theory

• Pesticide resistance

28
Evidence to Darwins Theory

• Sickle Cell Anemia and Malaria

29
Evidence to Darwins Theory

• Antibiotic Resistant Bacteria
• Video

30
Artificial Selection

• Selective breeding of plants and animals to
  produce offspring with genetic traits that humans
  value.
• Breeders play the role of the environment

31
Review

• Darwin- Natural Selection
• Lamarck- Acquired Characteristics
• Malthus- Population/ food growth
• Lyell- earth is constantly changing
• Wallace- similar to Darwin

• Evidence for Natural Selection
• Fossils
• Peppered Moths
• Pesticides
• Sickle Cell Anemia Malaria
• Antibiotic Resistant Bacteria

32
Microevolution
33
Populations and their Gene Pools

• Population- local group of individuals belonging
  to the same species
• Individual organisms in a population DO NOT
  evolve
• Natural selection is seen over time

34
Gene Pool

• All the different forms of a gene that make up a
  population.
• Environment favors genetic combos that contribute
  to survival and reproductive success.
• What mechanisms can change a gene pool? (genetic
  drift natural selection)

35
1) Genetic Drift

• Change in gene pool of a population due to chance.

36
Genetic Drift

• The smaller the population, the more impact
  genetic drift will have.
• If a population is large, genetic drift does not
  have that big of an effect.
• Consider this example

37
Genetic Drift Example

• THE BOTTLENECK EFFECT- decreases genetic
  variation in a population example p. 313

38
Bottleneck Effect

• Variation low in cheetah population
• Can they resist disease or adapt to environmental
  changes?
• Bottleneck Events
• Ice Age
• Hunting to extinction

39
Genetic Drift Example

• FOUNDER EFFECT- genetic drift in a new colony

40
Founder Effect
p. 313
41
Fitness

• The contribution that an individual makes to the
  gene pool of the next generation compared to
  contributions of other individuals.