2. EVOLUTION & SPECIATION

3. VOCABULARY REVIEW EVOLUTION – CHANGE OVER TIME
NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE.
A.K.A. “SURVIVAL OF THE FITTEST”

4. NEW VOCABULARY
POPULATION – GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED
GENE POOL – COMMON GROUP OF ALL GENES PRESENT IN A POPULATION

5. Gene Pool Combined genetic info. of all members
Allele frequency is # of times alleles occur

6. Variation in Populations
2 processes can
lead to this:
Mutations -
change in DNA
sequence
Gene Shuffling –
from sexual
reproduction

7. Genetic Drift changes populations…….
Random change in allele frequency causes an allele to become common

8. Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population

9. Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations)

10. Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes)

11. Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment

12. Sexual selection
Sexual dimorphism: secondary sex characteristic distinction
Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism

13. Evolution of Populations
Occurs when there is a change in relative frequency of alleles

19. Phenotype Expression
Depends on how many genes control that trait

20. Single-Gene vs. Polygenic Traits
2 Distinct Phenotypes
Polygenic:
Many Phenotypes
(EG: tongue rolling)

22. Natural Selection on Polygenic Traits
Shifts to
middle range
2 extremes
1 extreme

24. Conditions needed for Genetic Equilibrium

25. SPECIATION THE FORMATION OF NEW SPECIES
AS NEW SPECIES EVOVLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED
REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.

26. 3 ISOLATING MECHANISMS……..
BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS)
GEOGRAPHICAL ISOLATION – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL)
TEMPORAL ISOLATION – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES.

27. Table 23.1a

28. Tigon
Result of male tiger and female lion mating incaptivity. Offspring are infertile.
Separated both geographically and ecologically.

29. Liger
Result of male lion and female tiger mating in captivity. Offspring are infertile.

33. Table 23.1b

35. Fig. 23.6
Four species of leopard frogs: differ in their mating calls. Hybrids are inviable.

36. These squirrels live on opposite sides of the Grand Canyon
These squirrels live on opposite sides of the Grand Canyon. This is an example of allopatric speciation.

37. Hawaiian Honeycreepers
An example of adaptive radiation –
these species all diverged from a
common ancestor (founder species)
FOUNDER SPECIES

38. SPECIATION IN DARWIN’S FINCHES
SPECIAITON IN THE GALAPAGOS FINCHES OCCURRED BY:
- FOUNDING OF A NEW POPULATION,
- GEOGRAPHIC ISOLATION which led to -- REPRODUCTIVE ISOLATION and
CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION.

41. Evidence of Evolution Fossil Record
Geographic Distribution of Living Species
Homologous Body structures
Similarities in Embryology

42. Evidence of
Evolution
Fossil Record provides evidence that living things have evolved
Fossils show the history of life on earth and how different groups of organisms have changed over time

46. Marsupial Mammals Convergent Evolution Placental mammals and
Flying Squirrel
Sugar Glider
Marsupial Mammals
Convergent Evolution
and
Analogous Structures
Placental mammals
Mammalia
Rat like common ancestor

48. Big Question!!! How did life arise on the big blue planet??
Scientists attempt to answer this question scientifically.

49. Relative Dating versus Absolute Dating

50. Relative Dating Can determine a fossil’s relative age
Performed by estimating fossil age compared with that of other fossils
Drawbacks – provides no info about age in years

51. Absolute dating Can determine the absolute age in numbers
Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain
Drawbacks - part of the fossil is destroyed during the test

52. Carbon-14 Dating

53. Fossil Formation

54. Big Bang Theory
A cosmic explosion that hurled matter and in all directions created the universe billion years ago
Evidence
it explains why distant galaxies are traveling away from us at great speeds
Cosmic radiation from the explosion can be observed
The Big Bang theory probably will never be proven; consequentially, leaving a number of tough, unanswered questions.

55. What was early earth like?
Earth was Hot!!
Little or no oxygen
Gasses in atmosphere:
Hydrogen cyanide (poison to you!)
Hydrogen sulfide
Carbon dioxide
Carbon monoxide
Nitrogen
water

56. So how did the earth get oxygen?
Some of that oxygen was generated by photosynthetic cyanobacteria
Some came from the chemical separation of water molecules into oxygen and hydrogen.

57. Others evolved ways of using oxygen for respiration
Oxygen drove some life forms to extinction
Others evolved ways of using oxygen for respiration

58. How did life begin? Miller and Urey’s Experiment
Passed sparks through a mixture of hydrogen methane ammonia and water
This produced amino acids – the building blocks of life

59. Miller’s experiment suggests that lightning could have produced amino acids

60. How can simple amino acids result in life? There are 3 theories
1. Formation of microspheres
Large organic molecules can sometimes form tiny proteinoid microspheres
Store and release energy, selectively permeable membranes, may have acquired more characteristics of living cells

61. 2nd Hypothesis for Life Evolution of RNA to DNA
RNA was assembled from simple organic molecules in a primordial soup
RNA was able to replicate itself and eventually form DNA
Not scientifically proven to be possible

62. 3rd Theory of Life Endosymbiotic theory
eukaryotic cells arose from living communities formed by prokaryotic organisms
Ancient prokaryotes entered primitive eukaryotic cells and remained there as organelles