Planet Earth

 

Extinction Event

 

At the end of the Permian period many organisms went extinct. It was known as the 'Great Dying'. Among the organisms that went extinct are trilobites, many amphibians, and many mammal like reptiles. It has been estimated that 50% of all families became extinct and thus 96% of all species went extinct. How can loss at one taxonomic level translate to a different level of loss at another taxonomic level?

Directions: Below are families represented by name with genera of each family represented by the numbers under each family.

For example the kangaroo family has one genus - #25. Using a calculator with a random number generator (or a logarithm table), generate numbers at random until a new genus becomes extinct. Pause for a moment to remember the extinct organism and repeat until 5 % of the families are extinct, answer question 1, and then repeat until 50% of the families are extinct. Answer the remaining questions.

Tytonidae (barn owl)

00 01 02 03 04

Characidae (piranha)

05 06 07 08

Leporidae (rabbit)

09 10 11 12 13

14 15

Felidae (jaguar)

16 17 18 19 20

21

Balaenopteridae (humpback whale)

22 23 24

Macropodidae (kangaroo)

25

Falconidae (kestral)

26 27 28 29 30

Lampyridae (fireflies)

31 32 33 34 35

36 37 38

Procaviidae (finches)

39 40 41 42 43

44 45

Mustelidae (otter)

46 47

Cervidae (reindeer)

48

Hominidae (chimpanzee)

49 50

Ursidae (bear)

51 52 53

Bovidae (buffalo)

54 55 56 57 58

Therididae (black widow spider)

59 60 61 62 63

64

Chamaeleonidae (chameleon)

65 66 67 68 69

70 71

Chrysomelidae (leaf beetle)

72 73 74 75 76

77 78 79 80 81

Trochilidae (hummingbird)

82 83 84 85 86

Equidae (horse)

87 88 89 90

Apidae (honeybee)

91 92 93 94 95

96 97 98 99

  

 

QUESTIONS:
  1. How many genera are extinct after 5% of the families are extinct? _______
  2. How many genera are extinct after 50% of the families are extinct? _______
  3. As this analogy of a real extinction event, what does it mean in this model when a number comes up more than once?
  4. What is more significant - an extinction on the family level or on the genus level? EXPLAIN.
  5. In what ways is this exercise an accurate simulation of an extinction event? EXPLAIN
  6. How does it differ? EXPLAIN.
  7. What is the importance of studying extinctions? EXPLAIN.
  8. What conditions would be necessary if 50% of all families went extinct but only 50% of all genera also went extinct?