1.5.4 The Coevolution of Horses and Plants

Question 1

coevolution

Answer 1

• the reciprocal evolution between two species

Question 2

cladogenesis

Answer 2

• a pattern of change characterized by the branching of a lineage into different paths. The evolution of genus
  Equus (horse species) is an example of cladogenesis. Each branch gave rise to several species, many of which are extinct.

Question 3

notes

Answer 3

• The ancestral species that gave rise to the modern-day horse was a much smaller, four-toed, twig-eating animal that was suited for life in the forest.
  • The fossil evidence for the evolution of the horse is an example of coevolution and cladogenesis

Question 4

merychippus

Answer 4

• an enlarged central toe with the two side toes reduced.

Question 5

hyracotherium

Answer 5

• earliest ancestor that the horse is known to have

descended from is Hyracotherium

Question 6

mesohippus

Answer 6

• was larger and had three toes (the two middle

toes fused)

Question 7

Of the following choices, the modern horse’s most recent ancestor was

Answer 7

• Merychippus

Question 8

Branching evolution in which one species gives rise to several is referred to as

Answer 8

• cladogenesis

Question 9

Based on studies of the grazing ecosystem of the Serengeti Plains in East Africa, interesting adaptations have been observed amongst herbivores and the plants that they feed on. The studies show that herbivores graze off the tops of plants and that their grazing may contribute to the evolutionary success of species that can withstand grazing. Given this information, identify which of the following would not represent evidence of coevolution.

Answer 9

• Grasses that grow inside enclosed areas protected from grazing have more vegetation per unit area than grazed areas.

Question 10

A good example of coevolution is the interaction of

Answer 10

• Hyracotherium and the dominant vegetation of the time.

Question 11

Which of the following is an accurate example of the evolution of the horse exhibiting both cladogenesis and coevolution?

Answer 11

• Some ancestral horse species got larger and developed an enlarged central toe for walking on the prairie, and this branch of the horse lineage experienced great success as a result of this adaptation.

Question 12

Which of the following was not a characteristic of hyracotherium ?

Answer 12

• reptile-like jaw