Species explosion & extinction

Question 1

Briefly describe what happened in the Cambrian explosion

Answer 1

the first animals developed from ediacaran fauna 565 mya - proliferation of animals with backbones and hard skeletons

Question 2

When did vertebrates evolve, according to the fossil record?

Answer 2

900 mya

Question 3

What was the most important development of cambrian radiation?

Answer 3

a hard skeleton

Question 4

What were the causes of the cambrian explosion?

Answer 4

the evolution of the metazoan (animal) cell combined with an atmospheric change creates new ecological niches to be filled by hard-bodied animals.

Question 5

Describe the equilibrium model of island biogeography

Answer 5

the extinction rate increases and the immigration rate decreases with increasing number of species, maintaining a species equilibrium

Question 6

Give 2 examples of biological causes of extinction

Answer 6

Red Queen Hypothesis breaking down and competition

Question 7

Describe the Red Queen Hypothesis

Answer 7

How a species needs to continue to evolve in order to stay one step ahead of their parasite or predator.

Question 8

Give 2 examples of non-biological causes of extinction

Answer 8

asteroids and changes in the physical environment

Question 9

Describe the relationship between the Harlequin and 2-spot ladybird

Answer 9

Arrival of Harlequin ladybird into Britain in 2003 resulted in 44% decline in 2-spot ladybird population. They both share the same habitat of deciduous trees.

Question 10

Describe the cretaceous mass extinction event

Answer 10

65 mya - asteroid wiped out dinosaurs and nearly half of the major groups of marine animals. 75% of all species wiped out, including many plants.

Question 11

Describe the triassic extinction event

Answer 11

207 mya - undersea volcano caused extinction of nearly 50% of all terrestrial and marine species.

Question 12

Describe the permian mass extinction

Answer 12

251 mya - volcanic eruption or asteroid caused extinction of 70% of terrestrial and 96% of marine species on planet. Also known as insect mass extinction.

Question 13

Describe the devonian extinction event

Answer 13

364 mya - unknown cause resulted in the extinction of 22% of all marine families

Question 14

Describe the ordovician extinction event

Answer 14

2 extinction bursts around 440 mya - a fall in sea level from the formation of glaciers caused the extinction of 25% of all marine families (over 60% of marine invertebrates, worse effected were bivalves, echinoderms, corals and trilobites)

Question 15

What qualifies an extinction event as a mass extinction event?

Answer 15

a loss of over 60% of species within 1 million years