lecture 14

Question 1

endosymbiotic theory

Answer 1

anaerobic bacteria would have difficulty surviving in aerobic (oxygen) environments. solution? endocytosis

Question 2

endocytosis

Answer 2

hypothesis for the origin of euakryotic organelles.

• mitochrondria - endocytosis of aerobic bacteria.
• chloroplasts - endocyotsis of photosynthetic bacteria.
• symbiotic relationship for both cells (symbiosis).

Question 3

life was

Answer 3

unicellular for most of earth’s history.

Question 4

O2 was

Answer 4

~absent from ocean and atmosphere for ~2 billion yeras after the origin of life.

Question 5

oxygenation is a factor in

Answer 5

eukaryote evolution.

Question 6

origin of animals

Answer 6

• multicelluarity - allowed for new levels of organization.

- differentiation - allocation of cells to different functions during development of organism.

Question 7

cambrian explosion

Answer 7

major animal diversification (~535-510 Ma). all major groups of animals and body plans, ecologies appear.

Question 8

burgess shale

Answer 8

fossil formation in Canadian Rockies 508 million years ago. Exceptional preservation.

Question 9

ordovician faunas of burgess shale type

Answer 9

rare soft-body preservation. not as much extinction at end of cambrian as thought. lead up to ordovician diversification within animal phyla.

Question 10

taxonomic and morphological diversity through time

Answer 10

diversity has generally increased over time, but not without some sharp declines.

Question 11

circularity

Answer 11

morphological diversity = taxonomic diversity.

Question 12

paleobiology database

Answer 12

no palezoic plateau, new cenozoic plateau. trend of increasing diversity? perhaps a diversity ceiling?

Question 13

taxonomic diversity is a

Answer 13

poor proxy for morphological diversity. direct measure of morphological diversity = morphological disparity.

Question 14

morphospace

Answer 14

the actual or potential range of morphologies.

Question 15

morphological disparity evolves

Answer 15

early and is present in each clade.

Question 16

macroevolution

Answer 16

large-scale evolutionary change; evolution at or above the level of species.

Question 17

gradualism

Answer 17

dawinian view; evolution is slow and steady. thus,

• the fossil record should consist of a long sequence of continuous and intermediate forms linking ancestors and descendants.
• morphological breaks in a hypothesized sequence are due to imperfections in the geological record.

Question 18

punctuated equilibrium

Answer 18

evolution of morphological diversity occurs during speciation with periods of stasis in between. Thus,
- new species arise by splitting.
- new species develop rapidly, especially on geologic time scales.
- a small subpopulation of the ancestral form gives rise to the new species.
- the new species originates in a very small part of the ancestral species’ geographic extent - in an isolated area at the periphery of the range.
> the fossil record should consist of a sharp morphological break between species (punctuation).
> migration of the descendant from the peripherally isolated area into its ancestral range.
> rarely discover the actual event of speciation in the fossil record.
> many morphological breaks in the fossil record are real.

Question 19

morphological stasis

Answer 19

does not equal genetic stasis.

Question 20

~20% extinct every

Answer 20

1 million years. >60% extinct in 1 million years.

Question 21

Permian-Triassic (P-T) extinction

Answer 21

PT boundary; extinction of 96% of all marine species, 70% of terrestrial vertebrates. Recovery took 10 million years.
- cause?
> catastrophic group - impacts, volcanism, methane release.
> gradual group - sea level change, increasing anoxia, increasing aridity.

Question 22

habitat loss due to expanding human populations

Answer 22

extinction is occurring at 100 to 1,000 times the normal background rate.