Unit 6 Lecture 31

Question 1

K-T boundary extinction may have been caused by what?

Answer 1

Asteroid Impact, which later cause an incineration of biosphere by shock wave of incandescent material. Causing a nuclear winter (debris injected into upper atmosphere circulated around the earth)

Question 2

What was survival like in the first hours of the Cenozoic?

Answer 2

• For several hours the entire earth was bathed with intense infrared radiation
• fires were being ignited
• sheltering underground within natural cavities
• Smaller animals survived along with reptiles

Question 3

What has caused mass extinctions in the past?

Answer 3

• alternating glacial and interglacial episodes
• global cooling
• drop in CO2
• rise in CO2
• global warming
• volcanism
• acidification of oceans

Question 4

What happened during the recovery period after extinction? (End Devonian)

Answer 4

There was a change in body size distribution
- vertebrates experienced body-size reduction after the hangenberg extinction

Question 5

What happened during the recovery period after extinction? (End Permian)

Answer 5

Reset of communities and more complex ecological interactions

Question 6

What happened during the recovery period after extinction? (Triassic and K-Pg mass extinctions)

Answer 6

• rapid diversification of mammals after the extinction of dinosaurs
• rapid evolution of body size in mammals
• While dinosaurs were around mammal size was not big, but after the extinction, size increased
• therapsids filled in a lot of the body size range

Question 7

To see if extinction selective, what 3 things would we look at?

Answer 7

1. Taxonomic affiliation: clades share characteristics or morphology
2. Ecological/life history traits: specialists vs. generalists, trophic level, etc.
3. Emergent properties: widespread vs. restricted geographic range

Question 8

How does geographic range correlate with origination rate?

Answer 8

Large geographic range size correlated with a lower origination rate (inverse relationship)

Question 9

How does geographic range size impact extinction risk?

Answer 9

A small geographic range size increases extinction risk

Question 10

Is there a general pattern with extinction rate and geographic range size?

Answer 10

Yes, extinction risk is correlated with geographic range size over the last 600ma

Question 11

Selectivity is least/most pronounced at major extinction events which indicates a positive/negative association between geographic range and survivorship

Answer 11

Least
Positive

Question 12

Geographic range size ______ with extinction intensity

Answer 12

decreases

Question 13

Does body size predispose species to a higher extinction risk?

Answer 13

Body size does not confer to an increased extinction risk

Question 14

When did size selectivity with mammal extinctions start happening (when did the body size of an animal impact extinction risk)?

Answer 14

When humans came around

Question 15

What factors make a species more prone to extinction in the fossil record
a. Large body size
b. Narrow geographic range
c. Large population sizes
d. B and C
e. All of the above

Answer 15

b. Narrow geographic range

Question 16

Why do humans have a reason to believe we are heading to our 6th mass extinction?

Answer 16

• Increasing carbon dioxide leads to warming temperatures
• Ocean acidification
• Habitat loss

Question 17

Megafauna are defined as?

Answer 17

Mammals larger than 44 kg

Question 18

Explain the megafaunal extinction

Answer 18

This extinction was unique mammalian history. It was extremely size biased, large bodied mammals were extinct and small bodied species survived.

Question 19

What was lost during the megafaunal extinction?

Answer 19

13 extinct species
- bears
- wolves (dire wolves)
- cats
- bison
- pronghorn
- 7 species of horses
- llamas
- peccaries and tapirs
- mastodons and mammoths
- African elephants
- Giant rodents
- 3 species of giant ground sloth
- giant armadillos and pampatheres

Question 20

Why were these species lost?

Answer 20

2 main Hypotheses:
1. human hunting: as humans traveled around the globe they hunted species to extinction
- they originated in Africa, went to Europe -> Asia -> North and South America and spread
2. climate change: extinction was a result of the climate change associated with glaciation

Question 21

What is one of the major things that happened during the late Pleistocene?

Answer 21

Global climate change: glaciation cycle where polar ice caps expanded to their maximum about 18,000 years ago and then contracted/ The changes in climate associated with glaciation had major effects on the distributions of organisms

Question 22

What happened as a result of the extinction in the late Pleistocene

Answer 22

• Body size distributions of species on all 4 continents
• Large bodied mammals were more like to go extinct

Question 23

Things larger than what animal were at risk go going extinct?

Answer 23

Fox

Question 24

What was the result for this size distribution?

Answer 24

Result was to fundamentally change the shape of the distributions where it happened.

Question 25

What is pairwise comparisons

Answer 25

Body size distributions of Pleistocene mammals before extinction event

Question 26

What orders are size biased?

Answer 26

Carnivores, Xenarthrans, artiodactyls, perissodactyls and depirotodonts - Extinction was particularly interesting because it wasn't a matter of removing large bodied clade i.e. in the carnivore clade the extinction was largely skewed towards larger body size

Question 27

Pattern suggest that size selectivity was or was not due to shared ecological traits

Answer 27

was not

Question 28

Name the order without size bias

Answer 28

Rodents and lagomorphs - these tend to be small bodied and suffered very few extinctions

Question 29

What was unique about the timing of the extinctions?

Answer 29

Approximately 12000 years ago in the new world and 46,000 years ago in Australia, the largest species in each fauna went extinct it was consistent with the timing of human arrival

Question 30

What continent(s) extinction rate had a coincidence with human arrival and climate change

Answer 30

North America and South America

Question 31

What continent(s) extinction rate had a coincident with human arrival but not climate change

Answer 31

Australia

Question 32

What continent(s) extinction rate had a coincident with climate change, humans were already there, but no real extinction

Answer 32

Africa

Question 33

How many continents were consisted with the hunting hypothesis How many continent were consistent with the climate

Answer 33

4 2

Question 34

Very large mammals had unique constraints such as?

Answer 34

Life history slowed - Low fecundity - Low gestation - Low population densities

Question 35

Over the previous 66ma were large mammals vulnerable to extinction?

Answer 35

NO

Question 36

What factor is correlated with extinction risk in fossil species?

Answer 36

Small geographic range size

Question 37

Species that had hunting as at least one of their listings for being endangered were larger/smaller than those who did not?

Answer 37

larger

Question 38

Explain overkill sites

Answer 38

During overkill, a predator invades the range of prey and constantly hunts it to extinction, but for climate change, the predator invades the range of the prey but does not hunt it to extinction. Instead climate change results in the extinction at a later time

Question 39

The overkill model predicts that the relationship between kill sites and latitude will be?

Answer 39

Linear and positive

Question 40

The uniqueness of the Pleistocene extinction implies that?

Answer 40

Increase extinction risk to large bodied species is a hallmark of human effects

Question 41

Shifts in mean body size on each continent follow what dispersal patterns

Answer 41

hominin