World Colonization

Question 1

What are the 6 mass extinctions?

Answer 1

1. ice age
2. drop in oxygen levels due to volcanism
3. Drop in oceanic oxygen due to volcanism
4. Global warming due to volcanism
5. chicxulub meteorite and volcanism
6. human impacts

Question 2

what is a mass extinction?

Answer 2

• Rapid and dramatic changes in climate, combined with significant changes in the composition of environments and land or in the ocean.

Question 3

Human colonization of Ice Age Earth: step 1

Answer 3

1. divergence of hominin species
   - Multiple species originate from Africa.
   - Mixture of human lineages.
   - First wave was Neanderthals.

Question 4

Human colonization of Ice Age Earth: step 2

Answer 4

2. Origin homo sapiens

Question 5

Human colonization of Ice Age Earth step 3

Answer 5

3. Population divergence

Question 6

Human colonization of Ice Age Earth step 4

Answer 6

Second human migration out of Africa – First migration of Homo sapiens into Europe.

Question 7

Mega fauna extinction

Answer 7

Eemian (126.000 BP) vs Holocene (12.000 BP)

Many large mammals that use to be present in the Eemian (126.00-116.000 BP). The climate was comparable to the climate of today. In the Holocene (12.00-0 BP) many of those species are extinct.

Due to the absence of large mammals (gradual extinctions), such as the mammoth, open steppes changed into forests. This led to a big extinction as species were not adjusted to living in forested areas.

The extinction of large mammals is due to the arrival of homo sapiens of the continents.

The reason the extinction is Africa is smaller is that people and animals used to co-exist and co-evolve. Animals used to evolve as a result of human hunting.
→ the further away → less co-evolution
- Also depending on the size of the continent / island

For example, the colonization of the pacific (rapid extict)
- New Zealand: 200 years of humans presence led to the extinction of Moa.

Question 8

3 adaptations coevolved species in Africa did to survive:

Answer 8

1. Refuge to unsuitable area for humans
2. Avoidance (elusive and nocturnal)
3. Physical defense

Question 9

3 hypothesis that leaded to the mega fauna extinction

Answer 9

1. Overkill hypothesis (Martin, 1973)
2. Keystone species hypothesis (Owen- Smith, 1987)
3. Second order predation hypothesis (Whitney-Smith, 2009)

Question 10

The overkill hypothesis

Answer 10

(large herbivore hunting) Proposes that many large animals (megafauna) went extinct at the end of the Pleistocene because humans overhunted them faster than they could reproduce.

Key idea: Human hunting → rapid megafauna decline.

Question 11

Keystone species hypothesis (Owen-Smith, 1987)

Answer 11

Suggests that the extinction of certain critical species (keystone species) caused ecosystem collapse, because these species had a disproportionately large effect on the environment and other species.

Key idea: Loss of key species → cascade of extinctions.

Question 12

Second order predation hypothesis (Whitney-Smith, 2009)

Answer 12

Argues that extinctions occurred due to indirect effects of predators: humans or new predators didn’t always hunt megafauna directly, but changed the behavior or population of prey and smaller predators, causing cascading extinctions.

Key idea: Indirect predation → ecosystem chain reaction → megafauna loss.

Question 13

viking expansion and ecosystem change.

Answer 13

• House Mice: After arrival there was a massive change in ecosystem characteristics on Iceland. Decrease in trees, such as Birch and Willow, leading to a decrease in leaf litter. There was an increase in grassland and SAR (sedimentation accumulation rate), indicating an increase in erosion.
• The Vikings travels corresponds with the expansion of a clade of house mice. The mtDNA clade of house mice are similar of the mice from where Vikings are from compared to where they travelled to.

Question 14

Polynasian colonisation

Answer 14

pacific rat impacts ecosystem

1. Predation (eggs, small birds, reptiles)
2. Forganing (of seedlings impacting plant community compositions)
3. cascading effects