L2 Tosh - Extinctions and changes in Biodiversity

Question 1

Why did animals such as mammoths become extinct in the present inter glacial era?

Answer 1

1. Environmental deterioration
   - retreat of glaciers caused conditions to change rapidly - which meant a change in feeding a reproduction cycles
   - habitat change - from forests and swamps to large areas of uniform drier vegetation

Question 2

Why was there a greater loss in this inter glacial than previous ones?

Answer 2

Humans over kill

• timing of mans arrival in N America killed over 35 large mammal species
• probably routes by which homo sapiens spread out of Africa

BUT

similarly there were extinctions in large and small birds, which are difficult to hunt. There is little archeological evidence that humans invaded (previously there has been marks on bones etc.)

Question 3

What is the biological cause for extinction?

Answer 3

competitive co-evolution

- e.g. predatory mite ate prey to extinction then also became extinct

Question 4

How did vulcanism cause extinction?

Answer 4

Climate change on a global scale

• santorini
• tamboura java

Question 5

What 2 patterns does diversity generally change over time?

Answer 5

1. General increase in diversity ovsuch as marine animal families)
2. an increase, usually with periods of decline, then continued decline or extinction (e.g. dinosaurs)

Question 6

How does continental drift effect diversity?

Answer 6

Over 220 million years ago the contents were joined together - Pangea.

As the continents split the continants drifted, splitting animals up, providing different climatic conditions and niches, meaning species specialised and diversified away from each other and to different habitats

Question 7

What diversification occurred in the early devionain period (380mya)?

Answer 7

Diversification of fish and coral reefs

• first time seeing separate fish and flora in cool
• amphibians then reptiles - most early fossils found near the equator in Euramerica

Question 8

What diversification occurred in the Late Permian

Answer 8

Coal swamps were replaced by deserts, and mountain ranges extended in N Africa

Land vertebrates in Euramerica slow migration is hindered by mountains and S deserts

Land vertebrates on Gondwana only after loss of polar ice cap. Reached Siberia and China only after land masses joined

Question 9

What consequences did the break up of Pangea (200mya) have on biodiversity?

Answer 9

• Migration routes destroyed
• new mountains, oceans, land barriers all deflected oceanic and atmospheric circulations - this contributed to global climate changes which in turn altered biodiversity

Question 10

What effect did the steroid impact have on plants?

Answer 10

• Pollen flora changed abruptly - fern spores were more numerous
• Gases and dust changed the climate rapidly
• Smoke and dust reduced light
• Fireball ignited forests over a huge acre, releasing CO2 SO2 and NOX