Extinctions And Changes In Biodiversity Flashcards
How many mass extinctions have there been so far?
5
What are the main contributors to a decrease in biodiversity?
Give a percentage if possible
Exploitation and habitat degradation (68.4%)
Climate change and invasive species come second
What makes a species more at threat from extinction?
3 points
Small populations/small geographical range
Species tied to a habitat favoured by humans
Those higher in the food chain
Who pointed out that there were discontinuities in the fossil records?
Mary Anning (early 1800s)
Who found that whole clusters of taxa disappeared at the same time in the fossil record?
A French palaeontologist called Cuvier (1825)
What famous scientist didn’t believe there had been mass extinctions?
Darwin
What are the five mass extinctions?
- Late Ordovician
- Late Devonian
- Late Permian
- Late Triassic
- End-Cretaceous
What is the Cretaceous-Paleogene extinction also known as and when was it?
K/T boundary
65 million years ago
What happened after the K/T boundary?
75% species extinct
Mammals replaced dinosaurs
Flowering plants diversified
Insects co-evolved with plants
What is believed to of caused the mass extinction at the K/T boundary?
Large asteroid impact approx. 1000x greater than Krakatoa eruption
What are the two hypotheses for the Pleistocene mammal extinctions?
- Environmental deterioration: retreat of glaciers, corridors lost
- Human overkill: beringia appeared allowing spread of H.sapiens into North America
Give an example of competitive co-evolution:
The predatory mite, which ate prey to extinction then also became extinct
What was it called when all the continents were joined, and when was it?
Pangea
220 million years ago
Why did land vertebrates in Euramerica have a slow migration in the Late Permian period?
Hindered by mountains and southern deserts
