Adaptive radiation Flashcards
What does the difference in size and beak shape reflect?
Different foraging strategies - ecological niche.
What was surprising about the birds darwin collected?
He thought they were all different species, but they were from the same lineage.
What are the closest relatives to the finches?
The tanagers from South America.
When do generalists compete well?
If resources are highly unpredictable year to year or season to season as it can rapidly shift to what is available.
When do specialists compete well?
When resources are stable year-to-ear and season to season.
What are the three features of adaptive radiation?
High diversity, wide range of niches occupied (diets, feeding adaptations, behaviours, body sizes etc) and occurs over a geologically short period - diversification of organisms into filling different ecological niches.
Honeycreeper finches?
SImilar to darwin finches but are more specialised for their lifestyles and more diverse.
What do honeycreeper finches evolve from?
Rosefinches.
SIlversword alliance?
Adaptive radiation of 50 species of plant in the Hawaiian islands. Grow everywhere - arid volcano craters to rainforest bogs.
Why are islands focused on within studies?
THey behave like continents but on a smaller scale and are easier to study. They show the same evolutionary processes but on a smaller scale - models.
Kangaroo?
Product of adaptive radiation.
What are colonization radiations?
Following a colonization of a vacant habitat, species can rapidly occupy empty niches.
What is strange about groups of organisms that have successful adaptive radiations?
They are not successful in the place they come from - niches already filled.
Why do adaptive radiations arise?
Due to opportunities - little or no competition for resources.
What is the creaceous-tertiary boundary?
When the dinosaurs and everything else went extinct.
What was found in the K-T boundary clay?
Iridium.
How does mass extinction have events similar to adaptive radiation?
Allows survivors to colonise disturbed environments and radiate. Similar to the galapagos but play out on the scale of continents.
What happens to birds at the K-T boundary?
They disappear and never show up again.
What happened to birds 10 million years after the K-T extinction?
New kinds of birds appeared - massive radiation.
What other organisms went extinct at the K-T boundary?
Lizards and snakes,
How have modern lizards formed?
Diversification to take advantage of niches left vacant by extinction of cretaceous lizards.
What is creative destruction?
Rise and spread of new tech. is linked to the destruction of old ones - economy is constantly renewing and destroying itself.
K-T extinction effects ?
75% of species eliminated but diversity rebounds rapidly and soon surpasses cretaceous diversity levels.
What are the 5 big mass extinctions?
Cretaceous-tertiary, triassic-jurassic, permian-jurassic, permian-triassic, late devonian and cambrian ordivician.