Adaptive radiation

Question 1

adaptive radiation has its roots where

Answer 1

galapagos

Question 2

What did Darwin collect

Answer 2

dozen different species of Galapagos birds- diverse bird fauna

Question 3

What do differences in size and shape of beak reflect

Answer 3

different diets, habitats
fill different niches
eg some crack open seeds with large beaks, some drink blood

Question 4

Despite the variation between birds, what did darwin discover

Answer 4

all represent a single lineage, come from a common ancestor, more closely related to each other than to any birds found elsewhere

Galapagos birds are related to other Galapagos birds, not european forms in the same habitat

Question 5

How did the birds end up on the galapagos

Answer 5

flock from S america got lost or was blown offshore by a storm, landed there then began to evolve

Specialised on different habitats because there were so many different habitats- drove them apart

Question 6

jack of all trades is master of none

Answer 6

generalists compete well if resources unpredictable year to year- rapidly shift to exploit whatever is available
but struggle if resources are stable year to year and season to season as have to compete with specialists

Question 7

Rapid radiation

Answer 7

after colonisation, finches rapidly occupied new niches

Question 8

adaptive radiation 3 main features

Answer 8

undergone by finches

• high diversity
• wide range of niches occupied ( wide range of diets, feeding adaptions, behaviours)
• Occurs over geologically short period

Question 9

Hawaii

Answer 9

twice land mass vs galapagos
higher rainfall, lusher
higher productivity and more area (species-area effect) to support diversity, and longer to adapt - hawaii seen more radiation

Question 10

silversword alliance

Answer 10

adaptive radiation of 50 species of plant in hawaiian islands- best known is the mount haleakala silversword
Grow everywhere from arid volcano craters to rainforest bogs
Include trees, shrubs, vines, rosettes, mats
Had extremely rapid evol

Question 11

Tarweeds

Answer 11

western north america
Origins of silversword alliance
small, weedy asters- members of the group that include daisies, sunflowers etc
not v diverse

Showed evol potential when hit HAwaii

Question 12

Drosophila

Answer 12

also colonised Hawaiian islands

Speciated to create 1000 species

Question 13

Why are islands a good model system

Answer 13

small area, short time frame
behave like continents but on a smaller scale- easier to study
Show same evol processes but smaller
Radiations play out same way

Question 14

Madagascar’s lemurs

Answer 14

result of dispersal from africa to madagascar

NO monkeys to compete with so diversified eg omnivores, herbivores, nocturnal and diurnal

Question 15

following colonization of a vacant habitat,

Answer 15

species are able to occupy empty niche

Question 16

facebook effect

Answer 16

can’t invent something like facebook, because already exists

Difficult to displace an established competitor

Question 17

When do adaptive radiations take off

Answer 17

when little/no comp

Question 18

Cretaceous-Tertiary (K-T) boundary

Answer 18

Disappearance of dinos, marine reptiles, pterosaurs
K-T boundary is a thin band of clay separating Cretaceous and Tertiary- when dinos etc went exctinct
Cretaceous: T rex an triceratops
Tertiary: no more dinos

Question 19

Iridium spike

Answer 19

elevated levels of iridium in the K-T boundary clay
Rare in the cretaceous and tertiary
Proposed an asteroid accounted for it

Question 20

additional evidence for the asteroid

Answer 20

• spherules (beads of silicate solidified from molten rock ejected by impact)
• shocked quartz ( quartz metamorphosed by intense pressure: found in meteor craters)
• Chicxulub

Question 21

Chicxulub

Answer 21

giant impact crater buried under the yucatan

Question 22

What happens when you wipe out an ecosystem

Answer 22

Plants and animals dispersing to the barren lava undergo adaptive radiation because they have no comp
Mass extinction: opportunities for survivors to colonise disturbed environments and radiate
Eliminate competitors and make areas of the earth barren

Question 23

mammal radiation

Answer 23

fossil evidence and molecular clocks show modern mammals eg marsupials, primate, bats all originate around the time of the impact
Rapid incr in body size
Without comp by dinos
New kinds of mammals: whales,, horses- new feeding strategies, habitats, locomotion

Question 24

bird extinction

Answer 24

fossils show birds were diverse in the cretaceous, but these were distantly related to modern forms
Disappear at the K-T boundary and don’t show up again

Question 25

Bird radiation

Answer 25

fossils and molecular clocks show birds had massive radiation after asteroid impact
New kinds: owls, penguins

Question 26

Lizard radiation

Answer 26

modern lizards- iguanas, pythons etc diversify to take adv of niches left vacant by extinction of cretaceous lizards
Worm lizards radiate- underwent major radiation after the extinction, spread to Europe and Africa

Question 27

Creative destruction

Answer 27

creation of new systems is a destructive process

Question 28

5 big mass extinctions

Answer 28

cretaceous-tertiary, triassic-jurassic, permian-triassic, late devonian and cambrian-ordovician
Suggests history of life may be repeated radiation and extinction

Question 29

cambrian explosion

Answer 29

modern arthropods, chordates appear in early cambrian
incr diversity
new kinds of organisms eg swimmers, grazers, burrowers
Biggest adaptive radiation in history
Happens quickly
First appearance of complex animals- brains, jaws, guts more complex
First predators
Beginning of modern life on earth

Question 30

Ediacaran extinction as a driver of cambrian explosion?

Answer 30

appearance of modern phyla preceded by destruction of the old order
Vegetable-like animals of edicaran period disappeared and modern phyla radiate in the aftermath
Creative destruction: origins of new complex, multicellular life lay in extinction of the old

Question 31

another way radiations can occur

Answer 31

organisms hit on novel ways of making a living

innovation

Question 32

Terrestriality

Answer 32

migration of plants, arthropods and vertebrates onto land creates a whole new ecosystem- doesnt compete with old, marine ecosystem
By moving onto land, plants able to radiate into prev unoccupied habitats
Creates new niches for plant eating arthropods, so can move onto land and radiate
New niches for predatory vertebrates created, so can move onto land and radiate

Question 33

Flight evol

Answer 33

opens up new niches
airborne predators, fish eaters etc
Animals exploit low density resources or seasonal ones

Question 34

punctuated equilibrium

Answer 34

idea that evol occurs in fits and starts

Question 35

adaptive radiation = punctuated evol

Answer 35

bursts of evol occur when there’s opportunity- eg new habitat colonised, extinction
Once all available niches occupied, settles down again