Distributions, Migrations And Dispersal Flashcards Preview

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Flashcards in Distributions, Migrations And Dispersal Deck (24)
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1
Q

When did the first egg laying mammals (monotremes) arise?

A

Triassic period

2
Q

When did modern mammals (placentals and marsupials) first appear?

A

The Late Cretaceous period

3
Q

Give some examples of ‘wandering families’:

A
Shrews
Squirrels 
Hamsters and voles 
Hares and rabbits 
Bears 
Dogs 
Cats 
Mustelids (except Australia)
Bovids (except S America and Australia)
Rats and mice (except N and S America)
4
Q

What is endemicity?

A

The number of endemic families x100/total number of families

If a land mass has 100% endemicity that means all those families occur there and nowhere else

5
Q

What are flowering plants called?

A

Angiosperms

6
Q

Why did flowering plants evolve so late?

A

Nature of fossil evidence: could have been present

Environmental considerations: not suitable until CO2 levels were high enough

7
Q

Give some advantages of angiosperms:

A

Tough leathery leaves- drought resistant

Resistant seed coat prevents desiccation

More efficient water conducting vessels

Rapid reproduction

Accelerated speciation- diversity of adaptive types

8
Q

Why was there such rapid diversification of angiosperms?

A

Insect-angiosperm co-evolution

Genetic exchange between widely spaced individuals and small populations

9
Q

What are cosmopolitan taxa/species?

A

Species that occur over all/most regions of the world

E.g humans

10
Q

What higher taxa are cosmopolitan?

A

Insects and grasses

11
Q

What are widespread taxa?

A

Species that are common in only suitable habitats in well-defined regions of the world

12
Q

Give some examples of widespread taxa:

A

Cacti: widespread in north, central and South America but not found anywhere else

Penguins

Heather

Pine

13
Q

What is the definition of disjunct distribution/taxa?

Give an example

A

Species that are found in one place and then found in another completely different place

E.g marsupials

14
Q

What are endemics?

Give an example

A

Species found in only one well-defined region, large or small

Finches on individual Galápagos Islands
Red grouse Britain
Rosy periwinkle Madagascar
Eucalyptus Australia

15
Q

What two countries are considered really important for endemic plant species?

A

South America and Madagascar

16
Q

Give an example of climatic relicts and describe it

A

Arctic spring tail

Glacial retreat led to speciation

Arctic springtail= 2x8 eyelets
Pyrenees springtail= 2x6 eyelets

17
Q

Why is dispersal and migration important?

2 points

A
  1. Successful species multiply and spread

2. Genetic isolation increases speciation

18
Q

What are the secrets of success for plant dispersal?

A
  1. Seeds are resistant to desiccation
  2. Long distance dispersal
  3. Many plants have both sexes on the same plant
  4. Aerial dispersal
  5. Plants with fruit attracts birds and other animals
  6. Vegetative reproduction
  7. Primary producers- self sufficient
  8. Seeds resistant to fungal diseases
19
Q

What are the disadvantages of animal dispersal?

A
  1. They need to individuals of the opposite sex to breed
  2. They need a food source to survive
  3. They may carry parasites and diseases
20
Q

When is migration most rapid?

A

When there is continuity of habitat

21
Q

What are corridors?

A

Stretches of continuous habitat, land or water that allow migration in both directions

22
Q

What are barriers?

A

Patches of unfavourable habitat, e.g oceans such as the English Channel

23
Q

What are filters?

A

They have selective corridors, e.g the Pyrenees allow cold tolerant species to disperse

24
Q

What are bridges? Give an example

A

They are temporary corridors

E.g beringia allowed the passage between Asia and North America for cold tolerant species