Distributions, Migrations And Dispersal Flashcards Preview

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

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

Triassic period

2

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

The Late Cretaceous period

3

Give some examples of ‘wandering families’:

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

What is endemicity?

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

What are flowering plants called?

Angiosperms

6

Why did flowering plants evolve so late?

Nature of fossil evidence: could have been present

Environmental considerations: not suitable until CO2 levels were high enough

7

Give some advantages of angiosperms:

Tough leathery leaves- drought resistant

Resistant seed coat prevents desiccation

More efficient water conducting vessels

Rapid reproduction

Accelerated speciation- diversity of adaptive types

8

Why was there such rapid diversification of angiosperms?

Insect-angiosperm co-evolution
Genetic exchange between widely spaced individuals and small populations

9

What are cosmopolitan taxa/species?

Species that occur over all/most regions of the world

E.g humans

10

What higher taxa are cosmopolitan?

Insects and grasses

11

What are widespread taxa?

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

12

Give some examples of widespread taxa:

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

Penguins

Heather

Pine

13

What is the definition of disjunct distribution/taxa?

Give an example

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

E.g marsupials

14

What are endemics?

Give an example

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

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

South America and Madagascar

16

Give an example of climatic relicts and describe it

Arctic spring tail

Glacial retreat led to speciation

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

17

Why is dispersal and migration important?

2 points

1. Successful species multiply and spread

2. Genetic isolation increases speciation

18

What are the secrets of success for plant dispersal?

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

What are the disadvantages of animal dispersal?

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

When is migration most rapid?

When there is continuity of habitat

21

What are corridors?

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

22

What are barriers?

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

23

What are filters?

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

24

What are bridges? Give an example

They are temporary corridors

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