Islands and Oceans

Question 1

2 early biogeographers:

• _____ ____ (1754-1794)
• __ ________ (1778-1841)

Answer 1

Georg Foster

de Candolle

Question 2

What are 2 observations Georg Foster made about the distinct patterns of diversity on islands?

Answer 2

• islands are species-poor relative to mainlands
• larger or ecologically diverse islands have more species

Question 3

What’s 1 observation de Candolle made about the distinct pattern of diversity on islands?

Answer 3

age & degree of isolation affects island species #

Question 4

3 themes in island biogeography:

Answer 4

1. dispersal
2. extinction
3. diversity

Question 5

Explain the process of how islands acquire species

Answer 5

1. initial dispersal event (to a previously unoccupied land)
   - can be natural (fly/swim) or artificial (on purpose or accidental)
2. subsequent adaptive radiation, because they don’t have any natural predators
   - adapt into niches

or reverse selection may occur

3. As more species are introduced the original species will decline

Question 6

chains of islands act as a ____

Answer 6

filter

• fewer species on the islands further from mainland
• most fit species disperse further

Question 7

islands tend to be populated by ___ _____. Once they get there, life may change (eg. altered ____ and _____)

Answer 7

good dispersers

resources and competition

Question 8

Ecological release=

Answer 8

relaxation of selective pressure
eg. when a species disperses to a new island and has lots of resources + little competition

Question 9

A population in a species-poor environment will likely occupy a _____ range of their fundamental niche

Answer 9

broader

Question 10

endemism=

Answer 10

being unique to that location

Question 11

What are 3 island phenomena?

Answer 11

• endemism
• reduced dispersal (eg. bird might lose its ability to fly after dispersing b/c it doesn’t need to, so cannot disperse further)
• giantism and dwarfism: usually small + large individuals

Question 12

Island Rule=

Answer 12

Tend towards medium size (dwarfism in large species, and gigantism in small species)

Question 13

Bergmann’s Rule=

Answer 13

Body mass increases with latitude

Question 14

Cope’s rule=

Answer 14

Trend towards larger body size (and
range of sizes) during the evolutionary diversification of a lineage

Question 15

List up to 5 scenarios where the term ‘island’ is appropriate to apply

Islands can be any kind of _____ or fragmented habitat

Answer 15

• Islands
• Lakes
• Mountain tops
• Forest fragments
• Remnant refuges

isolated

Question 16

Post-Pleistocene elevational shifts have created modern day ____ in the North American Southwest

Answer 16

refugia (islands)

Question 17

What factors control biodiversity on islands and how is biodiversity
affected by island size, distance from the mainland, and the age of the island?

Answer 17

Two general patterns have been observed
1. Bigger island = more species
2. Greater distance to island = fewer species

Question 18

species richness increases ___(more/less) rapidly for larger islands

Answer 18

less

Question 19

Isolated islands support _____species than islands that are located nearer to continents
* Decline in species richness b/c decline in ____opportunities with isolation

Answer 19

fewer
dispersal

Question 20

What is the theory of island biogeography? Who developed it?

Answer 20

a model developed by Robert MacArthur and E.O. Wilson in 1967 that suggested:
- # of species inhabiting an island represents a dynamic EQ b/w immigration/ extinction