Islands and Oceans Flashcards
2 early biogeographers:
- _____ ____ (1754-1794)
- __ ________ (1778-1841)
Georg Foster
de Candolle
What are 2 observations Georg Foster made about the distinct patterns of diversity on islands?
- islands are species-poor relative to mainlands
- larger or ecologically diverse islands have more species
What’s 1 observation de Candolle made about the distinct pattern of diversity on islands?
age & degree of isolation affects island species #
3 themes in island biogeography:
- dispersal
- extinction
- diversity
Explain the process of how islands acquire species
- initial dispersal event (to a previously unoccupied land)
- can be natural (fly/swim) or artificial (on purpose or accidental) - subsequent adaptive radiation, because they don’t have any natural predators
- adapt into niches
or reverse selection may occur
- As more species are introduced the original species will decline
chains of islands act as a ____
filter
- fewer species on the islands further from mainland
- most fit species disperse further
islands tend to be populated by ___ _____. Once they get there, life may change (eg. altered ____ and _____)
good dispersers
resources and competition
Ecological release=
relaxation of selective pressure
eg. when a species disperses to a new island and has lots of resources + little competition
A population in a species-poor environment will likely occupy a _____ range of their fundamental niche
broader
endemism=
being unique to that location
What are 3 island phenomena?
- 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
Island Rule=
Tend towards medium size (dwarfism in large species, and gigantism in small species)
Bergmann’s Rule=
Body mass increases with latitude
Cope’s rule=
Trend towards larger body size (and
range of sizes) during the evolutionary diversification of a lineage
List up to 5 scenarios where the term ‘island’ is appropriate to apply
Islands can be any kind of _____ or fragmented habitat
- Islands
- Lakes
- Mountain tops
- Forest fragments
- Remnant refuges
isolated
Post-Pleistocene elevational shifts have created modern day ____ in the North American Southwest
refugia (islands)
What factors control biodiversity on islands and how is biodiversity
affected by island size, distance from the mainland, and the age of the island?
Two general patterns have been observed
1. Bigger island = more species
2. Greater distance to island = fewer species
species richness increases ___(more/less) rapidly for larger islands
less
Isolated islands support _____species than islands that are located nearer to continents
* Decline in species richness b/c decline in ____opportunities with isolation
fewer
dispersal
What is the theory of island biogeography? Who developed it?
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
