Biogeography

Question 1

Darwins logic - Islands

Answer 1

1. Remote islands only have species that can disperse long distances (bats)
2. Most island species descend from nearby mainland species
3. the proportion of endemic species on an island is highest when the opportunity for dispersal to the island is low (More endemism when islands are far from a mainland)
4. Island species bear marks of a continental ancestry; seeds have hooks adaptation for dispersal by animals– many seeds on islands lacking mammals have hooks

Question 2

Historical factors affecting geographic distributions

Answer 2

Extinction, Range Shifts, Dispersal, Vicariance

Question 3

Range shifts

Answer 3

when a species geographical range changes

• leaves behind a relict population (a group of organisms that currently occupy a limited geographic area, but were once much more widespread in the past)

Question 4

Dispersal (two kinds)

Answer 4

Oceanic islands = never connected to mainland (birds, bats, tortoises common)
Continental Islands = connected to mainland in past

Question 5

Vicariance

Answer 5

the separation of a continuously distributed ancestral taxon into separate parts due to the development of geographical or ecological barriers

Question 6

Vicariance example

Answer 6

Central and South America connected = Panama; North Pacific Ocean and Caribbean Sea separated, was once one; separation of taxon (snapping shrimp)

Question 7

Vicariance example

Answer 7

Gondwana - southern countries used to be connected; shift of species once in one country —> to the next (Banksia: a genus of plants with a Gondwanan distribution)

Question 8

Marsupials

Answer 8

Originated in Asia, dispersed around globe, to north america, NA to Asia, Africa, South America, Australia – became extinct in NA, Europe, Antartica – found today in South America/Austrailia

Phylogenetic evidence among extant taxa suggests marsupials evolved in South America!
(Even though they are more diverse in Australia today)

Question 9

Wallace’s Line

Answer 9

Plate tectonics brought Bali and Lombok closer in distance, though still very different life

Question 10

Biogeography

Answer 10

study of the distributions of populations, species, and higher taxa - including causes/consequences of species distributions

Question 11

Endemic

Answer 11

native species that are found only in a specific habitat within a given area

Question 12

The Pleistocene Epoch “Ice Ages”

Answer 12

Large bodied mammals (mammoths), Species distributed further south, humans restricted to Africa

Question 13

Milankovitch Cycles

Answer 13

Eccentricity, Obliquity, Precession

Angle sun hitting the planet

Question 14

Eccentricity

Answer 14

the shape of earth’s elliptical orbit around the sun

Question 15

Obliquity

Answer 15

earth’s tilt & axial precession (wobble); think like a top spinning

Question 16

Precession

Answer 16

change in orientation of earth’s rotational axis

Question 17

Consequences of Milankovitch Cycles

Answer 17

– Changes in the amount of solar radiation hitting earth
– Changes in the angle that solar radiation hits the earth
– Led to Glacial and interglacial periods

Question 18

Where did species move?

Answer 18

• In Europe; mountains moved east to west; animals had to take distinct path due to cold/glaciers coming from north and coming off the mountains as well
• In North America; run north to south; animals much more dispersed
• animals and vegetation moved
• some animals adapted to cold (wool mammoth thick coat; large body size)

Question 19

Pleistocene Megafauna

Answer 19

Large-bodied mammals, birds, reptiles around earth

Question 20

Why did Pleistocene Megafauna go extinct?

Answer 20

1. Climate change (overchill) but many extinctions occurred at diff times
2. Hunted by humans (timing of when humans arrived, megafauna went extinct)