Zoogeography

Question 1

Biogeography

Answer 1

– Study of the geographical distribution of living

things in time and space

Question 2

– Zoogeography

Answer 2

is the study of animal distribution

Question 3

Approaches
– Common question: Are current distributions the
result of dispersal or vicariance?

Answer 3

• Ecological – contemporary factors contribute to ranges
• Historical – phylogenetics, diversification
• Vicariance or dispersal might result in the disjunct
distribution of species

Question 4

• Species’distributions are dynamic
– Former and present ranges differ
• Climatic shifts
• Facilitated dispersal

Answer 4

• Shared patterns can inform
– Earth history
– General evolutionary forces

Question 5

Significant Patterns

Answer 5

• Distinct biogeographic regions
• Latitudinal diversity patterns
• Elevational diversity patterns
• Area relationships
• Island syndromes

Question 6

Alfred Wallace (1823-1913)

Answer 6

“Father” of biogeography
• Traveled world documenting diversity and
distributions

Question 7

Dispersal

Answer 7

• Occurs when an individual or population moves

from its place of origin to a new area

Question 8

• Dispersal tendency due to

Answer 8

pressures exerted
by reproduction and necessity for the spacing
of individuals

Question 9

Dispersal Depends on:

Answer 9

–Dispersal ability of species
– Breadth of tolerable environmental conditions
– Presence and permeability of barriers

Question 10

Vicariance

Answer 10

• Species distribution patterns explained by splitting of
previously occupied region
• Emergent barriers divide species distribution
• Gene flow is restricted
• Geographic isolation and speciation

Question 11

Avenues of Faunal Interchange

Answer 11

• Corridors
– Pathway offering little resistance to movement
• Filter route
– Pathway allows passage of only certain
species
• Sweepstakes route
– Pathway probably not crossed by large
numbers of any given type of animal, but may
be followed by an occasional individual

Question 12

Wallace’s Zoogeographic Regions

Answer 12

Palearctic Region
Nearctic Region
Neotropical Region
Afrotropical Region
Indo-Malayan Region
Australasian Region
Antarctic Region
Oceania

Question 13

Palearctic Region

Answer 13

• Northern part of Old World
• Primarily temperate climate
– Shares 76% of families with Indo-Malayan region

Question 14

Nearctic Region

Answer 14

• Includes nearly all of North America north of
the tropical sections of Mexico, and
Greenland
• Arctic tundra to semitropical thorn forest

Question 15

Neotropical Region

Answer 15

• Americas from tropical Mexico south, Caribbean, southern tip
of Florida
• Tropical or subtropical (some deserts, alpine tundra, and
savannas)
• Characteristic mammals include marsupials, bats, primates,
xenarthrans, and hystricognath rodents

Question 16

Afrotropical Region

Answer 16

• Africa south of Sahara, southern Arabian
Peninsula, Madagascar
• Deserts, tropical savannas, tropical forests,
montane forest, alpine tundra
• High diversity of ungulates

Question 17

Indo-Malayan Region

Answer 17

• India, Indochina, southern China, Malay Peninsula,
Philippines, Indonesia west of Wallace’s line
• Tropical climate dominates
• Resembles Palearctic region (share 90% of families)
• Five families of primates, very high rodent and bat
diversity

Question 18

Australasian Region

Answer 18

• Australia, Tasmania, Indonesian islands east of
Wallace’s line, New Guinea, islands of Melanesia,
New Zealand
• Tropical forests, savannas, and deserts
• 18 marsupial families and 9 native terrestrial eutherian
families (21 endemic). High rodent diversity in parts.

Question 19

Antarctic Region

Answer 19

• Antarctica
• No land mammals since covered in ice in the
Neogene
– Seals only current terrestrial (semi) residents

Question 20

Oceania

Answer 20

• Oceans of the world and isolated islands
– Relatively homogeneous from basin to basin
– Potential for global dispersal
• Marine mammals and bats
– Cetaceans and pinnipeds
– Verspertilionids and emballonurids
– Flying foxes on many Pacific Islands

Question 21

Latitudinal Species Gradient

Answer 21

• Greatest diversity in the tropics
• Researchers have suggested that the
tropics:
– Have higher rates of evolutionary origination
(speciation) and act as a “diversity pump”
– Have lower rates of extinction and tend to
accumulate more species

Question 22

Island Syndrome

• On islands:

Answer 22

– Competition reduced
– Fewer predators
– Flora may be depauperate
– Mammals tend to diverge from mainland stock
• Pattern of divergence is not consistent for all
species
• Mammals on islands tend to evolve toward a
fundamental or optimal body size for a particular
ecological strategy or body plan

Question 23

Island Syndrome
• Island mammals different in size from
mainland

Answer 23

– Small mammals on islands generally larger
• Murids
– Large mammals on islands generally dwarfed
• Elephants

Question 24

The History of Mammals in North and

South America

Answer 24

• Contemporary observations…
– Many mammalian families native to South America
– South America shares more families with North America
than any other continent
– But there are intriguing mammalian similarities with other
continents, too…
• Australian marsupials
• African and S. American rodents & primates
• Paleontologist George G. Simpson divided the history of
South American mammals into three “strata” (historical
groups)

Question 25

Stratum 1: The Natives

Answer 25

• Original	inhabitants	when	
South	America	became	
isolated	~65	mya
• Includes	ancestors	of	
modern	armadillos,	
anteaters,	sloths,	and	
marsupials

Question 26

Stratum 2: The Mystery Guests…from

Africa?

Answer 26

• Two types of mammals appear in the fossil record
of South America about 30 mya, and diversified
extensively since:
– New World rodents (guinea pigs, capybara, porcupines, etc…)
– New World monkeys (tamarins, spider monkeys, capuchins, etc…)
• Africa was ~1400km away from South America at
this time!

Question 27

Evidence for Long-Distance Dispersal

from Africa

Answer 27

• Molecular evidence: closest relatives are still in Africa;
timing is after S. Am. and African continents split
• Fossil monkeys and rodents start to appear 30 mya in
South America, no earlier
• A floating island…It’s possible
– Paleoclimate and ocean models suggest ~ 10-15 day rafting
trip was possible

Question 28

Stratum 3: The Great American Biotic

Interchange (GABI)

Answer 28

• GABI: Huge shuffling of species after sea levels fell,
continents moved, and isthmus of Panama formed
– From S. Am. to N. Am.: Sloths, opossums, armadillos,
porcupines, monkeys
– From N. Am. to S. Am.: Rodents, cats, weasels,
raccoons, horses, camels, deer, bears, dogs, skunks