Historical Biogeography
CH 7
Current Distribution
• Result of the interaction of:
– Early history and place of origin
– Fragmentation of continents
– Climactic changes during Cenozoic
– Cooling and eventual ice age in Pleistocene
– Mass extinctions and adaptive radiations
– Land Bridges
• Bering
• Greenland
I.
Deep Time Perspective
A. 4 Zoic Eras
B. Overview of Major Events
C. Historic Biogeography
Table 25-1b
The rise and fall of dominant groups
reflect continental drift, mass extinctions,
and adaptive radiations
Continental Drift
Cenozoic
Eurasia
Africa
65.5
South
America
India
Madagascar
Antarctica
Mesozoic
135
251
Paleozoic
Millions of years ago
• At three points in time, the land
masses of Earth have formed a
supercontinent: 1.1 billion, 600
million, and 250 million years
ago
• Earth’s continents move slowly
over the underlying hot mantle
through the process of
continental drift
• Oceanic and continental plates
can collide, separate, or slide
past each other
• Interactions between plates
cause the formation of
mountains and islands, and
earthquakes
Present
Mass Extinctions
• The fossil record shows that most species that have
ever lived are now extinct
• At times, the rate of extinction has increased
dramatically and caused a mass extinction
• In each of the five mass extinction events, more
than 50% of Earth’s species became extinct
Dimetrodon
Hallucigenia
Fig. 25-14
800
20
600
15
500
400
10
Era
Period
300
5
200
100
0
E
542
O
Paleozoic
S
D
488 444 416
359
C
Tr
P
299
251
Mesozoic
C
J
200
Time (millions of years ago)
145
0
Cenozoic
P
65.5
N
0
Number of families:
Total extinction rate
(families per million years):
700
Adaptive Radiations
• Adaptive radiation is the evolution of many new
species adapted from a common ancestor upon
introduction to new environmental opportunities (new
niches)
• Occurs via:
–
–
–
–
Evolution of novelty (i.e., seeds)
After a mass extinction (i.e., mammals)
Formation of new land (i.g. islands)
Piggyback on other organisms (insect radiations follow
flowering plants)
BASICALLY, any time many new niches (ecological livelihoods)
are available, there is opportunity for adaptive radiation.
Table 25-1a
Table 25-1a
III. Multicellular Life - Neoproterozoic
Table 25-1a
V. First Life on Land
VI. Conquest of Land
Challenges:
structural support
dehydration
reproduction
Solutions:
exoskeleton, lungs in animals
what about plants?
cuticle, stomata, vascular tissue,
pollen – not all at once
Table 25-1a
Massive extinction – 250mya
followed by adaptive radiation
Table 25-1b
Cenozoic
Present
VIII. Emerging Modern Lineages
Triassic/Jurassic:
global warming, arid Pangaea
interior, mountain formation
Eurasia
Africa
65.
5
South
America
India
Madagascar
Mesozoic
135
251
Paleozoic
Millions of years ago
Antarctica
Reptiles loved it!
Table 25-1b
Cenozoic
Present
Eurasia
Africa
65.
5
South
America
India
Madagascar
Mesozoic
135
251
Paleozoic
Millions of years ago
Antarctica
Extinction
Fig. 25-17
Ancestral
mammal
Monotremes
(5 species)
ANCESTRAL
CYNODONT
Marsupials
(324 species)
Eutherians
(placental
mammals;
5,010 species)
250
200
100
150
Millions of years ago
50
0
Cenozoic
Present
Eurasia
Africa
65.5
South
America
India
Madagascar
251
Mesozoic
135
Paleozoic
Millions of years ago
Antarctica
Mountain ranges: Himalayans ,
Rockies (Eocene), Sierra
Nevada (Miocene), Cascades,
Coast ranges (late Miocene)
Great American Interchange
Panama Isthmus
formed 3 mya
Panama bridge
26 genera S
12 went N
Tapirs/llamas went extinct in N Am, so
disjunct w/Asian