Diversity: Patterns and Processes

1
Diversity Patterns and Processes I. Pattern 1
Diversity is Inversely Correlated
with Latitude Summary - Direct Climatic Causes
- Trophic Causes (not primary) - productivity
(qualititative/quantitative) -
competition/niche specialization - predation
- structural complexity
2
Diversity Patterns and Processes I. Pattern 1
Diversity is Inversely Correlated
with Latitude Summary - Are the tropics a
cradle (birthing species?) - Or a museum (where
species persist longer because of lower
extinction rates?)
3
Cradle or museum? David Jablonski, Kaustuv Roy,
James W. Valentine. 2006. Out of the Tropics
Evolutionary Dynamics of the Latitudinal
Diversity Gradient. Science 314
102-106. Diversity is a function of speciation
rate, extinction rate, and immigration rate
(range expansion into that region).
4
Cradle or museum? David Jablonski, Kaustuv Roy,
James W. Valentine. 2006. Out of the Tropics
Evolutionary Dynamics of the Latitudinal
Diversity Gradient. Science 314
102-106. Diversity is a function of speciation
rate, extinction rate, and immigration rate
(range expansion into that region).
"Out of the tropics" model
5
Cradle or museum? David Jablonski, Kaustuv Roy,
James W. Valentine. 2006. Out of the Tropics
Evolutionary Dynamics of the Latitudinal
Diversity Gradient. Science 314 102-106.
Looked at the origin of bivalve taxa (genera) in
tropics and beyond
Genera first appearing in the Pleistocene (2mya)
6
Cradle or museum? David Jablonski, Kaustuv Roy,
James W. Valentine. 2006. Out of the Tropics
Evolutionary Dynamics of the Latitudinal
Diversity Gradient. Science 314 102-106.
Genera first appearing in the Pliocene (5 mya)
7
Cradle or museum? David Jablonski, Kaustuv Roy,
James W. Valentine. 2006. Out of the Tropics
Evolutionary Dynamics of the Latitudinal
Diversity Gradient. Science 314 102-106.
Genera first appearing in the Miocene (23 mya)
8
Cradle or museum? David Jablonski, Kaustuv Roy,
James W. Valentine. 2006. Out of the Tropics
Evolutionary Dynamics of the Latitudinal
Diversity Gradient. Science 314 102-106. SO
The tropics may be both cradle and museum. And
that begs the question regarding divergence
rates... could pairs of species in temperate zone
with recent common ancestors have a tropical
origin?
9
Conclusion There are a range of factors that
probably contribute differentially depending on
the taxon.
Climate
Trophic Relationships
Evolutionary Processes
DIVERSITY
10
(No Transcript)
11
Diversity Patterns and Processes I. Pattern 1
Diversity is Inversely Correlated
with Latitude II. Pattern 2 Diversity Changes
with Time
12
Diversity Patterns and Processes I. Pattern 1
Diversity is Inversely Correlated
with Latitude II. Pattern 2 Diversity Changes
with Time A. Geological Time
13
II. Pattern 2 Diversity Changes with Time A.
Geological Time
- diversity increases through time - there are
periodic mass extinctions, followed by faunal
recovery
14
II. Pattern 2 Diversity Changes with Time A.
Geological Time
Competitive replacement seems likely, as do
adaptive radiations of competitively successful
group.
15
II. Pattern 2 Diversity Changes with Time A.
Geological Time
But predation has been important, too.
This is Spriggia, thought to be a soft-bodied
arthropod precursor.
Animals of the Vendian Period 650-543 mya
These are Cnidarians - stinging predators
16
II. Pattern 2 Diversity Changes with Time A.
Geological Time
But predation has been important, too.
Animals of the Cambrian Period 543-490 mya
Hard parts evolve... leading to a burst in
preserved specimens
Predation - selects for anti-predator traits in
prey
17
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession
18
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions - succession a
change in a community over time
19
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions - succession a
change in a community over time - primary
succession occurs on unvegetated substrate
20
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions - succession a
change in a community over time - primary
succession occurs on unvegetated substrate -
secondary succession occurs on a vegetated
substrate - seasonal succession change in
activity w/seasons (such as a change in the
species flowering over the year) -
heterotrophic succession changes in animal fauna
21
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions 2. Mechanisms Facil
itated early species change environment and
increase the probability of successful
colonization by later species.
22
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions 2. Mechanisms Facil
itated early species change environment and
increase the probability of successful
colonization by later species. examples
colonization of bare rock lichens, moss, herbs
colonization of carcasses beetles, flies,
etc.
23
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions 2. Mechanisms Toler
ance early species have no effect on later
species. This occurs if there is 'ecological
equivalence' among the species. Many stages in
later forest succession seem dominated by this
mechanism. Also, later species tolerate early
species... so shade tolerant secies come to
dominate because they tolerate the shade of early
species.
24
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions 2. Mechanisms Inhib
ition Early species retard the colonization
success of later species. If these effects vary
among early species, there can be "priority
effects". The species that gets there first has
a differential and deterministic effect on the
subsequent structure of the community. Important
where allelopathic interactions occur.
25
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions 2. Mechanisms 3.
Model Tilman (1985).... ready?
26
3. Model Tilman (1985).... ready?
A
A, B
B
Our old 2-species model with stable coexistence
possible.
27
3. Model Tilman (1985)
A
A, B
B
If resource supply rates are negatively
correlated, then the community may succeed from A
to A-B coexistence to B as concentrations change
28
3. Model Tilman (1985)
A
A, B
B
B, C
C
...and then to B,C and C.... and etc....
29
3. Model Tilman (1985)
A
A, B
B
B, C
C
...and then to B,C and C.... and etc....
C, D
D
30
II. Pattern 2 Diversity Changes with Time A.
Geological Time B. Ecological Time -
Succession 1. Definitions 2. Mechanisms 3.
Model Tilman (1985) 4. Patterns in Succession
31
4. Patterns in Succession (From Morin,
1998) Variable Early Late Organism
Size small large life history r K Biomass l
ow high Richness, Diversity low high Structura
l complexity low high Niches broad narrow Nu
trient cycles open closed Stability low high
trophic relationships linear web-like connectan
ce low high
32
example...
33
Island Biogeography
34
Island Biogeography I. Their Historical Relevance
35
Island Biogeography I. Their Historical
Relevance A. Darwin - Galapagos - Sept-Oct,
1835
36
Island Biogeography I. Their Historical
Relevance A. Darwin - Galapagos - Sept-Oct,
1835
37
Island Biogeography I. Their Historical
Relevance A. Darwin - Galapagos - Sept-Oct,
1835
- Fauklands species same as mainland -
Galapagos species different from mainland
degree of isolation correlated with uniqueness of
inhabitants..
38
Voyage of the Beagle Darwin (1845) "The
natural history of these islands is eminently
curious, and well deserves attention. Most of the
organic productions are aboriginal creations,
found nowhere else
Flightless Cormorant
39
there is even a difference between the
inhabitants of the different islands yet all
show a marked relationship with those of America,
though separated from that continent by an open
space of ocean, between 500 and 600 miles in
width.
Green Iguana Central and South America
40
The archipelago is a little world within
itself, or rather a satellite attached to
America, whence it has derived a few stray
colonists, and has received the general character
of its indigenous productions. Considering the
small size of the islands, we feel the more
astonished at the number of their aboriginal
beings, and at their confined range.
Galapagos Land Iguana, pallid species, only on
Santa Fe island.
41
Seeing every height crowned with its crater,
and the boundaries of most of the lava streams
still distinct, we are led to believe that within
a period geologically recent the unbroken ocean
was here spread out.
42
Hence, both in space and time, we seem to be
brought somewhat near to that great fact -- that
mystery of mysteries -- the first appearance of
new beings on this earth. The Voyage of the
Beagle Charles Darwin
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
(No Transcript)
53
(No Transcript)
54
(No Transcript)
55
Island Biogeography I. Their Historical
Relevance A. Darwin - Galapagos - Sept-Oct,
1835
a. Isolation correlates with uniqueness b.
islands are dominated by dispersive forms