Transcript Hierarchies and Agroecosystems on the Canadian Mixed Grassland

Paleontology in Decline:
Making Fossils Live Again
Todd A. Radenbaugh, PhD
Research Fellow
Canadian Plains Research Center
Geological Society of America
16-19th,October, 2005
Salt Lake City, UT
Evolution Under Siege
August 11, 2005
On May 5, 1925, biology teacher John Scopes was arrested
for teaching Darwin's theory of evolution in violation of
Tennessee state law.
NEW Monkey
Trials
http://www.theonion.com
New Vision of the Future?
Geologist wanted:
Posted January, 2005 from:
COLLEGE OF ARTS AND SCIENCES- Dr. R Hawkins, Dean.
Geology: Ph.D. required. Teaching Introductory Geology,
Paleontology, and History of Life. Compatibility with a
young-earth creationist position required…
Contact:
Liberty University
1971 University Boulevard, Lynchburg, Virginia 24502
434-582-2000
http://www.liberty.edu/Administration/HumanResources/index.cfm?PID=4353
Making Paleontology Relevant
Paleontology courses need to be made more relevant
in geology and environmental science departments’
curricula.
• The economy is dependent on fossil fuels.
• Anthropogenic forced climate change,
habitat loss, and alteration of natural
selection pressures has caused extinctions
and extensive changes.
No longer concentrate on only morphology and taxonomy.
Paleontology in Virginia
Virginia Universities – Bachelor Programs
Public (n=15)
Geology Programs = 5 (33%)
Geology Classes = 12 (80%)
Private (n=22)
Geology Programs = 1 (5%)
Geology Classes = 12 (55%)
Paleo Classes = 7 (47%)
Paleo Classes = 2 (9%)
College of William and Mary (2)
George Mason University
James Madison University
Old Dominion University (2)
Radford University (2)
University of Mary Washington
Virginia Tech (2)
Virginia Wesleyan College
Washington and Lee
Most Geology classes are Taught in
Environmental Studies Departments
37 Virginia Universities – Bachelor Programs
Department Type
#
16
Geology
Paleo classes
6
6
14
Geology
12
10
Environmental and Earth Sci.
Paleo classes
16
3 (19%)
8
Env. /Earth
Sci
6
Other
Other (Physical sciences, Science survey, etc.)
Paleo classes
3
0
4
None
Paleo classes
12
0
No Geol
2
0
Geol
Paleo
Retooling Paleontology
Make room for Paleo and macroevolution classes
in the environmental science curricula
• Link recent environmental change to its geologic history
• Use evidence from paleoecology and glean lessons for
society and economy.
Two examples
Two examples of how to use paleontological theory
relevant to today’s environmental science
programs:
1. Ediacaran Fauna Reconstruction
•
To show different ecological rules of assembly
2. Comparisons between Modern and Paleozoic
Ecospace Use
•
Extinctions - past and present
Ediacaran Fauna Example
 650 to 540 Million years ago
 frond-like forms, jellyfish-like imprints, and trace fossils.
 Perhaps evolved as nutrient supplies increased in
shallow waters
 causing a radiation of trophic links in food webs
Photo Credit: http://www.ucmp.berkeley.edu/vendian/critters.html
Garden of Ediacara
A time when today’s rules of ecological
assembly did not apply.
• No major predators
• Few mobile fauna
• Dominated by suspension feeding
Ediacaran Fauna Clay reconstructions
Ediacaran Fauna
Complete reconstructions of students
Ecospace Example
Ecospace: ecological resources used by species based on adaptive
morphologies (bauplan), space utilization, and food sources
From Bambach (1983)
Megaguild: Summation of the guilds occupied by a species or group of
species.
Shallow Marine Megaguilds Through
Time
Sediment-water interface (cm)
Tiering and Bulldozing
100
50
0
C
O
S
D
M
vP
P
Tr
J
K
T
Q
-50
-100
Max Above
Trace Fossil
Max below
From Ausich and Bottjer 1982
Paleozoic Bulldozing
– Changes in Ecological Rules of Assembly
Bulldozers
Victims
Irregular echinoids
Sponges
Crinoids
Crab burrows
Columinals
Brachiopods
Blastoid reconstruction
Bryozoans
Gastropods
Pelcypods
Ecospace Comparisons of a Modern
and Late Paleozoic Assemblage
2
1.5
Recent
1
Mississippian
0.5
Other
P/H
DEnSD
SENSD
DEnS
SEnS
0
EpS
Importance Value
2.5
Magaguild
Megaguild Key
EpS = Epibenthic suspension
SEnS = Shallow endobenthic suspension
DEnS = Deep endobenthic suspension
SENSD = shallow endobenthic surface deposit
DEnSD = Deep endobenthic surface deposit
P/H = Predator or Herbivore
Ecosystem Stability
Stable ecosystems:


Persistence of similar niches and guilds within species
assemblages, and the same lineages occupy these niches and
guilds for extended periods of geological time (3-7 m.y.).
Little selection pressure and speciation.
Assemblage restructuring.
1. Changing resource use -> new organisms create or occupy new
niches and guilds.
2. Guild decline and species extinction -> Decline or loss of old
niches and guilds.
3. Speciation -> Vacant niches are filled by newly evolved species,
some are similar to previous ones but new guilds cause different
assemblage types (change in rules how species associations are
structured).
Are We Changing the Landscape?
 What broad scale changes to biotic
structure have occurred as a result of
human activities similar to those in
the fossil record?
 Can human activities act as a
selection force with the capacity to
change the functional roles and
assembly rules at the ecosystem
level?
Estimation of Vegetation Changes
Mixed Grassland Ecoregion of Saskatchewan
Circa 1880
Grassland
Woodland
Wetland
Cultivated
1990s
0
20
40
60
80
100
Sources:
Pre-1880 - Archibold and Wilson (1980)
1990s - Statistics Canada, 1986, 1991 and 1996
Agricultural Census and the South Digital Land Cover
Ecospace for Birds
Foraging Method
Foraging Habitat
Nesting Habitat
Diet
Dabbler
Diver
Gleaner
Picker
Prober
Sallier
Stalker
Swooper
Brush/woodland
Grassland
Wetland
Other
Cavity
Cliff
Ground
Floating Mat
Vegetation
Seeds
Omnivore
Aquatic
-invertebrates
-vertebrates
-vegetation
Terrestrial
-invertebrates
-vertebrates
-vegetation
Adapted form Bambach (1985)
Bird Assemblages Comparisons
1990s
Circa 1900
Present
Absent
Present
108
2
Absent
25
0
Total Species = 135
Match Coefficient = 0.80
Circa 1900
1990’s
Species Richness
Species Diversity*
110
1.89
133
2.11
Horn’s Index of Similarity* = 0.77
* Calculated using the Shannon-Weiner
index : the relative abundance score was
substituted for number of individuals.
Guild and Habitat Trends
Guild Type
Foraging Habitat
Nesting Habitat
Guild
Habitat Trend
Brushland/woodland
+
Grassland
Wetland
Other
+
Cavity
+
Cliff
+
Ground
Floating Mat
Vegetation
+
Guild trend
+0.69 **
-0.29
-0.19
+0.35 *
+0.81 **
+0.60 *
-0.21
-0.24
+0.44 **
Significance: ** p<0.01; *p<0.05 by Mann-Whitney test
Extinctions
Extinction rate 100 to 1,000 times more rapid than
before human domination – one species every hour
to minute
• “…two-thirds of all species of plants, animals and organisms
could be lost in the second half of the next century.” Peter
Raven, 2003
Similar scale those in the
fossil record.
At this rate we may loose
20% of families or 55%
of species in the next 100
years.
From Raup and Sepkoski 1992
Extinction Recovery
How long does it take to recover
from a mass extinction event?
The origination rate peaks about 20
million years after the peak in
extinction rates
From Sepkoski's 1998
Conclusions
 Using paleoecology analogs, we can show that current trends are
changing the landscape in terms of:
 resource use
 regional species composition
 Evolution’s influences on the biosphere, atmosphere,
oceans, and solid earth making it a key topic in
environmental science departments.
 Paleontology tell us how ecosystem structure has changed,
and how it might change.
Regional natural selection forces are diversifying and
evolutionary changes as seen in the fossil record may be
occurring.
Future?
If current declining trends towards
paleontology continue,
there will be negative long-term
consequences to science and society
in understanding our future.