Download The fossil record, biostratigraphy and diversity of life

Diversity of life; geological control on
biogeography; the fossil record
Jarðsaga 1
– Þróun Lífs og Lands –
Ólafur Ingólfsson
The Diversity of
Life
Biodiversity (fjölbreytileiki lífsins) is the totality of genes,
species, and ecosystems
The wealth of life on Earth is the product of
hundreds of millions of years of evolutionary history.
The Tree of Life
Relationships
between taxa that
constitute the
Archaeobacteria
(forngerlar), Eubacteria (raungerlar), Protists
(frumdýr), Plants
and Animals is not
so straight foreward as we used
to think...
The Six Kingdoms (ríki) of living things on
Earth
The six kingdoms of life on Earth
When Evolved
Structure
Photosynthesis
Bacteria
3 to 4 billion years ago
Unicellular
Sometimes
Archaea
3 to 4 billion years ago
Unicellular
No
Protista
1.5 billion years ago
Unicellular
Sometimes
Fungi
1 billion years ago
Unicellular or
Multicellular
No
Animalia
700 million years ago
Multicellular
No
Plantae
500 million years ago
Multicellular
Yes
Kingdom
Prokaryotes:
(Dreifkjörnungar)
Eukaryotes:
(Einkjörnungar)
(Frumdýr)
(Sveppir)
Number of species of living
organisms
Kingdom
Named species
Total species
Prokaryotes
~4 000
>1 000 000
Protista
~80 000
>600 000
Fungi
~72 000
>1 500 000
Plantae
~270 000
>320 000
Animalia
~1 326 000
> 10 000 000
Bacteria and Archaea
• Known total world species: ~ 1 752 000
• Estimated total world species: 10-100 million
2/3rds of all animal species are insects - It is humbling to realize that
humans and other large animals are freakishly rare life forms, since
99% of all known animal species are smaller than bumble bees ...
Evolutionary trends through time:
• Organisms evolve from simple to complex
forms over time
- Bacteria ⇨ protists ⇨ multicelluar organisms ⇨ plants
and animals
• There is a general tendency for size to
increase during the evolution of a group of
animals
• Evolution never goes in reverse, from complex
to simple forms
Classification and
evolution
Carolus Linnaeus
(1707-1778)
Charles Darwin
(1809-1882),
Since Darwin's time,
biological classification is
understood to reflect
evolutionary distances and
relationships between
organisms. The creatures of
our time have had common
ancestors in the past... they
are members of the same
family tree...
Adaptive radiation
The great diversity of life is largely a result of adaptive
radiation (aðlögunarkvíslun) = the diversification of a
species as it adapts to different ecological niches and
ultimately evolves into different species. Natural
selection (náttúruval) is the principle mechanism driving
adaptive radiation.
Animal phylogeny (þróunarferill)
This structure grows as new species arise, each forming a new branch...
The Earth and all its
contents have a very
long history, during
which they have developed and become altered: life has changed
and diversified as it
descended through
myriad generations
since its unique origins
in the remote past,
spreading across the
globe as circumstances
permitted.
Taxonomy
•
Taxonomy is the science of classifying organisms. The
Linnaean system breaks down organisms into seven
major divisions, called taxa (singular: taxon; Ís:
flokkunarheild). The divisions are as follows (Example:
taxonomy of Man):
• Kingdom (ríki) animalia (dýr)
• Phylum (fylking) chordata (seilýr); subphylum:
•
•
•
•
•
vertibrata (hryggdýr)
Class (flokkur) mammalia (spendýr); subclass:
eutheria (legkökuspendýr)
Order (ættbálkur) primate (prímati)
Family (ætt) hominidae (mannætt)
Genus (ættkvísl) homo (maður)
Species (tegund) sapiens (hinn viti borni maður)
Biogeography
- The distribution and abundance of organisms in
time and space on a broad geographical scale -
Boundary conditions in biogeography area defined by
temperature (solar energy and its distribution), precipitation
and the existance of physical barriers
Today´s biogeography reflects global
distribution of energy...
Simplified model for global atmospheric circulation
Surface currents are generated
by stable wind systems
The Great Ocean
Conveyor Belt
The most important ecosystems of the world
1. (light green) well-tempered rain forests, 2. evergreen boreal coniferous woods, 3.
(green) tropical rain forests, 4. (dark green) summer-green deciduous forests, 5.
(yellowish orange) tropical dry forests, 6. (orange) dry forests of temperate areas, 7.
(light violet) thorny and succulent vegetation, 8. (violet) semi-deserts, 9. (dark violet)
xeromorphic vegetation 10. (light blue) dry steppe, 11. dry savannah, 12. (blue) moist
savannah, 12, 13. (dark blue) pasture, steppe, 14. (brown) deserts, 15. (white) tundra,
16. (grey) ice
Global biodiversity – vascular plants
Vegetation and climate
Iceland
Latitudional temperature
zones in the Oceans
Surface water zonation in the N Atlantic
...and biogeography also reflects
development of barriers through time
Examples of types
of barriers:
• Oceans and straits
• Mountain chains
• Continental scale
glaciers
• Large deserts
• Large river canyons
Zoogeography is the study of geographical distribution
of animals about the globe.
The Wallace Line
Alfred R.Wallace
(1823 - 1913)
Alfred Russel Wallace was the now-almost-forgotten co-discoverer of the
theory of evolution. Darwin had pretty well formulated the theory when he
learned that Wallace was about to publish a similar idea. When Wallace
heard about Darwin, he politely stood aside and let Darwin publish first.
The Wallace Line is a major break
in faunal composition
West of it, the fauna is
related to mainland Asia,
with its tigers, elephants
and monkeys...
Java tiger
Java rhino
Macaque Monkey
Orangutang
...east of it the fauna is
Australian, with
kangaroos, wallabies
and possums.
Cassovari
Possum
Kangaroo
Wallaby
Why the Wallace Line?
It marks the bondary between the Australian the Eurasian Plates
The take-home messages
• The wealth of life on Earth today is
the product of hundreds of millions of
years of evolutionary history.
• The great diversity of life is largely a
result of the diversification of a
species as it adapts to different
ecological niches and ultimately evolves
into different species.
The take-home messages
• The development of ecological niches is
over time controlled by large-scale
geological events (ocean spreading,
mountain-building, opening and closing of
straits etc)
• Today´s biogeography primarily reflects
global distribution of energy (which is
largely controlled by continent
configuration) and the geological
development of barriers to spreading of
organisms.
Fossils and the diversity of life
• Our knowledge of past life is derived
mostly from fossils
• Fossil = the preserved remains or
traces of a once living organism
– Usually thousands or millions of years old
(if it still smells, it ain’t a fossil)
Earth History, Ch. 3
28
Fossils reflect evolution, and
biogeography of the past
The fossil record contains evidence of how life and environments have changed and evolved
throughout the earth’s history.
What are Fossils?
• Fossils are the prehistoric remains or
traces of life which have been preserved
by natural causes in the Earth's crust.
• Fossils include both the remains of
organisms (bones or shells), the traces of
organisms (tracks, trails, and burrows called trace fossils), and chemical traces
of ancient organisms (molecular fossils).
How to become a fossil...
To be preserved as a fossil, an organism must:
•
•
•
Have preservable parts. Hard parts (bones,
shells, teeth, wood) have a much better
chance at being preserved than do soft
parts
Be buried by sediment. Burial protects the
organism from decay.
Escape physical, chemical, and biological
destruction after burial. The remains of
organisms could be destroyed by burrowing
(bioturbation), dissolution, predation,
metamorphism, or erosion.
There are several ways in which
fossils are preserved...
1. Unaltered preservation (Insects or plant parts
trapped in amber)
2. Petrification (Rock-like minerals seep in slowly and
replace the original organic tissues)
3. Replacement (An organism's hard parts dissolve and
are replaced by other minerals)
4. Carbonization=coalification (Only the carbon
remains in the specimen)
5 Recrystalization (hard parts revert to more stable
minerals or small crystals turn into larger crystals)
6. Authigenic preservation (molds and casts of
organisms that have been destroyed or dissolved).
How likely is it that an organism is preserved
as a fossil...
• There are >1,7 million living species today, probably >10 million.
• There are only about 250,000 known fossil species.
• The fossil record covers many hundreds of millions of years, and
the living flora and fauna represent only one "instant" in geologic
time. Maybe >100.000.000 species have occurred through Earths
history.
• If fossil preservation were common, the number of fossil
species should far outnumber the number of living species.
•The fact that the number of fossil species is so small suggests
that the preservation of organisms as fossils is extremely rare.
The noted paleontologist Stephen Jay Gould estimates
that 99% of all plant and animal species that have existed
have already become extinct with most leaving no fossils.
Why is fossil preservation so rare...
1. Habitat – most plants and animals live on
dry land, where the probability of
becoming buried in sediments is small
2. Lack of hard parts - For soft parts of
organisms to be preserved, it is necessary
to isolate them from oxygen almost
immediately after death. This most likely
occurs when organisms are rapidly buried
in fine-grained sediment in anoxic water;
this only happens in rare environments.
3. The activities of the geological engines
– sea floor is constantly destroyed by
subduction; weathering and erosion
destroys fossiliferous sedimentary rock.
Completeness of the fossil record
100%
Con
t
Scavenging
i nu
ou s
rem
ova
l of
Decay
of soft
tissues
“ po
ten
tia
l”
Abrasion
And
transport
Burial
fos
sils
Final
Preservation
Decreasing probability
Death
?%
The probability of preservation depends on the anatomy and habitat of the
organism—marine organisms with
hard
parts
Earth
History,
Ch. 3 are most likely to be preserved
35
William Smith
1769-1839
In 1819, he
published a work
entitled Strata
identified by
organized
fossils.
English engineer and geologist who is
best known for his development of the
science of stratigraphy. He
determined the succession of English
strata across the whole country, from
the Carboniferous up to the
Cretaceous. He also established their
fossil specimens and laid the
foundations for faunal successions in
biostratigraphy. Smith's geologic map
of England and Wales (1815) set the
style for modern geologic maps.
Distribution of fossils
• The distribution of fossils within Earth´s history is not
random - fossils occur in a consistent order. This is true
at a regional, and even a global scale.
• Fossil organisms are more unique than rock types, and
much more varied, offering the potential for a much
more precise subdivision of the stratigraphy and events
within it.
Faunal Succession
- stratigraphic ordering of fossil
assemblages (William Smith), which was
the basis of worldwide correlation
Principle of faunal and floral succession
Flowering
plants
Dinosaurs
Plesiosaurs
Ferns
Fishes
Trilobates
Everywhere in the
world, trilobites
are found lower in
the stratigraphy
than marine
reptiles. Dinosaurs
occur after the
first occurrence
of land plants.
Ferns always found
before the
occurrence of
flowering plants...
Index fossils
References and good web-sites
Stanley, Earth System History, chapters 3, 4 and 7.
Fortey, R. Life, a natural history of the first four billion years of life on
Earth. New York, Vintage Books, 346 pp.
http://fossils.valdosta.edu/index.html
http://fossils.valdosta.edu/index.html
http://www.ucmp.berkeley.edu/alllife/threedomains.html
http://www.palaeos.com/Default.htm
http://www.pbs.org/wgbh/evolution/library/index.html
http://www.fossilmuseum.net/Time%20Machine/Geologic_Time_Machine.htm
http://www.seaworld.org/just-for-teachers/guides/diversity-of-life/
http://www.palaeos.com/Kingdoms/default.htm
http://www.earth.uni.edu/~groves/EHCh03lecture.ppt
http://www.cartage.org.lb/en/themes/Sciences/Zoology/AboutZoology/Dive
rsityLife/DiversityLife.htm
http://www.ucmp.berkeley.edu/index.html