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• Earth is 150 million km away from Sun
• Diameter 8000 km
• Over 70 of surface covered by water
• Age 4 billion years

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Chapter 1 The Evolution of Biodiversity
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• What is Biodiversity?
• Biodiversity short for biological diversity
  is the extraordinary variety of the living things
  on Earth from genes to ecosystems, their
  interactions, and the processes that sustain
  them.
• Life in nature is indelibly intricately linked
  (complex web of interactions among species).
  Changes in the life cycle of one species could
  impact the life cycles of many other species. As
  well, conversion or loss of biodiversity
  inevitably impairs the function of ecosystems.
• There are primarily three levels of biodiversity
  genetic, species, and ecosystem. In effect, these
  levels cannot be separated. Each is important,
  interacting with and influencing the others. A
  change at one level can cause changes at the
  other levels.

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Connected life
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• Three Levels of Biodiversity
• Genetic the variety of genotypes. Genetic
  variation, responsible for different traits of
  individuals, interacts with local environmental
  conditions to determine the extent to which
  population can adapt to environmental changes and
  survive exposure to new diseases. GV is extremely
  important to the survival of populations.
  Isolated populations (e.g., on a small island)
  tend to have less gv, therefore, are more
  susceptible to extinction.
• Species Groups of actually or potentially
  interbreeding natural populations genetically
  isolated from other such groups by one or more
  reproductive isolating mechanisms. Bacteria,
  fungi, flowering plants, insects (ants, beetles,
  butterflies), birds, and large animals
  (elephants, whales, bears).
• Ecosystem Genes determine the traits of
  individuals that form populations of a species.
  Populations and their environments (e.g., water
  or minerals) interact dynamically to form an
  ecosystem. Loss of genetic or species diversity
  will affect the performance of ecosystems.

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Known Species (evolved over 3.8 billion years)
How many species on Earth? 5 10 millions
Source A. Alonso, F. Dallmeier, E. Granek and P.
Raven. 2001. Biodiversity connecting with the
tapestry of life. Smithsonian Institution/Monitori
ng Assessment of Biodiversity Program and
Presidents Committee of Advisors on Science and
Technology, Washington, D.C.
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• Why Biodiversity Matters?
• Biodiversity is the finest celebration of nature.
  It is the historical sediment. Loss of
  biodiversity is a cutoff of our connection to
  nature and to history.
• Diversity has provided humanity with the very
  basis of civilization (crops, domestic animals,
  medicines and a wide variety of products, etc.).
  90 of the calories consumed by human beings come
  from 80 plant species. An estimated 4.5 billion
  people (80 of the world population) use plants
  as their primary source of medicine. Close to 30
  of all pharmaceuticals on the market today were
  developed from plants and animals.
• Inspiration and cultural heritages Species
  inspire songs, stories, dances, poetry, myths,
  arts, cuisine, rituals, festivals Nature is an
  unsurpassed source of relaxation, wonderment,
  rejuvenation, beauty and peace.
• Microorganisms, plants, and animals play a
  critical role in providing free ecosystem
  services.

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The dynamics of taxonomic diversity on Earth is
determined by two processes Speciation and
Extinction
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The dynamics of taxonomic diversity
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The Yule process (1924) It is a pure birth
process assuming that speciation is a random
process and speciation rate is a linear function
of the species that are already in the system. It
is a generalization of the Poisson process.
? is the per capita birth rate
We have the difference-differential equation (use
the law of total probability) with initial
conditions
n 1, 2,
(n gt1)
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Yule process ? A geometric distribution
Yule process leads to an exponential increase in
biodiversity
Sojourn time (time between two adjacent births)
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Simple birth-death process
? is the per capita birth rate ? is the per
capita death rate
The growth of biodiversity
Chance of extinction at t ??
Bailey, N.T.J. 1964. The elements of stochastic
processes. John Wiley Sons, NY. Taylor, H.M.
Karlin, S. 1998. An introduction to stochastic
modeling, 3rd. Academic Press, NY.
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The fact that taxon diversity does not
monotonically increases or decreases suggests
that ? and ? are not constants but functions of
other factors and change with time. One of
primary goals of biogeography and paleobiology is
to understand what processes would affect ? and
?. Before examining the processes of speciation
and extinction, lets examine the stochastic
nature of speciation and extinction.
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Speciation Organisms make mistakes in
reproduction Many mistakes are harmful
(deleterious) but some mistakes are favored and
are fixed by selection
Mutation Selection Speciation
Extinction Bad Gene or Bad Luck? Demographic
stochasticity Environmental stochasticity Catastro
phes
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Extinction Bad Genes or Bad Luck?(D. Raup, J.
Sepkoski Jr. data and interpretation)
http//nicholnl.wcp.muohio.edu/NaturalSystems/Mass
Extinct2a.html
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• Factors affecting speciation and extinction
• Since Triassic (???, 248-208 mya), the rate of
  speciation of marine animals has been greater
  than the rate of extinction.
• Degree of ecological specialization avoid
  competition through specializing use of
  resources, patchy distribution.
• Population dynamics Species with low or
  fluctuating population sizes are more susceptible
  to extinction.
• Geographical range Large home range has low risk
  of extinction but may also have low rate of
  speciation because of a high capacity for
  dispersal.
• Demographic stochasticity It affects small
  populations and causes local extinction.
• Environmental variation Environmental
  stochasticity is often considered to reduce
  species survivorship.
• Catastrophes Volcanoes, earthquakes, meteorite
  collision

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Background extinctions (1 - 10 species/year) Most
extinctions (perhaps up to 95 per cent of all
extinctions) occur as background extinctions,
occurring throughout time. These extinctions are
not caused by major catastrophes or horrendous
climactic changes, but by small changes in
climate or habitat, depleted resources,
competition, and other changes that require
adaptation and flexibility. Of all the species
that have lived on Earth since life first
appeared 3.8 billion years ago, only about one in
a thousand is still living today.
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The extinction of dinosaurs History Until
recently, people simply knew that dinosaurs went
extinct - their fossils were found throughout the
Mesozoic Era (???, 248-65 mya), but were not
located in the rock layers (strata) of the
Cenozoic Era (???, from 65 mya). So, we knew that
dinosaurs went extinct some 64-66 million years
ago, but that was all. Many wild ideas about how
the dinosaurs were rendered extinct were
presented over the years. Two forms of
extinctions background and massive
extinctions. Note Mesozoic Era (248 65 mya)
The age of reptiles, Triassic period (???,
248-208 mya, 1st dinosaur appeared), Jurassic
period (???, 208-146 mya, first bird
appeared). Cenozoic Era (65 mya today) The
age of mammals. The 1st humans evolve during the
Last Ice Age (1.8-0.011 mya). Human civilization
started from when?
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Background extinctions (1 - 10 species/year) Most
dinosaur species perished in background
extinctions that occurred throughout the Mesozoic
Era. For example, Edmontosaurus were probably
decimated in background extinctions. The
flowering plants (angiosperms) appeared during
the Cretaceous period (???,146-65 mya),
displacing most conifers and many other plants.
This had major effects on dinosaurs. Some
herbivorous dinosaurs, like Edmontosaurus, ate
only conifers. As flowering plants came to
dominate the landscape, Edmontosaurus died out,
unable to find enough conifers to sustain itself.
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• Mass extinction
• A mass extinction is a relatively sudden, global
  decrease in the diversity of life forms. Mass
  extinctions have occurred periodically throughout
  the existence of life on Earth. To be a mass
  extinction, the following must occur
• Extinctions occur all over the world.
• A large number and many types of species go
  extinct.
• The extinctions are clustered in a short amount
  of geological time (a few million years is very
  short in terms of the geological time).

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The extinction of dinosaurs Evidence about
asteroid cause of mass extinction The K-T
Boundary (Cretaceous-Tertiary, ??????)

Asteroid
Signature The thin clay layer (iridium) that
marks the boundary between the Cretaceous and
Tertiary rocks. This layer has been found at many
localities around the Earth. (Source
http//web.ukonline.co.uk/a.buckley/dino.htm)
Tertiary period (65-1.8 mya)
Cretaceous perios (146-65)
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The Five Mass Extinction in Earths History
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The Sixth Mass Extinction? Todays extinction
rate is estimated to be 100 - 1000 times than
the background rate and higher than any other on
record. Many scientists think we are now in the
midst of an unnatural mass extinction. This time,
extinction is not caused by catastrophic events
such as the asteroid crash that we believe caused
the extinction of many dinosaurs. The current
threat to biodiversity stems primarily from
growing human population and increased human
consumption of natural resources. Background
extinction rate 0.0001-0.00001 per year (based
on fossil record), 1-10 species/year Present
extinction rate 1/yr, equivalent to 100 -
1000 species/year(?)
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• Factors contributing to the loss of biodiversity
• Accelerating growth of human population
• Land-use changes (habitat destruction,
  fragmentation leading to inbreeding, loss of
  genetic diversity and local extinction)
• Increase of atmospheric carbon dioxide (global
  warming, raising sea level, changes in climate
  patterns, prolonged droughts)
• Invasive species (outcompete native species,
  35-45 of endangered or threatened species in US
  is caused by invasive species. Estimated 137
  billion annual loss.)
• Pollution (oil spill, acid precipitation, toxic
  chemicals in fertilizers and pesticides, urban
  sewage runoff, etc.)
• Overuse of resources (populations cannot sustain
  if exploitation rate is greater than growth
  rates. Nine of worlds major ocean fisheries are
  declining because of over fishing as well as
  water pollution and habitat destruction.)

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World Population Growth, 17502150
1950 2.5 billion 2000 6.1 billion 2050 10
billion It would require 4 more Earth to support
todays population if all people worldwide
enjoyed the same living standard of Canadian.
Source United Nations, World Population
Prospects, The 1998 Revision and estimates by
the Population Reference Bureau.
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Regional Differences in Population Density and
Growth Rate (The present and predicted increase
in human population is very unevenly distributed
over the globe)
Although developed countries such as US, Canada,
Australia and most European nations have only 20
of world population, they consume 80 of global
energy use and 85 of the worlds economy a
disproportional share of natural resources. These
developed countries also produce far more waste
than developing nations such as China, India and
many LA and African nations.
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Population and availability of renewable resources

 Source Postel, S.1994. Carrying capacity
Earth's bottom line. State of the World.
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Size Up to 50 mm Originated in the Balkans,
Poland, and the former Soviet Union. Zebra
mussels were first discovered in North America in
1988. The first account of an established
population came from Canadian waters of Lake St.
Clair, a small water body connecting Lake Huron
and Lake Erie. By 1990, it had been found in all
the Great Lakes. Caused hundreds of millions of
dollars in damage to water equipment and power
plant, etc
Zebra mussels
Native to the Atlantic Ocean, sea lampreys
probably entered the Great Lakes via the Hudson
River and its artificial extension, the Erie
Canal, which was opened to Lake Ontario in 1819.
Canada US spend 13 million/year to control
invasive sea lamprey which collapsed lake trout
in the Great Lakes.
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The Status of Endangered Biodiversity in
Canada Canadas endangered species list includes
353 species as of May 2000. Among them are the
wolverine, killer whale, eastern barn owl,
western rattlesnake, tailed frog, white-throated
swift, peregrine falcon, and whooping
crane. Many of Canadas ecosystems are also in
danger. According to the Canadian Nature
Federation, 240 acres of wildlife habitat are
converted or fragmented every hour in Canada, and
habitat destruction threatens more than 80 of
Canadas endangered species with
extinction. Internet link http//www.cnf.ca/
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• Conservation of Biodiversity
• Increase knowledge Need to know more about how
  ecosystems work and about their fundamental
  components (species, genetic variation, complex
  habitats).
• Protected area Effective approach.
• Ecological restoration very expensive. 80
  billion for restoring the Florida Everglades in
  next 35 years.
• Botanical gardens and zoos Important as seed
  banks and breeding grounds for many endangered
  species.
• Public environmental education.
• Scientific research No matter what course of
  action we may take to protect ecosystems,
  credible science should underlie every plan and
  decision.

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• Questions to think
• Are older taxa more resistant to extinction than
  young taxa because they are better adapted?
• Is extinction/speciation correlated with
  life-history traits? Do some traits make species
  more vulnerable than others?
• Why there is a correlation between extinction and
  speciation rates?
• How to estimate the number of species from the
  number of genera or families?