Global Biodiversity
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• What is Biodiversity?
• Biological diversity is the sum of all
living things
• It can be considered at many levels (e.g.
genetic, regional, evolutionary lineage,
number of ecosystems)
• Hierarchical perspective: genes, pop(s),
species, communities, ecosystems,
landscapes
Global Biodiversity
Patterns and Processes
• Genetic Diversity
• Genetic diversity is the ultimate source
of biodiversity at all levels
• Recent advancements now allow us to
measure (and quantify) genetic diversity
• Important in establishing breeding
programs
• May allow species to broaden tolerances
Global Biodiversity
Patterns and Processes
• Genetic Diversity
• Consider the use of genes in crops and
livestock…can be either incorporating genes
or just preserving existing breadth
• Consider Bt cotton: Bacillus thuringiensis (Bt)
is a spore forming bacterium that produces
crystals proteins, which are toxic to many
species of insects.
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• There are trade-offs
Global Biodiversity
Patterns and Processes
• Population-level Diversity
• The variation within members of a species or
population is extremely important (represents
evolutionary history and is the source of
potential future adaptations)
• Also provides a great deal of information
about the amount and rate of gene flow
between and among populations (more later)
Global Biodiversity
Patterns and Processes
• It is the local populations where
environmental challenges occur and
genetic diversity is maintained
• Consider a species/population of corn
that evolved in soil with high mineral
(e.g. metals or salt) levels
• That population maybe become an
invaluable crop species in some locations
Global Biodiversity
Patterns and Processes
• Guppies in Trinidad streams have
evolved without fish predators
• Consequently, they have very different
life-history characteristics than
species/populations exposed to
predators
• If a reintroduction or population
supplementation is needed, knowledge of
genetics and plasticity important
Global Biodiversity
Patterns and Processes
• Populations may also serve a functional
role, which may be independent of other
populations
• E.g. pollinators
Global Biodiversity
Patterns and Processes
• Human Cultural Diversity
• Consider human cultural diversity and
the reservoir of knowledge, skills, and
traditions throughout the world
• E.g. 6,526 distinct languages
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Non-random distribution of habitats
Global Biodiversity
Patterns and Processes
• Diversity of Species
• Despite many references to
‘biodiversity’ and others at the species
level (e.g. ESA, CITES) it is the
populations that are as or more
important (but not as easily
comprehended by the public or
politicians)
Global Biodiversity
Patterns and Processes
• What is the difference between a
species and population?
• Can be somewhat difficult to determine
if they are one species or two…
• Why? It is really a gradient
• Problems: fossils, asexual organisms,
lack of knowledge
Global Biodiversity
Patterns and Processes
• For many ‘bioinventories” or rapid
assements, may use concept of
‘morphospecies’
• As species (and populations) evolve, they
continue to accumulate genetic
differences
• To determine relatedness among these
species (or pop(s)), biologists attempt
to reconstruct phylogenies (more later)
Global Biodiversity
Patterns and Processes
• Biological classification system based
upon the idea of hierarchical
organization and relatedness
• King Phillip Came Over For Golf Saturday
• Should always be a bifurcating tree
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• How many species are there?
• Approximately 1.75M named with
another 300K fossil sp
• On average, 300 sp named each day
• Two new phyla have been named in past
25 yrs
• Range is 10M-50M
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• For starters, the immense richness of
viruses, bacteria, archaea (singled-cell
organisms in extreme environs), protists
and other unicellular organisms
• Only 80,000 fungi described
• In Britain, 6x fungi vs. vascular plants
• Extrapolate worldwide, 1.6M fungi
• Nematodes >200 sp in a few cm3
Global Biodiversity
Patterns and Processes
• Mites: 30,000 sp described (but
probably >1M)
• Insects: almost 1M described, but
consider canopy fogging 55%
• 4 sites <70km proximity, 1% common
Global Biodiversity
Patterns and Processes
• Diversity of higher taxa
• Until recently, 5 kingdoms recognized
Plantae
Animalia
Fungi
Monera (bacteria)
Protista
Global Biodiversity
Patterns and Processes
• Today, there is a recognized division
among the prokaryotes and we have the
Archaea and Bacteria
• Genetic diversity is as great as that
across Eukaryotes
• Many new kingdoms ascribed to
Archaea, Bacteria, and Protists
• Why care?
Global Biodiversity
Patterns and Processes
• They evolutionary lineage of each species is
important for several reasons
• 1) evolutionary potential relies on the diversity
of life (many differences, albeit small)
• 2) lineages are storehouses of info on the
history of life
• 3)functioning ecosystems depend upon the
variety of life
• 4) aesthetic benefits correlated with diversity
Global Biodiversity
Patterns and Processes
• Diversity of biological communities
• The composition of communities changes over
time and space
• Membership within a community is
probabilistic
• 3 common metrics
– Sp richness, evenness, abundance
• Frequently compare metrics across habitats
or sites (or genes)
• Could also use weighted measures…
Global Biodiversity
Patterns and Processes
• Are there limitations to using a metric
like diversity?
– Species identity…lose valuable information
on functional role, exotic vs. native, lifehistory characteristics
• Biological communities are of
conservation interest because the
relative abundances, combinations, +/can all provide valuable information
Global Biodiversity
Patterns and Processes
• Ecosystem and Biome Diversity
• Typically terrestrial systems typically
classified by shape and life-forms of
the plants that dominate them
• Holdridge’s widely used life zone system
is entirely based upon climatic variables
• Although communities grade into one
another, major divisions are useful for
analyses and descriptions
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Things also change at relatively large
scales based upon: latitude, altitude,
and precipitation gradients
• At a finer scale, things change with soil
type, slope, and species composition
• Recently the WWF reclassified the
Earth’s biomes into 867 terrestrial
biomes (thought to represent distinct
assemblages)
Global Biodiversity
Patterns and Processes
• Ecosystem approach
• Managing at the ecosystem allows for
common goals across multiple owners
and allows for ‘large scale’ planning that
is likely appropriate for even relatively
large organisms
Global Biodiversity
Patterns and Processes
• Species Richness over Geologic Time
• The number of species at any given
moment represents the balance between
extinction and speciation rates
• That number will vary according to the
frequency and intensity of extinction
and/or speciation events
Global Biodiversity
Patterns and Processes
• The fossil record shows a rough
estimate of trends in species richness
during the history of life on Earth
• Cellular life began about 3.8 bya
(bacteria) and eukaryotics probably
about 2 bya
• Things were relatively quiet until the
‘Cambrian explosion’
Global Biodiversity
Patterns and Processes
• Fig 2.5
Diversity
of marine
families
from
Cambrian
to present
Global Biodiversity
Patterns and Processes
• Terrestrial plant appeared early in the
Silurian and their richness increased
rapidly during the Devonian
• Then during the Cretaceous, another
important event occurred, the
appearance of ‘angiosperms’
• Had ‘cascading effects’
Global Biodiversity
Patterns and Processes
• Fig 2.6
• Each group,
ferns,
gymnosperms
and
angiosperms,
have all
dominated at
one time
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Rates of species formation
• Speciation rates are not consistent
• When do you think it accelerates?
Global Biodiversity
Patterns and Processes
•
•
•
•
Rates of species formation
The first was the Cambrian (500mya)
Second Paleozoic (440mya)
The third set diversity way back in
Permian (250mya), followed by Triassic
explosion
Global Biodiversity
Patterns and Processes
• Cambrian: all major groups of living
organisms appeared during this time
(and some that did not make it)
• Paleozoic and Triassic greatly increased
families, genera and species, but no new
phyla emerged
Global Biodiversity
Patterns and Processes
• Factors impacting rates of speciation
• Any guesses?
– Mass extinctions
– Increasing separation of landmasses
– New species and species interactions
Global Biodiversity
Patterns and Processes
• Diversity
explosions
throughout
the ages
• Break-up of
Pangea in
Laurasia ad
Gondwanaland
followed by
more isolation
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Rates of
Extinction
• Similarly,
rates vary
throughout
time
• 6 major
events
60%
75% 95% 65%
75% **
Global Biodiversity
Patterns and Processes
• Although species generally recovered,
there is a lag of about 10my
• The major impact of mass extinctions
events has been to eliminate some
lineages while opening ecological niches
for others
Global Biodiversity
Patterns and Processes
• Current patterns of species richness
• Diversity is not spread evenly
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• To properly preserve species, it is
important to know where species occur
• One such tool is a GIS
• Another useful approach is to divide
species richness into major components
– Alpha-richness (small homogeneous area)
– Beta (rate of change across communities)
– Gamma (changes across larger landscapes)
Global Biodiversity
Patterns and Processes
• High α generally means many rare sp
• High β means the cumulative number of
species recorded rapidly increases as
additional areas are censused along
some environmental gradient
• High γ may result from having many
different types of habitats within a
larger landscape and each of those
habitats having some unique members
Global Biodiversity
Patterns and Processes
• Species
turnover for
birds in
Mediterranean
Global Biodiversity
Patterns and Processes
• Differentials
of turnover
curves
Global Biodiversity
Patterns and Processes
• Patterns of Endemism
• Everything is endemic at some scale
• There are areas of high endemism,
usually resulting from isolation (e.g.
islands, large dispersal barriers)
• Areas of endemism are usually not
associated with areas of high diversity
• Why?
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Patterns of Endemism
• Not surprisingly, patterns of endemism
differ greatly across taxa
• For example, SAf and sw Aust have very
high levels of plant endemism, but not
animals
• However, there are correlates for
endemism among vertebrates
Global Biodiversity
Patterns and Processes
• Marine
diversity
(damselfish)
• IndoPacific a
hotspot
Global Biodiversity
Patterns and Processes
• Latitudinal Gradient in Species Richness
• In both terrestrial and marine
environments, tropical regions have
more species than temperate ones for
many (or most) all taxonomic groups
• Exceptions: marine birds and mammals,
seaweeds, salamanders
Global Biodiversity
Patterns and Processes
• Bivalve
mollusks
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Although the pattern is widespread, the
mechanism (process) generating it
remains in question
• Additionally, it is likely that different
groups have different combinations of
factors determining their distribution
Global Biodiversity
Patterns and Processes
• Species-area Curve
• One of the first ecological relationships
established empirically was the
relationship between area and number
of species
S=cAz
• S is species number, A is area, z
represents how quickly species are
accumulated and c is a constant
Global Biodiversity
Patterns and Processes
• z varies across taxonomic groups and
habitats
– E.g. relatively low values ≈0.15 on oceanic
islands to 0.25 to 045 for continents
Global Biodiversity
Patterns and Processes
• Reptiles and amphibians
Global Biodiversity
Patterns and Processes
• Landbirds and freshwater birds in SE
Asia
Global Biodiversity
Patterns and Processes
• One confounding factor is the relatively
large area of the tropics
• Consequently, is the higher diversity in
the tropics a result of simply larger
areas?
• What other factors may contribute to
higher diversity in the tropics?
Global Biodiversity
Patterns and Processes
• Species Richness-energy Relationships
• Simply the more energy that is available
the more biomass enables more
individuals (hence species) to coexist
• In tropics, even less energy used to
maintain oneself
• Higher productivity can also allow for
dietary specialization
Global Biodiversity
Patterns and Processes
• Evidence for these patterns are not
consistent
– E.g. strong correlation between annual
evapotranspiration and tree sp richness in
NAm
– E.g. some of the most productive
ecosystems (estuaries, hotsprings, seagrass
beds) are species-poor
• Look at relationship between soil fertility,
plant richness & seed dispersers
Global Biodiversity
Patterns and Processes
• Marine systems: richness and depth
• ‘the paradox of enrichment’
• Sp do well in
either fresh
or saltwater
Global Biodiversity
Patterns and Processes
• Energy may also influence richness
indirectly through increases habitat
complexity (structure)
• Habitat complexity and richness is
generally positive for a wide-ranging
group of organisms (think birds in
grasslands vs. forests)
• Conversely, think about lizard richness
in the desert…
Global Biodiversity
Patterns and Processes
• Disturbance and Species Richness
• Easy to understand how large climatic
variation could reduce sp richness
• More poleward populations are impacted
by remaining individuals having
characteristics that favor lower
speciation rates (less specialization,
larger ranges and greater vagility)
Global Biodiversity
Patterns and Processes
• Disturbance and Species Richness
Global Biodiversity
Patterns and Processes
• Disturbance and Richness
• Physical disturbances can influence local
richness by destroying habitat,
selectively (or not) killing individuals,
and sterilizing soils
• Consider a constant environment, what
should this lead to? Why?
Global Biodiversity
Patterns and Processes
• Intermediate Disturbance Hypothesis
Global Biodiversity
Patterns and Processes
• Consider the rocky intertidal
communities of the Pacific Coast
• Pisaster ochranceus feeds on the
competitively dominant mussel Mytilus
californianus
• When it is removed, allows ‘less’
competitive individuals to become
established on the rocks
Global Biodiversity
Patterns and Processes
• Intermediate Disturbance Hypothesis
Global Biodiversity
Patterns and Processes
• Interactions between local and regional
species richness…
• Local species richness can strongly be
influenced by local interactions and
process operating at larger spatial and
temporal scales (e.g. dispersal,
speciation, historical biogeography)
• Ultimately, are there limits to
community numbers?
Global Biodiversity
Patterns and Processes
• Is it limited by niche overlap?
• Does the chemical warfare between plants and
herbivores set limits to sp richness or does it
promote speciation?
• Are there limits to the size of mimicry
systems and do mimicry systems allow for
more or less species to coexist?
• Has the richness generated by plantpollinators been reached? Seed dispersers?
Global Biodiversity
Patterns and Processes
• Importance of Biodiversity
• Merit vs. money?
• Many examples of ecosystem services
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
•
•
•
•
Importance of Biodiversity
Merit vs. money?
Many examples of ecosystem services
However, it is not clear what the
relationship between ecosystem
function and species richness
• Importance of rare species, which are
most common, is poorly understood
Global Biodiversity
Patterns and Processes
Global Biodiversity
Patterns and Processes
• Increasingly there are opportunities for
researchers to test some ecosystem
theory at very large spatial scales
Global Biodiversity
Patterns and Processes
• Biological dynamics of forest fragment
project (Manaus, Brazil)
Global Biodiversity
Patterns and Processes
• Calling Lake fragmentation exp (Canada)
Global Biodiversity
Patterns and Processes
• Savannah River Corridor Project
Global Biodiversity
Patterns and Processes
• Future of Biodiversity Studies
• Need to generate many more
taxonomists; especially in tropical
countries and in groups poorly studied
Global Biodiversity
Patterns and Processes
• E.O. Wilson: 50yr inventory
• Rapid Assessment Program: focus on
areas of high endemism and diversity
– Groups of experts on the better known
groups (e.g. butterflies, birds, flowers)
• Establish research stations in same area
• Combine RAP and intensive studies from
research stations
Global Biodiversity
Patterns and Processes
• Continue phylogenetic studies
• Further examinations on anthropogenic
stresses on the environment
• Millennium Ecosystem Assessment: a multiagency, governmental coalition of
international development and conservation
organizations, and scientists to assess the
status the Earth’s ecosystems
• Hope is to help focus research on the
connections between the status of
biodiversity and ecosystem services
Global Biodiversity
Patterns and Processes
• MEA
Global Biodiversity
Patterns and Processes
• The end of chap 2
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Global Biodiversity Patterns and Processes