BISC530: Biology Conservation Kedong Yin

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BISC530 Biology ConservationKedong Yin

• Introduction
• Habitat fragmentation
• Demographic Processes on heterogeneous
  landscapes Metapopulation dynamics

Key references Meffe and Carroll and et al.
1997. The Principles of Conservation Biology.
Sinauer Assoc. Inc. McCullough, DR. 1996.
Metapopulation and Wildlife Conservation Chapter
9 http//teaching.ust.hk/bisc530/
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Introduction
Genetic material Gene pools Species Populations Co
mmunities Habitats Ecosystems Biosphere
Focal levels of Conservation
Biological Conservation
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Some postulates in conservation biology

1. The diversity of organisms is good
2. The untimely extinction of populations and
   species is bad
3. Ecological complexicity is good
4. Evolution is good
5. Biological diversity has intrinsic values

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Biodiversity

• Species diversity remain to be the most important
  one

• Focusing on important species may provide short
  cuts to conservation

• Keystone taxa predominating ecological role in
  community they may help to characterize
• Umbrella taxa species providing shelter for
  many others
• Flagship taxa public appeal
• Indicator taxa environmental change

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Guiding Principles for Conservation Biology
Principle 1 Evolution is the basic axiom that
unites all of biology (the evolutionary
play) Principle 2 The ecological world is
dynamic and largely non-equilibrial (the
ecological theatre) Principle 3 The Human
presence must be included in conservation
planning (Humans are part of the play)
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Habit Fragmentation

1. Habitat fragmentation
2. Fragmentation and Heterogeneity
3. The Fragmentation Process
4. Insularization and Area effects
5. Biological Consequences of Fragmentation

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Historical lessons on habitat loss

• Classified Greek period -- the barren landscape
  of deserts in the middle east (Turkey, Syria,
  Irag and Iran) used to be fragile woodlands
• Humid tropics -- shifting practices with gaming,
  rotating practices in farming, not possible in
  crowded world today
• Europe -- Great Britain, many forests destroyed
  by 12th century, public forests eliminated by the
  late 18th century, due to the demand for charcoal
  supply

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1. Habitat fragmentation

• Reduction of the total amount of a habit type, or
  perhaps of all natural habitat in a landscape
• Divide a continuous landscape into smaller, more
  isolated patches

Critical habitat -- a specific area within the
species range with physical or biological
features either (1) essential to conservation
of the species or (2) which may require
special management considerations or protection
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Fig. 9.1 Changes in wooded area of Cadiz
Township, Green Country, Wisconsin, during the
period of European settlement.
Wooded area
1831
1882
1902
1950
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2. Fragmentation and Heterogeneity
Patches (heterogeneity) vs continuous
(homogeneous), a matter of scales zoom in or
zoom out
Different vegetations
A side view of the mountain
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Large disturbances like fires create a course
grained pattern
High mortality patch
Medium mortality patch
Low mortality patch
Small disturbances a fine-grained pattern
10 km
Different 7 phases of canopy gaps by death and
fall of individual trees
1 km
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2. Fragmentation and Heterogeneity
Patches (heterogeneity) vs continuous
(homogeneous), a matter of scales zoom in or
zoom out

• Spatial scale (physical gradients, light,
  moisture, elevation)
• Temporal (seasonality)
• Disturbances (fires, storms)
• Microhabitats

So, if habitat heterogeneity is good for
diversity, what is the difference between
human-fragmented and natural patchy landscape?

• Internal structure
• Edge effects
• Barriers
• Evolutionary

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3. The Fragmentation Process
A

• Biological integrity -- Ecological system
• Disruption of continuity in pattern or processes
• Spatial scale
• Temporal scale

Gap formation
B
C
Fragmentation
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Typical Habitat Fragmentation
A ranch subdivided into ranchettes
1983
1994
1957
Building
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Effects when land is subdivided into ranchettes
Fragmentation Population Density Roads Fences Subs
idized predators Exotic Species Nuisance
problems Wildlife generalists Wildlife Specialists
Increase
Decreases in
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4. Insularization and Area effects

• Area-species relationship difference between
  island and a patch of habitat, or
• A phenomenon of statistic sampling
• The equilibrium theory of island biogeography

ScAZ or Log S Log C z Log A
Sspecies richness, A area, c- constant
Island
S
Quadrats
Log S
Log S
A
A
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Probability of occurrence of birds vs forest areas
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Equilibrium Theory of Island Biogeography Species
richness is the balance between colonization and
extinction rates
Colonization
Extinction
Near N
Small S
Rate of Colonization or Extinction
Large L
Far F
FS
FL
NS
NL
Low
High
Species Richness
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5. Biological Consequences of Fragmentation
1) Speciation 2) Initial exclusion 3) Barriers
and Isolation 4) Crowding effects 5) Local and
Regional Extinctions 6) Species vulnerable to
fragmentation 7) Edge Effects 8) Changes in
Species Composition 9) Effects on Ecological
Processes
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1) Speciation
Speciation a process a new species is
formed. Speciation process is ultimately a
genetic divergence between populations through
time, reflecting local adaptation
How selection works giraffe long neck
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Selective pressure stops
Selective pressure toward a longer-necked, taller
animal
Short-necked animals starve and die. Gene for
shorter neck does not enter gene pool
Many generations
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Gradual allopatric speciation
Founder model or Quantum Speciation
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Gradual Allopatric Speciation Arctic vs Gray fox
Subpopulations spread northward and southward and
separate
Conditions differ giving different selective
pressures causing evolution into different species
Adaptations to warm climate thin fur long tail,
ears, legs, and nose dark color
Adaptations to cold climate heavy fur short
tail, ears, legs, and nose light color
Arctic Fox
Gray Fox
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Exmaple of quantum speciation of finches
Cactus Ground
Warbler
Woodpecker
Sharp-Beaked Ground
Sharp-Beaked Ground
Small Ground
Small insectivorous
Medium Ground
Large insectivorous
Large Ground
Vegetarian
Darwins finches. The similarities among these
birds attest to their common ancestor. Selective
pressures adapting subpopulations to feed on
different foods has caused their modification and
speciation.
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Geographic modes of speciation
1) Gradual allopatric speciation Reproductive
isolation is a result of divergence. If
divergence is relatively short, the two groups
comes into second contact-hybrid-no advantage
-stable . If long, hybrids -- natural selection
works -- become distinguishable specie.
2) Founder model or quantum speciation

• small gene pool
• gene drift -- genetic drift--rapid and
  substantial genetic change
• speciation -- rapid

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Effects of fragmentation of habitats on the
speciation
Two scenarios
1) quantum speciation occurs rapidly and results
in several species 2) local extinction -- more
quickly than speciation
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2) Initial Exclusion
One of the most rapid and obvious effects of
fragmentation elimination of the species by the
initial exclusion Home ranges are destroyed,
endemic species are sometimes quite restricted in
its distribution, many rare species are endemics
with narrow distributions Species with narrow
distribution are vulnerable when their habitat is
fragmented
Endemic species species only exist in this
country, not in other countries or in this area
not in other areas.
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3) Barriers and Isolation
A species require several patches to survive
A
A
B
B
A constellation of separate habitat patches may
be critical to the survival of individuals or
populations. When a species requires several
patches (green area) to survival, then species in
site A would survive better.
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A species require different habitats (A and B) to
survive
A
A
B
B
Many animals require a suite of different
habitats or resources to survive. A population
in Site A in the proximity of different habitat B
would survive better than in Site B.
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Roads as barriers to the movement of small animals
Carabid beetles releasing experiment Lines
movement of marked bettles between capture and
recapture
Beetle density
Ngt100
Ngt50
Ngt20
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3) Barriers and Isolation
A constellation of separate habitat patches
critical to the survival of a population A mix of
different habitats with different resources-
important Barrier species specific Roads as a
major barrier to many species Barrier effects are
both relative and cumulative Structural contrast
between fragmented habitats and the matrix for
the species is one measure of fragmentation, as
the landscape around fragments is altered, the
functional isolation of these fragments
increases Dams or other marine engineering
projects
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5. Biological Consequences of Fragmentation
1) Speciation 2) Initial exclusion 3) Barriers
and Isolation Barriers are species
specific Relative and cumulative 4) Crowding
effects
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4) Crowding Effects
Population densities may initially increase in
the fragment when the fragment is isolated This
packing phenomenon crowding on the ark The
initial increase is often followed by the
population collapse
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5. Biological Consequences of Fragmentation

• 1) Speciation
• 2) Initial exclusion
• Home ranges are destroyed, endemic species are
  sometimes quite restricted in its distribution
• 3) Barriers and Isolation
• Barriers are species specific
• Relative and cumulative
• 4) Crowding effects
• Local and Regional Extinctions
• Even common species can disappear from the
  fragments when the fragments are altered.

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5. Biological Consequences of Fragmentation
1) Speciation 2) Initial exclusion Home ranges
are destroyed, endemic species are sometimes
quite restricted in its distribution 3)
Barriers and Isolation Barriers are species
specific Relative and cumulative 4) Crowding
effects 5) Local and Regional Extinctions 6)
Species vulnerable to fragmentation

• Species vulnerability
• Abundance
• Extent of ecological specialization
• Geographical range

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6) Species vulnerable to fragmentation

• Naturally rare species
• Species with limited or patchy geographic
  distributions (e.g. endemic species)
• Species with low population densities (e.g.
  animals with a large home range)
• Wide-ranging species large carnivores needs a
  large area for food hunting or seasonal movement
• Nonvagile species species with poor dispersal
  abilities may not travel far from their birth
  place, e.g. many insects of old growth forests
• Species with low fecundity species with low
  reproductive capacity

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6) Species vulnerable to fragmentation
Species with short life cycles more vulnerable
than longer-lived species Species dependent on
patchy or unpredictable resources or otherwise
highly variable in population size Grounded
Nesters nesting on or near the
ground Large-patch or interior species species
living in the interior of a habitat, thus
vulnerable to fragmentation of their
habitat Species vulnerable to human exploitation
or persecution
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5. Biological Consequences of Fragmentation
1) Speciation 2) Initial exclusion Home ranges
are destroyed, endemic species are sometimes
quite restricted in its distribution 3)
Barriers and Isolation Barriers are species
specific Relative and cumulative 4) Crowding
effects 5) Local and Regional Extinctions 6)
Species vulnerable to fragmentation 7) Edge
Effects
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Loss of quail eggs
7) Edge Effects
There is edge if a habitat island is different
from the surrounding landscape There is a
gradient of environmental factors across the
edge Ecological trap animals are attracted to
edge habitat
The structural contrast to the surrounding
landscape is an indicator of the strength of edge
effects The ratio of the edge length to the
interior area is a measure of the edge effects
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A comparison of breeding success of
fragmentation sensitive birds (16 species) in two
forest fragments with similar total areas, but
vastly different core areas (forest interior). A
is entirely edge habitat (light) B contains 20
ha of interior habitat.
No birds bred successfully
A
39 ha
20 ha
B
47 ha
6 species / 16 species bred in core area
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5. Biological Consequences of Fragmentation
1) Speciation 2) Initial exclusion Home ranges
are destroyed, endemic species are sometimes
quite restricted in its distribution 3)
Barriers and Isolation Barriers are species
specific Relative and cumulative 4) Crowding
effects 5) Local and Regional Extinctions 6)
Species vulnerable to fragmentation 7) Edge
Effects 8) Changes in Species Composition
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5. Biological Consequences of Fragmentation
1) Speciation 2) Initial exclusion Home ranges
are destroyed, endemic species are sometimes
quite restricted in its distribution 3)
Barriers and Isolation Barriers are species
specific Relative and cumulative 4) Crowding
effects 5) Local and Regional Extinctions 6)
Species vulnerable to fragmentation 7) Edge
Effects 8) Changes in Species Composition 9)
Effects on Ecological Processes
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Species Persistence in a fragmented landscape
3 options

• Survive well or thrive in a matrix of human land
  uses weedy species
• Maintain viable population within individual
  habitat fragments species with a small home
  range
• Highly mobile some birds

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Habit Fragmentation

1. Habitat fragmentation
2. Fragmentation and Heterogeneity
3. The Fragmentation Process
4. Insularization and Area effects
5. Biological Consequences of Fragmentation