Title: 2. Community Processes: Species Interactions and Succession – Chapter 9 a. The Ecological Niche (9-1,) 1) Role of Species in an Ecosystem 2) Fundamental and Realized Niche
1Chapter 8 Community Structure, Appearance and
Species Diversity
2Equilibrium Theory of Biodiversity
- Diversity is a balance of factors that increase
diversity and factors that decrease diversity - Production of new species (speciation), and
influx can increase diversity - Competitive exclusion, efficient predators,
catastrophic events (extinction) can decrease
diversity - Physical conditions
- variety of resources
- Predators
- environmental variability
3Comparison of Two Communities
- Richness (number of species)
- Relative abundance
- How do we describe these differences?
4Biogeographical Changes
- Richness declines from equator to pole
- Due to
- Evolutionary history
- Climate
Fig 53.23 Bird species numbers
5Geographic (Sample) Size
- Species-area curve
- The larger the geographic area, the greaterthe
numberof species
Fig. 23.25 North American Birds
6Species Richness on Islands
- Depends on
- Rate of immigration to island
- Rate of extinction on island
- These in turn depend on
- Island size
- Distance from mainland
7How do species move?
- Humans (accidental and intended)
- Animals (sticky seeds and scat)
- Wind and ocean currents ( or -)
- Land bridges
- Stepping stone islands
- affected by climactic changes (glaciation)
- ocean levels
- short-term weather patterns
8What allowed colonization?
- Niche opening
- No competition
- Endemics not utilizing resources
- Accessibility to colonists
9Theory of Island Biogeography
- Immigration rate decreases as island diversity
increases - Extinction increases as island diversity
increases - Species equilibrium on islands is a balance of
immigration and local extinction
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11Theory of Island Biogeography
- Smaller islands have lower total populations
- Probability of extinction increases with lower
population - Smaller islands have lower species diversity
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13Theory of Island Biogeography
- Islands further from mainland have lower
immigration rates - More distant islands have lower species diversity
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15Community Relationships
16- Niche is
- the species occupation and its
- Habitat
- location of species
- (its address)
17Niche
- A species functional role in its ecosystem
includes anything affecting species survival and
reproduction - Range of tolerance for various physical and
chemical conditions - Types of resources used
- Interactions with living and nonliving components
of ecosystems - Role played in flow of energy and matter cycling
18Niche
19Types of Species
- Native species normally live and thrive in a
particular ecosystem - Nonnative species are introduced - can be called
exotic or alien - Indicator species serve as early warnings of
danger to ecosystem- birds amphibians - Keystone species are considered of most
importance in maintaining their ecosystem
20Nonnative Species
- Nonnative plant species are invading the nation's
parks at an alarming rate, displacing native
vegetation and threatening the wildlife that
depend on them - At some, such as Sleeping Bear Dunes National
Lakeshore in Michigan, as much as 23 percent of
the ground is covered with alien species, and the
rate of expansion is increasing dramatically.
21Indicator Species
- a species whose status provides information on
the overall condition of the ecosystem and of
other species in that ecosystem - reflect the quality and changes in environmental
conditions as well as aspects of community
composition
22Keystone Species
- A keystone is the stone at the top of an arch
that supports the other stones and keeps the
whole arch from falling - a species on which the persistence of a large
number of other species in the ecosystem depends.
- If a keystone species is removed from a system
- the species it supported will also disappear
- other dependent species will also disappear
- Examples
- top carnivores that keep prey in check
- large herbivores that shape the habitat in which
other species live - important plants that support particular insect
species that are prey for birds - bats that disperse the seeds of plants
23r-Selected Species
Cockroach
Dandelion
Many small offspring Little or no parental care
and protection of offspring Early reproductive
age Most offspring die before reaching
reproductive age Small adults Adapted to
unstable climate and environmental
conditions High population growth rate
(r) Population size fluctuates wildly above and
below carrying capacity (K) Generalist
niche Low ability to compete Early successional
species
24K-Selected Species
Saguaro
Elephant
Fewer, larger offspring High parental care and
protection of offspring Later reproductive
age Most offspring survive to reproductive
age Larger adults Adapted to stable climate and
environmental conditions Lower population growth
rate (r) Population size fairly stable and
usually close to carrying capacity
(K) Specialist niche High ability to
compete Late successional species
25Species Interaction
26Competition
- Any interaction between two or more species for a
resource that causes a decrease in the population
growth or distribution of one of the species - Resource competition
27Competition
28Resource Competition
29Competition
- Any interaction between two or more species for a
resource that causes a decrease in the population
growth or distribution of one of the species - Resource competition
- Preemptive competition
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31Competition
- Any interaction between two or more species for a
resource that causes a decrease in the population
growth or distribution of one of the species - Resource competition
- Preemptive competition
- Competitive exclusion
32Competitive Exclusion
33Competition
- Any interaction between two or more species for a
resource that causes a decrease in the population
growth or distribution of one of the species - Resource competition
- Preemptive competition
- Competition exploitation
- Interference competition
34Competition
35PREDATION
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37Predator Adaptations
- Prey detection and recognition
- sensory adaptations
- distinguish prey from non-prey
- Prey capture
- passive vs. active
- individuals vs. cooperative
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41Predator Adaptations
- Prey detection and recognition
- sensory adaptations
- distinguish prey from non-prey
- Prey capture
- passive vs. active
- individuals vs. cooperative
- Eating prey
- teeth, claws etc.
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45Prey Adaptations
- Avoid detection
- camouflage, mimics,
- diurnal/nocturnal
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50Prey Adaptations
- Avoid detection
- camouflage, mimics,
- diurnal/nocturnal
- Avoid capture
- flee
- resist
- escape
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54Prey Adaptations
- Avoid detection
- camouflage, mimics,
- diurnal/nocturnal
- Avoid capture
- flee
- resist
- escape
- Disrupt handling (prevent being eaten)
- struggle?
- protection, toxins
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58Symbiosis Mutualists, Commensalists and Parasites
59- Symbiosis and symbiotic relationship are two
commonly misused terms - Translation of symbiosis from the Greek literally
means living together - Both positive and negative interactions
60Mutualism
- DEFINITION
- An interaction between two individuals of
different species that benefits both partners in
this interaction
61Mutualism
- Increase birth rates
- Decrease death rates
- Increase equilibrium population densities,
- Raise the carrying capacity
62Pollination
- Animals visit flowers to collect nectar and
incidentally carry pollen from one flower to
another - Animals get food and the plant get a pollination
service
63Yucca and Yucca Moth
- Yuccas only pollinator is the yucca moth. Hence
entirely dependent on it for dispersal. - Yucca moth caterpillars only food is yucca
seeds. - Yucca moth lives in yucca and receives shelter
from plant.
64Lichen (Fungi-Algae)
- Symbiotic relationship of algae and
fungaeresults in very different growth formas
with and without symbiont. - What are the benefits to the fungus?
65Nitrogen Fixation
- Darkest areas are nuclei, the mid-tone areas are
millions of bacteria Gram -, ciliate
66Obligatory Mutualism
- Obligatory An organism can't live without the
mutualism--either cannot survive or cannot
reproduce. - the common pollinator systems like bees and
flowering plants - protozoans in the guts of termites
- the alga in the lichen partnership
67Facultative Mutualism
- Facultative This is "take it or leave it" for
one or both partners - While the organism benefits when the mutualism is
present, it can still survive and reproduce
without it - ant mutualisms, such as ants protecting plants
from predation - ants tending aphids
68Commensalists
- Benefit from the host at almost no cost to the
host - Eyelash mite and humans
- Us and starlings or house sparrows
- Sharks and remora
69Parasites and Parasitoids
- Parasites draw resources from host without
killing the host (at least in the short term). - Parasitoids draw resources from the host and
kill them swiftly (though not necessarily
consuming them).
70Parasitic wasps
- Important parasites of larvae.
- In terms of biological control, how would this
differ from predation?
ovipositor
71Ecological Processes
72Ecological Succession
- Primary and Secondary Succession
- gradual fairly predictable change in species
composition with time - some species colonize become more abundant
- other species decline or even disappear.
73Ecological Succession
Gradual changing environment in favor of new /
different species / communities
74Primary Succession
- Gradual establishment of biotic communities in an
area where no life existed before - No preexisting seed bank
- newly formed islands (i.e. volcanic origin)
- retreat of a glacier
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76Primary SuccessionGlacier Retreat
77Secondary Succession
- Gradual reestablishment of biotic communities in
an area where one was previously present. - Preexisting seed bank
- treefall gaps
- "old field succession"
- forest fire
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80Disturbance
- Event that disrupts an ecosystem or community
- Natural disturbance
- tree falls, fires, hurricanes, tornadoes,
droughts, floods - Humancaused disturbance
- deforestation, erosion, overgrazing, plowing,
pollution,mining - Disturbance can initiate primary and/or secondary
succession
81Ecological Stability - Stress
- Drop in Primary Productivity
- Increased Nutrient Losses
- Decline or extinction of indicator species
- Increased populations of insect pests or disease
organisms - Decline in Species diversity
- Presence of Contaminants