Ecology Flashcards
Ecology
The scientific study of the interactions between organisms and the environment
- These interactions determine distribution of
organisms and their abundance
- Reveals the richness of the biosphere
What is Walker Branch Watershed?
Pipes and troughs used to move water between plots to study how forests responds to altered precipitation
What kind of enrichment allows experiments to be conducted in these fields?
Free-air carbon dioxide enrichment allows experiments with controlled atmospheric concentrations of carbon dioxide to be conducted in the fields
Organismal ecology
Studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges
Population ecology
Focuses on factors affecting how many individuals of a species love in an area. Analyzes the factors that affect population size and how and why it changes through time
- Population is a group of individuals of the same
species living in an area
Community ecology
Deals with the whole array of interacting species in a community. Examines how species interactions (predation and competition) affect community structure
- Community is a group of populations of different
species in an area
Ecosystem ecology
Emphasized energy flow and chemical cycling among the various biotic and abiotic components (i.e., between organisms and environment =)
- Ecosystem is the community of organisms in an
area and the physical factors with which they
interact
Landscape ecology
Deals with arrays of ecosystems and how they are arranged in a geographic region. Focuses on factors controlling flow of energy, materials, and organisms across ecosystems
- Landscape or seascape is a mosaic of connected
ecosystems
Global ecology
Examines the influence of energy and materials on organisms across the biosphere. Examines how the regional exchange of energy and materials influences the function and distribution of life on earth
- Biosphere is the global ecosystem, the sum of all the planet’s ecosystems
What do ecologists provide?
The scientific understanding that underlies environmental issues
What do environmentalists do?
Advocate for environmental protection
What did Rachel Carson do?
She is credited with starting the modern environmental movement with the publication of Silent Spring in 1962
What do long term data series do?
- Serendipitously studied intertidal communities
in Scilly Isles - Showed that applying toxic dispersal chemicals
was more detrimental than oil itself - Also able to quantify time to dull ecosystem recovery
What is the value of long-term ecological data series?
- To assess rate and direction of change
- To distinguish directional trends from short-term
variability - To forecast environmental conditions in the
future
How do ecology and evolutionary biology link?
Study of ecology helps to interpret the evolution of body plans and other environmental adaptations
How do ecological interactions cause evolutionary change, and vice versa?
- Ecological change leads to,
- Alters in selective pressures in populations,
leads to, - Evolutionary change, leads to,
- Alters in outcomes of ecological interactions
Biogeography
Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere
What are the two kinds of factors that ecologists consider when attempting to explain the distribution of species?
- Biotic: living factors
- Abiotic: nonliving factors
What is dispersal?
- Movement of individuals away from centers of
high population density or from their area of
origin - Dispersal contributes to global distribution of
organisms - Understanding the capacity for each species for
dispersal is critical to understanding global
patterns of subspecies distribution
What is Natural Range of Expansions?
Natural range expansions show the influence of dispersal on distribution
What are invasive species?
Species transplants can disrupt the communities or ecosystems to which they have been introduced
what is a species transplant?
Includes organisms that are intentionally or accidentally relocated from their original distribution
What does a successful invasion indicate?
That the potential range of a species is larger than its actual range, i.e., species could live in certain areas if natural dispersal mechanisms carried them there
Does behavior limit the distribution of species?
- Some organisms do not occupy all of their
potential range even though they can disperse
into new areas - Species distribution may be limited by habitat
selection behavior, e.g., specific cues for larval
settlement or egg-laying may be absent or
temporal
Do biotic factors, such as other species, limit the distribution of a species?
Yes, some biotic factors can affect the distribution of organisms may include
- Interactions with other species
- Food availability
- Predation
- Competition
What are some examples of species dependence?
- Plants may require specific pollinators
- Clownfish require anemones for protection
How does food availability affect species?
- Specific types of food required by juveniles or
adults - Feeding apparatus, behavior, or physiology is
tailored to certain food items and animals
cannot adjust to new diet
How do abiotic factors limit species distribution?
Temperature, water, sunlight and wind amount to climate
- Macro climate consists of patterns on the global,
regional, and local level
- Micro climate consists of very fine patterns, such
as those encountered by the community of
organisms underneath a fallen log
Most abiotic factors vary in space and time
What is environmental oxygen?
An important factor in distribution of many organisms because it is needed for respiration
What is important about environmental temperature?
It is an important factor in distribution of organisms because of its effects on biological processes
Endotherms
Expend energy to regulate their internal body temperature
Ectotherms
Body temperature fluctuates with that of the environment, physiological performance affected by temperature changes
What can range shifts in response to climate change affect?
It can dramatically affect the distribution of other species
- For example, the long-spined sea urchin (C.
rodgersii) expanded its range in response to
increasing water temperature
- C. rodgersii consumed the seaweed in its new
range and destroyed the diverse communities
that formerly inhabited the seaweed stands
What does salinity affect?
Water balance of organisms through osmosis
- Hypertonic = not enough water
- Isotonic = perfect balance
- Hypotonic = too much water
What can sunlight affect?
Light intensity and quality affect photosynthesis
- Water absorbs light, thus in aquatic
environments most photosynthesis occurs near
the surface
What are some of the characteristics of soil that limit distribution of plants and thus the animals that feed upon them?
- Physical structure
- pH
- Mineral composition
What is zonation?
It is determined by relative lengths of exposure to the air and to the action of waves
- High stress/low predation = Splash & Spray zone and high tide zone
- Low stress/high predation = Mid and low tide zone
Fluctuations in abiotic factors
- Predictable changes in light and temperature
over diurnal cycle - Others can be unpredictable, e.g., intertidal:
interplay of wind, tidal height, seasons, and
cloud cover
Who sets the limits in the intertidal system?
- Predation sets the lower limit
- Predators feed when submerged, the lower an
organism lives on the shore the longer it is in
potential contact with predators
- Predators feed when submerged, the lower an
- Abiotic factors set the upper limit
- Tradeoff, live high to escape predation but lose
opportunity to feed and risk damage from
abiotic factors
What are community interactions classified by?
Whether they help, harm, or have no effect on the species involved
- Examples are competition, predation, herbivory,
and symbiosis (parasitism, mutualism, and
commensalism)
- Interspecific interactions can affect the survival
and reproduction of each species, and the
effects can be summarized as positive (+),
negative (-), or no effect (0)
Interspecific competition
(-/- interaction) occurs when species compete for a resource in short supply
What is the competitive exclusion principle?
The competitive exclusion principle states that two species competing for the same limiting resources cannot coexist in the same place
What are ecological niches?
The total of a species’ use of biotic and abiotic resources
- Can also be thought of as an organism’s
ecological role
- Ecologically similar species can coexist in a
community if there are one or more significant
differences in their niches
What happens to a species niches as a result of competition?
A species’ fundamental (or potential) niche may differ from its realized niche
Resource partitioning
Differentiation of ecological niches, enabling similar species to coexist in a community, via evolution by natural selection
Character displacement
A tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species
Exploitation
Refers to any +/- interaction in which one species benefits by feeding on the other species
- Exploitative interactions include predation,
herbivory, and parasitism
Predation
(+/- interaction) refers to interaction where one species, the predator, kills and eats the other, the prey
Behavioral defenses
Include hiding, fleeing, forming herds or schools, self-defense, and alarm calls
- Animals also have morphological and chemical defense adaptations
Aposematic coloration
Animals with effective chemical defense often exhibit bright warning coloration
Cryptic coloration
Makes prey difficult to spot
Batesian mimicry
A palatable or harmless species mimics an unpalatable or harmful model
Müllerian mimicry
Two or more unpalatable species resemble each other
Herbivory
(+/- interaction) refers to an interaction in which an herbivore eats parts of a plant or alga
- Has led to the evolution of plant mechanical and
chemical defenses and consequent adaptations
by herbivores
Symbiosis
A relationship where two or more species live in direct and intimate contact with one another
Parasitism
(+/- interaction), one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process
Mutualism
(+/+ interaction), an interspecific interaction that benefits both species
- Obligate, where one species cannot survive
without the other
- Facultative, where both species can survive
alone
Commensalism
(+/0 interaction), one species benefits and the other is apparently unaffected
Population
A group of individuals of a single species living in the same general area
- Share same resources
- Are likely to interact and breed with one another
- A description of a population is normally
described by its boundary and size
Dispersion
The pattern of spacing among individuals within the boundaries of the population
- Environmental and social factors influence
spacing of individuals in a population
- In a clumped dispersion, individuals aggregate in
patches
- A clumped dispersion may be influenced by
resource availability and behavior
What is a uniform dispersion?
A uniform dispersion is one in which individuals are evenly distributed
- May be influenced by social interactions such as
territoriality, the defense of a bounded space
against other individuals
What is a random dispersion?
In a random dispersion, the position of each individual is independent of other individuals
- It occurs in the absence of strong attractions or
repulsions
Density
The number of individuals per unit area or volume
- In most cases, it is impractical or impossible to
count all individuals in a population
- Sampling techniques can be used to estimate
densities and total population size
What can population size be estimated by?
Either extrapolation from small samples, an index of population size (e.g., number of nests), or the mark-recapture method
Mark recapture method
- Scientists capture, tag, and release a random
sample of individuals (s) in a population - Marked individuals are given time to mix back
into the population - Scientists capture a second sample of individuals
(n), and note how many of them are marked (x) - Population size (N) is estimated by N= sn/x
What is density the result of?
An interplay between processes that add individuals to a population and those that remove individuals
Immigration
The influx of new individuals from other areas
Emigration
The movement of individuals out of a population
What does exponential models describe?
Population growth in an idealized, unlimited environment
Why is it useful to study population growth in an idealized situation?
Idealized situations help us understand the capacity of species to increase and the conditions that may facilitate this growth
What is a populations growth rate?
A populations growth rate equals birth rate minus death rate
- The population growth rate can be expressed
mathematically using differential calculus
What can birth and death rates be expressed as?
Per capita rate - average number of births and deaths per individual during the specified time interval
Exponential population growth
Population increase under idealized conditions
- Under these conditions, the rate of increase is at it’s maximum, denoted ar rmax
What kind of curve does exponential population growth result in?
A J-shaped curve
- Characterizes some rebounding populations
Carrying capacity
The maximum population size the environment can support (varies with the abundance of limiting resources)
What kind oc curve does the logistic model of population growth produce?
A sigmoid (S-shaped) curve
What is the logistic growth model?
In the logistic population growth model, the per capita rate of increase declines as carrying capacity is reached
- The logistic model starts with the exponential
model and adds an expression that reduces per
capita rate of increase as N approaches K
What is an allee effect?
In which individuals have a more difficult time surviving or reproducing if the population size is too small
What factors determine the carrying capacity of a population?
- Most populations show density-dependent
regulation, birth rates fall and death rates rise
with population density - Example of a negative feedback that regulated
population growth
Competition for resources
In crowded populations, increasing population density intensifies competition for resources and results in a lower birth rate
Disease
Population density can influence the health and survival of organisms
- In dense populations, pathogens can spread
more rapidly
Territoriality
In many vertebrates and some invertebrates, competition for territory may limit density
Intrinsic factors
For some populations, intrinsic (physiological) factors appear to regulate population size
- Increasing frequency of interactions between
individuals leads to stress and a decrease in
birth rate
Predation
As a prey population builds up, predators may feed preferentially on that species
Toxic waste
Accumulation of toxic wastes can contribute to density-dependent regulation of population size
What does the study of population dynamics focus on?
The complex interactions between biotic and abiotic factors that cause variation in population size
What is a population cycle?
Some populations undergo regular boom-and-bust cycles
- Cycle is driven by the availability of prey and in
turn the abundance of predators
Species diversity
A community is the variety of organisms that make up the community
Why is diversity a good thing?
Higher diversity communities more resistant to stress, more, productive, more resistant to invasions
Species richness
The total number of different species in the community
Relative abundance
The proportion each species represents of the total individuals in the community
What are species that have a large impact on community structure called?
They are dominant or play a pivotal role in community dynamics
Dominant species
Those that are most abundant or have the highest biomass
- Competitively superior in exploiting resources
- More successful at avoiding predators
Keystone species
Exert strong control on a community by their ecological roles, or niches
- Not necessarily abundant in a community
- Often predators or “ecosystem engineers”
Foundation species
Cause physical changes in the environment that affect community structure
What is the bottom-up model?
The bottom-up model of community organization proposes a unidirectional influence from lower higher trophic levels
- Presence or absence of mineral nutrients
determines community structure, including
abundance of primary producers
What is the top-down model?
The top-down model, also called the trophic cascade model, proposes that control comes from the trophic level above
- Predators control herbivores, which in turn
control primary producers
What is a disturbance?
An event that changes a community, removes organisms from it, and alters resource availability
- Fire is a significant and sometimes necessary
disturbance in most terrestrial ecosystems
What is nonequilibrium?
Communities that are constantly changing after being buffeted by disturbances
The intermediate disturbance hypothesis
Suggests that moderate levels of disturbance can foster greater diversity than either high or low levels of disturbance
- High levels of disturbance exclude many slow-
growing species
- Low levels of disturbance allow dominant
species to exclude less competitive species
Human disturbance
- Humans have the greatest impact on biological
communities worldwide - Human disturbance to communities usually
reduces species diversity - Humans also prevent some naturally occurring
disturbances, which can be important to
community structure, e.g., preventing wildfires
Who won the Nobel Peace prize in 2007 and why?
R. K. Pachauri and Albert Arnold Gore Jr. for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change
What is most affected by rising atmospheric CO2 levels and global warming?
Marine biomes
- Temperature increases
- Ocean acidification
Why were so many mussels killed by the heat wave?
Because biotic factors lower down the shore (predation) force them to live higher up shore where they are vulnerable to abiotic factors (heat and desiccation)
What are the key concepts of ocean acidification?
- More CO2 in atmosphere leads to more CO2
dissolved in the ocean - More CO2 dissolved in the ocean makes the
ocean more acidic
