Transcript Chapter 50…odds & ends

Chapter 50
• ecology: interaction between organisms and their environment
• from Greek oikos, meaning ‘home,’ and logos, meaning to study
• rapidly growing and exciting science
• distribution: geographic range
• abundance: number of organisms
• abiotic components: nonliving chemical and physical factors
• biotic components: all organisms that are pare of an
environment
organism
population
community
ecosystem
landscape
• several different ecosystems linked by exchanges of energy,
material, and organisms
biosphere
sum of Earth’s ecosystems
precautionary principle
• “Look before you leap”
• “An ounce of protection is worth a pound of cure”
• “To keep every cog and wheel is the first precaution to
intelligent tinkering”
biogeography
• study of the past and present distribution of individual species
exotic species
zebra mussel
exotic species
zebra mussels
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feed on phytoplankton
 phytoplankton population
water becomes more clear
 in light levels in water
more plants with roots along bottom
loss of habitat for benthic organisms
biotic factors affect the distribution
of organisms
• Ex. predators
• can be studied with “removal and addition” experiments
• Ex. sea urchins and kelp
abiotic factors affect the
distribution of organisms
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temperature
water
sunlight
wind
rocks and soil
CLIMATE
• determined by four main abiotic factors:
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temperature
water
light
wind
BIOMES
solar radiation and latitude
seasons
affect of mountains on rainfall
lake stratification and turnover
microclimate
• variation in climate along a fine scale
• Ex. forest floor
• Ex. under a rock or log
impact of climate change
• conformers: allow some conditions within their bodies to vary
with external changes
• Ex. spider crabs
• principle of allocation: each organism had a limited amount of
energy that can be allocated for obtaining nutrients , escaping
from predators, coping with environmental fluctuations, growth
and reproduction
• therefore, energy required for maintaining homeostasis is not
available for other functions
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http://www.royaloakschools.com/portal/sites/default/files/apBIOsemester
semeste
• acclimation: involves substantial but reversible changes that
shift an organism’s tolerance curve in the direction of the
environmental change
aquatic biomes
• make up the largest portion of the biosphere
• divided into
• freshwater biomes (less than 1% saltwater)
• marine biomes (~3% saltwater)
• marine biomes cover 75% of Earth’s surface
• evaporation is main source of rain water
• water temperatures have major influence on climate
• algae and bacteria near surface provide substantial
portion of O2 and consume large amounts of CO2
• photic zone: receives light
• aphotic zone (profundal): little light
• benthic zone: bottom
• littoral zone: rooted and floating aquatic plants
• limnetic zone: floating phytoplankton
(high rate of photosynthesis)
lakes: classification based on
quantity of organic matter
• oligotrophic (Ex. Lake Michigan)
• deep
• nutrient-poor
• sparse phytoplankton
• mesotrophic
• eutrophic (Ex. golf course pond)
• more shallow
• nutrient-rich
• abundant phytoplankton
other aquatic biomes
• wetlands
• area covered with water that supports aquatic plants
• can be periodically flooded or permanently saturated
• includes marshes, swamps, and bogs
• estuaries
• area where a freshwater stream or river merges with the ocean
marine zones
• intertidal zone: where land meets water
(parts are not always covered by water)
• neritic zone: shallow regions over continental
shelf
(always underwater)
• oceanic zone: water past the continental shelf
• pelagic zone: open water
• abyssal zone: very deep; continuous cold (3 C),
high water pressure, near absence of light, low
nutrient concentrations
terrestrial biomes
• classification is based on abiotic factors (especially climate)
• often names for physical or climatic feature, along with
predominant vegetation
• vertical layers:
• canopy
• permafrost
tropical forest
savanna
desert
chaparral
temperate grassland
temperate deciduous forest
coniferous forest
tundra
behavior: what an animal
does and how it does it
• influenced by both genetic and environmental factors
• includes nonmotor components such as learning and memory
• deals with two types of questions:
• proximate…mechanisms (environmental
stimuli, triggers, physiological
mechanisms)
• ultimate…evolutionary significance
Example:
• magnolia warbler breeds in spring and early summer
• P = triggered by increase in daylength (mating can be triggered
experimentally by increasing light exposure)
• U = Why did natural selection favor spring/summer?
(maximize fitness…)
• most behavioral traits are
polygenic
• behavior is a product of genes and
environment
• phenotype (expression of genes)
depends on both genetic and
environmental components
• behavioral traits evolve in order to
maximize fitness
fixed action pattern (FAP)
• sequence of behavioral acts that is essentially unchangeable
and usually carried to completion once initiated
• triggered by external sensory stimulus
(often involves another species as sign stimulus)
fixed action pattern (FAP)
• Ex. Tinbergen study
• Ex. moths fold wings and drop to ground in response to
ultrasonic signals of predatory bats
• Ex. three-spined stickleback fish
• attack other males that invade territory
• stimulus = red belly
• won’t attack individuals without red belly
• will attack many red-bellied shapes
behavioral ecology
emphasizes evolutionary
hypotheses
• Ex. cost-benefit analysis of foraging
• foraging: food-obtaining behavior
• crows & mollusks: choose height that provides most food / energy
expended
• bluegill sunfish: feed on Daphnia
• low density  less selective
• high density  more selective
• smallmouth bass and minnows vs. crayfish: tradeoff between
quantity and quality
foraging behavior is not just
about calories
• must minimize risk of predation
• must involve obtaining essential nutrients
learning = modification of
behavior resulting from
specific experiences
• most innate behaviors improve with performance as animals
learn to carry them out more efficiently
• Ex. alarm calls of vervet monkeys (improve
performance by learning)
• distinct calls when the see different animals
• leopard  loud barking  run up tree
• eagle  short, double syllable cough  look up
• snake  “chutter”  look down
• young are indiscriminate
• Ex. Give eagle call for all birds
• accuracy of calls improves with age
• positive reinforcement
• if infants give correct call, adult immediately follows
learning vs. maturation
•maturation = ongoing
developmental changes in
neuromuscular system
• Ex. birds learning to fly
• Ex. herring gull feeding behavior
habituation
•loss of responsiveness to
stimuli that convey little or no
information
•Ex. Hydra response to initial
touch
•Ex. response to alarm calls
•may allow nervous system to
focus on important stimuli
imprinting
•learning that is limited to
specific time period
•Ex. Lorenz and geese
sensitive period
•limited time in development
when learning of particular
behaviors can take place
•Ex. sensitive period for sexual
identity in finches
bird song as model for
understanding development
of behavior
bird song as model for
understanding development
of behavior
• isolated bird can learn song of another species
after sensitive period through live interaction with
individual
• exception to white-crowned sparrow learning
scenario
• deafened birds still able to learn song
• region of canary brain for song varied dramatically
according to season and complexity of song
• region is largest during breeding
• must somehow increase fitness
associative learning =
associate one stimulus with
another
• classical conditioning = associate one event with
another
• Ex. Pavlov’s dog
• operant conditioning = trial and error learning
• associate behavior with reward or punishment
• Ex. coyote learns to avoid porcupine
• Ex. Skinner box
play
• no apparent external goal, but involves movements associated
with goal-directed behaviors
• consumes energy + potential costs
• play used to perfect behaviors needed in functional
circumstances
social biology
• at times, social behavior can appear inefficient or even
counterproductive to reproductive success
competitive social behaviors
• because members of a population share a niche, potential for
conflict exists
•agnostic
• contest involving both threatening and submissive behavior
determines which competitor gains access to resource (I.e. food or
mate)
• Ex. test of strength
• dogs
• ground squirrels
competitive social behaviors
•dominancy hierarchy
• alpha individual, who is assured
resources, controls the behavior
of the others
• beta is second in command
• omega is last in the chain
competitive social behaviors
•territoriality
• individual defends area for feeding,
mating, rearing young
• defended through agnostic behavior
• defense is usually only directed at
members of the same species
• natural selection favors mating
behavior that maximizes quantity
or quality of mating partners
• courtship
• behavior patterns that lead up to
copulation (or gamete release)
• helps identify mates of same species
• impact of parental investment
• eggs are more energetically
expensive to produce for females
• females often invest large amounts
of time to carry and nourish offspring
• male reproductive success is
proportional to # of partners
• example of sexual selection
• stalk-eyed flies
mating systems
•promiscuous
•monogamous
•polygamous
• needs of young are ultimate
factor
• certainty of paternity is another
signal
•behavior that causes change in
behavior in another animal
phermones
•chemical signals that are
detected by odor
altruistic behavior
• behavior that reduces fitness of
individual while increasing fitness
of recipient of behavior
• Ex. alarm call of Belding ground squirrel
• Ex. worker bees
• Ex. mole rats
Chapter 52
Population Ecology
• population: group of individuals of a single species that
simultaneously occupy the same area
• rely on same resources
• influenced by same environmental factors
• high likelihood of breeding with one another
population density
• density: number of individuals per unit area or
volume
• In most cases, it is impractical or impossible to
count all individuals in a population
• Sampling allows scientists to estimate densities
and total population sizes
• Ex. mark-recapture method
• Animals within a study area are tagged then released
• After a period of time, second round of animals is
caught (recaptured)
# marked in 1st catch x total # in 2nd catch
N=
# of recaptures in 2nd catch
population dispersion
• dispersion: pattern of spacing among
individuals within the geographic boundaries
of the population
• clumped: individuals aggregate in patches
• Ex. butterfly fish in schools
• uniform: individuals are evenly spaced
• Ex. nesting penguins exhibiting territoriality
• random: position of one individual is
independent of others
• Ex. trees in a forest
demography
• studies changes in populations
• increase (+)
• birth
• immigration
• decrease (-)
• death
• emigration
survivorship curves
• plots proportion of individuals in a cohort still
alive at each age
• Type I = low deaths rates until late in life
• Ex. humans
• Type II = constant death rate throughout life
span
• Ex. squirrel
• Type III = very high death rates early in life
• Ex. oyster
life histories
• includes traits that affect an organism’s schedule of
reproduction and survival (from birth through
reproduction to death)
• big-bang reproduction (semelparity)
• all resources devoted to one reproduction event
• Ex. Pacific salmon, agave plant
• repeated reproduction (iteroparity)
limited resources mandate trade-offs
between investments in reproduction
and survival
• Darwinian fitness is measured not by how many offspring
are produced but by how many survive to produce their
own offspring
• heritable characteristics of life history that result in the most
reproductively successful descendants will become more
common within the population
population growth
• change in population size during time interval = births –
deaths
• N = B - D
t
• zero population growth occurs when the per capita birth
rates and death rates are equal
carrying capacity
• maximum population size that a particular environment
can support with no degradation of the habitat
• logistic growth
• K-selection
• density-dependent
(sensitive to population density)
• population thrives near carrying capacity
• Ex. Drosophila
• r-selection
• density-independent
(successful in uncrowded environments)
• well below carrying capacity
population-limiting factors
• If death rate increases (or birth rate decreases) as population
density increases, population density is DENSITY DEPENDENT
• If birth and death rates do not change, population density is
DENSITY INDEPENDENT
factors leading to negative
feedback in populations
• 1. resource limitation
• competition for food and nutrients
• 2. territoriality
• Ex. limited suitable nesting sites
• 3. health
• Ex. plants
• Ex. cannibalism among beetles
factors leading to negative
feedback in populations
• 4. predations
• Ex. trout focus on emerging larvae
• 5. accumulation of toxic wastes
• 6. disease
• 7. intrinsic factors
• Ex. aggression among mice
Chapter 53
Community Ecology
• community: all species living in an area
Communities differ dramatically
in…
• species richness
• number of different species
• Ex. Pond A = 17 species / Pond B = 18 species
• relative abundance
• number of each species
• Ex. Pond A = (1) toads=7; (2) crayfish=36; ….
•
Pond B = (1) toad=78; (2) crayfish=367
interspecific interactions—
relationships between the species
of a community
• competition (- / -)
– can occur when resources are in short supply
– Ex. grasshoppers and bison compete for grass
– competitive exclusion
• two species that are so similar that they compete for the same limiting
resources cannot coexist in the same place; one will use the resources
more efficiently
– niche
• sum total of a species’ use of biotic and abiotic resources in its environment
• competition (- / -)
– niche
• sum total of a species’ use of biotic and abiotic resources in its environment
– resource partitioning
• differentiation of niches that enables similar species to coexist in a
community
– character displacement
• tendency for characteristics to be more divergent in sympatric populations
than in allopatric populations of the same species
• Ex. Galapagos finches (together on same island  evolution of great variety
in beak shape and other features over time)
• predation (+ / -)
– interaction includes herbivores and parasites
– potent factor in adaptive evolution
– predator adaptations
• acute senses
• weapons such as claws, teeth, stingers, poison
– plant defenses
• chemical toxins, thorns
– animal defenses
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hiding, camouflage (cryptic coloration)
escape (energy intensive)
alarm calls
aposematic coloring warns of potential chemical defenses
Batesian mimicry: palatable or harmless species mimics unpalatable or harmful model
Mullerian mimicry: two or more unpalatable species resemble each other
• predation (+ / -)
• parasites derive nourishment from another organism (host, which is
harmed by interaction)
• endoparasites live within their hosts
• Ex. Tapeworm
• ectoparasites feed on an external surface
• Ex. mosquitoes
• mutualism (+ / +)
• interaction benefits both species
• Ex. nitrogen fixation by bacteria in legume root nodules
• Ex. digestion of cellulose by bacteria in termite digestive system
• Ex. ants and acacia trees
• commensalism (+ / 0)
• benefits one species and has no known effect on other species
• Ex. cowbirds and grazing cattle
• coevolution
• reciprocal evolutionary adaptations of two species
• change in one species acts as selective force on first species
food chains
food webs
dominant species
• biomass: sum weight of all individuals in a population
• dominant species are those in a community that have the
highest abundance or biomass
• exert control over the occurrence and distribution of other
species (Ex. sugar maple)
• Why do some species become dominant in an ecosystem?
dominant species
• Ex. American chestnut
• dominant tree in deciduous forest before 1910
• wiped out by fungal disease after Asian trees were introduced to
botanical garden in NYC
• impact:
• oaks, hickories, beech, and maples have filled in
• however, 7 (of 56) species that fed on chestnut trees went extinct
• no mammals or birds seem to be affected
keystone species
• exert control on community structure based on their ecological
Ex. Pisaster ochraceous
• sea star is keystone predator of mussels in rocky intertidal
communities of western North America (promotes diverse
community with 15 – 20 species)
• once removed by Robert Paine, mussel Mytilus californianus was
able to monopolize space and exclude other invertebrates and algae
(leads to community with less than 5 species)
• predation by Pisaster allows other species to occupy space
The structure of a community may
be controlled bottom-up by
nutrients or top-down by
predators.
•N  V  H  P
• N = nutrients
• V = vegetation
• H = herbivores
• P = predators
ecological succession
• transition in species composition over ecological time
• primary succession: begins in virtually lifeless area where soil has not
yet formed
• Ex. new volcanic island, glacial moraine
• bacteria  lichens, mosses  grasses  shrubstrees
• secondary succession: occurs where existing community has been
cleared by some disturbance that leaves the soil intact
• Ex. fire, abandoned farms
biodiversity
• number of species in ecological community
• two key factors:
• size
• small islands tend to have fewer species than large islands
• geographic location
• Ex. plant and animal life more abundant and varied in tropics than in
other parts of the Earth
• species richness
• total number of different species in the community
• relative abundance
Chapter 54
Ecosystems
• ecosystem: consists of all the organisms living in a community,
along with all the abiotic factors with which they interact
• like populations and communities, boundaries are usually not
discrete
• trophic levels of feeding relationships allows us to follow the
transformation of energy in ecosystems
• primary producers = autotrophs
• primary consumers = herbivores
• secondary consumers = eat herbivores
• tertiary consumers = eat other carnivores
• detritovores (decomposers) = consumers that get their energy from
detritus (nonliving organic material)
an ecosystem’s energy budget
depends on primary production
• primary production: amount of light energy converted to
chemical energy by an ecosystem’s autotrophs during a given
time
• the amount of solar radiation reaching the surface of the
globe ultimately limits the photosynthetic output of
ecosystems
• 1-2% of visible light that reaches producers is converted to
chemical energy
• gross primary productivity (GPP): amount of light energy that is converted
to chemical energy by photosynthesis per unit time
• net primary productivity (NPP): equal to gross primary productivity minus
the energy used by producers for respiration
– represents storage of chemical energy available to consumers in an
ecosystem
– can be expressed in energy per unit area per unit time (J/m2/yr) or biomass
of vegetation added to the ecosystem per unit time (g/m2/yr)
• standing crop measures existing biomass; primary productivity measures
new biomass
in aquatic ecosystems, nutrients
(and light) limit primary
production
• nitrogen and phosphorus are the nutrients that most often
limit marine production
eutrophication
• Process where lakes with phytoplankton communities
dominated by diatoms and green algae change to host mainly
cyanobacteria
• Mostly a result of fertilizer and sewage runoff (rich in
nutrients)
•  nutrients   bacteria  respiration =
 dissolved oxygen   diversity
Chapter 54
Ecosystems
• ecosystem: consists of all the organisms living in a community,
along with all the abiotic factors with which they interact
• like populations and communities, boundaries are usually not
discrete
• trophic levels of feeding relationships allows us to follow the
transformation of energy in ecosystems
• primary producers = autotrophs
• primary consumers = herbivores
• secondary consumers = eat herbivores
• tertiary consumers = eat other carnivores
• detritovores (decomposers) = consumers that get their energy from
detritus (nonliving organic material)
an ecosystem’s energy budget
depends on primary production
• primary production: amount of light energy converted to
chemical energy by an ecosystem’s autotrophs during a given
time
• the amount of solar radiation reaching the surface of the
globe ultimately limits the photosynthetic output of
ecosystems
• 1-2% of visible light that reaches producers is converted to
chemical energy
• gross primary productivity (GPP): amount of light energy that is converted
to chemical energy by photosynthesis per unit time
• net primary productivity (NPP): equal to gross primary productivity minus
the energy used by producers for respiration
– represents storage of chemical energy available to consumers in an
ecosystem
– can be expressed in energy per unit area per unit time (J/m2/yr) or biomass
of vegetation added to the ecosystem per unit time (g/m2/yr)
• standing crop measures existing biomass; primary productivity measures
new biomass
in aquatic ecosystems, nutrients
(and light) limit primary
production
• nitrogen and phosphorus are the nutrients that most often
limit marine production
eutrophication
• Process where lakes with phytoplankton communities
dominated by diatoms and green algae change to host mainly
cyanobacteria
• Mostly a result of fertilizer and sewage runoff (rich in
nutrients)
•  nutrients   bacteria  respiration =
 dissolved oxygen   diversity
algal bloom in Lake St.
Clair and Lake Erie due
to increased nutrients
(rich in nitrogen)
cultural eutrophication
• eutrophication:
• as nutrients are added, lakes change…
• oligotrophic  mesotrophic  eutrophic
• addition of sewage, runoff from animal wastes, and fertilizer
accelerate the process
acid precipitation
• rain, snow, or fog that has a pH less than 5.6
• most commonly caused by burning of wood and combustion
of fossil fuels, releasing NOx and SOx
note lower pH
values in eastern
U.S. (prevailing
wind is from west)
biological magnification
• toxins become more concentrated at highest trophic levels
• as a result, top consumers are most severely affected by toxic
compounds
atmospheric CO2
• since the Industrial Revolution, the
concentration of CO2 in the atmosphere has
increased as a result of the combustion of fossil
fuels and the burning of large amounts of wood
removed by deforestation
• greenhouse effect: absorption of infrared
radiation by CO2 and H2O vapor in the
atmosphere
depletion of atmospheric
ozone
• mainly a result of accumulation of chlorofluorocarbons (CFCs)
in the atmosphere
algal bloom in Lake St.
Clair and Lake Erie due
to increased nutrients
(rich in nitrogen)
cultural eutrophication
• eutrophication:
• as nutrients are added, lakes change…
• oligotrophic  mesotrophic  eutrophic
• addition of sewage, runoff from animal wastes, and fertilizer
accelerate the process
acid precipitation
• rain, snow, or fog that has a pH less than 5.6
• most commonly caused by burning of wood and combustion
of fossil fuels, releasing NOx and SOx
note lower pH
values in eastern
U.S. (prevailing
wind is from west)
biological magnification
• toxins become more concentrated at highest trophic levels
• as a result, top consumers are most severely affected by toxic
compounds
atmospheric CO2
• since the Industrial Revolution, the
concentration of CO2 in the atmosphere has
increased as a result of the combustion of fossil
fuels and the burning of large amounts of wood
removed by deforestation
• greenhouse effect: absorption of infrared
radiation by CO2 and H2O vapor in the
atmosphere
depletion of atmospheric
ozone
• mainly a result of accumulation of chlorofluorocarbons (CFCs)
in the atmosphere