symbiosis
A close relationship between two species that benefits at least one of the species.
example of symbiosis
tapeworm in human intestines
parasite
organism that obtains nutrients from other living organism (host)
is it rare for parasites to directly kill their hosts?
yes because parasites feed on their hosts and need them to survive
how do parasites decrease the fitness of their hosts?
by feeding off of the blood or tissue it takes up energy of the host to heal themselves rather then using that energy on growth and reproduction
what are the kingdoms that include parasites?
all 6 kingdoms: bacteria, protozoan, fungi, animals, and plants
hemiparasitic
obtain some of their nutrients from the host (ex: misletoe)
holoparasitic
gain all their nutrients from hosts (ex: broomrape)
ecto-parasite
inhabit external surfaces of the host (ex: mosquito, deer tick)
endo-parasite
live within their hosts (ex: tapeworm)
why are parasites economically important?
bacteria and fungi used in the production of cheese (+ other foods)
why do some parasites use multiple host species?
because they cannot complete their life cycle in a single host
describe the life cycle of the brainworm parasite parelaphostrongylus tenuis
adults are found in deer, but larvae inhabit snails
how did parasites influence the surfacing and jerking behavior of killifish?
killifish infected with the parasitic flukes show abnormal behavior
parasites require live hosts for their survival. then, why does the fluke parasite of killifish cause indirect mortality of killifish?
conspicuous behavior of infected fish affects fish eating birds
2 adaptations of parasites
1. transmission adaptations
2. adaptations to establish within the host
transmission adaptations
massive reproductive output, use of vectors, and host behavior manipulation
vector
facilitate transmission of parasites between hosts; the vector themselves are not affected by the parasite
host manipulation example
the hairworm causes the infected insects to "jump into water" because the water is where the parasite completes its lifecycle
adaptations to establish within the hosts
molecular mimicry and antigen variation
molecular mimicry
parasites cover themselves with host antigens or blood
how does molecular mimicry help the parasite to escape the immune response of the host?
the immune system doesn't normally attack itself
antibody
blood protein produces in response to and counteracting a specific antigen
antigen
a toxin or other foreign substance which induces an immune response
antigenic variation
Pathogens alter their surface antigens (and antibodies are rendered ineffective)
4 adaptations of host
1. behavioral adaptations
2. inflammation
3. gall/cyst formation
4. production of antibodies
red queen hypothesis
co-evolution of parasites and hosts
Dr. lively and colleagues observed that the snails reproduce sexually when the parasitic infections are high. What benefit do snails gain from sexual reproduction?
genetic variation
what do we mean when we say "an evolutionary arms-race" is going on between parasites and hosts?
whoever evolves better and faster, will survive
parasites may regulate population structure
introduced parasites drastically reduce host pops
how do the parasites control host pops in a density-dependent manner?
crowding can increase the parasite transmission rate
mutualism
both benefit
symbiotic mutualism
two species involved are closely associated with each other
non-symbiotic mutualism
two organisms are involved but do not physically live together
trophic mutualism
species involved are specialized to obtain energy and nutrients
defense mutualism
involves defending the partner in exchange for food or shelter
dispersive mutualism
involves transport of seed and pollen
How can mutualism influence population dynamics?
mutualism improves the growth and reproduction of individuals involved in the association
why is it difficult to identify the effects of non-symbiotic mutualism?
many different species are involved
community
an association of interacting pops
closed community
distributions of many species coincide closely
open community
local association of species having independent and only partially overlapping ecological distributions
closed communities details
-distributions of many species coincide closely
-strict boundaries
-communities have different assemblages of species
how are communities often labeled?
named after dominant plant species
ecotone
boundaries between closed communities that represent regions of rapid replacement of species along a gradient
open communities details
-abundance of a particular species changes independently of the other species
-no strict boundaries (no ecotones)
contiuum concept
species distributions often change gradually along an environmental gradient
contiuum
a gradient of environmental characteristics or change in the composition of communities
what environmental gradient exists in the eastern United States?
-North/south: temperature gradient
-East/West: rainfall gadient
gradient analysis
the plotting and interpretation of the abundances of species along an environmental gradient
species richness
the number of species in a particular area
primary producer
plants and other autotrophic organisms that occupy the bottom level
primary consumer
consumer of primary producers such as herbivores
secondary consumer
carnivores that reside on the levels above primary consumer
trophic level
a position in a food web
food web
a representation of the various interconnected paths of energy flow through pops in a community, taking into account the fact that each pop shares resources and consumers with other pops
omnivory
feeding on more than one trophic level
how can food web complexity be ranked?
based on the # of trophic levels and the # of feeding links between species
is the relationship between food web complexity and species richness positive or negative?
positive
keystone predator presence
results in greater species diversity
constancy
the ability of a system to resist change in the face of outside influences
resilience
the ability of the system to return to some reference state after the disturbance
what did Chris Steiner find regarding the influence of species diversity on community stability?
-high nutrient levels: high resilience independent of diversity
-low nutrient levels: there was a positive relationship between species diversity and resilience
trophic cascade
occurs when a consumer-resource interaction influences additional trophic levels of the community
bottom-up control
when the size of a trophic level is determined by the rate of production of its food source
top-down control
when higher trophic levels determine the size of the trophic levels below them
succession
a sequence of changes in the species composition of a community in a newly formed or disturbed habitat that progresses to a stable state
pioneer speceis
first colonizers
climax community
a community that has reached a steady-state under a particular set of environmental conditions
sere
a series of stages of community change in a successional sequence leading toward a stable state
primary succession
establishment and development of communities in newly formed habitat that is DEVOID OF LIFE
secondary succession
regeneration of a community following a disturbance
How was primary succession initiated on Krakatau island?
volcanic explosion in 1883
early successional species
shade intolerant, fast growing, many small seeds, and rapid growth rate
why do early successional species benefit from being shade intolerant and fast growing?
bc when an area is first able to be grown on, there is lots of sunshine. so these plants must be able to survive in high sunlight conditions. They grow fast and then provide shade for other plants
late successional species
shade tolerant, lower rates of photosynthesis, few large seeds
why do late successional species benefit from being shade tolerant and slow growing?
begin to grow under the early successional species and will eventually outgrow and overtake the early successional species
facilitation
processes by which one species increases the probability of a second species becoming established
inhibition
one species fitness is suppressed by the presence of another
tolerance
the ability of a species to tolerate the physical conditions in the environment
how do black walnut threes inhibit the establishment of other plant species?
produce juglone, which inhibits enzymes in other plants (allelopathy)
are early successional species generally tolerant or intolerant of varied environmental conditions?
able to tolerate stressful conditions
how does succession influence the animal species in a community?
carnivores start to colonize at the end when high trees start to grow
how are pine trees adapted to periodic fires?
fire-resistant species and do not shed their seeds unless triggered by a fire
transient community
communities in seasonal ponds
biodiversity
the variation among organisms and ecological systems at all levels, including genetic variation within pops, morphological and functional differences between species, and variation in biome structure and ecosystem processes in both terrestrial and aquatic
abundance
can be measured as the number, density or biomass of individuals in an area
relative abundance
is the proportional representation of a given species among all species in a sample or community
rank-abundance plot
displays the abundances of species usually on a logarithmic scale ranked from the most common to the rarest
what kind of relationship is there between species richness and the size of the area being sampled?
positive
why does a heterogeneous habitat support higher species richness?
there is more variability that is able to support more types of species
energy-diversity hypothesis
a hypothesis that sites with higher amounts of energy are able to support more species
local diversity
the # of species in a small area of homogeneous habitat
regional diversity
the total # of species observed in all habitats within a geographic area
beta diversity
the difference in species composition from one habitat to another
jaccard index
-0: species composition between habitats is dissimilar
-1: species composition between habitats is exactly the same
species pool
the entire group of species within a source region from which colonists on an island or habitat patch are drawn
fundamental niche
the range of conditions and resources within which individuals of a species can persist
realized niche
the range of physical conditions and resources within which individuals of a species can persist in the presence of competitors and consumers
species sorting
the process that determines membership in a local community based on the tolerance of species from the regional species pool to local conditions, as well as their resource requirements and interactions with other species
ecological release
when pops will expand of habitat and resource use, and increase in abundance due to low levels of competition
niche diversity
the difference types of specialization and different ways of life that species exhibit
why does extinction rate increase as time goes on?
because colonization decreases
equilibrium theories of diversity
the # of species on an island balances regional processes governing immigration against local processes governing extinction
ecosystem
as assemblage of organisms together with their physical and chemical environments
how much energy is transferred from one trophic level to the next?
only 5-20%
assimilated energy
the energy that is actually absorbed by the consumer
excreted energy
the energy that is excreted as nitrogen-containing organic wastes like ammonia and urea
respired energy
the energy that is used for respiration
what is production energy allocation to?
growth and reproduction
production energy equation
production energy=assimilated-respired-excreted
assimilation efficiency
the ratio of assimilated energy to ingested energy
net production efficiency
the energy channeled into growth and reproduction as a percentage of the total assimilated energy
do warm blooded or cold blooded animals have higher net production efficiency?
warm-blooded: 1-6%
cold-blooded: 75%
oxidation
LEO: giving up electrons and releasing energy
reduction
GER: accepting electrons and gaining electrons
if the energy produced by the oxidation is greater than the energy required by the reduction, what happens to the left over energy?
excess energy is lost in the form of heat
what processes allow carbon to move from inorganic to organic states?
photosynthesis
what processes allow carbon to move from organic to inorganic states?
leaching
assimilatory
transformations that incorporate inorganic forms of elements into the molecules of organisms (ex: photosynthesis)
dissimilatory
transfer of organic forms into an inorganic form (ex: respiration, excretion, leaching)
how does evaporation drive the hydrologic cycle?
atmosphere can only hold so much water in the form of evaporated water. So once evaporation exceeds precipitation (such as over the ocean), it will fall in the form of rain and return to the ground. This cycle will continue over and over again
carbon cycling
1. assimilatory and dissimilatory reactions
2. exchanges of carbon dioxide between the atmosphere and oceans
3. precipitation of carbonate sediments in the oceans
is it difficult for carbon dioxide to move between atmosphere and ocean?
no, it is easy and a constant event
what happens when carbon dioxide dissolves in water?
forms carbonic acid
carbonic acid can dissociate into what ions?
bicarbonate and carbonate ions
calcium and carbonate forms what molecule that can precipitate out of water and form sediments?
calcium carbonate
given that carbon dioxide concentrations were 20 times higher in the Paleozoic than they are today, why do scientists worry about increasing carbon dioxide concentrations and global warming?
the atmosphere is changing over a span of decades instead of over a span of millions of years, which is very bad
nitrogen cycle steps
1. ammonification
2. nitrification
3. denitrification
4. nitrogen fixation
ammonification
proteins are broken into amino acids and the carbon from those amino acids is oxidized. This results in the production of ammonia, which transforms into ammonium
nitrification
oxidation of ammonia to nitrites and nitrates
denitrification
in the absence of oxygen, nitrite and nitrates reduced to nitric oxide
nitrogen fixation
biological assimilation of atmospheric nitrogen to form organic nitrogen-containing compounds by specialized bacteria like Rhizobium
does phosphorus commonly undergo oxidation-reduction reactions??
rarely
is carbon limited in pond communities?
no
does sulfur commonly undergo reduction and oxidation reactions?
yes, many
why do organisms need sulfur?
to produce amino acids
why do organisms need phosphorus?
to produce nucleic acids, cell membranes, bones, and teeth
how is sulfur oxidized in oxygen-rich systems?
the reduction of sulfate to organic sulfur is balanced by the oxidation of organic sulfur back to sulfate (dissimilation)
how is sulfur oxidized in oxygen-poor systems?
specialized bacteria use sulfate to oxidize carbon. The reduced sulfur can then bind with hydrogen to form hydrogen sulfide
landscape
made up of many different habitat types
anthropogenic effect
an effect mediated by humans
what legacy effects have influenced the modern-day composition of landscapes?
volcanic eruptions and the movement of glaciers
esker
the remnant of an ancient stream that once flowed under or inside a glacier
ecosystem engineer
any organism that creates, significantly modifies, maintains or destroys a habitat
Global Positioning System (GPS)
an array of satellites placed in orbit around the earth that send out signals that can be picked up by recievers on earth and used to calculate the latitude, longitude and altitude of any location
Geographic Information System (GIS)
a computer program that allows researchers to compile diverse sets of geographic info and to quantify characteristics of the landscape
source-sink model
describes how variation in habitat quality may effect the pop growth or decline of organisms
metapopulation model
the simplest type: you have a landscape with a certain # of habitable patches. Patches are either occupied or not
landscape model
the most complex: the actual movements and routes of individuals between patches depend on the surrounding landscape and the habitats found along the way
edge specialist
one that specializes for living in the transition zone between habitat patches
habitat corridors
narrow strips of habitat that facilitated the movement of organisms between adjacent habitat fragments
stepping stones
small intervening patches within a habitat matrix where organisms moving between patches of favorable habitat can stop to rest or forage
grain
the degree of resolution at which a landscape is viewed
extent
the size of a landscape area of interest
what does the term (1-N/K) represent?
the reduction in growth rate caused by intraspecific competition
which of the following is correct?
if harvest>recruitment, prey pops decline
an example of trophic mutualism is...
mutualism between herbivores and their ruminant bacteria
regarding trophic cascades, with which do you agree?
-in a study conducted by Matthew Leibold and colleagues, the abundance of zooplankton was positively correlated with the abundance of phytoplankton across a large # of natural lakes. this pattern is consisten with bottom-up control
-a trophic cascade is a
a consumer that promotes diversity by manipulating competitive relationships at a lower trophic level is called...
a keystone predator
communities with high species richness tend to have...
higher food web complexity
following its 1883 volcano, krakatoa island serves as a good example of..
primary succession
at the global scale, the # of species will increase with area because...
larger areas support distinct evolutionary lineages
beta diversity, or species turnover, would be at its minimum if all species occurred in all habitats within a region. Beta diversity would be at its maximum if each habitat had a unique biota, and regional diversity would equal...
the sum of the local diversities of all the habitats within the region
regarding the equilibrium theory of island biogeography, which is true?
variation in numbers of species on islands of different distances from the mainland is seen as a function of differences in colonization rates
the percentage of total assimilated energy that is channeled into net production (growth and reproduction) is the organism's net production efficiency. Which types of animals would you expect to have the highest net production efficiency?
sedentary, cold-blooded animals
the following statements correctly characterize the phosphorus cycle
-phosphorus undergoes relatively few oxidation and reduction reactions
-phosphorus can be limiting in aquatic habitats
-phosphorus is relatively unavailable in both basic and acidic soils
the following is a typical path by which nitrogen could flow through an ecosystem
1. N2 gas is assimilated in to organisms through fixation
2. then the organic N is broken down into NH4+ through ammonification
3. NH4+ is then oxidized to nitrite, which is oxidized to NO3- through nitrification
4. Finally, denitrification reduces nitrit
sulfides are commonly associated with coal deposits. When mine wastes are exposed to oxygen and water, the resultant reactions can ultimately lead to the formation of...
sulfuric acid
areas suitable for a species to live in are called?
habitat patches
areas that are unsuitable for that species to live in are called?
matrices
what is directly responsible for an overall decrease in species richness in the fragments?
average patch size decreases
the most complex model of pops subject to habitat fragmentation that takes into account differences in quality of the habitat patches as well as differences in matrix quality is called a?
landscape model
A set of 10 habitat patches each 10 m2 in size would be a more viable option for preserving a group of edge specialist species than a single, 100 m2 patch because...
the habitat of 10 patches would increase the edge space, increasing habitat for edge specialists
areas that connect two habitat patches and allow animals to disperse from one to the other are known as...
corridors
ecosystem services
the benefits provided by ecosystems that support human life
overexploitation
Practice of harvesting or hunting to such a degree that remaining individuals may not be able to replenish the population
What is shifting agriculture?
Method of cultivation - areas are cleared for planting during a period, then left fallow to regrow
habitat conversion
the alteration of land from a natural community into developed or agricultural land
what negative effect does erosion continue to have on agricultural fields in the US?
loss of topsoil
what are the benefits and costs of irrigation?
-benefit: can turn unproductive land into productive cropland
-cost: wells, dams, and dikes that make irrigation possible can have negative environmental effects
toxins
Various poisonous substances produced by some microorganisms (bacteria and viruses).
acid rain
rain containing nitric and sulfuric acids
mercury, arsenic, lead, copper, nickel, and zinc are all...
heavy metals
how are heavy metals introduced to the environment?
during mining and mineral smelting
what organic compounds does crude oil contain?
both organic nitrogen and sulfur
how does oil kill organisms?
can coat the surfaces of organisms and disrupt biological membranes
in the presence of nitric oxide, molecular oxygen is oxidized and forms...
ozone
ozone in the stratosphere has what benefits to humans?
shields the earth from ultraviolet radiation
ultraviolet radiation
damages DNA molecules, interferes with photosynthesis
greenhouse effect
an increase in average global temp resulting from an increase in the concentration of carbon dioxide and certain other heat-absorbing gases in the atmosphere
what is a standard of living?
the degree of wealth and material comfort available to a person or community.
carrying capacity
the # of individuals in a pop that the resources of a habitat can support
ecological footprint
the amount of land required to sustain the energy needs of a single human individual at his or her material standard of living
acid rain
precipitation with high acidity caused by the dissolution of certain gases (sulfur dioxide and nitrous oxide) released into the atmosphere by combustion of fossil fuels
inflection point
1/2K, which is when the growth of pop is the fastest
recruitment rate
the rate at which new individuals are added to the pop per unit
two harvesting strategies
1. fixed quota
2. fixed effort
fixed quota harvesting
harvest a fixed # of individuals in a given time interval
maximum sustainable yield (MSY)
highest harvesting rate that the pop can match with recruitment
Fixed harvest effort strategy
harvest of a certain % of prey pop
what needs to be done to ensure that long-term viability of prey pops?
sustainable harvesting and more efficient fishing methods