Unit 5:Lesson 4 Flashcards
dispersal
-movement of individuals (or gametes) away from their area of origin or from centers of high population density
species transplants
ecologists may observe the results of transplants to determine if dispersal is a key factor limiting species distribution
- sucess=some organisms reproduce sustainably
- means that species potential range> than actual range
Habitat Selection
some individuals tend to avoid certain habitats, even when they are suitable and accessible
Limiting Biotic Factors
- negative interactions with predators or herbivores restrict potential to survive and reproduce
- polinators, food resources, parasites, pathogens, and competing organisms may also be limiting factors
Limiting factors: Temperature
-temps outside a certain range may damage or stress an organism
Limiting Factors: Water and Oxygen
- some organisms may dry up if not enough water
- low oxygen levels in deep water or water with much organic matter limits organism processes
Limiting Factors: Salinity
- affects water balance of organisms through osmosis
- some do have osmoregulating adaptations
Limiting Factors: Sunlight
- too little can limit distribution of photosynthetic species
- high light levels can increase temp stress
- UV radiation can inhibit trees at high level elevations
Limiting Factor: Rock and Soil
-ph, mineral composition, and physical structures
interspecific interactions
includes competititon, predation, herbivory, symbiosis, and facilitation
interspecific competition
-/- interaction, species compete for a resource that limits their growth and survival
Competitive Exclusion
When two species, who have identical niches compete for the same resource, in the absence of disturbance, one species will use resources more effectively and grow while the other will be eliminated
ecological niche
the sum of a species use of resources in an environment
- fundamental: potential
- realized: actual
resource partitioning
the difference between niches that enable similar species to coexist in a community
-time can also differentiate niches
Character Displacement
tendency for characteristics to diverge more in sympatric (competitive) than allopatric populations of two species
Predation
+/- interaction
Predator adaptations
- have acute sense to detect prey
- adaptations to help them detect and subdue prey
- may use mimicry to lure prey
prey adaptations
- behavioral defenses;hiding, fleeing, forming groups, alarm calls, some vigorously protect young, some have mechanical/chemical defenses
- mimicry and coloration
cryptic coloration
camouflage that makes prey difficult to see
aposematic coloration
warning coloration
Batesian mimicry
a palatable (harmless) species mimics an unpalatable (harmful one)
Mullerian mimicry
2 or more unpalatable species resemble each other
- predators learn to avoid these prey quicker
Herbivory
adaptations of herbivores
- insects have sensors on feet to help them detect edible and nutritious food
- mammals use sense of smell
- specialized teeth or digestive systems
plant adaptations (against herbivory)
-have toxins or structures such as spines or thorns
Symbiosis
when individuals of two or more species live in direct and intimate contact with one another
-parasitism, mutualism, commensalism
Parasitism
+/-; one organism (parasite) derives it nourishment from a host
endoparasites
parasites that live within the body of the host
-parasites can cause atypical behaviors and damage to host
ectoparasites
parasites that feed on the external surface of a host
Mutualism
+?+
- obligate: atleast one has lost its ability to survive without the other
- facultative; both can survive alone
- often involves related adaptations in both species as a change in one is likely to affect the other
Commensalism
an interaction that benefits one species but has a neutral affect on the other
-possibly expose food
Facilitation
species have positive effects on survival and reproduction of other species without symbiosis
Benefits of higher diversity communities
- more productive
- can better withstand environment stresses,
- more stable productivity
- more resistant to invasive species (fewer resources are available)
Food webs
-link multiple food chains, given species may be a part of one or more trophic levels
energetic hypothesis
suggests that short length of food chains is due to the inefficiency of energy transfer along the chain (10%)
-most research supports this hypothesis
dynamic stability hypothesis
proposes that long food chains are less stable
- longer it is, the more slowly predators can recover from environment setbacks
Dominant species
the most abundant species or that which collectively has the most biomass
- possibly competitively superior or better at avoiding predation and disease
- discover impact, by removing them from a community
Keystone species
not abundant but exert strong control because of their pivotal ecological roles
ecosystem engineers
species that dramatically alter their environment
bottom up model
unidirectional influence from lower to higher trophic levels
N—>V—>H—>P
-adding predators would not affect lower levels
top-down model
predation controls community organization
N<—P
biomanipulation
applies top-down model to alter ecosystem characteristics
nonequilibrium model
describes most communities as constantly changing after being affected by disturbances
intermediate disturbance hypothesis
states that moderate levels of disturbance foster greater species diversity than do low or high levels do
- high levels= stress exceeds species tolerance
- low levels= dominant species exclude less competitive ones
- intermediate= opens up habitats
ecological succession
transition in the species composition of a community following a disturbance
primary succession:
when ecological succession begins in a virtually lifeless area where soil has not yet formed
-lichens and mosses are usually the first to colonize area
secondary succession
ecological succession in an existing community that has been cleared by some disturbance that leaves soil intact
Latitudinal Gradients
plant and animal life is generally more abundant and diverse in the tropics
- do not have many major disturbances, allowing more speciation
- larger growing season= faster biological time
- high solar energy input and water availability
evapotranspiration
the evaporation of water from soil plus the transpiration of water from plants
-higher in hot areas with high precipitation
species-area curve
all other factors being equal, the larger the geographic area of a community, the more species it has
-greater variety of habitats
Island Equilibrium Model
on an island, an equilibrium will eventually be reached where the rate of species immigration equals rate of equal extinction
- # of species at this point is correlated with the island’s size and distance from the mainland
- usually applies over short periods
pathogens
disease-causing microorganisms or molecules
- can be harmful in a new habitat because organisms have not had a chance to become resistant
- can affect biotic structures that provide habitats or food for other species
zoonotic pathogens
those that are transferred to human from other animals
vectors
animals (like ticks)that spread disease from an animal to a human
Nutrient Cycling Rates
- depends on the rate of composition
- quicker in warm and wet climates
- decomposers can slow when conditions are too dry or too wet
- decomposers grow poorly in cold and wet environments
Amount of Nutrients leaving a forest community
mainly controlled by plants
