Flashcards in References Deck (23)
community is an assemblage of species pops that occur together in space and time
(Begon, Townsend & Harper 2006, pg. 467)
case study for mutualism:
(Muscatine and Porter, 1977)
CORAL - coral provides shelter and compounds for photosynthesis for zooxanthellae/photosynthetic algae. Algae provides food for coral in nutrient poor environments. (also trophic mutualism)
case study of commensalism:
(Rittschof et al., 1999)
Hermit crabs and anemones - anemones live on the claws on the hermit crab protecting the claws of the crab & mop up food & as body guards. less clear why anemone decides to live there.
obligate mutualism and case study:
interaction is not optional for either species.
Goby and shrimp. Shrimp are blind and gobys warn shrimp when leaving the burrow is unsafe. Goby get refuge from predation. (Lyons, 2013) (also habitat mutualism)
facultative mutualism and case study:
some species may co-evolve unique features that benefit eachother.
the interacting species derive benefit from each other but not being fully dependent that each cannot survive without the symbiotic partner.
When mussels are present in seagrass meadows, they elevate seagrass productivity through either increased nutrient resource pools or reduced epiphytic loads on the leaves, while the seagrass increases mussel survivorship. (Peterson & Heck, 2001)
nemo & anemone are not completely dependent.
Give an example of a mutualist withdrawing rewards:
In an obligate mutualism between a yucca and a yucca moth, the female moth collects pollen in one yucca and then lays their own eggs in another, depositing the pollen in this flower. Larvae complete development by eating the seeds in the flower. Cheating can occur if moths lay too many eggs and the larvae eat too many seeds.
But yuccas can selectively abort flowers with too many eggs before the moth larvae hatch
Plants turn off the production of seeds if there are too many eggs. (Powell, 1992)
A concept that is the cornerstone of ecological thought. Considers the niche of an organism in all conditions and things it needs. where all niche dimensions are accounted for and make a volume of limits to an organism and where it can survive e.g. temp, food, light, altitude etc etc. can compare organisms quantatively.
(Hutchinsons, 1957). n-dimensional hyperspace.
region of environmental space where fitness is greater than or equal to one in the absence of competitors or predators i.e. limits to where an organism can survive
(Hutchinson, 1957). fundamental niche
P. caudatum and P. aurelia both grown separately & measured, very similar in growth of population density & time.
Grown together in same conditions, was thought a mixture would occur, but not the case. Grew quite happily but then suddenly resources are in short supply e.g. food & P. aurelia drew P.c to extinction.Showed two species with same niche cannot live indefinitely in same habitat without further disturbance
(Gause, 1934) Gause's principle of competitive exclusion
Salamanders. 2 species coexisting. Put them in enclosure separately and 1 together. The salamanders put together faced negative impacts compared to the ones on their own. Direct evidence for competition
(Hairston, 1980). field experiment showing competition.
when two individuals that do not directly compete for resources affect each other indirectly by being prey for the same predator: Consider a hawk (predator, see below) that preys both on squirrels and mice. In this relationship, if the squirrel population increases, then the mouse population may be positively affected since more squirrels will be available as prey for the hawks.
(Hatcher et al. 2006)
possibility that in ecosystems or habitats more species can exist than are present at a particular point in time, because many possibilities are not used by potentially existing species (vacant niche)
Disturbance: a relatively discrete event in time and space that alters the structure (identity and abundance of organisms) of populations, communities and ecosystems and causes changes in resource availability or the physical environment”
(Pickett & White, 1985)
IDH looked at communities where disturbances were:
- intermediate frequency
- very frequent
He found low diversity where disturbance was absent, and where it was very frequent. Highest diversity was found at intermediate disturbance frequencies.
Huston (1979) (Connell, 1978)
Explain the patch/gap dynamics theory (spatial heterogeneity):
(Paine & Levin, 1974)
IDH example seaweeds on boulders, small pebbles, medium boulders, large boulders. Medium has most seaweeds, medium get disturbed a medium amount of time. Small ones all the time & big ones need a storm to turn. This represents frequency of disturbance.
Predation: The consumption of one organism (part or whole) by another and the first organism is alive after the attack
(Begon et al., 1996)
case study for frequency dependent predation: guppies feeding on a mixture of naididae and fruit flies. The guppies ate more of whichever was more available (generalists i suppose)
however, some species exhibit consistent preference such a study composed by (new ref) where a species of gastropod would consistently prefer Mytilus edulis over Mytilis californianilus no matter the abundance.
(Murdoch et al., 1975) Murdoch and Stewart-Oaten (1975)
A case study of specialist predator used as biological control: A cactus (prickly pear) from south america and became hugely invasive in Australia. Found a predator from south America, moth (Cactoblastis). Just 3 years after introduction was pretty much all gone, but still a few that survived. Rare that species will ever wipe another species out, but hold back the pop size, therefore target species can’t competitively exclude other species as they won’t reach carrying capacityHowever not always best solution cane toad introduced to eat beetles turned out to be a generalist predator and ate everything but.
(Dodd, 1936) (Phillips et al., 2007)
Explain the polyclimax theory: more than one climax vegetation can exist (“polyclimax”) - determined by climate, soil, topography, disturbance regime, predation, and so on
Explain climax - pattern hypothesis: came up with the climax-pattern hypothesis
- a continuum of climax types
- varying along environmental gradients
- not necessarily separable into discrete climaxes
obligate mutualism another case study
clownfish & select anemones have a obligate relationship. (Lubbock et al., 1980)