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A plant occurs on several islands off the coast of Florida, but is absent
from the mainland.
List three hypotheses that might explain this pattern (each hypothesis should
emphasize a different process).
the plant is unable to disperse to the mainland;
competitors (or herbivores, or seed predators, or pathogens) on the mainland prevent
the successful establishment and growth of the plant;
soil conditions (or climate, or related factors) on the mainland do not permit the
successful establishment and growth of the plant (even in the absence of negative
interactions with other species);
a species that has a beneficial effect on the plant (e.g., a pollinator) is absent from
the mainland (or has a smaller effect on the mainland) and this prevents the
successful establishment, growth, or reproduction of the plant.
of these hypotheses (indicate which one), generate a prediction derived
from the hypothesis.
If the plant is absent because of dispersal, then if we transplant seeds to the mainland,
they should germinate, grow, survive and reproduce.
If the plant is absent because of deleterious effects of other species, then if we transplant
seeds to the island, they should fail to survive and reproduce, but if we transplant seeds
and protect them from the other species, then they should do well.
If the plant is absence because of abiotic conditions, then the plant should fail to
germinate, grow, reproduce when we tranplant it.
This should be true even if we exclude
interactions with species that might have deleterious effects on the target species.
Design an experiment to test this hypothesis.
Include all relevant information,
including details about the key components of a well designed experiment.
sure to mention what you will measure and what you should “see” if your hypothesis
is correct (and what you should see if it is incorrect).
Dispersal limitation: collect seeds from the island.
Randomly allocate seeds to 10
groups, which will be equally allocated to two treatments: "island" and "mainland".
ten groups get handled similarly, except the "island" group gets planted on the island (in
the habitat within which the plant normally occurs – but in plots that have been cleared