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Question: Do more complex ecosystems have greater biodiversity?
Hypotheses:
More complex ecosystems:
1)have greater biodiversity because they have more available niches to support more organisms;
2) have equal biodiversity compared to simple ecosystems because niche availability does not limit diversity;
3) have less biodiversity because only a few types of generalist organisms can occupy complex ecosystems;
4) complexity of an ecosystem does not have a predictable affect on biodiversity.
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Important things to remember when writing predictions:
- They need to be in-line with the hypothesis.
- They need to be written in terms of what you will measure.
- They need to be specific and refer to some testable implication of the hypothesis.
Examples of bad predictions for Hypothesis 1-"More complex ecosystems have greater biodiversity because they have more available niches to support more organisms"--
- There is more biodiversity as the number of links in an ecosystem food web increases. (Unclear how biodiversity will be measured.)
- There are more organisms in more complex ecosystems. (Biodiversity refers to number of species, rather than how many total organisms there are--need to be specific)
- There are more species in more complex ecosystems. (Definition of "more complex" is ambiguous.)
Examples of good predictions for each hypothesis--
H1) More complex ecosystems have greater biodiversity because they have more available niches to support more organisms.
Prediction: The number of species in an ecosystem increases with complexity the number of trophic levels.
H2) More complex ecosystems have equal biodiversity (compared to simpler ecosystems) because niche availability does not limit diversity.
Prediction: The difference in number of trophic levels between ecosystems do not correspond to differences in number of species.
H3) More complex ecosystems have less biodiversity than simpler ecosystems because in complex ecosystems, each trophic level is made up of only a few generalist species.
Prediction: As the number of trophic levels goes up, the total number of organisms goes down.
H4) Complexity of an ecosystem does not have a predictable effect on biodiversity.
Prediction: Changes in the number of trophic levels in an ecosystem do not affect the number of species found there.
*Note that there are other predictions for each hypothesis, but I have only listed one for each to keep things simple.
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Here are some predictions from my own work:
Question: Does divergent sexual selection reduce hybridization between subspecies in sympatry?
H1) Divergent sexual selection (different types of mate preference) reduces interbreeding when subspecies come into contact.
P1) Populations in which females have different cues for mating choices will not interbreed when they encounter each other.
H2) Divergent sexual selection does not reduce interbreeding when subspecies come into contact.
P2) Differences in female mating preferences disappear when divergent populations encounter one another, and individuals from different populations interbreed readily.
H3) In some cases divergent sexual selection does reduce interbreeding when subspecies come into contact and sometimes it does not, depending on the strength and direction of selection or other factors.
P3) Some contact zones between populations experiencing divergent sexual selection show interbreeding, while others do not.
Cool Link of the Day: Parasite uses mind control on snail host
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