BIOL 302 Lecture Notes - Littoral Zone, Limnetic Zone, Character Displacement

32 views3 pages
22 Nov 2012
Lecture 25: Competition (cont.)/Predation
8:28 AM
2. Why is competition an important ecological process?
- the most compelling evidence for competition is demonstration character displacement
- competition should lead to divergence in characters of species in areas where they co-occur
(sympatry), compared to areas where each lives alone (allopatry)
- character displacement may be reproductive or ecological; both required for speciation
- avoid interbreeding which lead to selection of sexual signals and ability to recognize those signals
- characters may have similar values in areas where species are separated but in areas of divergence,
there should be a difference in character value
- infers that the two s
pecies diverges which is a result of evolutionary character displacement
- criteria necessary to show character displacement:
- chance should be ruled out
- phenotypic differences must have genetic basis
- phenotypic differences in sympatry should result from evolutionary shifts
- phenotypic differences should related to resource use
- sites of symatry and allopatry should be similar
- environment is not very different between those two sites
- should be evidence that that similar phenotypes compete for resources
- replicate tests to eliminate any local effects
*Competition and Character Displacement in Stickleback (Schluter 1994)
- morphology reflects feeding niche (efficiency in feeding on inverts)
- littoral zone bottom feeders
- wide gape (vacuuming the ocean floor)
- few short gill rakers
- large, deep-bodied
- phytoplankton open water eaters
- narrow gape
- many long gill rakers
- small, slender
- when the two species are in allopatry, they can feed in either zone (although not as efficient in their
own zone)
- when found together, each specialize in their own zone of feeding
- differences in characteristics are heritable
Unlock document

This preview shows page 1 of the document.
Unlock all 3 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.