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Lecture 8

BIOL 215 Lecture Notes - Lecture 8: Cyperaceae, Midlake, Daphne Major


Department
Biology
Course Code
BIOL 215
Professor
Neil Price
Lecture
8

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Speciation
Diversification is the natural tendency in lineages.
-Mutations drive diversification: allows diversity
-Dandelions are asexual so there is no limit on the diversifications
-Lineages combine in sexual organisms so there is less diversification.
-Can group and categorize species based on breeding system but ecological systems
as well.
Divergent selection leads to more or less strongly marked varieties
Ex: In Littorina saxatilis
-Found in crevices high up in the rocks/cliff, the shell is much thinner: crabs predation
is not a problem, but need a wider & thinner shell to grip onto the high rocks.
-Found in the boulders low in the shore rocks, the shell is much thicker to allow
protection from predation of crabs near the tide.
Strongly marked varieties are called subspecies
-Lice have evolved with our clothes because we lost most of our hair.
-Human louse evolved into 2 subspecies
- Body louse
- Head louse
-The two forms of lice are morphologically different and have diverged after the
appearance of clothes.
Populations that are permanently separated may diverge through drift or selection
Variety: most general term
Morph: variety distinguished by single genetic difference
Cultivar: variety consciously produced by artificial selection
Ecotype: variety with restricted ecological distribution
Race: variety with restricted geographical distribution
Subspecies: race differentiated from others to be given a formal trinomial
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