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Final

BISC 102 Final: Study Notes - Lectures 16, 17
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3 Pages
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Fall 2017

Department
Biological Sciences
Course Code
BISC 102
Professor
Erin Barley
Study Guide
Final

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Lec 16: Species & Speciation
- Incipient species: populations on the cusp of speciation
1. Hawthorn Maggot Fly
- Hawthorn tree: native North American tree
- Fruit = small
- Hawthorn maggot flies prefer to feed + lay fertilized eggs on this fruit
2. Apple maggot fly
- Apples introduced to NA in 1600s
- Bigger than hawthorn fruit
- Apple maggot flies prefer to feed/lay fertilized eggs on apple
3. Comparisons between flies:
- Physically indistinguishable, genetically distinct
- 4-6% hybridization
Between food:
- Apple provides 220x more food
- Hawthorn fruit = higher quality
- 52% hawthorn maggots survive, 27% apple maggots
- Apple maggots can burrow deeper + avoid being killed by parasitoid wasps more easily.
4. Morphological Species Concept: discrete groups of organisms, defined by unique reliable morphological
characters.
- Advantages: simple
- Living, extinct groups, sexual, asexual
- Disadvantages: doesn’t resolve cryptic groups (look the same, don’t interbreed)
- Confounded by morphs (interbreeding population w/ different appearances)
- Not useful for studying speciation
5. Biological Species Concept: groups of potentially or actually interbreeding natural populations that are
reproductively isolated from other such groups.
- Emphasizes reproductive isolation (minimal gene flow among species)
- Advantage: most useful for studying speciation
- Disadvantage: not applicable to extinct, asexual or prokaryotes
- Problem of scale: how much hybridization + gene flow = too much?
6. Phylogenetic Species Concept: This states that species are the tips of a phylogenetic tree, and these are normally
determined using DNA (or molecular data). The phylogenetic tree for hominins is incomplete and we cannot extract
DNA from hominin fossils beyond a certain age.
- Smallest diagnosable group of organisms that form an unbroken lineage on a phylogeny
- Has implications for conservation biology
- Advantage: can include genetic + morphological data
- Living, extinct, sexual, asexual
- Disadvantage: species status changes w/ changing phylogeny
- Trivial characteristics can define unique species
7. Ecological Species Concept: set of organisms occupying a single niche, including a unique habitat and set of
resources (food, predator, parasites)
- Emphasizes role of natural selection
- Advantage: asexual, sexual
- Disadvantages: not applicable to extinct groups
- Trivial characteristics can define unique species
8. Allopatric vs sympatric speciation:
- Allopatric: a species is split into 2 geographical groups by dispersal or vicariance. The groups diverge over
time to become 2 species.
- Sympatric: species diverges into 2 groups within a single geographical area.

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Description
Lec 16: Species & Speciation - Incipient species: populations on the cusp of speciation 1. Hawthorn Maggot Fly - Hawthorn tree: native North American tree - Fruit = small - Hawthorn maggot flies prefer to feed + lay fertilized eggs on this fruit 2. Apple maggot fly - Apples introduced to NA in 1600s - Bigger than hawthorn fruit - Apple maggot flies prefer to feed/lay fertilized eggs on apple 3. Comparisons between flies: - Physically indistinguishable, genetically distinct - 4-6% hybridization Between food: - Apple provides 220x more food - Hawthorn fruit = higher quality - 52% hawthorn maggots survive, 27% apple maggots - Apple maggots can burrow deeper + avoid being killed by parasitoid wasps more easily. 4. Morphological Species Concept: discrete groups of organisms, defined by unique reliable morphological characters. - Advantages: simple - Living, extinct groups, sexual, asexual - Disadvantages: doesnt resolve cryptic groups (look the same, dont interbreed) - Confounded by morphs (interbreeding population w/ different appearances) - Not useful for studying speciation 5. Biological Species Concept: groups of potentially or actually interbreeding natural populations that are reproductively isolated from other such groups. - Emphasizes reproductive isolation (minimal gene flow among species) - Advantage: most useful for studying speciation - Disadvantage: not applicable to extinct, asexual or prokaryotes - Problem of scale: how much hybridization + gene flow = too much? 6. Phylogenetic Species Concept: This states that species are the tips of a phylogenetic tree, and these are normally determined using DNA (or molecular data). The phylogenetic tree for hominins is incomplete and we cannot extract DNA from hominin fossils beyond a certain age. - Smallest diagnosable group of organisms that form an unbroken lineage on a phylogeny - Has implications for conservation biology - Advantage: can include genetic + morphological data - Living, extinct, sexual, asexual - Disadvantage: species status changes w/ changing phylogeny - Trivial characteristics can define unique species 7. Ecological Species Concept: set of organisms occupying a single niche, including a unique habitat and set of resources (food, predator, parasites) - Emphasizes role of natural selection - Advantage: asexual, sexual - Disadvantages: not applicable to extinct groups - Trivial characteristics can define unique species 8. Allopatric vs sympatric speciation: - Allopatric: a species is split into 2 geographical groups by dispersal or vicariance. The groups diverge over time to become 2 species. - Sympatric: species diverges into 2 groups within a single geographical area.
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