Lect 5- Hybrid Zones/Character Displacement/Geographical Variation

Question 1

Why care about allele freq in hybrid zones

Answer 1

• with the balance between gene flow and selection against hybrids you can estimate the strength of both
• clines differ btwn parts of genome- narrower parts can be responsible for reproductive isolation

EX: junco and sparrow- hybrid had mixed song, and preferred sparrow’s call

Question 2

Character displacement

Answer 2

difference in trait among similar spp whose distributions overlap geographically are accentuated in regions wheer spp co-occur, but decreased when distributions do not overlap

more different in sympatry than allopatry

EX 1: Gal finches-

sympatry: beak diff (narrower eat small seeds, wider eat big seeds)- might have evolved due to interspecific competition
allopatry: less beak differences and eat variety of seeds

EX 2: stag beetles
allopatric- body size/genitles same size
sympatry- different sizez

Question 3

Ring species

Answer 3

chain of interbreeding pops where the ends of the change overlap but cannot interbreed
-geographical barrier forms ring
EX: salamanders in CA
greenish warbler, tibetan plateau

Question 4

Geographic Variation

Answer 4

within sp, variation in pheno or genotype that shows a geographic pattern

Question 5

Sub species

Answer 5

geographic races can be called this but
subspecies recongnized by scale count, color, etc, may not be genetically different
- reveals probs with IDing sub species based on a few traits

EX: of not realy subspp- polytyptic snake
EX: of real sub spp- southern pocket gopher
specific soil preferences, stays in burrow, TF low gen flow btwn pops and lots of differentiation (even with just genetic drift)

Question 6

Bergman’s rule

Answer 6

larger animals in colder areas (higher latitudes)
- surface area/mass; more fat
EX: short tail weasel

Question 7

Allen’s rule

Answer 7

longer limbs in warmer weather

EX: people africa vs. alaska

Question 8

Common Garden Experiment

Answer 8

transplant 2 different from environment to common environment
- each will do best in own

Question 9

Glogger’s rule

Answer 9

Birds and Mammals darker in more humid (warmer) environment

EX: tree shrew
human skin color- likely adaptive to protect from UV rays/melanoma; excess vitamin D