Reconnection and Speciation Rates + Genes, Mutations, and Inheritance

Question 1

Hybrid Zones

Answer 1

An area where two closely related species interact and interbreed
-Zones may change depending on fitness of hybrids and reproductive barriers (like reinforcement)
-After speciation as occurred, the two separate but closely related species may continue to produce offspring in the hybrid zone. Reinforcement, fusion, or stability may result depending on reproductive barriers and the relative fitness of the hybrids

Question 2

Reinforcement

Answer 2

Process where hybrids are less fit, and thus there is a nudge towards further divergence between the two species until hybridization can no longer occur
-Single line goes into a v-shape

Question 3

Fusion

Answer 3

Reproductive barriers weaken until the two species become one
-Single line goes into a diamond-shape and returns to a single line

Question 4

Stability

Answer 4

Fit hybrids continue to be produced
-Single line goes into v-shape and becomes two straight lines parallel to original single line

Question 5

Gradual Speciation

Answer 5

Species diverge gradually through time with small steps
—> * —> * —> *
*–|
—> * —> * —> *

Question 6

Punctuated Equilibrium

Answer 6

Species exhibit a large change in a relatively short period of time followed by long periods of stasis
—> * ———> *
*–|
—> * ———> *

Question 7

Charles Darwin (1859)

Answer 7

-Continuous variation in species
-Accumulation of differences in offspring

Question 8

Mendel (1866) + DeVries (1890-1900)

Answer 8

-Discrete genetic factors in individuals
-No blending; no “accumulation”
-Importance of mutations

Question 9

Sutton-Boveri (1902)

Answer 9

-Chromosome theory of inheritance

Question 10

Morgan (1910s)

Answer 10

-Mutations and modern genetics

Question 11

Phenotypic Variation

Answer 11

-A product of genetics and environment
-Leads to non-heritable variation
-Expression is environmentally influenced

Question 12

Microevolution

Answer 12

-Requires inherited variation
-Discrete variation at a single gene locus
–2 alleles like flower color in pea plants
–Multiple alleles like rabbit coat color

-Continuous variation involving effects of two or more genes
–Combination of multiple genes

Question 13

Where does genetic diversity among offspring originiate?

Answer 13

Gamete formation and fertilization
-Alleles are combined in new, unique ways
–crossover (synapsis) -> meiosis 1
–independent assortment
–random fertilization
-Biggest source of phenotypic variation in a species

Question 14

How does genetic diversity within a gene originate? A.

Answer 14

New alleles arise from random DNA mutations
-Must be in gametes during their formations
-Typically point mutations (1-3bp)
ex) Sickle cell mutation

Question 15

How does genetic diversity within a gene originate? B.

Answer 15

Chromosomal altercations - deletions, duplications, translocations
-gene duplications expand size of genome
–can mutate into new alleles
Ex) Goblin gene

Question 16

Harm masked in…

Answer 16

Most new genes are deleterious (harmful)
-harm masked in heterozygotes
–2 heterozygotes reproduce and offspring have dominant homozygote
Ex) Tay-Sachs carriers; heterozygotes dont show symptoms

Question 17

Some alleles may be…

Answer 17

Some alleles may be selection neutral
-Novel phenotype does not affect likelihood of leaving offspring
–Variations in hair or eye color

Question 18

Adaptive alleles arise when…

Answer 18

Adaptive alleles arise when environment changes
-Novel phenotype (harmful or neutral) now increases or decreases odds of leaving offspring in altered environment
–Adaptive alleles increases odds
Ex) Sickle cell in malaria environment
*Most DNA variability does not affect phenoptype