Micro and Macro evolution

Question 1

Lactase

Answer 1

Enzyme that breaks down lactose into glucose and galactose (simple sugars)

Question 2

Lactose

Answer 2

A disaccharide sugar in milk

Question 3

Lactose maldigestion

Answer 3

The difficulty to digest lactose

Question 4

In all non-human mammals, the body stops manufacturing lactase after weaning…

Answer 4

So adults can’t digest milk
- this is also true of most humans

Question 5

Lactase persistence (LP)

Answer 5

When the body continues to produce lactase into adulthood so adults can still digest milk
(adaptation!)

Question 6

The gene responsible for making lactase (LCT) is on chromosome 2

Answer 6

Genetic variation is not in the gene itself, but instead in the regions around the gene
- these genes affect when and how the gene is expressed

There are a few different genetic variations associated with LP (most common in European ancestry is locus upstream from the lactase gene; instead of having C in that position)

Evolution took place
Speciation did not take place

Question 7

Two different scales of evolution

Answer 7

1.) Microevolution
2.) Macroevolution

Question 8

Microevolution

Answer 8

Evolution within a species
- Modern synthesis gives us a definition regarding change in allele/genotype frequency in a population
- detect through departure from H-W equilibrium (given assumptions)

Question 9

Macroevolution

Answer 9

Evolution of new species and higher taxonomic groups
- occurs over longer time spans
- detect through the fossil record
~Evolutionary acquisition of “novel” structures
~Change in pattern of adaptation

Question 10

Biological species concept

Answer 10

Groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups

Question 11

Recognition species concept

Answer 11

The most inclusive population of individuals that share a common fertilization system

Question 12

Mechanisms of isolation

Answer 12

Biological properties of individual organisms that prevent the interbreeding of populations of different species where they are sympatric
- space isn’t enough
- can be leaky

Question 13

Two types of mechanisms of isolation

Answer 13

1.) Pre-zygotic
2.) Post-zygotic

Question 14

Pre-zygotic

Answer 14

• Temporal or habitat differences
• Courtship differences
• Mechanical isolation

Question 15

Post-zygotic

Answer 15

• Gametic isolation
• zygote mortality
• inviability
• sterility

Question 16

Allopatric speciation

Answer 16

Speciation occurs as the result of gene flow reduction due to geographic isolation

Question 17

Allopatric speciation steps

Answer 17

1.) Reduce gene flow (geographic barrier)
2.) Mutation, selection, and/or drift cause population divergence (reproductive isolation)
3.) When species rejoin, they can’t exchange genes anymore
- competition to extinction
- non-overlapping territories develop (allopatry)

Question 18

Sympatric speciation example

Answer 18

Cichlid fishes live in different levels of the lake so can’t mate with one another

Question 19

Parapatric speciation

Answer 19

Occurs when a species is widely distributed and phenotypes in different environments have different fitness
- speciation with gene flow
- this is thought to be rare but there are examples such as Papio baboons

Question 20

Are humans still evolving?

Answer 20

Evolution continues to change the frequency of alleles over time as it does in all biological populations