speciation

Question 1

microevolution

Answer 1

-changes in allele frequencies and phenotypic traits within a population of species: happens over shorter time period (few gen.)

Question 2

macro evolution

Answer 2

-large scale changes including formation of new species: happens over longer time period (centuries, millennia)

Question 3

what is a species?

Answer 3

• A group of individuals that actually or potentially interbreed in nature to produce viable or fertile offspring
• ex, these happy face spiders look different, but since they can interbreed, they are considered the same species
• ex, tigon male tiger and female lion produce infertile offspring
• ex liger of male lion and female tiger produce infertile offspring

Question 4

what is speciation?

Answer 4

• The formation of a new species

- due to accumulation of numerous micro evolutionary mechanisms (mutations, gene flow, etc)

Question 5

reproductive isolation

Answer 5

• members of two populations cannot interbreed and produce fertile offspring
• there are two types pre zygotic mechanisms and post zygotic mechanisms
• pre zygotic: prevent mating between species or prevent fertilization of eggs
• post zygotic: if fertilization successful prevention of zygotes from developing into fertile individuals

Question 6

pre zygotic mechanisms

Answer 6

• prevents different species from mating and fertilizing

- look at chart in photos

Question 7

post-zygotic mechanisms

Answer 7

• prevents maturation and reproduction of inter species offspring
• look at chart in photos

Question 8

2 modes of speciation

Answer 8

• allopatric

- sympatric

Question 9

allopatric speciation

Answer 9

• Evolution of population into two different species caused by a geographic barrier like rivers canyons mountains or large bodies of water
• barriers prevents gene flow, mutations/variance to arise in both populations, Drift and selection cause divergence between isolated populations until reproductive isolation
• Gene pool of the split populations become so distinct that the two groups are unable to interbreed even when brought back together
• isolated groups within populations will not automatically survive and thrive when separated many isolated populations do not last long enough to change into a new species
• ex. oahu tree snail- mountain range barriers

Question 10

sympatric speciation

Answer 10

• populations within same geographical areas diverge and become reproductively isolated
• Evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region
• example: hawthorn fly and apple maggot flies in north america based on feeding preferences