Speciation

Question 1

Speciation

Answer 1

is the bridge between microevolution and macroevolution. The process of one species diverges into two or more.

Question 2

Biological Species Concept

Answer 2

Species = a group of organisms that can potentially interbreed and produce viable offspring.

Question 3

gene flow

Answer 3

(interbreeding) between populations holds the phenotype of a species together. Species are made up of populations that are connected by gene flow.

Question 4

reproductive isolation

Answer 4

intrinsic biological barriers that prevent members of two species from producing viable, fertile offspring

Question 5

prezygotic barriers

Answer 5

a) Habitat isolation (physical separation)
b) Temporal isolation (timing of mating differs)
c) Behavioral isolation (mating dances and other behaviors)
d) Mechanical isolation (physical differences)
e) Gamete incompatibility (no fusion)

Question 6

Postzygotic barriers:

Answer 6

a) Reduced hybrid viability
b) Reduced hybrid fertility
c) Hybrid Breakdown

Question 7

Limits to Biological Species Concept

Answer 7

Doesn’t work for asexual species or fossils

Question 8

Morphological Species

Answer 8

species defined by physical structures

Question 9

Ecological Species

Answer 9

species defined by its ecological niche

Question 10

Allopatric speciation

Answer 10

(“other homeland”) geographic isolation of populations

Question 11

3 steps to allopatric speciation

Answer 11

i. Isolation of populations - Barrier depends on dispersal abilities. eg ground squirrel vs hawks in Grand Canyon
ii. Evolutionary change in population (mutation, genetic drift, selection)
iii. Evolution of reproductive isolation

Question 12

Sympatric speciation

Answer 12

(“same country”) speciation occurs in populations within the same geographic area.
i. polyploidy - Gene flow reduced when chromosome duplication occurs
1. Autopolyploid – with more than two sets of chromosome from a single species. (diploid gametes mistakenly produced)
2. Allopolyploid – a species with multiple sets of chromosomes derived from different species. A fertile hybrid polyploidy that can reproduce with other allopolyploids but not either parent species
ii. Habitat differentiation – new ecological niche can provide speciation opportunity. e.g. Hawthorn and apple maggot flies
iii. Sexual Selection – mate choice can lead to speciation (cichlids example)

Question 13

Gradualism

Answer 13

continuous evolution - an accumulation of tiny changes over millions of years
– Darwin & Lyell believed

Question 14

Punctuated equilibrium

Answer 14

no change for millions of years and then drastic changes that are fairly quick (thousands of years)
Promoted by Stephen Jay Gould