speciation - 8.2

Question 1

what is a species

Answer 1

• all members of a population that can interbreed under natural conditions
• individuals of different species are reproductively isolated

Question 2

methods of speciation definition

Answer 2

for a new species to form, individuals from the original species must evolve to become reproductively isolated from the remainder of the population (establishing a new interbreeding population)

Question 3

what are reproductive isolating mechanisms

Answer 3

factors that prevent 2 populations from interbreeding

Question 4

2 reproductive isolating mechanisms

Answer 4

prezygotic
postzygotic

Question 5

prezygotic definition

Answer 5

prevents species from mating and prevents fertilization (no zygote is created)

Question 6

postzygotic definition

Answer 6

these mechanisms DO NOT prevent mating (sperm may fertilize the egg and create a zygote), but maturation and reproduction in offspring are prevented

Question 7

5 examples of prezygotic mechanisms (isolation)

Answer 7

behavioural isolation
temporal isolation
ecological isolation
mechanical isolation
gametic isolation

Question 8

behavioural isolation

Answer 8

different courtship and mating rituals
eg. birds of paradise

Question 9

temporal isolation

Answer 9

mating at different times of year
eg. american toad mates in early summer while the fowler’s toad mates in late summer

Question 10

ecological isolation

Answer 10

occupy different habitats
eg. one cricket species lives in sandy soils while the other lives in loamy/grassy soils

Question 11

mechanical isolation

Answer 11

differences in morphology = incompatibility
eg. dragonfly claspers

Question 12

gametic isolation

Answer 12

sperm cannot fertilize the egg of another species
eg. red and purple sea urchins are chemically incompatible :(

Question 13

3 postzygotic mechanisms

Answer 13

zygotic mortality
hybrid inviability
hybrid infertility

Question 14

zygotic mortality

Answer 14

zygote is unable to develop
eg. sheep x goat
can mate but but fertilized egg doesn’t continue to divide (unable to create another being)

Question 15

hybrid inviability

Answer 15

offspring develops but dies before birth or cannot survive
eg. leoger (lion x tiger)
very rare, usually dies before birth

Question 16

hybrid infertility

Answer 16

healthy but sterile
eg. mule, infertile

Question 17

4 types of speciation

Answer 17

allopatric speciation
sympatric speciation
peripatric speciation
parapatric speciation

Question 18

allopatric speciation definition

Answer 18

the formation of a new species (as a result of evolutionary changes) following geographical isolation

Question 19

allopatric speciation; explain

Answer 19

genetic information is no longer shared in allopatric speciation, so mutations aren’t shared either
- natural selection causes the species to become less and less alike

Question 20

allopatric speciation examples

Answer 20

mountain formation
continental drift
migrating to a remote island

Question 21

sympatric speciation definition

Answer 21

the evolution of populations within the same geographical area into separate species

Question 22

sympatric speciation; explain

Answer 22

individuals WITHIN a population become isolated from other members
polyploidy

Question 23

polyploidy

Answer 23

a mutation which causes the number of chromosomes to double (results in sympatric speciation)

Question 24

sympatric speciation example

Answer 24

hawthorn flies and apple maggot flies, apple maggot flies evolved when apple trees were introduced in an area with only Hawthorn trees
(some stayed with the Hawthorn trees, some went to the apple trees)

Question 25

peripatric speciation

Answer 25

a small population at the PERIPHERY of a large population breaks off and becomes an isolated niche

Question 26

parapatric speciation

Answer 26

a small population enters a niche which is not isolated and adjacent to the population(s)