20.6 Speciation and artificial selection

Question 1

what is speciation?

Answer 1

the formation of new species through the process of evolution

Question 2

what are the features of offspring produced from speciation?

Answer 2

they cannot interbreed to produce fertile offspring

Question 3

what are the steps to speciation?

Answer 3

1. isolation
2. random mutations
3. evolution

Question 4

what happens during isolation?

Answer 4

members of a population become isolated and therefore don’t interbreed

this means that there is no gene flow

Question 5

what happens during random mutations?

Answer 5

the alleles in the 2 groups will undergo random mutations

due to the different selection pressures in the different groups there will be different changes in characteristics

Question 6

what happens during evolution?

Answer 6

over many generations, the changes in the alleles will be significant enough for a large change in the phenotypes of the 2 populations

the 2 populations are now different species

Question 7

what are the 2 types of speciation?

Answer 7

allopatric
sympatric

Question 8

what is allopatric speciation?

Answer 8

when a group of organisms are separated from the rest of the population by a geographical barrier

this leads to speciation occuring

Question 9

what is an example of a geographical barrier?

Answer 9

river
sea
valley

Question 10

what is an example of allopatric speciation?

Answer 10

when finches arrived on the Galapagos they were separated on different islands

different selection pressures acted upon the different finches and after evolution and many generations, different species were formed

Question 11

what is sympatric speciation?

Answer 11

SHARE THE SAME HABITAT
when 2 different species interbreed and form fertile offspring to form a hybrid

mainly occurs in plants

Question 12

why can the hybrid not breed with their parent species?

Answer 12

they have a different number of chromosomes to the parents so they cannot breed with the parent species
this leads to isolation

Question 13

what is an example of sympatric speciation?

Answer 13

modern wheat has undergone 2 hybridisation events
it made the modern wheat more isolated from it’s ancestor species
BUT
the wheat is in the same habitat as it’s ancestor

Question 14

what is being polymorphic?

Answer 14

an organism which displays more than one distinct phenotype

Question 15

what is the wild type allele?

Answer 15

the allele which codes for the most common characteristic

Question 16

what is artificial selection?

Answer 16

when plants and animals with the desirable characteristics are bred by farmers

Question 17

what is inbreeding?

Answer 17

when closely related individuals breed

Question 18

why is inbreeding done?

Answer 18

once done over many generations, the frequency of alleles decreases which leads to speciation

Question 19

what are the problems with inbreeding?

Answer 19

it limits the gene pool and reduces genetic diversity

reduces chance of evolution and survival

Question 20

why does inbreeding increase the chance of recessive expression?

Answer 20

when organisms which are closely related inbreed, it is very likely to have the same recessive alleles

the offspring thus have a greater chance of being homozygous recessive

Question 21

what are seed banks?

Answer 21

keep samples of seeds
important genetic store of resources

Question 22

what is outbreeding?

Answer 22

when alleles from gene banks are used to increase the genetic diversity

Question 23

what does outbreeding do?

Answer 23

reduce the occurrence of homozygous recessive genotypes