20.6 Speciation and Artificial selection Flashcards
What needs to happen for speciation to occur? (2 marks)
The new species needs to become morphologically or physiologically different from members of the original species.
What is sympatric speciation? (3 marks)
Random mutations can lead to reproductive isolation. Two groups (within a species) become so different that they are no longer able to interbreed, they are now different species.
What is allopatric speciation? (3 marks)
When some members of the population are separated from the rest of the group by a physical barrier; they become geographically isolated, and can no longer breed with each other, so over time different species form.
What is an ecological barrier? ( 1mark)
Where two species live in the same area at the same time, but they rarely meet.
What is a temporal barrier? (2 marks)
The species (live in the same place) are prevented from interbreeding because they active at different times in the day or reproduce at different times of the year.
Give 4 reproductive barriers, that prevent species from interbreeding. (4 marks)
The species have different courtship behaviuors
They have mechanical problems mating
Their gametes are incompatible
Their zygotes are incompatible
What does it mean if an organism is polymorphic? (1 mark)
That the organism displays more than one distinct phenotype.
What is a wild type allele? (1 mark)
The most common/normal characteristic.
What are alleles that are not the wild type allele called? (1 mark)
Mutants
Define artificial selection. (1 mark)
When the selection for breeding of plants or animals with desirable characteristics is done by farmers or breeders, instead of by natural selection.
What is inbreeding? (1 mark)
When individuals who are closely related breed.
Explain two problems with inbreeding. (4 marks)
Inbreeding limits the gene pool, resulting in less genetic diversity, so a population of inbred organisms is less likely to evolve and adapt to changes in their environment.
Organisms that are closely related are genetically similar, so are more likely to have the same recessive alleles, so inbred organisms are more likely to be affected by genetic disorders that are caused by recessive alleles.
Why are seed banks/gene banks used? (1 marks)
To help promote genetic diversity within species, so animals/ plants do not need to meet/be near each other to breed. These situations can happen with human intervention instead.
