20.6 Speciation Flashcards
Speciation
Formation of new species through the process of evolution
Events causing speciation
Members of a population become isolated and no longer interbreed with rest of the population
Alleles continue to undergo random mutations
Accumulation of mutations and change in allele frequencies
Allopatric speciation
When members of a population are separated from the rest of the group by a physical barrier (geographical isolation)
Sympatric speciation
Occurs within a population that share the same habitat - occurs when members of different species interbreed and form fertile offspring
Hybrid organism cannot reproduce with the parent population
Reproductive barriers
Prezygotic reproductive barriers prevent fertilisation and formation of a zygote
Postzygotic reproductive barriers due to hybridisation reduce viability of offspring
Polymorphic
Display more than one distinct phenotype for most characteristics
Wild type allele
Allele coding for the most common or normal characteristic
Artificial selection
Selection for breeding of plants or animals with desirable characteristics by farmers or breeders
Inbreeding
Breeding of closely related individuals
What does inbreeding eventually cause?
Process repeated over many generations causing changes to the frequency of alleles within the population and eventually causing speciation
Problems caused by inbreeding
Limits gene pool - decrease genetic diversity, reduces evolution and adapting to changes in the environment
Many recessive disorders are caused by recessive alleles - greater chance of being homozygous for recessive traits
Organisms are less biologically fit
Seed banks
Keep seed samples from both wild type and domesticated varieties
Gene banks
Store biological samples such as sperm or eggs
