Formation of a new species Flashcards
Genetic engineering
the direct manipulation of the genes in an organism
GMO (genetically modified organisms)
- the result of genetic engineering
- improve quality of life/productivity
transgenic organism
-organism which genes have been altered using genetic engineering techniques
recombinant DNA
DNA that contains foreign genes
species
individuals with similar characteristics that can interbreed freely and produce fertile offspring
Main causes of variation in a species
- crossing over and random assortment of homologous chromosomes pairs (meiosis)
- random fusion and random mating (reproduction) (greater genetic pool)
- mutations (gene and chromosome mutations)
inbreeding
- crossing of closely related individuals
- promotes homozygosity
advantages of inbreeding
- predictable offspring
- undesirable characteristics can be isolated
- recessive genes can be isolated
- disadvantages of inbreeding
- high mortality rate
- offspring have low resistance to diseases
- offspring can be sterile e.g. poor sperm quality
- decrease in frequency of heterozygous gene pairs
- disadvantages of inbreeding
- gene pool decreases (increases possibility of extinction)
- increase in abnormalities
- recessive genetic diseases (more evident)
- loss of vigour
outbreeding
- crossing of unrelated individuals - offspring that is genetically diff
- promotes heterozygosity
- same species - diff breed
advantages of outbreeding
- reintroduces lost characteristics
- individuals are still “pure”
- increases hybrid vigour in offspring
- new characteristics are introduced - genetic variation increases - gene pool enlarges
disadvantages of outbreeding
- typical characteristics are lost
- loss of seperate race / breed - new races / breeds develop
- less predictability in offspring
outbreeding
- crossing of unrelated individuals - offspring that is genetically diff
- promotes heterozygosity
- same species - diff breed
advantages of outbreeding
- reintroduces lost characteristics
- individuals are still “pure”
- increases hybrid vigour in offspring
- new characteristics are introduced - genetic variation increases - gene pool enlarges
disadvantages of outbreeding
- typical characteristics are lost
- loss of seperate race / breed - new races / breeds develop
- less predictability in offspring
founder effect (deliberate isolation)
when a small fraction of the population moves away
How does the founder effect work?
- starts with large population with different phenotypes
- small fraction of population moves away
- isolation - leads to inbreeding
- recessive allele is expressed in phenotype
genetic bottle neck
animals
speciation
formation of new species
allopatric speciation
occurs when there is geographic isolation
- How allopatric speciation occurs?
- variation occurred in original population (name trait)
- population became separated by geographical barrier (name barrier)
- gene flow between the two populations stopped
- became reproductively isolated
- How allopatric speciation occurs?
- populations adopt separately to their environments
- the different environments exert different pressures (name them)
- over time mutations occur and they become genotypically and phenotypically different
- if two populations meet again, they won’t recognise each other - new species developed through allopatric speciation
sympatric speciation
occurs when there is absence of a barrier
- How sympatric speciation occurs?
- occurs in the same geographical area (they become reproductively separated even though they occupy the same area)
- moved away to avoid competition
- population became separated (state the type of isolation)
- gene flow between the two populations stopped
- How sympatric speciation occurs?
- became reproductively isolated
- populations adopt separately to their environments
- the different environments exert different pressures (name them)
- over time mutations occur and they become genotypically and phenotypically different
What can geographical isolation to?
It can lead to behavioural isolation over time
Temporal isolation
breeding at different times of the year/day
Ecological isolation
live in diff habitats in same environment and use diff resources
Behavioural isolation
if courtship is unsuccessful, mating and fertilisation will not take place
Mechanical isolation
the reproductive organs don’t fit into each other - cannot reproduce
Hybrid
hybrids are infertile
