Isolation and selective breeding Flashcards
what are the two types of of isolating mechanisms
pre-reproductive isolation and post-reproductive isolation
isolating mechanisms
mechanisms which prevent species from interbreeding to pproduce viable and fertile offspring
example of hybrid sterility
horse and donkey producing amule
why are horses and donkeys considered different species
because a mule cannot produce offspring due to its chromosome number being 63 (odd) so meiosis cannot occur
morphology
characteristics of physical form, another way of cllassifying species
what are the pre0reproductive isolating mechanisms
geogrpahical, ecological, temporal, structural, behavioural GETSB
ecological pre-reproductive isolating mechanism
individuals iinhabit different ecological niches or habitats so they dont interact with each other
geographical pre-reproductive isolating mechanism
individuals are uunable to interact with each other due to seperation by barriers
temporal pre-reproductive isolating mechanism
the time of day/year when individuals breed differ
behavioural pre-reproductive isolating mechanism
mating behaviours differ
structural/morphological pre-reproductive isolating mechanism
physical characteristics differ/reproductive structures,shapes or sizes prevent mating, physically preventing breeding
types of post-reproductive isolation
gamete mortality, zygote mortality and hybrid sterility
gamete mortality
the sperm is unable to penetrate the ovum for fertilisation
zygote mortality
fertilisation may occur and a zygote may form but it wont survive
hybrid sterility
a viable offspring may form and may survive until adulthood but it will not be fertile
selective breeding is aka
artificial selection
selective breeding
the changing of a populations gene pool due to humans altering the breeding behaviour of animals/plants to develop a selected trait
why is artificial insemination used
increases the efficiency of selective breeding
adaptive potential
the ability for a population to adjust to new environmental selection pressures
similarities between selective breeding and natural selection
- requirement for variation 2. pressence of selection pressure 3. heritability of trait (also the requirements of artificial selective to occur)
how does artificial selection differ from natural selection
the origin of the selection pressure, in artificial selection it is the person and the humans select which individuals mate which is different to natural selection where any pair can mate
how does selective breeding occur
humans select which phenotype is more desirable and select/remove traits from a population by breeding individuals wiyh the desirbale phenotype
artificial indemination
where one desirable individual can impregnate a large amount of females
why is artificial selection bad (in animals)
it reduces genetic diversity which can cause inbreeding and can cause a genetic bottleneck
genetic bottleneck
can genetic diversity significantly decreases in a large population due to only a small percentage of individuals expressing traits desired by humans
what does inbreeding cause
increases the presence of deletrious alleles and lowers adaptive potential
desirable trait
a heritable phenotype that humans select for during artificial selection
what are the potential consequences of articifical selection in plants
plants may lose the ability to produce viable seeds and can only reproduce asexually, which reduces the gene pool and diversity of the population, making them vulnerable to environmental changes
