FORMATION OF
NEW SPECIES
MATRIC IEB LIFE
SCIENCE
these notes are a section from evoltuion
, formation of new species
definitions
species
population
A species is a group of organisms all
sharing the same structural features
which are able to breed among themselves A group of individuals of the same species
but not with any other species, and occupying the same habitat
produce fertile offspring.
Sexual Reproduction
causes of variation :
Meiosis,
Chance fertilisation,
Random mating
Mutations
Inbreeding vs outbreeding
The mating of closely related The mating of individuals not
individuals to maintain desirable closely related to introduce new or
traits stronger traits
Inbreeding
self-fertilization, eg wheat species
the crossing of offspring of the same parents, eg highly pedigreed dogs
leads to loss of vigour [strength of body / mind] and poor survival as the
offspring (homozygous for a higher proportion of undesirable recessive genes)
Inbreeding in humans Inbreeding was very common among the
royal families of Europe.
The presence of haemophilia in the
when closely related family members royalty of Europe started with Queen
produce offspring Victoria of England.
high chance of passing on a mutated
recessive gene to offspring increased prevalence of Tay-Sachs disease
in certain Jewish populations where
arranged marriages are encouraged. It is an
inherited metabolic abnormality that is fatal
in early childhood.
, outbreeding
Eg. Mongrel dogs= resultant offspring are tougher and more fertile with a greater
chance of survival (heterozygous with undesirable recessive alleles being masked
by normal dominant alleles)
also seen in outbreeding cows and plants
founder effect
A founder effect occurs when a new colony is started by a few members of the original population.
This small population size means that the colony may have:
1. reduced geneticvariation from the original population.
2. a non-random sampleof the genes in the original population.
Human example Animal example
Afrikaner population of Dutch settlers 10 000ya, due to climate change, major extinction of large
in South Africa has a high frequency of mammals occurred
the gene that causes Huntington's all but a founder population of cheetah died causing much
disease, because those original Dutch inbreeding with few surviving members, gene pool shrinks =
colonists just happened to carry that poor sperm quality, few healthy offspring, high cub mortality,
gene with unusually high frequency. breeding and survival is difficult, most cheetahs dont live to
become adults
NEW SPECIES
MATRIC IEB LIFE
SCIENCE
these notes are a section from evoltuion
, formation of new species
definitions
species
population
A species is a group of organisms all
sharing the same structural features
which are able to breed among themselves A group of individuals of the same species
but not with any other species, and occupying the same habitat
produce fertile offspring.
Sexual Reproduction
causes of variation :
Meiosis,
Chance fertilisation,
Random mating
Mutations
Inbreeding vs outbreeding
The mating of closely related The mating of individuals not
individuals to maintain desirable closely related to introduce new or
traits stronger traits
Inbreeding
self-fertilization, eg wheat species
the crossing of offspring of the same parents, eg highly pedigreed dogs
leads to loss of vigour [strength of body / mind] and poor survival as the
offspring (homozygous for a higher proportion of undesirable recessive genes)
Inbreeding in humans Inbreeding was very common among the
royal families of Europe.
The presence of haemophilia in the
when closely related family members royalty of Europe started with Queen
produce offspring Victoria of England.
high chance of passing on a mutated
recessive gene to offspring increased prevalence of Tay-Sachs disease
in certain Jewish populations where
arranged marriages are encouraged. It is an
inherited metabolic abnormality that is fatal
in early childhood.
, outbreeding
Eg. Mongrel dogs= resultant offspring are tougher and more fertile with a greater
chance of survival (heterozygous with undesirable recessive alleles being masked
by normal dominant alleles)
also seen in outbreeding cows and plants
founder effect
A founder effect occurs when a new colony is started by a few members of the original population.
This small population size means that the colony may have:
1. reduced geneticvariation from the original population.
2. a non-random sampleof the genes in the original population.
Human example Animal example
Afrikaner population of Dutch settlers 10 000ya, due to climate change, major extinction of large
in South Africa has a high frequency of mammals occurred
the gene that causes Huntington's all but a founder population of cheetah died causing much
disease, because those original Dutch inbreeding with few surviving members, gene pool shrinks =
colonists just happened to carry that poor sperm quality, few healthy offspring, high cub mortality,
gene with unusually high frequency. breeding and survival is difficult, most cheetahs dont live to
become adults
