Summary
Summary Grade 12 IEB Biology Evolution Mind Maps
- Course
- Grade 12 IEB Life Sciences
- Institution
- University Of The Witwatersrand (wits)
Evolution mind maps for grade 12 IEB biology / life science students.
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Life SciencesGrade 12
Evolution Mind Maps
, Similar organisms that interbreed to produce
Species
fertile offspring
An evolutionary process to form new species Speciation Very important in speciation
Species that exists in a specific area / time – they Crossing over (meiosis)
Population
freely interbreed
Genetic recombination Random assortment
The total number of alleles shared in a population Gene pool
This is due to: Random fertilisation
The exchange of alleles between populations
Gene flow
– sexual reproduction creates a gene flow
Blocks the gene flow – this is very important Reproductive
for speciation isolation
New populations colonise a specific place
Founder effect Sudden, unexpected change in the
and they interbreed
Important terms: genetic make up of an individual
The change that occurs at or above the
Macro-evolution Harmful / lethal mutations lead
species level
to proteins that cannot perform
Variation within a species Micro-evolution normal functions
Relations among species Phylogeny Neutral mutations have no effect
Gene mutations:
Evolutionary relationships among groups that on the genotype / phenotype
Phylogenetics
have been discovered through lines of evidence When all individuals have this
Beneficial mutations increase
A common ancestor that has divided into mutation, it is said that they
Cladogenesis the chances of survival
two new species Variation: have a ‘fixed’ mutation
Variation is the differences between
The ancestor gradually evolved into a new individuals as well as their appearances
Anagenesis
species Types of mutations: The change in the section of the
Long periods of stasis and short periods of drastic Punctuated chromatid
change happens which leads to speciation equilibrium The change in the chromosome
Mutations:
number (aneuploidy)
Chromosome mutations: This type of mutation plays no
role in evolution
Polyploidy in plants creates
Increases hybrid vigour (more fertile) variation
↳ 2n + n = 3n
Increases gene pool / variation Advantages: ↳ 2n + 2n = 4n
Reintroduces lost traits
This is the crossing of unrelated
Outbreeding (in animals
individuals resulting in offspring
Certain traits can be lost being genetically different
and plants): Mutations lead to genotypic variation (they can or cannot
Evolution: be visible in the phenotype)
Offspring becomes less predictable the formation of Genotypic variations e.g. Galapagos finches (beak sizes differ), or the white lion
Disadvantages:
in populations:
Loss of a separate race / breed, thus a new species Adaptive radiation = single ancestor, and
new races / breeds develop many evolved due to natural selection
For the process of speciation,
reproductive isolation is needed
Increase in genetic mutations There is a geographical barrier
This is when closely related e.g. oceans, mountains, canyons or rivers
Increase in genetic diseases
individuals produce offspring
Increase in homozygosity The population is separated in two, and
they become reproductively isolated, thus
This is when a new species no gene flow
Inbreeding in humans: Allopatric speciation
Small populations arises from an existing species
Natural selection then happens on
Geographical isolation both sides, and new gene pools form
Reasons for inbreeding:
Religion and culture There are two main types of Two separate species then form
speciation: on both sides
Royalty
There is no geographical barrier between
the two species, BUT there is a repro-
This is when a new species ductive barrier
Sympatric speciation
arises in the same area The reproductive barriers means that they
Speciation:
Larger crops will have specific habits, eat specific foods
Disease resistant Advantages: and will have specific sexual strategies
Controlled process where humans This prevents gene flow between populations
Resistant to climatic conditions Selective breeding:
select specific traits
It can include behavioural or structural patterns, or physiological
processes which prevent populations from interbreeding
Decrease in variation Disadvantages:
Species-specific courtship = behavioural isolation
Prevents mating: Different habitats in the same
environment = ecological isolation
Mechanisms of reproductive This includes breeding at
Pre-zygotic isolation: Adaptations of plants to different pollinators
isolation: different times of the year
= mechanical or structural isolation
If the population decreases, in Prevents fertilisation:
order to survive, they therefore Physical incompatibility in animals
have to self-pollinate The prevention of inbreeding prevents fertilisation
Inbreeding in plants happens
in plants happens by cross Inbreeding in plants:
If there is a change in environ- naturally
pollinating
ment, the whole population can Development of sterile offspring
become extinct Post-zygotic isolation Hybrid isolation:
in hybrids
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