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Evolution
A population is a group of individuals
of the one species that breed together
in a particular environment.
E.g. 3 x groups...
The gene pool of a population is the sum of all
genes of all the individuals in a population
Changes in gene pool can be b...
Variation
Variation is essential for the process of evolution to
occur. The extent of this variation will be
determined by...
Theory of Evolution
Suggests that
- All life forms have evolved from a
single, simple common ancestor
- That species chang...
Charles Darwin
1859 “On the Origin of Species”
Evolution was due to natural selection. Nature
or the environment (biotic a...
Voyage of the Beagle
The evolution of species in general is an extremely
slow process but there are exceptions.
Strong selective pressures lead...
However the rare darker species now had the
distinct advantage due to change in its abiotic
environment.
Other examples in...
Resistant strains of bacteria
Some bacterial strains are resistant to specific
antibiotics as they have a genetic makeup t...
Image credit: https://answersingenesis.org/natural-selection/is-natural-
selection-the-same-thing-as-evolution/
Geographical Isolation
Speciation is the name of the process that gives rise
to the origin of new species.
It is caused by...
Geographical isolation caused by the movement
and separation of continents over 250 million
years have led to the reproduc...
Evolution
Evolution
Evolution
Evolution
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Evolution

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ecosystem evolution

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Evolution

  1. 1. Evolution
  2. 2. A population is a group of individuals of the one species that breed together in a particular environment. E.g. 3 x groups of Rosellas (Adelaide, Yellow & Crimson) are known as subspecies. Reveal overlap in distribution leading to their gradual divergence. Individuals in one population are members of the same species and form a “breeding group”.
  3. 3. The gene pool of a population is the sum of all genes of all the individuals in a population Changes in gene pool can be brought about by Mutations- Changes in the organisms DNA are rare and unlikely to be beneficial Natural Selection- Is the most important process during evolution and is the cause of change in the gene pool of the population Gene flow- Is the exchange of alleles between populations, which leads to diversity
  4. 4. Variation Variation is essential for the process of evolution to occur. The extent of this variation will be determined by whether the species reproduces asexually or sexually. Asexual Mutations provide the only source of variation. Sexual While mutations are still the only way that new alleles arise, meiosis and fertilisation ensure new combinations of genes and chromosomes are found in offspring compared to their parents
  5. 5. Theory of Evolution Suggests that - All life forms have evolved from a single, simple common ancestor - That species change over time - Can be recognized in a species by the changing frequencies of genes in populations.
  6. 6. Charles Darwin 1859 “On the Origin of Species” Evolution was due to natural selection. Nature or the environment (biotic and abiotic) selected individuals who were best adapted or the fittest “survival of the fittest” This variation gave the organisms a reproductive advantage enabling offspring to survive
  7. 7. Voyage of the Beagle
  8. 8. The evolution of species in general is an extremely slow process but there are exceptions. Strong selective pressures leading to changes have been observed over a short period of time. I.e. Biston betularia Over a period of 80-100 years of industrialization the light coloured species became visible to birds as tree trunks became darker with soot.
  9. 9. However the rare darker species now had the distinct advantage due to change in its abiotic environment. Other examples include the rabbit population and the “myxoma” virus. Natural selection soon favoured those rabbits which suffered a milder form of the virus. As a result commenced reproducing at a faster rate.
  10. 10. Resistant strains of bacteria Some bacterial strains are resistant to specific antibiotics as they have a genetic makeup that enables them to survive exposure to that antibiotic. Individual variation exists between bacteria, with some being more resistant to certain antibiotics than others. Antibiotics act as selective agents and those bacteria that have the resistant gene are more likely to survive. Over time, by the process of natural selection, there is an increase in the frequency of the gene for resistance to specific antibiotics.
  11. 11. Image credit: https://answersingenesis.org/natural-selection/is-natural- selection-the-same-thing-as-evolution/
  12. 12. Geographical Isolation Speciation is the name of the process that gives rise to the origin of new species. It is caused by geographic isolation such as seas, lakes, mountain ranges, grasslands, deserts, separating and isolating groups of individuals from one another, preventing flow of genes. Over time this will lead to significant differences developing. These subspecies are now reproductively isolated.
  13. 13. Geographical isolation caused by the movement and separation of continents over 250 million years have led to the reproductive isolation and unique evolution of Australian flora and fauna.

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