All the species that are alive today- and many more which are now extinct- evolved from simple life forms that first developed more than 3 billion years ago
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Who was Jean-Baptiste Lamarck?
French biologist
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What were Lamarck's two main laws on evolution?
The law of use and disuse, the law of inheritance of acquired characteristics
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What was Lamarck's theory of evolution?
His theory stipulated that a characteristic which is used more and more by an organism becomes bigger and stronger. One that is not used disappears eventually. Any characteristic of an organism that is improved through use is passed to its offspring
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What was Darwin' theory of evolution?
All living organisms have evolved from simpler life forms by a process of natural selection. reproduction always give more offspring than the environment can support. Only the fittest withe inherited features suited to their environment will survive
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What happens when a species breeds?
They pass on the genes for their useful characteristics to their offspring who will survive and reproduce.
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Why did it take Darwin so long to publish his ideas?
He spent years trying to pt lots of evidence together to support his theories and convince other scientists
Why did acceptance of Darwin's ideas take a long time?
Natural selection conflicted with the widely held belief that God made all the animals and plants on the Earth, insufficient evidence, no mechanism for explaining variety and inheritance- genetics were not understood for another 50 years
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Why were fossils good evidence?
Show how organisms have changed over millions of years, show similarities with living organisms found in the same area, show common ancestors
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Why were fossils bad evidence?
Few organisms fossilised leaving gaps in the fossil record, soft bodied organisms not preserved, fossils are incomplete, fossils are squashed and distorted so they are difficult to interpret
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What is natural selection?
The process by which the individuals with genes for better adaptations have more offspring and therefore pass more of their genes onto the next generation, survival of the fittest
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Why do organisms in the same species show a wide range of variation?
Because of the difference in their genes
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What is a mutation?
The change in the DNA which results in a new form of gene
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What is classification?
The organisation of living things into groups according to their similarities
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How does classification help us understand evolution?
We can work out evolutionary and ecological relationships which mean that we can see how long ago different organisms had a common ancestor
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What is extinction?
The disappearance of a species, either globally or locally
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What are the causes of extinction?
Habitat destruction, introduced specis, hunting and fishing, environmental change and extinction of a species form a food web or chain
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What is speciation?
The formation of a new species
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What are species?
Individuals that can mate with each other to produce fertile offspring
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What is a hybrid?
Infertile offspring, cannot pass on genes/reproduce, cross breed
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