Chapter 3: Natural Selection & Evolution Flashcards
Define evolution
The genetic change in species over many generations, resulting in new species.
Explain, using examples such as the horse and transitional forms, how fossils provide evidence for evolution.
Fossils show how much or how little organisms have changed over time. The horse is a good example as its record is quite complete and has multiple variations of the species, showing its gradual change over time which provides good evidence for evolution.
Use examples to describe artificial selection and selective breeding methods.
Selective breeding involves choosing parents with particular characteristics to breed together and produce offspring with more desirable characteristics. E.g Crop plants with better yeilds or Belgium Blue cattle to have more muscle/meat
Define natural selection
Natural selection is the process through which species adapt to their environments and is the mechanism for evolution (survival of the fittest).
State the key points in natural selection.
Variation- individuals within a population show variations that can be passed to next generation
A selective pressure puts constraints on organisms and determines which individuals are best suited to the conditions
Survival of the fittest- individuals with favourable variations have a greater chance of survival
Inheritance - individuals with favourable variations pass these traits on to their offspring in reproduction
Isolation: If a population is isolated from the original population, interbreeding will be prevented over a period of time. This can lead to Speciation when individuals within the population become so different that they can no longer interbreed. The population is then considered to be a new species.
Define variation and explain how it occurs (mutation).
Genetic variation is the presence of differences in sequences of genes between individual organisms of a species. Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. They account for variation in a population.
Define natural selection in terms of genetics, using the concepts of phenotype and genotype.
In simple terms, the proportion of phenotypes (characteristics) in species changes because individuals with a particular genotype are being favoured to breed due to selective pressures.
Describe the earliest hints of Darwin’s theory in his studies of the adaptations of finches on the Galapagos Islands.
Darwin observed that beak shape varies among finch species. He suggested that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources.
Describe how comparative embryology, comparative anatomy and biogeography provide evidence for evolution.
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