Extended response Flashcards
What is the theory of evolution
All species come from a common ancestor and are distantly related. Through genetic changes
How does natural selection cause evolution
Individuals with traits best suited to their environment survive and reproduce, passing those traits. Affects gene pool because advantageous traits become more common over generations
How does natural selection cause speciation
As these traits accumulate and populations adapt to different environments, they may become so genetically distinct that they can no longer interbreed with the original population.
How does genetic drift cause evolution
A random process that causes changes in allele frequencies in a pop. Caused by natural disasters or the migration of a small group leaving a population. As a result, the population size decreases and therefore contains less genetic diversity within the gene pool, the alleles have been randomly selected not because they are advantageous or disadvantageous.
How does genetic drift cause speciation
Over time the isolated populations will have different alleles that have been randomly selected and they will become so genetically different that they can no longer interbreed with the original population.
How do fossils give evidence for evolution
Once living thing that has been preserved in rock. Evidence that there has been a gradual change in characteristics in organisms overtime. They allow us to see the sequence of evolution. We can see extinct species that no longer exist showing that life has changed
How do embryology give evidence for evolution
The embryos of vertebrate animals look very similar in the early stages, which suggests that they share some of the genetic information that contributes to embryo development. This genetic information has been inherited from a common ancestor.
How does comparative anatomy give evidence for evolution
Homologous and analogous structures can be studied in animals. Homologous structures have a similar structure but perform different things. Homologous structures show that these animals have evolved from a common ancestor.
What is an example of a embryology giving evidence
For example, a very early stage human embryo has gill slits, a tail and a simple heart, similar to that of a fish. At later stages, the human embryo develops body proportions similar to the embryos of reptiles and then apes. This shows that humans and other mammals, and fish, have evolved from a common ancestor
What is an example of a fossil giving evidence
For example, scientists looked at dinosaur fossils and found that there bones were hollow, this is common in modern birds today showing that birds might have evolved from dinosaurs.
What is an example of a comparative anatomy giving evidence
A human, bat, whale and cats forelimbs are made up of the same basic parts
eg a dolphin, penguin and orca, they all have a similar use but don’t evolve from a common ancestor
