Evolution of species Flashcards
What is the definition of species?
Species are a group of organisms which can interbreed t produce fertile offspring.
Why are there so many species on earth?
Earths biodiversity is a result of evolution.
What is evolution?
Evolution is the gradual change of a species over time which can lead to a change within species or the production of a new species. This relies on there being variation within a species.
What is a mutation?
A mutation is a random change to an organism’s genetic material (DNA).
What is an important source of variation in a population?
Mutations are spontaneous and are the only source of new alleles (which code for particular characteristics). Mutations are, therefore, an important source of variation in a population.
What are some environmental factors that can increase the natural rate of mutation?
Environmental factors which can increase the natural rate of mutation include:
Radiation (e.g. UV Radiation, X rays)
Chemicals (e.g. mustard gas)
What are mutagenic agents?
Environmental factors that increase the natural rate of mutation are also known as mutagenic agents.
What are the effects of mutations on organisms?
A mutation can have a neutral advantageous or disadvantages effect on an organism, depending on the environment the organism lives in. Most mutations have a neutral effect on an organism.
What is an adaption?
An adaption is an inherited characteristic that makes an organism well suited to survival in its environment/niche.
What is the result of new alleles produced by mutation?
New alleles produced by mutation can result in plants and animals becoming better adapted to their environment.
What does variation help organisms to achieve?
Variation within a population makes it possible for a population to evolve over time in response to changing environmental conditions.
What are the sequence of events that occur during the evolution process?
Species produce more organisms than the environment can sustain.
Natural selection or survival of the fittest occurs when there are selection pressures.
The best-adapted individuals in a population survive to reproduce, passing on the favourable alleles that confer the selective advantage.
These alleles increase in frequency within the population.
What are selection pressures?
Selection pressures are factors which affect an organisms ability to survive in a given environment e.g. predation, food shortage or disease.
What is speciation?
Sometimes evolution can be a result in the formation of new species. This process is called speciation.
What is the sequence of events which occur during speciation?
Isolating mechanisms
Mutations
Natural selection
Speciation.
