Adaptations Flashcards
Define the term mutation
Mutations are random changes in genetic material. They happen spontaneously, without any warning. When they happen, an entirely new allele (type of gene) is created. This is the only way new alleles can be created.
Define the term Allele
The type, or variation, of a gene. For example, if the gene is for eye colour, the allele may be blue, brown or green.
Define the term adaptation
An inherited characteristic that makes an organism well suited to survival in its environment/niche
Define the term variation
The variety of differences between members of the same population. (For example, depth of fur, length of legs, et cetera.)
Define the term natural selection
Where the best adapted individuals are more likely to survive and breed, passing on their favourable alleles to the next generation.
Define the term evolution
The process by which a population gradually changes, in response to environmental changes, to become a new species.
Define the term speciation
The production of two or more new species from one.
Isolation barrier
Any change that prevents two sub-populations breeding. Types include Geographical, Ecological and Reproductive.
Define the term selective pressure
Any environmental or behavioural feature that selects for individuals with certain traits. (Warm coats, breeding plumage,
longest necks, et cetera.)
What happens when mutations occur
When mutations occur in gametes (sex cells, e.g. eggs and sperm, pollen and ovules), they can be passed on to the next generation. This can lead to offspring with green eyes instead of blue, a longer neck, smaller wings, or any number of other possibilities.
What are mutagenic agents?
Mutagenic agents are factors that increase the rate of mutation.
•high temperature
•radiation
•chemicals
Types of mutations
mutations can be useful, harmful or have no effect at all
•useful mutations offer a selective advantage
•harmful mutations offer a selective disadvantage
•mutations that have no effect are termed neutral
Adapting to the environment
New alleles produced by mutation can result in plants and animals becoming better adapted to their environment. These new alleles and adaptations create variation within a population. This variation makes it possible for a population to evolve over time in response to changing environmental conditions, as there is a greater likelihood that someone will have a favourable trait.
Why does natural selection occur?
Natural selection occurs because species produce more offspring than the environment can sustain.
How does natural selection occur?
Natural selection, or survival of the fittest, occurs when there are selection pressures, usually caused by competition for resources. The best adapted individuals in a population are more likely to survive to reproduce, passing on the favourable alleles that conferred the selective advantage on them. These alleles will then gradually increase in frequency within the population.
