1. Genetics:
* Mutations: Random changes in the DNA sequence can introduce new traits. Some mutations are beneficial, some are harmful, and some have no effect.
* Gene shuffling: During sexual reproduction, genes are recombined, creating new combinations of traits in offspring. This process is called genetic recombination.
* Gene flow: The movement of individuals between populations can introduce new genes and increase genetic diversity.
2. Environment:
* Environmental factors: The environment can influence the expression of genes. For example, a plant might grow taller in sunny conditions than in shady conditions, even if it has the same genetic makeup.
* Natural selection: The environment selects for traits that help individuals survive and reproduce. Individuals with favorable traits are more likely to pass on their genes to the next generation.
3. Chance:
* Genetic drift: Random fluctuations in allele frequencies can occur, especially in small populations. This can lead to the loss or fixation of certain alleles, even if they are not necessarily beneficial or harmful.
In summary:
Variations within a species are a result of the interplay between genetics, environment, and chance. While genetics provides the blueprint for traits, the environment influences how those traits are expressed, and chance can play a role in the distribution of those traits within a population. This variation is crucial for the survival and adaptation of species, allowing them to cope with changing environments and exploit different resources.