Final answer:
Gene flow occurs when individuals or gametes move between populations, carrying alleles that can alter genetic diversity. An example is young male lions joining new prides and introducing new genes. It is crucial for species diversity and evolution.
Step-by-step explanation:
Gene flow involves individuals moving into and out of a population and is a pivotal evolutionary force. As individuals or gametes migrate, they carry alleles with them, potentially altering allele frequencies in both the source and destination populations. This can introduce new genetic variation into the population they enter and affect the genetic makeup of the population they leave.
For example, plants may disperse their pollen or seeds to new areas through wind or animal carriers, introducing new genetic material into a different population of the same species. Similarly, animals like a pride of lions may experience gene flow as young males leave to find new prides, thus introducing their genetic material into a new group.
Gene flow can have a substantial impact on the genetic diversity within populations, which is essential for a species' survival and evolution. It contrasts with specific evolutionary forces such as genetic drift, which may occur due to random chance events like natural disasters.