What is the term used to describe the flow of genes between species through hybrid offspring?

The flow of genes between species through hybrid offspring is indeed referred to as "leakage." This term captures the concept of gene flow occurring when individuals from distinct species interbreed and produce hybrids that can carry alleles from both parental species. This process can result in genetic material being transferred across species boundaries, which can have significant implications for evolution and biodiversity.

When hybridization occurs, it can lead to the introduction of new genetic variations in the population, potentially allowing for adaptations and changes in traits that may benefit the participating species. Leakage highlights how interconnected species can be over evolutionary time, influencing each other's genetic makeup through this kind of interaction.

In contrast, the other terms do not accurately describe this process. Gene drift refers to the random changes in allele frequencies that occur in small populations, which is more about statistical variance rather than hybridization. Speciation is the process by which new species arise, often as a result of reproductive isolation, and does not inherently involve gene flow between existing species. Mutation refers to a change in the DNA sequence that creates new alleles but does not involve interactions between species. Thus, "leakage" is the most relevant term for gene flow through hybrid offspring.