Final answer:
Lions and tigers last shared a common ancestor likely due to geographical isolation. As species evolve, natural selection, genetic mutations, and environmental changes can further differentiate them. Male lions leaving their prides affect allele frequencies through genetic drift or gene flow.
Step-by-step explanation:
The last time lions and tigers shared a common ancestor, the cause could have been geographical isolation. This process is known as allopatric speciation, where groups of animals become separated, leading to the evolution of separate species. Over time, natural selection, genetic mutation, and environmental changes then work to create even more distinct species.
Male lions leaving their pride at sexual maturity can alter allele frequencies through genetic drift, or in some cases, gene flow if they join another population. Charles Darwin and Alfred Wallace independently discovered that natural selection plays a crucial role in the evolution of species, as populations evolve when certain conditions are met. One of these conditions is the variation of traits, which is crucial for natural selection to act upon.