Parallel evolution

Parallel evolution was an evolutionary process by which separate groups of organisms occupying different but equivalent environments developed similar adaptations or characteristics for survival.

Cybermen

The Cybermen of the Mondasian colony ship encountered by the Twelfth Doctor. (TV: The Doctor Falls)

Main article: Genesis of the Cybermen

The Twelfth Doctor cited this as the process that led to the independent development of several factions of Cybermen on various planets throughout time and space, including Mondas (and on a Mondasian colony ship), Telos, Earth, Planet 14, and Marinus. (TV: The Doctor Falls)

Daleks

Main article: Creation of the Daleks

When later historians and scientists discovered Bryant Anderson's research that suggested that the Daleks were descended from humans transplanted onto Ameron, parallel evolution was suggested as an explanation to reconcile this with the known history of the Daleks being native to Skaro. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) Indeed, the Dalek Survival Guide suggested that all sophisticated humanoid species ran the risk of allowing themselves to develop into a Dalek-like race. (PROSE: Dalek Survival Guide)

Qualen came to believe that the Daleks were destined to arise, regardless of the Doctor's involvement; based upon Davros' own research, he believed that the ongoing nuclear civil war on Skaro would have inevitably resulted in the creation of the Daleks "or something very like them." (PROSE: The Dalek Problem) Indeed, the Dalek Prime once claimed Davros had interfered with their development by bringing them into being earlier than they were destined to, (PROSE: War of the Daleks) although Davros proclaimed at other times that the Daleks only acted the way they did because he made them in his own image. (AUDIO: The Davros Mission, et al.)

Human historians in the post-Time War universe were aware of conflicting accounts of the creation of the Daleks which did not involve Davros, most notably their creation at the hands of Yarvelling, a scientist of the blue-skinned Humanoid Daleks. Historians suggested that these alternative "origin stories" may have temporarily became true as the Time Lords "reached back to reconstruct the past" during the Time War. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Other references

When Marc Cory explained to Gordon Lowery that vargas on Kembel meant the Daleks were there, Lowery suggested that they could've grown naturally via parallel evolution or even been transplanted, but Cory explained they were developed in Dalek laboratories. (PROSE: Mission to the Unknown)

Historians suggested that the late Silurians' broad resemblance to humans was an example of parallel evolution. (PROSE: The Monster Vault)

Behind the scenes

In the real world, this mechanism whereby largely unrelated organisms independently develop similar traits (becoming more similar than their ancestors had been) is actually called convergent evolution.

In parallel evolution, organisms develop similar characteristics within the same environment, rather than simply responding to similar environmental pressures.