The research proves that natural barriers can result in the emergence of subspecies and consequent speciation, which is the formation of a new species.
One hundred and forty years after Charles Darwin’s death, researchers at the University of Cambridge in the United Kingdom published an article in the scientific journal PNAS demonstrating that the scientist was right: subspecies of mammals play a more important role in evolution.
“In Chapter 3 of On the Origin of Species Darwin said animal lineages with more species should also contain more ‘varieties’. Subspecies is the modern definition,” explains Laura van Holstein, the research leader, in a statement. “My research investigating the relationship between species and the variety of subspecies proves that sub-species play a critical role in long-term evolutionary dynamics and in future evolution of species. And they always have, which is what Darwin suspected when he was defining what a species actually was.”
A species is a group of animals that can reproduce with each other. Some species contain subspecies, which are populations within a species that differ in that they have different physical characteristics.
The anthropologist confirmed Darwin’s hypothesis by looking at data collected by naturalists over hundreds of years – long before Darwin visited the Galapagos Islands onboard the HMS Beagle. On the Origin of Species was first published in 1859, after a five-year voyage of discovery, and in Darwin’s work, he argues that organisms gradually evolved through natural selection – also known as survival of the fittest.
Van Holstein’s research also proved that evolution happens differently in terrestrial mammals, marine mammals and (non-terrestrial) bats due to divergences in their habitats and their ability to move freely. “We found that the evolutionary relationship between species and subspecies of mammals differs depending on their habitat. Subspecies form, diversify and increase in number differently in non-terrestrial and terrestrial habitats, and this, in turn, affects how subspecies can eventually become species, ” explained the researcher.
According to her, if a natural barrier such as a mountain range disrupts the interaction between members of a species, for example, individuals in the groups will begin to evolve independently, which can lead to the formation of subspecies. Van Holstein’s research explored whether the subspecies could be considered an early stage of speciation, which is the formation of a new species.
“The answer was yes. But evolution isn’t determined by the same factors in all groups and for the first time we know why because we’ve looked at the strength of the relationship between species richness and subspecies richness,” said van Holstein. “Evolutionary models could now use these findings to anticipate how human activity like logging and deforestation will affect evolution in the future by disrupting the habitat of species.”