Millions of people feed birds, even people who don’t watch birds will put food out for them. Recently, scientists found that feeding birds during winter could alter their evolutionary future. In less than thirty generations, one population of birds can break into two populations that do not breed together anymore. This could be true of rare and common birds.
For three years, scientists followed blackcaps, which are in Central Europe and that have been fed by humans. After a while, the group split up into two groups and had two different migration routes. One shorter route to the northwest in the UK and one longer route to the southwest in Spain. In the shorter route the birds feed on human-given food and in the longer route the birds feed on fruits. The northwest group of blackcaps have changed their morphology by having rounder wings an d longer, narrower bills. The rounder wings are better for maneuverability, but not so good for long migrations routes. The narrower bills are now not suited for the fruits and olives the other group eats.
This new data gives new light to a debate whether geographic isolation brings new species. Even though the two groups live together for part of the year, they have developed reproductive isolation. This study shows that evolution is not just super slow, but can happen within a few generations. If the current isolation continues, these birds can become different species.
Birds may not be the only ones that can be changed in a few generations due to humans. When people introduce honeybees to pollinate plants where there was none, the plants may change to be more honeybee-friendly.
Speciation may not necessarily occur with blackcaps, but it is apparent that ecological changes can change populations. However, this may not be applied to all species.
