Looking different to your parents can be an evolutionary advantage
Looking different to your parents can provide species with a way to escape evolutionary dead ends, according to new research from Queen Mary University of London (QMUL).
Unlike humans, which are diploids -- with two copies of each of their 23 chromosomes (one from each parent), - polyploids can have three, four or more copies of each chromosome. This makes them particularly prone to producing hybrids and, - in contrast to better-known hybrids such as the mule which is (the sterile product of a cross between a male donkey and a female horse), means that crosses between polyploids are often fertile.
While hybrids might be expected to be a blend of the two parent species, the researchers found that they tended to have shorter and wider flower openings than both of the parent species which means that a wider range of pollinators can enter the flowers.
By allowing a wider range of insects to pollinate them, hybrids make themselves much less vulnerable to the extinction of a single pollinator.
Dr Elizabeth McCarthy, who carried out the work as part of her PhD at QMUL but who is now at University of California Riverside, said: "Some plants evolve increasingly specialised relationships with the species that pollinate them. A classic example is Darwin's Madagascan orchid, first discovered in 1798. Its exceptionally long nectar spur led Charles Darwin to propose that it was pollinated by a moth whose proboscis -- the organ that extracts the nectar -- was longer than that of any moth known at the time. Darwin's prediction was spectacularly verified 21 years after his death when just such a moth was discovered."
The problem with this sort of specialised relationship -- which we now term coevolution -- is that if one of the two species involved becomes extinct, the other is also doomed.
The findings are published in Nature Plants.
Source: Queen Mary University of London [August 08, 2016]