World Biodiversity Day: Climate Change Also Drives Evolution
BERLIN - New scientific evidence confirms that human action, such as carbon emissions causing global warming, and industrial-scale search for food, is decimating biodiversity - and, in some cases, is driving threatened species to evolve and adapt at unexpected speed to new living conditions.
An example of this evolution accelerated by human action is the new sexual behaviour of codfish, says the Austrian biologist Ulf Dieckmann, an evolution and ecology researcher at the International Institute for Applied Systems Analysis (IIASA), near Vienna.
According to Dieckmann, codfish has within a couple of decades adapted to new age structure within its own species, provoked by fishery.
Until some decades ago, codfish reached sexual maturity at the age of 10, and only when it measured at least one metre. Now, codfish reaches sexual maturity at the age of six, and when it measures only 65 centimetres, Dieckmann told IPS.
"Some fish species have the capability to adapt to modern living conditions within a very short period of time," Dieckmann said. "Given that large-scale fishery hunts especially the larger and older (codfish) exemplars, the survival of the species rests upon the younger animals," he added.
Dieckmann has been observing codfish behaviour for several years. "Industrial fishery has decimated codfish, and one consequence of this is that there is more food for less fish in the seas," he said. "That's why the younger fish exemplars are growing more quickly, and reach sexual maturity in earlier years."
"You can simply say: If a fish waits too long to procreate, it might be too late, either because the fish has been caught in a net, or because younger competitors have already taken this function over," Dieckmann pointed out.
Dieckmann's findings have been corroborated elsewhere. Biologist David Reznick of the University of California, observed a similar evolutionary process among guppies, a small, freshwater fish, often kept in aquariums.
Reznick observed that if the oldest guppies are retired from a population, their sexual places are occupied by younger exemplars. Since guppies grow more quickly than codfish, the process of evolution occurs within five years, while the adaptation by codfish to new age structure within the population can take as much as 40 years.
Species' capability to adapt to new living conditions is a founding evolutionary element of life. In the absence of massive disturbances, such as a climate catastrophe, evolution takes place at a very slow pace.
However, human-made changes in climate and living conditions of species are accelerating this process of adaptation.
"No species can survive if it is not able to adapt," biologist Matthias Glaubrecht, professor at the Humboldt University in Berlin, told IPS. "The decisive factor is the dimension and the speed of the change in the species' habitat," Glaubrecht, also director of research at the Museum of Natural History in Berlin, added.
Glaubrecht said that it is possible that species in general always have the capacity to adapt to very quick changes in their living conditions. "But, in many cases, human action is evidently the accelerator of evolution."
However, some species cannot adapt to drastic changes. This is the case of the black cock, which used to inhabit large regions of Central Europe, especially in marshlands. As a result of the destruction of its habitat with the industrial exploitation of peat, the species is only found in some northern German regions.
While the black cock is considered a loser in the battle of evolution in the ecological context created by human action, another bird, the white-tailed eagle, is seen as a winner.
"Until some 15 years ago, we believed that this eagle could only survive in the large, quiet forests of old, tall trees in Central Europe," Rainer Kollmann, a biologist at the University of Kiel, some 250 kms northwest of Berlin, told IPS.
"But we had to change our hypothesis," Kollmann said. "We have found that the white- tailed eagle has been able to adapt in a very quick manner to new habitats, in Northern Germany, in Poland, and even in Scandinavia."
Kollmann said that the eagle has been able to adapt to habitats, which, at first glance, appear as less-than-optimal. "If the bird finds the right foodstuff in the middle of cities, then it can even choose that location as its breeding place."
Such an unusual phenomenon has been observed in several Northern German cities, and even along freeways, Kollmann explained.
Other evolutionary changes observed are new singing patterns and earlier sexual activities among birds living in the middle of large cities, compared to similar species inhabiting forests.
But such changes are the benign part of evolution accelerated by human action.
According to the Intergovernmental Panel on Climate Change (IPCC), global warming is already decimating biodiversity all over the world, with some 150 species disappearing every day.
In the report released by the body's working group II last April, the IPCC warns, "climate change is likely to affect forest expansion and migration, and exacerbate threats to biodiversity resulting from land use/cover change and population pressure in most of Asia. Marine and coastal ecosystems in Asia are likely to be affected by sea level rise and temperature increases."
Food insecurity and loss of livelihood are likely to be further exacerbated by the loss of cultivated land and nursery areas for fisheries by inundation and coastal erosion in low- lying areas of tropical Asia.
Similar destruction of habitats for numerous species is to be observed in biological hotspots, such as the Amazons, and in Central Africa, the report added.
Copyright © 2007 IPS-Inter Press Service.