Biodiversity Crisis Redefined: Flora And Fauna Are Becoming More Homogenous
When they looked at various plant and animal systems over the past 150 years worldwide, ecologists were surprised to find that the Earth is not losing its biodiversity; it's just changing the type of biodiversity it has. Researchers from the University of St. Andrews in Scotland; the University of Maine, the University of Vermont; and Keio University in Japan culled more than six million observations of 35,000 species of plants and animals from terrestrial, freshwater, and marine habitats all over the globe. Instead of finding a loss in biodiversity, they discovered that species have been becoming more similar to each other. "We found as many surveys with a systematic loss as well as gain in the number of species," said the meta-study's lead author, Dr. Maria Dornelas, of the Centre for Biological Diversity and Scottish Oceans Institute at the University of St Andrews, in a press release. "This is surprising given current concerns of a biodiversity crisis and abnormally high extinction rates." The authors attributed this to the war on habitats waged by "invasive species, which have been rapidly spreading around the globe, and the shifting ranges of species in response to climate change," among other culprits.
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The mechanism at work in our bland new world is so-called "biotic homogenization," whereby species' invasions and extinctions increase the genetic or functional similarities between species. The trend towards biotic homogenization is a distinct facet of the broader biodiversity crisis, loaded with threatening ecological, evolutionary, and social consequences, the authors wrote, adding, "Monitoring and understanding change in species composition should be a conservation priority." The researchers insist that the study should not detract from the threat many of the world's species are under, but that policy-makers should focus on changes in biodiversity composition as well as loss.
Policy-makers have begun that focus. The the UN Food and Agriculture Organization has said that homogeneity could be a factor in world hunger in the future. The loss of biodiversity among livestock is striking, with almost a quarter of domesticated breeds at risk of extinction due to product-focused selection of more uniform breeds from industrialized countries. About three-quarters of genetic diversity of crops was lost in the last century as farmers worldwide switched to genetically uniform, high-yielding varieties and abandoned local varieties. There are 30,000 edible plant species, but only 30 crops account for 95 percent of human food energy. About a year ago, Zakri Abdul Hamid, who heads the International Science-Policy Platform on Biodiversity and Ecosystem Services,urged policy-makers to be mindful of those challenges. "A changing environment makes it more important than ever to have a large genetic pool to enable organisms to withstand and adapt to new conditions," Dr. Hamid said.
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