Humans had shaped species distributions since the Late Pleistocene, PNAS study confirms

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Humans had begun to engage in activities that has led to the alterations in the distributions of a vast array of species across most, if not all, taxonomic groups by the Late Pleistocene, a new study published today on PNAS confirms ( PNAS, Special Feature: Perspective, 7 June 2016 vol 113 no 23). It’s important to note that “changes to biodiversity included extinctions, extirpations and shifts in species composition, diversity and communities  structure”. Authors explain how the human ability to reshape global biodiversity is not a result of contemporary civilization : “the evolutionary trajectory of Homo sapiens has seen an exponential increase in the scope and impact of human niche constructing activities that have culminated in fundamental changes to planetary ecosystems”. The authors’ insight into microfossils and ancient DNA reveals “a pattern of significant long-term, anthropogenic shaping of species distributions on all of the Earth’s major occupied continents and islands (…) Few, if any, regions can be characterised as pristine. Extinction has been the starkest of these anthropogenic impact, but widespread changes to species abundance, composition, community structure, richness, and genetic diversity as a result of human niche construction are also increasingly demonstrable and of equally lasting impact”.

In settling the Planet, a lot of species stopped being only wild and became domesticated, invasive, commensal and pathogenic. “Diverse archeological assemblages from Africa, Europe and South Asia document the Late Pleistocene appearance of small, quick and difficult-to-catch game, such as fish, birds, rabbits, rodents and monkeys, that may signal anthropogenic impacts to resource availability. Other studies document decreases in the size of certain species as limpets and tortoise that may also reflect resource overexploitation”. We can see the same pattern in the current hunting for bushmeat in Angola ( find more at: UNEP : Angola, bushmeat trade threats eco-tourism ) and South East Asia. One of the main traits of Homo sapiens is the trophic plasticity related to cultural schemes.

But this study remarks also the importance of enormous urbanised settlements that have been creating interrelated networks of trade, economies, social interactions on a global scale. Cities are hot spots of the niche construction ability because they elaborate mindsets that indirectly affect ecosystems and species diversity. And defaunation too is an expression of it. “Defaunation is another enduring legacy of ancient human activities. The emergence of socially stratified urban societies in the Near East and Egypt, for instance, was linked to the extirpation of a number of wild animal species (…) Equus hemionus, Gazella subgutturosa, Alcelaphus buselaphus, Orix leucorix, Struthio camelus were all extirpated largely from ungulat mass kills. Ancient urbanisation contributed to a major reduction in large-bodied mammal species in Egypt, from 37 in Late Pleistocene/Early Holocene to only 8 today”.

One of the main point of the study is the striking link between present-day patterns and past-days patterns, that means we must think extinction processes historically and over time. “Most landscapes are palimsests shaped by repeated episodes of human activity over multiple millennia “( E.Ellis et al. quoted from 2013, Used planet: a global history, Proc Natl Acad Sci USA 110 (20): 7978-7985). The second remarkable point is that the speed of the process – it worked by pauses and accelerations – is both culturally and ecologically determined. But the third point crucial to our understanding of the problem – maybe the most relevant point – is that the dramatic change in species distribution across the globe has been the key factor to sustain an even bigger human population.

So, after two thousand years of evolution, can we still imagine a place for animals ? And is the common  concept of species still relevant to us ?

Annunci

Tracking Extinction on lastampa.it

Starting with today 30th of June La Stampa (lastampa.it) publishes my Tracking Extinction series. Here the schedule and hot topics :

30th of June : Neofelis nebulosa in Thailand

6th of June : Bushmeat and wildlife trade in Hanoi with Education Nature Vietnam Ngo

13th of June : Bear bile farming and Tam Dao Sancturay of Animals Asia Ngo

20th of June : Cuc Phuong NP, Vietnam, and Save Vietnam’s Wildlife Ngo

27th of June : Butterflies at Natural History Museum in Hanoi

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The future of Vietnamese turtles at Cuc Phuong NP

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Biodiversity crisis has entered  into an acceleration process. It means not only that the main benchmarks of habitat loss, defaunation and deforestation are getting worse. The more the situation becomes critical, the more grows the grey zone in which species struggle to survive, for instance in the rescue centres at the borders of protected areas. This is the case of Turtle Conservation Center at Cuc Phuong NP in Vietnam. Cuc is a spectacular patch of primary forest – or better an island of primary tropical forest – in the district of Ninh Binh. The park is isolated from big investments in conservation and research and looks encapsulated in a sphere out of time. The old compound of tourist facilities (lodges and restaurant) are dated to the seventies. In this atmosphere of remoteness Turtle Conservation Centre speaks up of the current status of Vietnamese tortoise and turtles by showing small, brown and muddy enclosures where rare species seems wait for the end of time. In Vietnam turtle hunters are professional. They scour forests with dogs : their goals is taking over how many turtles they can. In some regions a turtle is worths a month’s salary. And species that up to a few years ago were an occasional delicacy are now on the brink of extinction. According to Education Nature Vietnam (ENV)  of the estimated 25 species of tortoise and freshwater turtles native to Vietnam “16 are listed as critically endangered  or endangered on Red List”. Cuc Phuong’s Center confirms this picture describing how Vietnam is a hot spot for turtle smuggling. The county is a transit for turtles that have been catched and trafficked in Laos and Cambodia. Poachers smuggle them across Vietnam northwards to China. This is the same old bushmeat story: in the last two decades Chinese life standards have dramatically improved. As a result a sensitive interest for sophisticated food has emerged. Furthermore the better diplomatic relations with China have fuelled transfrontier trade between the two countries. And this helps poachers. In just one week a turtle can pass from a forest to a Chinese market. Vietnamese and south Eastern Asia turtles are at the centre of this perfect storm. After 200 millions of years, a sad poster at the Centre says, fresh waters turtles are on the edge. The keepers live within the park not far from here; theirs dogs go around among the green sinks and smell dead leaves. These dogs remind me how our species was succeful in eradicating animals from their habitat. By inventing always more ways of eating. The time capsule of Cuc Phuong sounds incredibly ancient here, where the most of animals I see are yet relics of another age.