Ecocentric

How Human Activity — and Extinctions — Are Driving Evolution

When humans cause species to go extinct, the effects ripple throughout the surrounding ecosystem

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Image courtesy of Edson Endrigo

A toucenet eats palm fruits in the Atlantic rain forest. The birds play an important ecological role in dispersing palm seeds

We’re likely in the middle of a mass-extinction wave, most of it likely because of human activity. For a species to go extinct is an intrinsic loss, if not exactly an unprecedented one. Ninety-nine percent of all the species that have ever existed on earth eventually went extinct — but they’ve rarely died out as rapidly as they are today. It’s like global warming — it’s not the simple fact that things are changing that is so worrying, it’s the speed. And as it turns out, the life on our planet can change very, very fast.

That’s the takeaway from a neat new paper published in the May 30 Science. Rain forests in the Brazilian Atlantic region became increasingly fragmented over the past century as settlers cleared land for agriculture or logging. As the forest broke up, numerous species were pushed into extinction or made increasingly endangered — including the channel-billed toucan, a tropical bird with a characteristically large bill (think Toucan Sam). The channel-billed toucans are frugivores — fruit eaters — that consume large-seeded fruits that smaller birds can’t handle. When they eat those fruits, they disperse seeds around the forest as they fly from tree to tree, helping to spread the very tree species they feed on. This is a healthy ecosystem at its best.

 (VIDEO: Timelapse: Watch the Planet Change Over 30 Years)

Or it would be, except that population levels of the toucan have fallen dramatically over the past century, thanks to hunting and deforestation. Bad for the birds, obviously. But what the Brazilian and Spanish researchers in the Science study found was that as the toucan disappeared, the forest around it changed. The palm trees that produced the fruit popular with the toucans adapted to the loss of the bird by producing fruit with smaller seeds — small enough for other birds to disperse. In short, the trees evolved.

But not exactly for the better. The new seeds produced by the palm trees in patchy, toucanless areas of rain forest were less fit, producing smaller and less vigorous seedlings than the larger seeds — which could be dispersed by the toucans — could have. This is the healthy ecosystem inverted — the loss of a species touches another, and even if the latter survives, it does so weakened and fragmented. It’s evolution in motion, but evolution fought as survival in a world that is changing too fast, as lead author Mauro Galetti from the Universidade Estadual Paulista in São Paulo put it in a statement:

Habitat loss and species extinction is causing drastic changes in the composition and structure of ecosystems, because critical ecological interactions are being lost. This involves the loss of key ecosystem functions that can determine evolutionary changes much faster than we anticipated. Our work highlights the importance of identifying these key functions to quickly diagnose the functional collapse of ecosystems.

Some 80% of the Atlantic rain forest biome has become fragmented, broken up by slash-and-burn agriculture and pastureland. You can see how one Brazilian state became deforested over the past 30 years at our Timelapse page. Deforestation rates in the Amazon had slowed in recent years, but now they seem to be picking up again — even as climate change and drought will only increase the stress on the rain forest. And the evolutionary experiment will keep playing out in front of us.

14 comments
RealitySucks
RealitySucks

So let's get this straight - the author believes that the TREES are somehow "aware" that the birds are not around to eat their seeds and therefore it "KNEW" it needed to make different seeds. Then, it "KNEW" that the problem was linked to the size of the bird, and then had the ability to change it's genetics to produce smaller seeds ? We are talking about a tree here, right ?

Really ? And evolutionists think that this makes more sense than Creationism ?

Gee, lets see - EVERY time man goes against God's word, there are severe consequences for those actions. There are exactly ZERO documented cases of evolution. Every time a "link" is supposedly made between man and some man-like organism, there is too great a leap between the two to prove and sort of evolution. If man evolved from something, there should be MILLIONS of skeletons of our predecessors. You know why there aren't ? Because evolution is BS...

Continue to deny God and he will eventually deny YOU.


DREGstudios
DREGstudios

Here in Tennessee, we’re just glad to have our thumbs.  Don’t think for a second this will end up in Southern Classrooms of the unprogressive.   Christian ideology teaches us to deny, deny, deny Evolution  as teachers are now allowed to put Creationism into debate against hard facts like this new discovery.  Read more about the pulpit in the classroom with some evolutionary artwork on my artist’s blog at http://dregstudiosart.blogspot.com/2012/04/pulpit-in-classroom-biblical-agenda-in.html  

kolagunta
kolagunta

In Indian urban areas we are finding the number of sparrows, crows and mynas depleting very fast. In fact in some areas they have virtually vanished all due to the mobile telephones. The natural cycle of worms being eaten by the birds is now not seen. The ant population has increased.

rutnerh
rutnerh

Our feeble human follies will have minimal impact on extinctions and evolution of new species that have occurred natur

KnowledgeCubed
KnowledgeCubed

Evolution is the idea of creating energy out of nothing (ie building up not tearing down), improving the ability to survive. What this article I believe is trying to say is that instead of maintaining our environment (like painting our house to protect from decay) we are hurrying it towards the natural end-state of entropy (like painting your house with a flame thrower.) If we do not control ourselves we are bound to destroy ourselves.

RedTapeMovement
RedTapeMovement

This is Human driven evolution. Activities of humans are destroying environment and pushing species into extinction. Well written blog article; thanks Bryan.

rebeccapistiner
rebeccapistiner

What makes these changes un-natural? Is it the speed in the change (as is stated in the article)? Or the change itself? 

rharris
rharris

Good to see Time addressing this topic. It would have been better if the article hadn't started "We're likely in the middle of a mass extinction...likely due to human activity." Replace "likely" with "definitely" and the report would be accurate.

Pale.Horseman
Pale.Horseman

The USA is a Super-organism and so is Humanity

Diagnosis: AIDS

With no change in life-style, it's death (extinction)

The Socio-Cultural Norms (Implicit Rules/Laws) that comes from conditioning keep causing people to perceive and interpret actions that destroy the Immune/Repair Systems of the Super-organism to become compromised.  

Super-organism can become sick.  Bee Colonies today are having Colony Collapse Disorder. What systems in the USA Super-organism act as an Immune/Repair systems for the body of the USA?  Social Security, Medicare/Medicaid, Health-care, Psychology, Psychiatry, Churches, and Vocational Rehab programs.


If all those systems have been compromised, then the USA has Acquired an Immuno-Deficiency Syndrome like Colony Collapse Disorder for bees!


DamnDirtyApes
DamnDirtyApes

@RealitySucks the trees are not "aware" that the birds are not around anymore. and a tree cannot change its genetics. the way it works is that the trees that produce smaller seeds because of a mutation (which would normally not benefit it) survive and produce offspring that has this mutation which go on to produce more trees with the mutation. Like you said trees do not "know" anything. And there is proof of evolution, read The Origin of Species by Charles Darwin. Its got everything you need to know. And as far as going against God's word, he promised not to interfere with our world after the whole noahs arc incident.

Hadrewsky
Hadrewsky

@rutnerh 

The human species could wipe out every inch of rain forest or burn the planet with nuclear fire.... what you call feeble is silly at best