So reveals dna-technology nature's secrets

Fjäderkvalster – small microscopic arachnids that live on the wing of a bird has long been regarded as parasites. But when scientists at the research station Estación Biológica de Doñana in Seville, Spain investigated the dna in the stomach contents of 1833 fjäderkvalster of 18 different species that were collected from 18 species of birds, they found no trace at all of either fågelblod or birdskins.

Instead had house dust mites feeding on the fungus that causes the infection and the bacteria.

" Everybody has thought that they are harmful, but as they eat only garbage and pollution, and is actually beneficial for the bird. Perception of who have the benefit of who change completely when we can explore nature at the molecular level. This would have been impossible to study with conventional methods, " says Tomas Roslin, professor of insektsekologi at the Swedish university of agricultural sciences in Uppsala.

has compiled this week's issue of the journal Molecular Ecology, a thematic issue on how the dna methods help researchers to understand how different species interact with each other and thus how all nature is built. The study of fågelkvalster is just one of the 22 articles about such diverse things as microbes späckhuggares skins and arctic spindlars favorite food.

– the Methods have changed virtually everything. Who would ten years ago have been able to imagine that today we can review samples of tens of thousands of creatures, or their feces, and stop us who has eaten who, who pollinate the who, or who is in whose roots, skin, or feathers?

in the Past, biologists dedicate themselves much more to pure guesswork. If they wanted to find out what bats eat, they got to look for small fragments of insects in the animal droppings and try to infer which species they may have come from. When they would study the number of species in an area, they got to collect a few thousand insects and send them off to the taxonomer, thus specialists to classify organisms in various parts of the world to get them identified.

– It could take a few years, and offered terrible amounts of work for everyone involved, " says Tomas Roslin.

instead, extract the dna and compare it with large reference library, and in this way the actual insect them in a few hours or days. They do not even need the whole insect: even if it would only be a single bone left, it is enough to find out which species it belongs to.

Suddenly, we can examine much larger material, and taxonomerna can devote themselves to what they want to do: to explore different exciting species, and thus offer unique and invaluable help to build up referensbiblioteken

Many of the discoveries have come as real surprises.

– An example from our own work is the realization that birds that hunt in the day, the bats that hunt the night, and even large predatory insects like dragonflies on the same prey, " says Tomas Roslin.

another surprise is how important migratory birds are spreading the seeds of trees and shrubs in the Mediterranean region.

– examining the dna from seeds in bird droppings, and discovered that it mostly happens in a really short period of time when the migratory birds come.

has vastly improved rapidly in the last few decades, with a speed that allowed the development of new computers seem slow. Thanks to the can the biologists for the first time, systematically determine how different organisms are interconnected with each other in nature's complex food webs.

– Previously we have usually tried to draw conclusions on the basis of which species live in the same area. Now we can begin to ask new questions – questions that previously could not even imagine, " says Tomas Roslin.

There is an ongoing international collaboration to build up the library of dna sequences, which serve as genetic barcodes that biologists can use to identify what they have found in their samples. An example is the database Bold, which currently includes variants of a certain gene from the more than 6.7 million organisms from all over the world.

located behind several of the studies in the temanumret. In a collaboration with researchers in other countries, they put out sticky blomattrapper next to the real fjällsippor throughout the Arctic: in Norway, Finland, Russia, Canada, Alaska, and in Greenland and Svalbard, and captured more than 1360 different species of insects.

– our Whole idea that the Arctic is artfattigt is just nonsense. It is envisaged that it is the world's easiest organic system, but it is terribly complicated. For that we should be able to understand how climate change is affecting nature, we must look at the whole picture, where many different species are jättehårt interconnected with each other, " says Tomas Roslin.

In another research project ground the scientists down matsvampar to puree in a standard blender. Out of the soup got to the front of the dna from all the insects, parasitsvampar and bacteria that live in and on the own little world as the mushroom is in the forest.

Similar massprover is also possible to do in the water from a lake or from a bucket full of insects collected in the same place.

– All forms of dna will out, and you get track of the whole mess at once, " says Tomas Roslin.

It is also possible to find the traces of animals that no longer exist in the wild.

– You can discover ancient and very weak tracks, dna from mammoths and wild oxen of the has been about and for the in an area for a longer period of time. But it requires even more refined methods, since only small amounts and the dna molecules are broken down with time. You must also be extremely careful so that one does not accidentally add dna that were not there from the beginning.

the researchers ' job easier, but also opens up completely new worlds and makes science so much more exciting, says Tomas Roslin.

– We cannot understand a species without understanding the interaction with the other, and we will now for the first time. We don't study longer species pairs, as a predator and a prey. Now we can see how the type 100 predators is linked to the 100 prey. It is really ultracoolt, " he says.

To study arctic spiders, mites on the birds and insects that live in mushrooms might seem unnecessary or uninteresting for other than insektsbiologerna themselves. However, according to Tomas Roslin, it is extremely important.

– this small species has been virtually impossible to study make up almost all life. You do not understand a damn if you don't understand them. It is they who are the life of the earth.