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From the remote lakes of a crater up to the ponds to deserts, life opens step. For a long time has been a mystery how some fish have come to colonise such isolated places , surrounded by dry land inhospitable. There are several theories, but none proven. Now, a new study claims to have data supporting that the secret is in the feces of the ducks. The results have just been published in the journal “Proceedings of the National Academy of Sciences” (PNAS).
The idea takes contemplating years: is it possible that some kind of bird can be transported in any way fish eggs in their guts ? Many scientists think that they are too fragile to survive in this “medium”. However, the new research has been tested in conditions of captivity that the 0.2% of all the eggs swallows a duck could be viable beating the entire digestive tract and even once after they eject from the anus.
this Is a process, called endozoocoria , which is common in the spread of plant seeds by some birds and insects. However, for fish, the first evidence was found last year, when it was proved that some fish eggs killifish survived after being swallowed up by a swan. But these eggs are special: they can survive in dry soil for months in a kind of sleep until rain make act of presence, filling the ponds in which they lived their parents.
The dominant theory (up to now)
Until now, the theory most supported was that the eggs of the fish probably travel in the legs, the beaks and the feathers of birds . However, have not found evidence and it is not known if the eggs could survive in these conditions. The new study builds on the experiment devised by the biologist Ádám Lovas-Kiss , the Research Institute of the Danube river in Hungary, who along with his colleagues fed with eggs of two types of carp -common carp (Cyprinus carpio) and prussian carp (Carassius gibelio) eight wild ducks (Anas platyrhynchos).
Each one of the birds was fed with about 500 eggs. Of all these, 18 eggs were recovered the feces of the ducks. is 12 were still viable , although only 3 hatched out with success. Although the numbers seem daunting, bearing in mind that a common carp you may put up to 1.5 million eggs in each spawning and there are many birds that feed on eggs -some marine species feed on single of eggs in certain periods of the year – the odds improve.
“survival was not a strange fact and it came to pass in the 75% of the cases and in the two species studied, ,” says the computer in the study. In addition, the majority of embryos that managed to pass by the digestive tract of birds but failed to hatch suffered a fungal infection that’s probably related to the artificial breeding of fish , according to say the researchers. Thus, in natural conditions, most specimens would have survived.
60 to 360 kilometers away
most of The eggs of carp, it took only an hour to get from one end to the other of the duck. The team calculated that this means a scatter range of about 60 miles for the eggs that travel into the ducks. However, one of the eggs hatched after 4-6 hours, which extends the range up to 360 kilometers.
This theory could explain that the common carp have come to dominate many waterways, australian, composing more than 80% of the fish biomass in some areas. This species damage to fragile ecosystems by modifying the waterways through their habits of sucking mud, we removed food from the native species and contribute to the proliferation of algae. The ability of carps to disperse throughout the endozoocoria would be key in understanding his success by invading sensitive areas. Therefore, the researchers point out the importance of this study on “the conservation of biodiversity and the dynamics of invasion in the exonsistemas of sweet water”.
