DIALOGUE WITH BETTINA MAHLER, Doctor of Biology, CONICET researcher
The eye and the chicks in the nest outside Hypothetical
Al Rider would love to take flight as a picocorto thrush. But not really want to descend on foreign nests. Distraught, he decided to consult with Dr. Bettina Mahler.
By Leonardo Moledo
"Let's start as usual, what do you do?
"During my PhD I began to study various aspects of the ecology and behavior of birds, and in recent years I was devoted to using molecular and genetic tools to answer questions on that topic. In particular, I am now devoting to the conservation of bird species using these tools.
- What are the questions we tried to answer?
"First I studied were parasitic breeding birds such as blackbirds and thrushes picocorto blackened. What do these species are laying eggs in nests of other species that incubate their eggs and raise chicks. Cowbirds become independent and do not charge for anything. It is very difficult, as you can imagine, go along to the thrushes and see where they leave their eggs. What we molecular tools is allowed to answer the question of where they lay eggs. Picocorto thrush, for example: put the eggs in any nest that is out there or pick especially for some reason? Since it is very difficult to follow, we could do is take a sample of cowbird chicks from different nests and see if the offspring belonged to a single female or several females. What we saw, moreover, that had a preference for the nests of a species or species that shared some features (for example, a similar nest type).
- What does not destroy the species parasitized this chick?
-No. Some what they do is recognize their own eggs and take them out of the nest. Other species do not discriminate against anything and accept everything.
"And if I put a plastic egg in these nests, what would happen?
"Depends on the color. We sometimes use eggs made of plaster, and painted a color that mimics the cowbird egg, with some spots. If we paint the same egg white, other refuse. The form of rejection varies with the host species. If a large species, the beak open, grab the egg and remove it. If it is a cute, do not give the opening peak. Then I poke it out. With plaster eggs, of course, can not chop.
- What do they do?
"Depends on what they are so rejected. If we put more than one, may be to leave the nest.
- How could such behavior evolutionarily parasitic structure? Seems to be very adaptive ...
"There is a hypothesis that was a transition from a species built their nests and laid its eggs there, and species that use nests built. The first thing you would have lost the ability to make nests, and then directly, it would have lost the need or the ability to incubate.
-known and once the narrative, what do you do?
-La idea is to see how this behavior affects the species that breed chicks parasites. Because these chicks compete with the young themselves, which lowers the reproductive success of the host. What will happen then? Will decrease the number of potential hosts. And that, in turn, would reduce the ability of the parasite to reproduce. If the parasite, however, several parasitic species, and one of them suffers a decline, that does not mean that the parasite reduces their success. This can affect the population of a host species.
- Are there many birds that do that?
"No, it's actually a very low percentage of species existing.
- And in general gives results?
"Yes. And as this can impact the host population, we wanted to see specifically what are the strategies used by these parasites.
- What are they?
"What we did was to study in Buenos Aires a population of four hosts. Three of them build an open nest cavities used. Females using open nesting species were different from those used by the cavity. So they were looking for, apparently, a particular type of nest to parasitize.
- And beyond that?
-Using genetics of other species that were investigated were problems of conservation. We started working then the pasture species in the province of Formosa, and two in particular: the Strange-tailed Tyrant and tachurí collar. What happened to these species is that grassland environment continued to decline as the expansion of the agricultural frontier, and also were fragmented. What you study hard, then, is the genetic variability represented by the remaining populations in isolated patches of the original environment. And that often gives an indication of what the viability of these populations are to survive, because there is a correlation between variability presented genetic and adaptive potential of the species. Because there is a large genetic variability, should it be a major environmental change, there will be some that will best suit the environment. When there is a large population reduction, there is also a reduction of genetic variability, and that makes adaptive potential of species decreases, it becomes more vulnerable to all kinds of change. When populations are small, also runs the risk of further inbreeding and, therefore, that the recessive alleles are expressed and that further reduce the population.
- How can you avoid inbreeding?
-No be avoided.
"But the primates or mammals have their ways. For example, young males will ... In birds, what happens?
"That depends on the dispersion. Usually, in birds is the female to be elsewhere. Young males are left. But just as there are patches of very isolated environment, the ability of dispersion decreases.
- And what about the yetapa and tachuríes?
"When we began to study the yetapa, we are dealing with other people in Formosa and Corrientes. What we wanted was to compare the genetic variability present in the two populations and whether and are differentiated from one another or if you just had migrations from one place to another.
"There must be a threshold of genetic variability to determine whether migrating or not, right?
"Yes, but it is very difficult to quantify.
"A bird does self-consciousness? Can identify themselves? Because it gives the feeling that if you have to woo if he has to find a nest, you have to perceive a difference between him and the world.
"What a tough question. I, the truth, I do not know that he is him.
- And how a bird mark their territory?
"I just traveled. I think it should have visual cues to recognize the area.
- But how it notifies the other that this is their territory?
"It tells them. And he sings, as if to say "here I am." But he has no clue as mammals.
lmoledo@yahoo.com
Go to link
http://www.unlugarenmismundos.com 
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