New evidence shows that the flightless birds, the ostrich and the emu, evolved separately from a flying ancestor, but underwent convergent evolution in different environments
The African ostrich, the Australian emu, the South American nando and the New Zealand kiwi are all birds similar to each other in that their wings are not used for flight. Kiwis don't have wings at all, just bumps under their plumage. To escape and defend themselves from predators, the birds use their muscular and strong legs. The knowledge until now was that they all had a common ancestor who lost the ability to fly, but new DNA evidence proves that each species that exists today lost its wings independently, after splitting from ancestors that were able to fly.
The new study, which appeared this week in the online edition of the prestigious scientific journal, PNAS, yields two important insights. First, it indicates that some flightless birds are more closely related to their flying cousins than to other flightless birds. The second insight is that these birds are the product of convergent evolution, in which different species in different environments develop according to the same evolutionary path.
Edward Brown, a professor of zoology at the University of Florida, and his colleagues began studying this group of flightless birds, collectively known as 'ratites', after recent progress was made during a large-scale project designed to trace the evolution of birds through their genomes. During the project, genetic samples extracted from the tissues of birds of many species were analyzed, and it was determined how they are related to each other.
When the researchers analyzed the genetic material extracted from the ratites, they discovered that these birds do not belong to a natural group based on their genetic structure. Surprisingly, it turned out that they belong to several related but distinct groups, including the tinamous group, which contains birds capable of flight.
The prevailing hypothesis in the past was that the ratites are a masterful example of the way in which one species splits into several geographical areas and undergoes evolution according to environmental conditions. The scientists hypothesized that the flightless ancestor of the ratites lived on the Gondwana supercontinent. This continent split into Africa, South America, Australia and New Zealand, and representatives of the ancestor remained on each of the continents. After the split, the ancestor underwent a different evolution on each of the different continents to today's ostriches, emuys and nandos.
According to Brown, it is now more likely that the early ancestors of the Ratites dispersed to the southern continents after the breakup of Gondwana, but in a much simpler way than previously suggested. They just flew away.
Although these new insights add much knowledge to evolutionary biology, they also raise many new questions. Why, for example, did these birds evolve into such similar life forms, in such different living environments?
"To know for sure, we'll have to go to the lab and actually study the genetics that control the developmental trajectory of the ratites," Brown said. "But no one would have asked this question if we hadn't collected the data that led to the question being raised in the first place."
The conclusions about the origin of the ratites are only a small part of a massive research project aimed at better understanding the evolutionary relationships between different bird species. The project involves five institutions, 18 researchers, funding of 2 million dollars and four years of work.
12 תגובות
Michael
There are things that even my place refuses to understand, if only for the sake of the required supreme protection.
Hugin
Hugin:
Apparently no one but you understood.
Convergence - in literal translation - Convergence and not in
Michael
I'm afraid you haven't yet understood the essence of what is being asked.
But, admittedly, there is an interesting process in the cerebral confederation that is forged in our conversations.
Hugin:
This is not loyalty - it is a misunderstanding.
The word "in" has the directional meaning of "in" while the word con has the meaning of sharing (like a confederation).
By the way - clearly not coincidentally, the term in Leaz is Convergent evolution as described in Wikipedia here:
http://en.wikipedia.org/wiki/Convergent_evolution
Note that this term also begins with a koon.
Michael
If so, I will go with the inverted chaining legality according to your "cubic" definition - which tends to add.
Evolution-convolution-involution.
By the way, since I am really original, my terminology is always valid in my opinion.
But what's interesting is that they took an originally foreign concept and dressed it in Hebrew and in this case I stayed
True to the foreign nomenclature - convergence = none.
Hugin
Hugin:
The accepted term in the profession is convergent evolution.
There are several examples of the process here and you can add to it the similar mechanisms used by spiders and lizards to stick to the wall or the surprising parallel between the types of marsupials and the types of animals with a lack of a pouch.
These are all examples of similar selection pressures creating similar phenotypic outcomes through different genetic mechanisms.
So the side of your question about the essence of "convergent evolution" is understandable to anyone who is familiar with the subject and now, I hope, to you too.
Why you always called "involution" we don't know.
It is you who said that for many years you call "this" involution, but you did not specify what you mean by the word "this".
From the context it can be understood that the word "this" is meant to represent what we call convergent evolution but then your question is tautological because it means "do when we say convergent evolution do we mean convergent evolution?"
By the way, in my opinion, the choice of the term "involution" is not successful. If I had already chosen "convolution" (just as lines that pass through the same point are concurrent and points on one line are collinear - and Yehuda - please hold back - I didn't mean for you to read it with a score that associates it with nutrition 🙂 )
Aryeh Seter
The nomenclature is very interesting, convergent evolution...I have been calling it "involution" for many years
Do we mean the same thing but with slightly different terminology?
Thanks for the comments, I changed accordingly.
A small note. It is written in the article about birds whose wings are not used for flight. I don't know how it is about the Nendo but the Kiwi has no wings at all! If you make an effort (and shave the down), you may find a tiny bump instead of the wing.
Regarding parallel evolution - it is customary to call it convergent evolution. Convergent evolution also exists between different classes, for example, the form of fish, whales and ichthyosaurs (an extinct marine reptile).
Oh, finally the genealogical gene of my evolutionary family is also found for scientific recognition.
It is recommended for those who have not yet seen the amazing documentary: "Migratory Birds", to watch and learn from them about miraculous harmony.
And to the credit of scientific developments: these were not the Levians, they could not be observed in the places where a human foot has walked
It is better not to defile their holiness (there are places we can only look at, but not touch!)
I saw (originally) the question "Why.., did these birds evolve into such similar life forms, in such different living environments?" ,
It is difficult to get an answer when you ask a question that is not formulated correctly:
Because the emu and the ostrich live in a similar environment, the nando and the kiwi live in a similar environment,
That is, similar development under similar environmental conditions,
A well-known and recognized phenomenon in zoology.
Much more important in my opinion is to investigate the gene responsible for burying the head in the sand and whether their common ancestors had this wild instinct