So where did birds come from - and where are they going?
By Charlie • June 28, 2008 • 16 commentsThere’s an interesting article doing the rounds at the moment that looks at the early history of bird evolution and speciation by studying avian genetics. Simply put (which is the only way most of us CAN put it, I suspect) geneticists have analysed the make-up of specific slices of DNA from 169 species and then compared the slices with each other. They have then recorded how closely the components that make up the slices match each other (or differ from each other) and have drawn some (or, ‘drawn, some would say, some’) interesting conclusions:
“WASHINGTON (AFP) - - A five-year project has revolutionized scientific
thought on the evolution of birds and the results are so surprising that now
even the textbooks will have to be rewritten, a study said Thursday.
“With this study, we learned two major things,” said Sushma Reddy, lead
author and a fellow at The Field Museum in Chicago, Illinois.
“First, appearances can be deceiving. Birds that look or act similar are not
necessarily related. Second, much of bird classification and conventional
wisdom on the evolutionary relationships of birds is wrong.”
The results of the largest ever study of bird genetics are so widespread
that the names of dozens of birds will now have to be changed, says the
study to be published in Science magazine.
The Early Bird Assembling the Tree-of-Life Research Project has been
researching the evolution of all major living groups of birds and has
already examined 32 kilobases of DNA data in 19 places of some 169 bird
species.
A kilobase in molecular biology is a unit of length for DNA fragments
representing 1,000 base pairs of DNA.
Among new discoveries the team found that birds repeatedly adapted to new
environments. For example, flamingos and grebes did not evolve from other
waterbirds, while birds that now live on land such as cuckoos did not evolve
from other landbirds.
Other findings were that, contrary to current thought, daytime hummingbirds
evolved from nocturnal nightjars, falcons are not related to hawks and
eagles and fast flying ocean birds are not related to pelicans and other
waterbirds.
“We now have a robust evolutionary tree from which to study the evolution of
birds and all their interesting features that have fascinated so many
scientists and amateurs for centuries,” Reddy said.
“Birds exhibit substantial diversity and using this ‘family tree’ we can
begin to understand how this diversity originated as well as how different
bird groups are interrelated.” ”
“…much of bird classification and conventional wisdom on the evolutionary relationships of birds is wrong”? So cuckoos aren’t related to other landbirds, flamingos aren’t ducks but are distantly related to grebes, and - oh, I don’t know - sparrows aren’t the same as penguins. Is it just me, but is a few kilobases of DNA in such a small sample (there are 10,000 species of bird and the study looked at some DNA in 169 of them) really that revealing, even if they did cover representatives of each group? And I wonder whether that it’s all going to mean very much to the vast majority of birders - or people in general - anyway? In a way it’s interesting - unprovable, subject to revision/addition (much like this post then) and of little value in the field to most of us - but not much more than that.
More importantly though, in the long run is it worth us knowing the history of birds when as a species the majority of us humans seem so indifferent to their future - which surely is more important?
I remember the great sense of discovery we all experienced (we did, honestly) when it turned out that New World vultures were supposedly genetically more closely related to storks than to Old World vultures resulting in all kinds of re-writing and taxonomic movement - a finding later disputed by the AOU who said that moving the group was an error and promptly dragged them away from the Ciconiiformes and back to the Falconiformes again!*. Interesting it all may have been to those of us who wanted to be able to discuss vulture taxonomy over lunch, but it didn’t stop us going on to destroy over 99% of India’s “Old World vultures”, and it hasn’t stopped a bunch of money-grubbing developers from trying to build 3,450 residential units, 750 hotel units, four golf courses and 160,000 square feet of commercial space on 28,250 acres of the Tejon Valley recently, including areas designated as critical habitat for the virtually extinct “is it a stork, is it a hawk” California Condor (http://actionnetwork.org).
Am I enriched by knowing that diurnal hummingbirds are perhaps distantly related to nocturnal Nightjars (which sounds ridiculous to be truthful, and makes little sense even if it’s correct)? Or more enriched knowing that hummingbirds somehow still exist despite the best efforts of clear-cut loggers, ranchers, and land speculators to clear their habitat and who could no more tell you what a hummingbird was than I could tell you if this new study has any long-term value whatsoever?
It could be that I’ve woken up on the wrong side of the bed today and rolled straight into the wall rather than my clothes (which might explain the dull headache), or it could be that I’m just in a particularly whiny mood, but when a geneticist (however well-meaning and vastly more intelligent than me) says something like “we can begin to understand how this diversity originated as well as how different bird groups are interrelated” I just want to ask them what they’re doing to ensure that that wonderful, incredible diversity that fills and enhances my life so spectacularly is still going to be around in another hundred years?
Having said that, I guess we should all be asking ourselves the same question, “What are WE doing to ensure that the wonderful, incredible diversity that fills and enhances our lives so spectacularly is still going to be around in another hundred years…?”
(*FORTY-EIGHTH SUPPLEMENT TO THE AMERICAN ORNITHOLOGISTS’ UNION CHECK-LIST OF NORTH AMERICAN BIRDS
p. 51. “Reconsideration of the evidence for moving the family Cathartidae from the order Falconiformes to the order Ciconiiformes (AOU 1998), re-evaluation of the analysis of Griffiths (1994), and preliminary information from continuing genetic studies (e.g., Cracra et al. 2004, Fain and Houde 2004, Ericson et al. 2006) indicate that the move was in error, although the true relationships and thus placement of the family are still not fully resolved. Move the entries for the family Cathartidae and the included species (pp. 51-53) to a position in the Order FALCONIFORMES just before the Suborder ACCIPITRES (p. 86) under the heading Suborder CATHARTAE: American Vultures. Under the heading for the Family Cathartidae, insert the following: Notes.—This family was moved to the order Ciconiiformes (AOU 1998) but is now tentatively returned to the order Falconiformes after re-evaluation of the reasons for the earlier change. Further, some genetic studies (Cracra et al. 2004, Fain and Houde 2004, Ericson et al. 2006) have shown that the New World vultures are not closely related to the storks, although their precise phylogenetic relationship to the Falconiformes is yet undetermined.”)
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I’m not even trying to pretend, that I have a clue about genetics. I know that neither they nor other theories are infallible and - much like evolution do evolve through he time. Thus said, charging geneticists with coming up for solutions ain’t proper, either. As it is each of us is charged with doing so. May it be to put a brake on your local governments desire to up tax income, by allowing development without regard to whether environment & region can actually harness the growth, or may it be that we ourselves get active in smaller things, where we can help without making a big deal out of it. I started a little thing, that asks do get active without waiting on others - and doing so is one way to get started. More Info here and it might be something 10000 Birds might be interested in promoting, too! Cheers, Klaus
Charlie, you make such a good point about what it all means when we are slowly killing our planet. I don’t have an answer. For the average birder, it won’t make much difference except possibly in how a field guide is laid out in the future. But for novice birders, field guides are terribly confusing anyway. No, it is of academic interest. Holding court over the water cooler now will be easier. But, will it matter in the long run? Doubt it. No answers here just a deep sense of depression over the future that we’re leaving to our future. Our jammy fingered kidlets deserve better!
I don’t think you should assume that geneticists are not contributing to conservation. This research is just their “day job”; we don’t know what they do in their free time, or what kinds of causes they contribute towards. Second, I think that any research that enhances our understanding of birds - whether from a genetic or behavioral or ecological perspective - ultimately aids the cause of making sure birds stick around. Some research contributes directly, like migration or habitat studies; something like this probably just builds up the knowledge base. Plus, most of the people who do this kind of research are university professors who have some responsibility for teaching the next generation of young adults. They can use some aspects of their research in the classroom to give students a better appreciation for the wonderful diversity produced by evolution.
One more thing - sometimes genetic studies identify distinctive populations within a species, which marks those populations as needing special conservation attention, even if the rest of the species is doing fine. (Southwestern Willow Flycatcher would be one example.) This study doesn’t do that specifically, but it does provide a broader context for the smaller scale studies.
Klaus: interesting idea yes, perhaps we should help promote it. Want to email me and discuss?
Liza Lee: Yes, it’s all very sad. I actually feel that being depressed about our environment/future should be a recognised illness: I remember a friend who worked in Alaska saying the Innuit she worked with were, in her words, ’shell-shocked beyond recovery’ about how much they’d lost. I can’t think why anyone who cares at all about our planet shouldn’t be recognised as feeling the same way…imagine the impact on how we treat our planet if it was!
John: I’m not assuming anything, I’m saying that studies like these always make me want to ask that particular question. If the researchers come back and say “I do this and that actually..” then that’s great. More power too them of course.
And I wonder how soon teaching the next gen about diversity will be included as part of a history course rather than a present-day subject?
I’ve long noted that genetic studies such as you refer to can contribute to better conservation but it’s worth noting too how the Bush Administration have used similar studies to de-list Endangered birds that they say are just a localised geographic variant of a more widespread species (often thereby allowing oil or timber concessions to be granted) - Marbled Murrelet, ‘Mexican’ Spotted Owl, pacific poulations of Mountain Quail etc etc…
Charlie, I guess I misunderstood where you were going with this piece. Apologies.
By the way, most of the Bush administration’s most egregious actions came after they ignored what all the government scientists were telling them and substituted think-tank “science” in their place.
John: You’re an intelligent guy and if you misunderstood where I was headed it’s because the piece isn’t written well enough. I’m the one who should be apologising…
Oh, and you’re right about Bush of course. I wonder how long it will be before such a divisive figure arises in mainstream politics again (”President” Mugabe aside…)
Conservation is getting people to act in ways that reduce their negative impact on the environment. Most of this work involves politics, laws and public relations. Scientists can support this work, but can rarely be leaders in conservation.
The people who do the most for conservation do conservation as their full-time job, like work for groups like Audubon. The skills required for these jobs are often very different than the skills scientists have.
Check out the movie “A Flock of Dodos” to get an idea why scientists sometimes don’t succeed outside of science.
http://en.wikipedia.org/wiki/Flock_of_Dodos
Joseph, I have a boundless admiration for field-workers and researchers, but I wonder if your comment that “The people who do the most for conservation do conservation as their full-time job, like work for groups like Audubon” is actually true? It’s an unproven observation, but broadcasters like David Attenborough, Jacques Cousteau, Bill Oddie etc etc have probably done more for conservation per se than almost anyone else by making conservation mainstream and bringing conservation issues to people who may never have thought about them before via the television. On a different tack, where would the researchers be without huge donations (often made without any fanfare) by successful business people like Ted Turner and others? Where, indeed would they be without the membership fees and donations made by millions of members of conservation organisations like Audubon, RSPB, WWF-N - out of work probably. Like I say, I genuinely have boundless admiration for the “workers on the coal-face” but I’d prefer to encourage everyone else with everyday jobs and everyday concerns by reminding them just how important they are too.
Charlie your post had two questions, and my earlier comment answered the first part and was about the role of scientists in conservation.
I’ll give an answer for the second question, “what are WE doing…” Conservation is a team effort. Everyone has an important role to play. In our everyday lives we can make choices that make a difference, like driving less. I would encourage all birders to consider starting an anti-global warming list like Cory.
In addition to that we can support the people in the forefront of conservation efforts. We should support conservation and environmental groups.
Your “unproven observation” is not so unproven. Public support, encouraged by people like Cousteau and Attenborough, is the strength of the environmental/conservation movement. When I was in school I took a course on environmental laws. The first assignments were reading excerpts from books like Silent Spring, A Sand County Almanac and Biophillia. This was unusual reading for a law school class. The professor explained how influential public opinion has been in environmental law and how these books influenced public opinion.
Joseph, I seem to have aroused a certain passion for defending scientists with this post. Never figured on that reaction…or that people would pick over my words so carefully (that’ll teach me). Just to make things clear when I used ‘unproven observation’ I was thinking of ‘verifiable experiment’ as I wrote the post and I used “unproven” in terms of doubting whether there would be data available which has been collected from projects which would have proved the observation one way or the other. Maybe there is data available, but I’ve not read it if there is. Feel free to point me in the right direction though, ta! Now I’ve been stirred to thought I’d love to know the answer. Incidentally your two comments about conservation seem to contain contradictory statements: “The people who do the most for conservation do conservation as their full-time job, like work for groups like Audubon” and then “Public support, encouraged by people like Cousteau and Attenborough, is the strength of the environmental/conservation movement.” I’d be interested to know which you think is more important? Or is that not what you meant?
And, yes, Corey should be a role model for everyone - not us dirty birders who use airplanes to do our birding
The June 2008 bird genetics study of Chicago’s Field Museum of Natural History (the Early Bird Assembling the Tree-of-Life Research Project) completely re-writes the avian evolutionary tree, and is stunning in its impact. The genetics study shows that, though they look alike, for example, falcons with their acute ultraviolet vision are not closely related to other birds of prey, hawks or eagles. Several birds that look very different, including woodpeckers, hawks, owls and hornbills, are all closely related to perching birds. Flamingos, tropicbirds and grebes, all of which are closely related, did not evolve from water birds. Contrary to conventional wisdom, daytime hummingbirds evolved from drab nocturnal nightjars. Tropicbirds (white, swift-flying ocean birds) are not closely related to pelicans or other waterbirds. But perching birds, on the one hand, and parrots and falcons on the other, which do not look all that much alike, in fact descend from a recent common ancestor. Shorebirds are not a basal evolutionary group, which refutes the established view that all modern birds evolved from shorebirds. It is an understatement that appearances are deceiving. Birds that look or act similar are not necessarily related. Modern birds evolved relatively rapidly within a few million years during an explosive radiation, sometime between 65 million and 100 million years ago. The same is true of flower evolution. One day there are no flowers in the fossil record, and the next ‘day’ there are flowers, as Charles Darwin observed. Likewise, flowers that look alike are frequently not closely related. So how does this genome-scale phylogenetic evidence on avian evolution possibly jive with Darwinian gradualism, incremental changes over millions of years? It does not and cannot. Something else is going on to explain this planet’s remarkable biodiversity. The best hope to answer these questions is more and better science, not reliance on rote 19th century conjecture. Whatever the causative mechanism for bird or other biological evolution, avian evolution is not the result of ‘natural selection.’ “What are we doing to ensure that the wonderful, incredible diversity that fills and enhances our lives so spectacularly is still going to be around in another hundred years…?” We sure need to do a lot more.
John Umana - in some ways I agree with you, but only to a point. Don’t confuse and equate ‘natural selection’ with ‘Darwinian gradualism’. I agree that gradualism is only rarely observed, instead we see many rapid bursts of innovation and evolution in the fossil record. I think developmental and other mechanisms have a very strong role in evolution that we’re only beginning to understand (Is that what you are referring to?). But, just because it is some rapid change resulting in a new morphology, doesn’t mean that selection doesn’t act upon those changes to fix them in the population and to modify them.
~ Nick
Just to clarify… natural selection acts on any heritable changes in a population. The source and relative importance of changes vary - gradualism says mostly small changes accumulate over a long period accounts for most evolution. Others think that other means of change are more important - including developmental changes (this is what evo devo studies) which can provide dramatic morphological jumps with relatively little genetic change. Both these sources of variability and others are operated on by selection, so long as they are genetic and heritable.
Yes, I agree there are many rapid bursts of innovation and evolution in the fossil record. There are extremely rapid changes (say, 10 to 15 years for bird speciation) resulting in new species. That’s what we need to be looking for. Natural selection may or may not be a causative mechanism in fixing certain changes in the population or in modifying them, though that certainly is the conventional wisdom. But it is not the operative mechanism behind the evolution of a single new species. Darwinian gradualism is not consistent with observation when it comes to radiation or speciation. Take, for example, a mockingbird and a parrot, both of which descend (according to the Early Bird study) from a recent common ancestor that presumably is no longer flying around. How in the world did parrots (or falcons for that matter) possibly evolve from song birds? But they did. How long did it take? Neither Darwinian gradualism nor natural selection can explain these dramatic new morphologies. The reason we are all rightly concerned with conservation is that all of these avian species are precious and unique, and when they’re gone, they’re gone. Happy 4th of July to all.
Charlie, this post is for you. Do you still think linking hummingbirds and nightjars makes little sense?
http://slybird.blogspot.com/2008/07/avian-relationships-what-do-we-know.html
John - have you reviewed the work of the Grants on Darwin finches? There is a pretty good example of natural selection operating within just a few finch generations to muck up species limits.