Olaf R. P. Bininda-Emonds
talks with ScienceWatch.com and answers a few
questions about this month's New Hot Paper in the field of
Multidisciplinary. The author has also sent along
images of their work.
Article Title: The delayed rise of present-day
ORP;Cardillo, M;Jones, KE;MacPhee, RDE;Beck,
RMD;Grenyer, R;Price, SA;Vos, RA;Gittleman, JL;Purvis,
Year: MAR 29 2007
* Univ Jena, Inst Spezielle Zool & Evolut Biol
Phyletischem Mu, D-07743 Jena, Germany.
* Tech Univ Munich, Lehrstuhl Tierzucht, D-85354 Freising
(addresses have been truncated)
Why do you think your paper is highly
In the first instance, it's because the paper tells an interesting story
with many interesting ingredients in the mix: mammals, dinosaurs, and the
Cretaceous-Tertiary mass-extinction event. Moreover, it apparently dispels
the long-held truth that it was the death of the dinosaurs that cleared the
way for the present-day mammals. It did, but only indirectly, in that the
modern mammals probably had to wait for another group of mammals to get out
of the way first. This story, these protagonists, and the contradiction of
a long-held truth have attracted a lot of attention.
But somewhat hidden beneath the story the paper tells is the first, nearly
complete evolutionary tree of all 4500+ living mammalian species, together
with estimates of times of evolution throughout the tree.
This tree represents an incredibly valuable tool to help investigate
diverse aspects of the biology of mammals—from their evolutionary
history, to their conservation biology, to the rates of evolution of their
DNA—and arguably represents the current standard reference for
evolutionary relationships among mammals. The tree reveals the increasing
power of modern phylogenetic methods to reveal ever-larger branches of the
Tree of Life.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
Through the relatively novel phylogenetic method called supertree
construction, we synthesized diverse information about the evolutionary
relationships of living mammal species to derive a supertree of nearly all
the species. It's a bit like a complex jigsaw puzzle, where we put all the
pieces together to reveal the final picture (the supertree). The supertree
algorithms, however, have to solve the problems that the pieces can both
overlap (instead of just snap together) and also show slightly different
pictures. We then mapped mutations in 68 different genes onto the tree and
calibrated these changes against 30 fossils to derive times of evolution
throughout the tree. Nothing like this had yet been attempted on a scale
such as this.
The size and comprehensiveness of the tree has the potential to unleash
many new discoveries. Our analyses of the timing of important events in
mammalian evolutionary history and that the death of the dinosaurs
apparently did not play an important, direct role in the evolution of
present-day mammals is only one such new discovery.
Would you summarize the significance of your paper
in layman's terms?
The paper is primarily important for two reasons.
First, the paper presents an evolutionary tree containing virtually all
4500+ living mammal species, together with estimates of times of evolution
throughout the tree. The tree, therefore, is by far the most complete
picture that we have of the evolutionary history of the present-day
mammals. It represents not only the current standard work in this regard,
but also a valuable tool to help us understand how evolution has shaped all
aspects of the biology of living mammals. For instance, the tree has formed
the evolutionary backbone of numerous studies trying to understand why
different species or groups of mammals show different levels of extinction
risk and which groups might be the most vulnerable in the future.
Second, in using the tree, we were able to cast doubt on the long-held
assumption that the death of the dinosaurs directly cleared the way for
present-day mammals, allowing them to flourish. Instead, our analyses
reveal that all the major groups of living mammals co-existed with the
dinosaurs (and for a minimum of 10 million years, often more) and only
began to flourish some 15 million years after the dinosaurs went extinct.
As such, the death of the dinosaurs did not impact directly on the
present-day mammal groups. Something, or someone, else was keeping them
down immediately after and for some time after the Cretaceous-Tertiary
boundary 65 million years ago.
How did you become involved in this research, and
were there any problems along the way?
"But somewhat hidden
beneath the story the paper tells is the first,
nearly complete evolutionary tree of all 4500+
living mammalian species, together with estimates
of times of evolution throughout the
The root of this research goes back to my time as a doctoral student at the
University of Oxford. When I arrived in 1995, Andy Purvis had just
published the first comprehensive supertree (for the mammalian order
Primates) and suggested that we do one for the order Carnivora together
with John Gittleman (then at the University of Tennessee). For the next few
years, our research circles were slowly checking off one order after
another before we decided sometime in about 2001/2002 to try and do the
entire mammalian tree. It then took about five to six years of concerted
effort by four different research groups to pull all the data together.
Perhaps the only problem was the sheer scale of the project: trying to
create and date a tree with over 4500 species in it. As I said, it took
four different research groups to pull all the data together (over 2600
individual evolutionary trees) and we still had to piece the final tree
from about 30 different subtrees together in the end because we couldn't
analyze all the data simultaneously.
Where do you see your research leading in the
My interests lie generally in evolutionary biology and also in deciphering
how things are related to one another. So, I'll still be building
evolutionary trees for different groups and will think again in a couple of
years of the possibility of updating the mammal supertree. At the moment,
however, I'm quite excited about tracking the evolution of chemical
communication in mammals and carnivores in particular. Chemical ecology is
poorly investigated in mammals, at least on a taxonomically comprehensive
scale, with many more questions currently than answers, and this area
provides a wonderful opportunity to research the interface between ecology,
evolution, and physiology.
Do you foresee any social or political implications
for your research?
Not directly. Any social or political implications will derive more from
how the tree is used, rather than from the tree itself. For instance, the
tree has been invaluable for deciphering the factors underlying
conservation biology in mammals: why are some species or groups under a
more acute threat of extinction than others? That kind of research has
obvious social, political, and economic ramifications.
Prof. Dr. Olaf R.P. Bininda-Emonds
AG Systematik und Evolutionsbiologie
IBU - Fakultät V
Carl von Ossietzky Universität Oldenburg
Keywords: mammals, dinosaurs, Cretaceous-Tertiary boundary, 65
million years ago, evolutionary tree, 4500+ living mammalian species,
Tree of Life, supertree algorithms, evolutionary history, extinction