Fossil study: Dogs evolved with climate change

Fossil study: Dogs evolved with climate change
Two early dogs, Hesperocyon, left and the later Sunkahetanka, were both ambush-style predators. As climate changes transformed their habitat, dogs evolved pursuit hunting styles and forelimb anatomy to match. Credit: Mauricio Anton

Old dogs can teach humans new things about evolution. In Nature Communications a new study of North American dog fossils as old as 40 million years suggests that the evolutionary path of whole groups of predators can be a direct consequence of climate change.

"It's reinforcing the idea that may be as directly sensitive to climate and habitat as herbivores," said Christine Janis, professor of ecology and evolutionary biology at Brown University, who worked with lead author Borja Figueirido, a former Brown Fulbright postdoctoral researcher who is now a professor at the Universidad de Málaga in Spain. "Although this seems logical, it hadn't been demonstrated before."

The climate in North America's heartland back around 40 million years ago was warm and wooded. Dogs are native to North America. The species of the time, fossils show, were small animals that would have looked more like mongooses than any dogs alive today and were well-adapted to that habitat. Their forelimbs were not specialized for running, retaining the flexibility to grapple with whatever meal unwittingly walked by.

But beginning just a few million years later, the began cooling considerably and in North America the Rocky Mountains had reached a threshold of growth that made the continental interior much drier. The forests slowly gave way to open grasslands.

Pups of the plains

Did this transition affect the evolution of carnivores? To find out, Figueirido and the research team, including Jack Tseng of the American Museum of Natural History in New York, examined the elbows and teeth of 32 species of dogs spanning the period from ca. 40 million years ago to 2 million years ago. They saw clear patterns in those bones at the museum: At the same time that climate change was opening up the vegetation, dogs were evolving from ambushers to pursuit-pounce predators like modern coyotes or foxes—and ultimately to those dogged, follow-a-caribou-for-a-whole-day pursuers like wolves in the high latitudes.

Fossil study: Dogs evolved with climate change
This is a skeleton of a 30-million-year-old fossil dog, Archaeocyon (“ancient dog”), in the American Museum of Natural History canid collection. The earliest dogs, going back 40 million years in North America, were animals no larger than a Chihuahua or a common house cat today. Credit: © AMNH/D. Finnin

"The elbow is a really good proxy for what carnivores are doing with their forelimbs, which tells their entire locomotion repertoire," Janis said.

The telltale change in those elbows has to do with the structure of the base where the humerus articulates with the forearm, changing from one where the front paws could swivel (palms can be inward or down) for grabbing and wrestling prey to one with an always downward-facing structure specialized for endurance running. Modern cats still rely on ambush rather than the chase (cheetahs are the exception) and have the forelimbs to match, Janis said, but canines signed up for lengthier pursuits.

In addition, the ' teeth trended toward greater durability, Figueirido's team found, consistent perhaps with the need to chow down on prey that had been rolled around in the grit of the savannah, rather than a damp, leafy forest floor.

Not an 'arms race' of limbs

The study, with some of Janis' prior research, suggests that predators do not merely evolve as an "arms race" response to their prey. They don't develop forelimbs for speedy running just because the deer and the antelope run faster. While the herbivores of this time were evolving longer legs, the predator evolution evident in this study tracked in time directly with the climate-related changes to habitat rather than to the anatomy of their prey species.

After all, it wasn't advantageous to operate as a pursuit-and-pounce predator until there was room to run.

"There's no point in doing a dash and a pounce in a forest," Janis quipped. "They'll smack into a tree."

If predators evolved with climate change over the last 40 million years, the authors argue, then they likely will have to continue in response to the human-created underway now. The new results could help predict the effects we are setting in motion.

"Now we're looking into the future at anthropogenic changes," Janis said.


Explore further

Competition from the ancestors of cats drove the extinction of many species of ancient dogs

More information: Nature Communications, DOI: 10.1038/ncomms8976
Journal information: Nature Communications

Provided by Brown University
Citation: Fossil study: Dogs evolved with climate change (2015, August 18) retrieved 23 October 2019 from https://phys.org/news/2015-08-fossil-dogs-evolved-climate.html
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Aug 18, 2015
Isn't it common sense to anyone reasonably well-read that successful species adapt successfully to climate change?

Aug 18, 2015
Re: "Now we're looking into the future at anthropogenic changes," Janis said.

This reminds me of the letter written by a graduate student who quit her PhD program just weeks shy of completion. She wrote ...

"I've lost faith in today's academia as being something that brings a positive benefit to the world/societies we live in. Rather, I'm starting to think of it as a big money vacuum that takes in grants and spits out nebulous results, fueled by people whose main concerns are not to advance knowledge and to effect positive change, though they may talk of such things, but to build their CV's an to propel/maintain their careers ..."

"I cannot help but get the impression that the majority of us are avoiding the real issues and pursuing minor, easy problems that we know can be solved and published. The result is a gigantic literature full of marginal/repetitive contributions ..."

Aug 18, 2015
"Academia: Where Originality Will Hurt You

The good, healthy mentality would naturally be to work on research that we believe is important. Unfortunately, most such research is challenging and difficult to publish, and the current publish-or-perish system makes it difficult to put bread on the table while working on problems that require at least ten years of labor before you can report even the most preliminary results. Worse yet, the results may not be understood, which, in some cases, is tantamount to them being rejected by the academic community ..."

"... many researchers, having grown dependent on the bandwagon, then need to find ways to keep it alive even when the field begins to stagnate. The results are usually disastrous. Either the researchers begin to think up creative but completely absurd extensions of their methods to applications for which they are not appropriate, or ..."

Aug 18, 2015
"... they attempt to suppress other researchers who propose more original alternatives (usually, they do both). This, in turn, discourages new researchers from pursuing original alternatives and encourages them to join the bandwagon, which, though founded on a good idea, has now stagnated and is maintained by nothing but the pure will of the community that has become dependent on it. It becomes a giant, money-wasting mess."

See full letter at http://crypto.jun...gnation/

Aug 18, 2015
What shock!.
Climate changes, animals adapt and evolve to that change.

Aug 18, 2015
What shock!.
Climate changes, animals adapt and evolve to that change.
there is a large difference in adapting to climate change over a long period versus a short period. even Lenski's e.coli took generations to adapt

Isn't it common sense to anyone reasonably well-read that successful species adapt successfully to climate change?
the difference is the time periods involved. to assume that species can and will adapt to rapid climate change is to chance extinction, as it has been shown that rapid climate change can be deadly to most species

Aug 18, 2015
Whether Doberman has evolved from the Pinscher. There are about 400 known dog breeds. Most of them are artificial selection of genes that are in the gene pool of this specie. This is not evolution but variations but combinations of existing genes from the gene pool of the specie. There are no new genes appeared out of nowhere.

Aug 18, 2015
Viko is wrong again. How a new gene arose in dogs: http://biologos.o...-origins

Aug 19, 2015
to assume that species can and will adapt to rapid climate change is to chance extinction, as it has been shown that rapid climate change can be deadly to most species

Adapt or die. Nothing personal.

Signed,

Mother Nature.

Aug 23, 2015
denglish claims
Isn't it common sense to anyone reasonably well-read that successful species adapt successfully to climate change?
Really ?

So you are stating with certitude are you (?) that a species (any species?) which adapted in the past is now classed in the static deterministic framework of "successful" which somehow automatically endows it with a power to adapt again to new variance any time thereafter ?

Given your naivety re statistical mechanics, specific heat, statistics, radiative forcing and all the essentials relevant to understand Earth's energy balance then pray tell just what sort of education you gained from which institute of higher learning that gives you such sense of certainty please ?

Why is your claimed "common sense" not congruent with mutative patterns observed in essentials which underpin the complex factors which are the foundation of evolution ?

Tell us denglish, how such "common sense" is utilised by you to ignore key education ?

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