Climate change responsible for the great diversity in horses

February 09, 2017

Changing environments and ecosystems were driving the evolution of horses over the past 20 million years. This is the main conclusion of a new study published in Science by a team of palaeontologists from Spain and Argentina. The team analysed 140 species of horses, most of them extinct, synthesising decades of research on the fossil history of this popular group of mammals.

Their conclusions challenge a classic theory, which links the evolutionary success of horses to several novel adaptations in response to the spread of grasslands around 18 million years ago. "According to the classic view, horses would have evolved faster in when grasslands appeared, developing teeth that were more resistant to the stronger wear that comes with a grass-dominated diet. They also became bigger to more effectively digest this low quality food, and as a strategy against predators in these new, open habitats", explains Juan L. Cantalapiedra, researcher at the Museum für Naturkunde in Berlin, Germany.

But did teeth and body size indeed evolve that fast? It seems they didn't. According to the new results, these evolutionary changes could have been much slower than previously assumed. In fact, Cantalapiedra and colleagues were able to show that all these newly evolved species of horses were ecologically very similar. Thus, rather than a multiplication of ecological roles, the new results point to external factors, such as increasing environmental heterogeneity, as the main evolutionary force.

"Environmental changes would have produced a lot more fragmented, mosaic-type ecosystems, where populations of horses with similar demands and adaptations could have evolved isolated from one another, resulting in different species but with a similar appearance", points Manuel Hernández Fernández at the Complutense Univerity in Madrid. "This was probably only possible in ecosystems with a lot of energy and biomass, so that very similar species, which otherwise would have been in strong competition, were all able to survive", adds Jose Luis Prado, at the National University of the Center of Buenos Aires Province.

Diversification accelerated again two more times, "when changes in sea level allowed their migration from North America into Eurasia and Africa, 11 and 4 million years ago", explains María Teresa Alberdi, at the National Museum of Natural Sciences in Madrid. "Then, again, new species appeared very fast, but without showing dramatic changes in appearance", concludes Cantalapiedra.
-end-


Spanish National Research Council (CSIC)

Related Evolution Articles from Brightsurf:

Seeing evolution happening before your eyes
Researchers from the European Molecular Biology Laboratory in Heidelberg established an automated pipeline to create mutations in genomic enhancers that let them watch evolution unfold before their eyes.

A timeline on the evolution of reptiles
A statistical analysis of that vast database is helping scientists better understand the evolution of these cold-blooded vertebrates by contradicting a widely held theory that major transitions in evolution always happened in big, quick (geologically speaking) bursts, triggered by major environmental shifts.

Looking at evolution's genealogy from home
Evolution leaves its traces in particular in genomes. A team headed by Dr.

How boundaries become bridges in evolution
The mechanisms that make organisms locally fit and those responsible for change are distinct and occur sequentially in evolution.

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Paleontology: Experiments in evolution
A new find from Patagonia sheds light on the evolution of large predatory dinosaurs.

A window into evolution
The C4 cycle supercharges photosynthesis and evolved independently more than 62 times.

Is evolution predictable?
An international team of scientists working with Heliconius butterflies at the Smithsonian Tropical Research Institute (STRI) in Panama was faced with a mystery: how do pairs of unrelated butterflies from Peru to Costa Rica evolve nearly the same wing-color patterns over and over again?

Predicting evolution
A new method of 're-barcoding' DNA allows scientists to track rapid evolution in yeast.

Insect evolution: Insect evolution
Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich have shown that the incidence of midge and fly larvae in amber is far higher than previously thought.

Read More: Evolution News and Evolution Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.