In the tree of life, youth has its advantages

March 26, 2019

It's a question that has captivated naturalists for centuries: Why have some groups of organisms enjoyed incredibly diversity--like fish, birds, insects--while others have contained only a few species--like humans.

Researchers trying to explain why the Tree of Life is so unbalanced have agreed on a few explanations--a species' ability to change colour, its body size, and how it interacts with its environment all influence how quickly it can form new species compared to other organisms.

Geological age has also been a major explanation--older groups of organisms have had more time to accumulate more species.

But new research in the Proceedings of the National Academy of Sciences shows the passage of time has a surprising, and consistent impact on evolutionary diversity--and might favour young species.

"If you look at rates of macroevolutionary diversification across 3.8 billion years, it's younger groups of organisms, on average, that accumulate diversity much more quickly than older groups," says Matthew Pennell, an evolutionary biologist at the University of British Columbia and senior author on the paper.

"This suggest that there are some time-dependant, hidden general principles governing how life diversifies on Earth--operating underneath all the other factors we typically think determine how quickly species diversify or go extinct."

The researchers estimated specification and extinction rates across almost 25,000 branches of multicellular organisms, using data from studies of over 100 groups of species and an independent data set of fossil time series. That enabled them to compare rates of diversification broadly over time. For example cichlids (a species of fish) from African rift lakes are diversifying incredibly fast, while whales are an example of a group that appear to be far past their prime in terms of diversity.

"If groups of species were simply reaching equilibrium and slowing down over time, we'd expect a more consistent pattern of slowing within every group we look at," says Pennell. "But our results aren't showing that."

When the researchers looked at individual groups, rates of diversification varied dramatically. What they did find at the macro-level was a strong pattern of faster growth of diversity in younger groups of species.

"This really throws a wrench in how we interpret how life diversified on Earth," says Pennell.

Evolutionary biologists have tended to look at particular features that have helped particular groups of animals diversify--or not.

"The far less explored, and potentially more interesting question, is why, despite all the complexity involved in the evolution of new species, that process looks so similar across the Tree of Life."
-end-


University of British Columbia

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.