Nav: Home

New mathematical model reveals how major groups arise in evolution

February 19, 2020

Researchers at Uppsala University and the University of Leeds presents a new mathematical model of patterns of diversity in the fossil record, which offers a solution to Darwin's "abominable mystery" and strengthens our understanding of how modern groups originate. The research is published in the journal Science Advances.

The origins of many major groups of organisms in the fossil record seem to lie shrouded in obscurity. Indeed, one of the most famous examples, the flowering plants, was called "an abominable mystery" by Darwin. Many modern groups appear abruptly, and their predecessors - if there are any - tend to be few in number and vanish quickly from the fossil record shortly afterwards. Conversely, once groups are established, they tend to be dominant for long periods of time until interrupted by the so-called "mass extinctions" such as the one at the end of the Cretaceous period some 66 million years ago.

Such patterns appear surprising, and often seem to be contradicted by the results from "molecular clocks" - using calibrated rates of change of molecules found in living organisms to estimate when they started to diverge from each other. How can this conflict be resolved, and what can we learn from it?

In a paper, Graham Budd, Uppsala University, and Richard Mann, University of Leeds, present a novel mathematical model for how the origin of modern groups based on a so-called "birth-death" process of speciation and extinction. Birth-death models show how random extinction and speciation events give rise to large-scale patterns of diversity through time. Budd and Mann show that the ancestral forms of modern groups are typically rather few in number, and once they give rise to the modern group, they can be expected to quickly go extinct. The modern group, conversely, tends to diversify very quickly and thus swamp out the ancestral forms. Thus, rather surprisingly, living organisms capture a great percentage of all the diversity there has ever been.

The only exceptions to these patterns are caused by the "mass extinctions", of which there have been at least five throughout history, which can massively delay the origin of the modern group, and thus extend the longevity and the diversity of the ancestral forms, called "stem groups". A good example of this is the enormous diversity of the dinosaurs, which properly considered are stem-group birds. The meteorite impact at the end of the Cretaceous some 66 million years ago killed off nearly all of them, apart from a tiny group that survived and flourished to give rise to the more than 10 000 species of living birds.

The new model explains many puzzling features about the fossil record and suggests that it often records a relatively accurate picture of the origin of major groups. This in turn suggests that increased scrutiny should be paid to molecular clock models when they significantly disagree with what the fossil record might be telling us.
-end-


Uppsala University

Related Diversity Articles:

Cultural diversity in chimpanzees
Termite fishing by chimpanzees was thought to occur in only two forms with one or multiple tools, from either above-ground or underground termite nests.
Bursts of diversity in the gut microbiota
The diversity of bacteria in the human gut is an important biomarker of health, influences multiple diseases, such as obesity and inflammatory bowel diseases and affects various treatments.
Underestimated chemical diversity
An international team of researchers has conducted a global review of all registered industrial chemicals: some 350,000 different substances are produced and traded around the world -- well in excess of the 100,000 reached in previous estimates.
New world map of fish genetic diversity
An international research team from ETH Zurich and French universities has studied genetic diversity among fish around the world for the first time.
Biological diversity as a factor of production
Can the biodiversity of ecosystems be considered a factor of production?
Fungal diversity and its relationship to the future of forests
Stanford researchers predict that climate change will reduce the diversity of symbiotic fungi that help trees grow.
Brain diseases with molecular diversity
Parkinson's and multisystem atrophy (MSA) - both of them neurodegenerative diseases - are associated with the accumulation of alpha-synuclein proteins in the brain.
United in musical diversity
Is music really a 'universal language'? Two articles in the most recent issue of Science support the idea that music all around the globe shares important commonalities, despite many differences.
Genetic diversity facilitates cancer therapy
Cancer patients with more different HLA genes respond better to treatment.
A new ranavirus threatens US amphibian diversity
In a study published in the Oct. 15 issue of Ecological Modelling, a team of University of Tennessee researchers along with a colleague from the University of Florida model how a chimeric Frog virus 3 (FV3)-like ranavirus, also known as RCV-Z2, can spread rapidly throughout a population of North American wood frog (Lithobates sylvaticus) tadpoles.
More Diversity News and Diversity Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#569 Facing Fear
What do you fear? I mean really fear? Well, ok, maybe right now that's tough. We're living in a new age and definition of fear. But what do we do about it? Eva Holland has faced her fears, including trauma and phobia. She lived to tell the tale and write a book: "Nerve: Adventures in the Science of Fear".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.