Department of Evolution, Ecology and Organismal Biology

Evolution at the speed of life

tomwt — Fri, 13 Feb 2026 19:37:14 +0000

Evolution at the speed of life tomwt Fri, 02/13/2026 - 11:37 More CNAS in the Media Big Biology Podcast February 12, 2026

BIG BIOLOGY PODCAST - What are eco‑evolutionary dynamics and how can we study them in the wild? Why do some fish evolve placentas?

In this episode, we talk with David Reznick, Distinguished Professor of Biology at the University of California, Riverside. David has spent much of his career studying Trinidadian guppies to understand adaptation in the wild. In our conversation, we discuss this work with David and in particular how his research provided evidence for rapid life history evolution. We also talk with him about his recent research into placental evolution in live-bearing fish.

Ep 145: Evolution at the speed of life (with David Reznick)

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Department of Evolution, Ecology and Organismal Biology

David Reznick

Dehydration makes elite mice exercise more, not less. What this means for humans

tomwt — Mon, 17 Nov 2025 18:07:43 +0000

Dehydration makes elite mice exercise more, not less. What this means for humans tomwt Mon, 11/17/2025 - 10:07 More CNAS in the Media John Anderer | Study Finds November 10, 2025

STUDY FINDS - Common sense tells us that when the body is dehydrated, physical performance declines. Athletes and coaches have long known that even modest fluid loss can hurt endurance and speed. However, research focusing on laboratory mice has uncovered a puzzling exception. The fittest animals actually ran more, not less, when deprived of water for 24 hours.

Researchers at the University of California, Riverside, tested what happens when mice go without water while given free access to running wheels. They used two types of mice. Normal control mice, as well as “High Runner” mice that had been selectively bred for decades to run about three times more than regular mice. When water bottles were removed for 24 hours, both groups lost roughly 20% of their body weight. On the other hand, their exercise responses couldn’t have been more different.

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Theodore Garland

Most known species evolved during 'explosions' of diversity, shows first analysis across 'tree of life'

tomwt — Wed, 20 Aug 2025 16:02:33 +0000

Most known species evolved during 'explosions' of diversity, shows first analysis across 'tree of life' tomwt Wed, 08/20/2025 - 09:02 More CNAS in the Media Michiel Dijkstra | Frontiers August 19, 2025

FRONTIERS - The British evolutionary biologist JBS Haldane is said to have quipped that any divine being evidently had ‘an ordinate fondness for beetles’. This bon mot conveyed an important truth: the ‘tree of life’ – the family tree of all species, living or extinct – is very uneven. In places, it resembles a dense thicket of short twigs; elsewhere it has only sparse but long branches. A few groups tend to predominate: as Haldane pointed out, more than 40% of extant insects are beetles, while 60% of birds are passerines, and more than 85% of plants are flowering plants.

But is such a concentration of species within a few exceptionally large groups a universal phenomenon of life on Earth? This question, important for our understanding of evolution and ecology, has long been the subject of controversy among biologists. But until recently, it was difficult to answer due to our poor knowledge of the number of species in existence, their evolutionary relationships, and the age of each group. But now, scientists in the US finally have provided an answer, published in Frontiers in Ecology and Evolution.

“Here we show for the first time that most living species do indeed belong to a limited number of rapid radiations: that is, they form groups with many species which evolved in a relatively short period of time,” said Dr John J. Wiens, a professor at the University of Arizona.

“Specifically, if we look among the kingdoms of life, among animal phyla, and among plant phyla, we find in each case that more than 80% of known species belong to the minority of groups with exceptionally high rates of species diversification.”

Wiens and his co-author Dr. Daniel Moen, an assistant professor at the University of California Riverside, here analyzed the distribution of species richness and diversification rates across ‘clades’ – groups of species that each evolved from a single ancestor, such as phyla, classes, or families.

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Daniel Moen

At the heart of conservation

tomwt — Tue, 20 May 2025 15:20:36 +0000

At the heart of conservation tomwt Tue, 05/20/2025 - 08:20 More College News Jules Bernstein | UCR Magazine May 20, 2025

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Department of Evolution, Ecology and Organismal Biology

Ellie Armstrong

UCR hosts inaugural Southern California Conference on Ecological Change

owenw — Mon, 17 Mar 2025 16:41:51 +0000

UCR hosts inaugural Southern California Conference on Ecological Change owenw Mon, 03/17/2025 - 09:41 More Blog Posts March 17, 2025

The UC Riverside departments of Evolution, Ecology & Organismal Biology, Botany and Plant Sciences, and Environmental Sciences hosted the inaugural Southern California Conference on Ecological Change on February 14.

The inaugural event was organized in response to the effects of warming climate, larger and more frequent fires, urbanization and land development, and invasive species on Southern California's changing ecosystems.

The conference was sponsored by the College of Natural & Agricultural Sciences, UC Natural Reserves, the Department of Entomology, and the Center for Conservation Biology. Over 90 attendees came together to discuss these ecological changes, share knowledge, and identify research opportunities for sustainable management of our Southern California ecosystems. Attendees included scientists and practitioners from five UC campuses, two California State university campuses, and several county, state, and federal agencies, including USGS, USFS, NPS, CDFW, Caltrans, Riverside County Parks, and MSHCP.

Also in attendance were representatives of the non-profit organizations California Botanic Garden, Dwelling on Carbon, Mojave Land Trust, Nature Conservancy, Point Blue Conservation Science, Rivers & Land Conservancy, San Diego Natural History Museum, San Diego Zoo Wildlife Alliance, Tejon Ranch Conservancy, Urban Ecology Conservancy, and the Santa Ana Watershed association.

The conference featured plenary speeches by Dr. Megan Jennings of San Diego State University, and Amy Waltz of the Ecological Research Institute at Northern Arizona University, who emphasized collaborative engagement among researchers, land managers and communities to address regional ecological research needs.

The conference also included breakout discussions which tackled pressing environmental issues in Southern California, grant and career panels, and many opportunities for attendees to network, build new collaborations, and share ideas.

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Department of Evolution, Ecology and Organismal Biology

Department of Botany & Plant Sciences

Center for Conservation Biology

UCR Natural Reserves

Department of Entomology

Department of Environmental Sciences

Here’s an easy way you can help California native wildflowers thrive

tomwt — Thu, 13 Mar 2025 15:04:35 +0000

Here’s an easy way you can help California native wildflowers thrive tomwt Thu, 03/13/2025 - 08:04 More CNAS in the Media Cato Hernández | LAist.com March 06, 2025

LAIST.COM - California wildflower blooms aren’t expected to be as big this year, but there’s an easy action you could take to help other native plants grow around you.

A new study from researchers at UC Riverside found that raking away thatch — a tan layer of dead plant debris produced by invasive plants like grasses — can be an effective way to increase biodiversity of native plants.

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Department of Evolution, Ecology and Organismal Biology

Megalodon may have been ‘even longer’ than we thought

tomwt — Thu, 13 Mar 2025 14:55:21 +0000

Megalodon may have been ‘even longer’ than we thought tomwt Thu, 03/13/2025 - 07:55 More CNAS in the Media Andrew Paul | Popular Science March 09, 2025

POPULAR SCIENCE - If you picture a megalodon, chances are you envision what amounts to a gigantic great white shark. The image is understandable, given almost every depiction of the ancient apex predators across research and pop culture. But last year, an international team put forth a new anatomical design based on their analysis of incomplete fossilized vertebrae. According to the researchers, the famous megalodon was likely “more slender and possibly even longer” than the prevailing theory. Rather than a great white, the team offered sleeker mako sharks for a frame of reference.

The hypothesis kicked off a heated debate among paleobiologists, many of whom contended the evidence still simply didn’t support giant prehistoric makos. Unfortunately, a follow-up study likely won’t satisfy anyone who disagrees with the mako idea, either. According to many of the original study’s authors, megalodons may have been even longer and leaner than they first proposed. In terms of today’s shark parallels, think less “mako” and more “lemon.”

The revised shape and size is detailed in a paper published on March 9 in the journal Palaeontologia Electronica. After comparing portions of a megalodon’s vertebral column to over 100 species of living and extinct shark species, researchers now estimate the megalodon may have topped out at around 80-feet-long, or about two school buses, while weighing as much as 94 tons—roughly as massive as a blue whale. For reference, the predominant megalodon theory puts them at 50-65 feet long and 53-115 tons. Based on their conclusions, even newborn megalodons were sizable creatures, and likely measured as large as a modern adult great white.

“It is entirely possible that megalodon pups were already taking down marine mammals shortly after being born,” Phillip Sternes, a co-author on both papers, argued in an accompanying statement. Sternes also contends the latest study “provides the most robust analysis yet of megalodon’s body size and shape.”

“Rather than resembling an oversized great white shark, it was actually more like an enormous lemon shark, with a more slender, elongated body,” he said. “That shape makes a lot more sense for moving efficiently through water.”

While the great white shark’s bulkier, torpedo-like frame makes it perfect for quick bursts of speed, the lemon shark evolved for energy-efficient, sustained ocean cruising. This concept of evolutionary efficiency played into the team’s alternative theory, as well. Tim Higham, a study co-author and biologist at University of California Riverside, offered Olympic swimmers as a comparison.

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Tim Higham

Megalodon Might Have Been Longer and Skinnier Than Previously Thought, Growing Up to 80 Feet

tomwt — Wed, 12 Mar 2025 21:28:29 +0000

Megalodon Might Have Been Longer and Skinnier Than Previously Thought, Growing Up to 80 Feet tomwt Wed, 03/12/2025 - 14:28 More CNAS in the Media Sara Hashemi | Smithsonian Magazine March 11, 2025

SMITHSONIAN MAGAZINE - Megalodons might have been longer and thinner than previously thought, according to a new study. The enormous, extinct sharks, scientists now say, grew to between 54 and 80 feet long and weighed about 94 tons. Earlier estimates had them at a maximum of 50 feet.

Based on the massive size of the animal’s serrated teeth, other scientists had suggested the megalodon resembled today’s great whites.

“Previous studies simply assumed that megalodon must have looked like a gigantic version of the modern great white shark without any evidence,” says study lead author Kenshu Shimada, a vertebrate paleontologist at DePaul University, to Jason Bittel at National Geographic.

Shimada and his colleagues first proposed that the megalodon might have had a skinnier body than great whites in a study published in the journal Palaeontologia Electronica in January 2024. The megalodon likely looked more like a mako shark, they said when that study came out.

This new paper, published in the same journal on March 9, argues that the megalodon might have been even narrower than they first proposed.

“It was actually more like an enormous lemon shark, with a more slender, elongated body. That shape makes a lot more sense for moving efficiently through water,” says study co-author Phillip Sternes, a shark biologist at the University of California, Riverside, in a statement.

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Megalodon Wasn’t a Fat Great White—It Was a Sleek Lean Killing Machine

tomwt — Tue, 11 Mar 2025 17:49:10 +0000

Megalodon Wasn’t a Fat Great White—It Was a Sleek Lean Killing Machine tomwt Tue, 03/11/2025 - 10:49 More CNAS in the Media Jordan Strickler | ZME Science March 10, 2025

ZME SCIENCE - If Meg 3 ever happens, the filmmakers might need to ditch the oversized great white shark trope. A new study published in Palaeontologia Electronica found that the famous megalodon wasn’t just an outsized version of today’s great white shark. Researchers now say this ancient super-predator was a longer, more streamlined animal built more like a modern lemon shark or even a large whale.

Crunching the Megalodon numbers
The megalodon (formal name Otodus megalodon) roamed Earth’s oceans between 15 and 3.6 million years ago. Though it is known mostly from enormous fossil teeth, one find revealed parts of its skeleton, particularly a fossilized vertebral column, or the “trunk” portion, of O. megalodon measuring about 11 meters (36 feet) in Belgium. The latest study begged the question “so, how big were they actually”?

A team of 28 scientists estimated just how big this vertebral column’s missing sections—namely the head and tail—would have been. Drawing on measurements from 145 modern shark species and 20 extinct species, the researchers concluded that the Belgian megalodon likely measured around 54 feet (16.4 meters) from nose to tail.

“This study provides the most robust analysis yet of megalodon’s body size and shape,” said Phillip Sternes, a shark biologist at the University of California-Riverside (UCR) who also studied at DePaul University, another institution involved in the research. “Rather than resembling an oversized great white shark, it was actually more like an enormous lemon shark, with a more slender, elongated body. That shape makes a lot more sense for moving efficiently through water.”

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Giant Megalodon super shark was actually more like a whale

tomwt — Mon, 10 Mar 2025 16:05:08 +0000

Giant Megalodon super shark was actually more like a whale tomwt Mon, 03/10/2025 - 09:05 More CNAS in the Media Ben Lynch | METRO UK March 10, 2025

METRO UK - Experts have said the prehistoric predator the Megalodon was a ‘sleeker’ creature than the one portrayed in the 2018 movie, where a beast akin to a great white shark wrought havoc in the ocean.

Using an innovative study approach, a team of scientists sought to better understand the biology of the animal that lived between 3.6 to 15 million years ago.

A new study published in the journal Palaeontologia Electronica suggests the creature was around 80 feet long, around one quarter the size of the Statue of Liberty.

It also weighed 94 tonnes, the rough equivalent of six double-decker buses.

Shark biologist Dr. Phillip Sternes, of University of California, Riverside (UCR), said: ‘This study provides the most robust analysis yet of megalodon’s body size and shape.’

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Department of Evolution, Ecology and Organismal Biology