The study, led by MIT scientist Fatima Husain, has shed new light on the mysteries of Snowball Earth – periods when much of the planet was frozen over. By analyzing modern-day meltwater ponds in Antarctica, the researchers discovered clear signatures of eukaryotic life, which could have sheltered during these planet-wide glaciation events.

The team found that eukaryotes, complex cellular lifeforms that eventually evolved into diverse multicellular life, could have survived the global freeze by living in shallow pools of water. These small, watery oases may have persisted atop relatively shallow ice sheets present in equatorial regions, where the ice surface accumulated dark-colored dust and debris from below, enhancing its ability to melt into pools.

The researchers analyzed samples from a variety of meltwater ponds on the McMurdo Ice Shelf, discovering clear signatures of eukaryotic life in every pond. The communities of eukaryotes varied from pond to pond, revealing a surprising diversity of life across the setting. The team also found that salinity plays a key role in the kind of life a pond can host: Ponds that were more brackish or salty had more similar eukaryotic communities, which differed from those in ponds with fresher waters.

“We’ve shown that meltwater ponds are valid candidates for where early eukaryotes could have sheltered during these planet-wide glaciation events,” says lead author Fatima Husain. “This shows us that diversity is present and possible in these sorts of settings. It’s really a story of life’s resilience.”

The study has important implications for our understanding of the origins of complex life on Earth, and highlights the importance of continued research into the mysteries of Snowball Earth. By studying ancient meltwater ponds, scientists can gain insights into how life endured during this pivotal period in Earth’s history, and shed light on the evolution of complex lifeforms that eventually gave rise to humans.

The article delves into the fascinating world of evolutionary biology, where scientists have made groundbreaking discoveries about the genetic mechanisms that allowed ancient marine worms to transition to life on land over 200 million years ago. This study, led by the Institute of Evolutionary Biology (IBE), challenges traditional views of evolution and reveals a more complex and dynamic process than previously thought.

The researchers sequenced the high-quality genomes of various earthworms and compared them to other closely related annelid species, such as leeches and bristle worms or polychaetes. Their analysis revealed an unexpected result: the annelids’ genomes were not transformed gradually, but in isolated explosions of deep genetic remodelling.

This phenomenon challenges the models of genome evolution known to date, given that many of the genomic structures observed in other species are almost perfectly conserved. The researchers discovered that marine worms broke their genome into a thousand pieces only to reconstruct it and continue their evolutionary path on land.

The study suggests that these adjustments not only moved genes around but also joined fragments that had been separated, creating new “genetic chimeras” which would have driven their evolution. This radical genetic mechanism could provide evolutionary responses to the challenges of adapting to life on land, such as breathing air or being exposed to sunlight.

The observations in the study are consistent with a punctuated equilibrium model, where we observe an explosion of genomic changes after a long period of stability. However, the lack of experimental data for or against makes it difficult to validate this theory.

This phenomenon has previously been observed in the progression of cancer in humans, and the term chromoanagenesis covers several mechanisms that break down and reorganize chromosomes in cancerous cells. The only difference is that while these genomic breakdowns and reorganizations are tolerated by worms, in humans they lead to diseases.

The study opens the door to a better understanding of the potency of this radical genomic mechanism, with implications for human health. It also reawakens one of the liveliest scientific debates of our time, as both visions – Darwin’s and Gould’s – are compatible and complementary.

In the future, a larger investigation of the genomic architecture of less-studied invertebrates could shed light on the genomic mechanisms shaping the evolution of species. There is a great diversity hidden in the invertebrates, and studying them could bring new discoveries about the diversity and plasticity of genomic organization and challenge dogmas on how we think genomes are organized.

The study involved the collaboration of research staff from various institutions, including the Universitat Autònoma de Barcelona, Trinity College, the Universidad Complutense de Madrid, the University of Köln, and the Université Libre de Bruxelles.

The study received support from SEA2LAND (Starting Grant funded by the European Research Council) and from the Catalan Biogenome Project, which funded the sequencing of one of the worm genomes.

The American Museum of Natural History has made groundbreaking discoveries about the ancient origins of biofluorescence in fishes. According to two studies published in Nature Communications and PLOS One, this biological phenomenon dates back at least 112 million years and has evolved independently more than 100 times among fish that live on coral reefs. The research suggests that biofluorescence involves a greater variety of colors than previously reported, spanning multiple wavelengths of green, yellow, orange, and red.

Emily Carr, the lead author on the studies, emphasized the importance of understanding the underlying evolutionary story behind biofluorescence. “We need to know why and how these species use this unique adaptation,” she said. By examining all known biofluorescent teleosts – a type of bony fish that make up the largest group of vertebrates alive today – the researchers found 459 species, including 48 previously unknown to be biofluorescent.

The team discovered that fish species living in or around coral reefs evolve biofluorescence at about 10 times the rate of non-reef species. This trend coincides with the rise of modern coral-dominated reefs and the rapid colonization of reefs by fishes following the Cretaceous-Paleogene extinction, which led to a significant loss of coral diversity.

In another study, Carr and colleagues used a specialized photography setup to examine the wavelengths of light emitted by fishes in the Museum’s Ichthyology collection. The results revealed far more diversity in colors emitted by teleosts than previously reported, with some families exhibiting at least six distinct fluorescent emission peaks corresponding to various wavelengths across multiple colors.

The researchers noted that this remarkable variation could mean that these animals use diverse and elaborate signaling systems based on species-specific fluorescent emission patterns. They also highlighted the potential implications for identifying novel fluorescent molecules used in biomedical applications.

Other authors involved in this work include Rene Martin, Mason Thurman, Karly Cohen, Jonathan Huie, David Gruber, and Tate Sparks. The research was supported by various institutions, including the National Science Foundation, the Dalio Foundation, and the Stavros Niarchos Foundation.