Gametophyte evolution, Hymenasplenium murakami-hatanakae Nakaike, the fifth family to produce independent gametophytes

NEWS - Nakaike spleenwort (Hymenasplenium murakami-hatanakae Nakaike) can survive for long periods without a spore-producing sporophyte. Researchers report that H. murakami-hatanakae undergoes alternation of generations as an independent gametophyte, the only one in the suborder Eupolypods II (Aspleniinae).

Aspleniineae appear to have evolved independent gametophytes to adapt to rocky and isolated environments. The research opens the way to elucidating gametophyte evolution and other important questions in plant ecology. A diversity of fern species reproduce and fill environmental niches.

Noriaki Murakami of Tokyo Metropolitan University in Tokyo, along with a team from Showa University in Yamanashi, and the National Museum of Nature and Science in Ibaraki, collected specimens from Izu-Oshima Island in southeastern Japan, and used DNA analysis to trace the generations.

Aspleniineae is a suborder called Eupolypods II that includes 30 percent of the ferns on Earth and is a rare group. Studying this species further promises to reveal more about how ferns diversify and adapt.

Plants and algae have a complex cycle that they use to reproduce. Each species has two generations in the cycle, a sporophyte that has two sets of chromosomes (diploid) and a gametophyte that has one (haploid). When the gametophyte matures, it produces gametes to produce a diploid zygote.

The zygote continues to divide and eventually becomes a sporophyte. The sporophyte produces spores through a process that halves the number of chromosomes. These spores divide and develop into gametophytes, and the cycle continues.

Sporophytes and gametophytes generally depend on each other for nutrition, but ferns have a special place in biology because they are independent of each other, raising the intriguing possibility that they can live long periods without each other or live as independent gametophytes.

Murakami and his team collected H. murakami-hatanakae that live in dark, humid environments on rocks along warm-climate rivers in Japan and Taiwan. The team collected specimens on Izu-Oshima Island and used DNA techniques to identify the species. DNA extracted from chloroplasts to identify sporophytes and gametophytes was then compared. They found that the gametophytes of this species can survive for long periods in an environment completely isolated from the spores.

Original research

Yoneoka, K., Fujiwara, T., Kataoka, T. et al. Morphological and functional evolution of gametophytes in epilithic Hymenasplenium murakami-hatanakae (Aspleniaceae): The fifth family capable of producing the independent gametophytes. Journal of Plant Research (2024). DOI:10.1007/s10265-024-01553-0

A deep-sea isopod Bathyopsurus nybelini adapted to feed submerged Sargassum algae

NEWS - Incredible footage shows a marine species, Bathyopsurus nybelini , feeding on something that sinks from the ocean’s surface. Researchers using the submersible Alvin found the isopod swimming 3.7 miles down using its paddle-like legs to catch an unexpected food source: Sargassum. Researchers from Woods Hole Oceanographic Institution (WHOI), the University of Montana, SUNY Geneseo, Willamette University and the University of Rhode Island found the algae sinking, while the isopod waited and adapted specifically to find and feed on the sinking nutrient source. The Sargassum lives on the surface for photosynthesis. The discovery of a deep-sea animal that relies on food that sinks from the waters miles above underscores the close relationship between the surface and the deep. “It’s fascinating to see this beautiful animal actively interacting with sargassum, so deep in the ocean. This isopod is extremely rare; only a handful of specimens were collected during the groundbreaking Swedis

Ngamugawi wirnagarri reveals evolution of coelacanth fish and history of life on earth

NEWS - An ancient Devonian coelacanth has been remarkably well preserved in a remote location in Western Australia linked to increased tectonic activity. An international team of researchers analysed fossils of the primitive fish from the Gogo Formation of Ngamugawi wirngarri , which straddles a key transition period in the history of coelacanths, between the most primitive and more modern forms. The new fish species adds to the evidence for Earth’s evolutionary journey. Climate change, asteroid strikes and plate tectonics are all key subjects in the origins and extinctions of animals that played a major role in evolution. Is the world’s oldest ‘living fossil’ the coelacanth still evolving? “We found that plate tectonic activity had a major influence on the rate of coelacanth evolution. New species are more likely to have evolved during periods of increased tectonic activity when new habitats were divided and created,” says Alice Clement of Flinders University in Adelaide. The Late Dev

Species going extinct every day and without warning

NEWS - The current rate of human-caused extinction is up to 700 times higher than it was in the past. Extinctions are no different for plants, animals and fungi, although the extinctions of botanicals and invertebrates have been far worse than those of vertebrates. The mass extinctions increased from 1890 to 1940, but a decline in extinctions was only recorded after the 1980s, likely due to taxonomic bottlenecks and the pre-1800 extinction rates being affected by a lack of data. The number of species varies from 2-8 million to 1 trillion, and estimates suggest that most species, especially microbes and fungi that may be key to healthy ecosystems, are still undiscovered. The biodiversity crisis is therefore extremely difficult to measure. “If we don’t know what we have, it’s impossible to measure how much we’re losing. This taxonomic gap urgently needs to be addressed,” say Maarten Christenhusz and Rafaël Govaerts of the Royal Botanic Gardens, Kew. Yet taxonomy is in decline. Misunderst

Dlium