Shark Bay, Western Australia, is a World Heritage Area dominated by temperate seagrass meadows. Recently, scientists from the University of Western Australia and Flinders University have discovered the most giant planet at Shark Bay.
They discovered an ancient and incredibly resilient seagrass, Posidonia australis, that stretches 180km and is estimated to be at least 4,500 years old.
Evolutionary biologist Dr. Elizabeth Sinclair from UWA’s School of Biological Sciences and the UWA Oceans Institute said, “The project began when scientists wanted to understand how genetically diverse the seagrass meadows in Shark Bay were and which plants should be collected for the seagrass restoration.”
“We often get asked how many different plants are growing in seagrass meadows, and this time we used genetic tools to answer it.”
UWA student researcher Jane Edgeloe, a lead author of the study, said, “the team sampled seagrass shoots from across Shark Bay’s variable environments and generated a ‘fingerprint’ using 18,000 genetic markers.”
“The answer blew us away – there was just one! Just one plant has expanded over 180km in Shark Bay, making it the largest known plant on Earth.”
“The existing 200km2 of ribbon weed meadows have expanded from a single, colonizing seedling.”
“What makes this seagrass plant unique from other large seagrass clones, other than its enormous size, is that it has twice as many chromosomes as its oceanic relatives, meaning it is a polyploid.”
“Whole-genome duplication through polyploidy – doubling the number of chromosomes – occurs when diploid ‘parent’ plants hybridize. The new seedling contains 100 percent of the genome from each parent, rather than sharing the usual 50 percent.”
“Polyploid plants often reside in places with extreme environmental conditions, are often sterile, but can continue to grow if left undisturbed, and this giant seagrass has done just that.”
“Even without successful flowering and seed production, it appears to be resilient, experiencing a wide range of temperatures and salinities plus extreme high light conditions, which would typically be highly stressful for most plants.”
- Jane M. Edgeloe, Anita A. Severn-Ellis et al. Extensive polyploid clonality was a successful strategy for seagrass to expand into a newly submerged environment. DOI: 10.1098/rspb.2022.0538