Research from the University of Adelaide has revealed the evolution of colour vision in front-fanged snakes following their transition from terrestrial to fully marine environments.

This research also provides the first evidence of where, when and how frequently the species have adapted their ability to see in colour.

Today, the journal Current Biology published the study is an international collaboration led by the University of Adelaide with the University of Plymouth, University of Bristol and The Natural History Museum, London, as well as others, involving scientists from the UK, Australia, Denmark, Bangladesh and Canada.

The research suggests sea snakes’ vision has been modifying genetically over millions of generations, enabling them to adapt to new environments and meaning they can continue to see prey – and predators – deep below the sea surface.

Study lead author Dr Bruno Simões, Adjunct Lecturer in the University of Adelaide and Lecturer in Animal Biology at the University of Plymouth, says sea snakes first entered the marine environment 15 million years ago and have been evolving ever since to survive in its changing light conditions.

“All snakes are descended from highly visual lizards, but advanced colour vision was lost in the early ancestors of snakes – probably because they inhabited dim-light environments, Dr Simões said.

“We used sequencing of vision genes and microscopy to reveal that sea snakes have undergone rapid changes in their visual pigments compared to their relatives on land.”

Video: Bruno Simões

“Gene losses during snake evolution have left living snakes with only two types of cone opsin, which are the pigments responsible for detecting bright light.

“In most terrestrial snakes, the short wavelength sensitive cone opsin (SWS1) has peak sensitivity to ultra violet (UV) light. But in sea snakes this pigment has undergone repeated shifts into the visible spectrum, which would be beneficial for vision underwater, where longer wavelengths dominate.”

Many living things have pairs of chromosomes (inherited from each parent) and consequently have two different copies of the same gene (alleles). The researchers were surprised to find that some sea snakes possessed two genetic alleles of the SWS1 gene, one with peak sensitivity to UV light and the other to visible (blue) light.

Because these alleles appear to have been retained across species during millions of years of sea snake evolution, they concluded that this spectral polymorphism was maintained by natural selection because it may confer expanded colour sensitivities.

In the retinae of sea snakes that possess both alleles, if some photoreceptors express the UV-sensitive allele and other photoreceptors express the blue light-sensitive allele, or these are activated in different light conditions, this could compensate for the ancestral loss of opsins in snakes.

Environment Institute member and senior scientist on the report, Dr Kate Sanders an Associate Professor at the University of Adelaide, says their research also suggests that diving sea snakes actually share their adaptive properties not with other snakes or marine mammals, but with some fruit-eating primates.

“Like sea snakes, marine mammals such as whales and seals are descended from terrestrial ancestors,” Dr Sanders said.

“Where sea snakes have evolved new visual abilities not seen in their closest terrestrial relatives, the visual systems of whales have degenerated since their separation from land mammals.

“An interesting comparison can also be made between sea snakes and primates; some fruit eating primates have expanded colour sensitivities attributed to the retention of different alleles of their long wavelength sensitive opsin.

“Our study suggests an intriguing parallel in diving sea snakes, but we have a lot to learn about the ecological and genetic mechanisms at play in sea snake visual evolution.”

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Infrastructure built along the River Murray during past ten years helps sustain critical floodplain ecological communities by recreating some of the natural inundation regime that would have occurred prior to development. The benefits of providing these floodplains events are relatively well known, but until recently it wasn’t clear what effects infrastructure was having on the […]

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An exciting find by Ramco Primary School proves there are still many wasp species yet to be discovered. Dr Erinn Fagan-Jeffries has spoken to ABC News and ABC Radio about a project she leads which focuses on discovering and documenting native Australian wasps. As part of this project she visits primary schools and trains students to catch insects using […]

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When people first arrived in what is now Queensland, they would have found the land inhabited by massive animals including goannas six metres long and kangaroos twice as tall as a human. A/Professor Lee Arnold has joined a national team to study fossil bones of these animals for the past decade. Their findings, published in Nature […]

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A research team led by the University of Adelaide has found that revegetation of green spaces within cities can improve soil microbiota diversity towards a more natural, biodiverse state, which has been linked to human health benefits. In the study, published in the journal Restoration Ecology, researchers compared the composition of a variety of urban […]

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As bushfire recovery begins on Kangaroo Island, it’s important remember the recovery of native flora and fauna. The Foundation for National Parks & Wildlife (FNPW) has selected the Echidna CSI project “Investigating the impact of bushfires on Kangaroo Island echidna diet and health” for funding through the FNPW Bushfire Recovery Small Grants. The project has been allocated […]

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Reduced water availability in the Murray-Darling Basin affects many stakeholders – producers of food and fibre, irrigators, and people involved in recreation and tourism. Communities and livelihoods are at stake, and environmental issues are significant. This Stretton Institute webinar features guest presenter Mr Mick Keelty AO APM, Interim Inspector-General of the Murray-Darling Basin will explore the key drivers […]

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The remote sensing work of University of Adelaide PhD candidate W. Boone Law has recently been selected for the 2020 May/June cover of Geoarcheaology. Geoarchaeology is an international journal dedicated to original interdisciplinary scientific research where geographical, geological, geophysical and Earth science techniques are used to better understand the archaeological record. (Pictured right: The front cover […]

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Researchers have found that South Australia’s population of Grey-headed flying foxes has been exposed to a number of viruses, including Hendra virus that can be transmitted to humans via horses. But they have not found evidence of exposure to Australian bat lyssavirus. University of Adelaide research published in PLOS ONE, details three years of research into the […]

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An international team of researchers has completed the first large-scale study of DNA belonging to ancient humans of the central Andes in South America and found early genetic differences between groups of nearby regions, and surprising genetic continuity over thousands of years. In the study, published in the journal Cell, researchers analysed the DNA of […]

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