Coral, meet coral: how selective breeding may help the world’s reefs survive ocean heating

Anna Scott, Author provided

Emily Howells, Southern Cross University and David Abrego, Southern Cross UniversityA single generation of selective breeding can make corals better able to withstand extreme temperatures, according to our new research. The discovery could offer a lifeline to reefs threatened by the warming of the world’s oceans.

Our research, published in Science Advances, shows corals from some of the world’s hottest seas can transfer beneficial genes associated with heat tolerance to their offspring, even when crossbred with corals that have never experienced such temperatures.

Across the world, corals vary widely, both in the temperatures they experience and their ability to withstand high temperatures without becoming stressed or dying. In the Persian Gulf, corals have genetically adapted to extreme water temperatures, tolerating summer conditions above 34℃ for weeks at a time, and withstanding daily averages up to 36℃.

These water temperatures are 2-4℃ higher than any other region where corals grow, and are on a par with end-of-century projections for reefs outside the Persian Gulf.

This led us to ask whether beneficial gene variants could be transferred to coral populations that are naïve to these temperature extremes. To find out, we collected fragments of Platygyra daedalea corals from the Persian Gulf, and cross-bred them with corals of the same species from the Indian Ocean, where summer temperatures are much cooler.

Platygyra, a brain-shaped coral found in many parts of the world.
Emily Howells, Author provided

We then heat-stressed the resulting offspring (more than 12,000 individual coral larvae) to see whether they could withstand temperatures of 33°C and 36°C — the summer maximums of their parents’ respective locations.

Immediate gains

We found an immediate transfer of heat tolerance when Indian Ocean mothers were crossed with Persian Gulf fathers. These corals showed an 84% increase in survival at high temperatures relative to purebred Indian Ocean corals, making them similarly resilient to purebred Persian Gulf corals.

Genome sequencing confirmed that gains in heat tolerance were due to the inheritance of beneficial gene variants from the Persian Gulf corals. Most Persian Gulf fathers produced offspring that were better able to withstand heat stress, and these fathers and their offspring had crucial variants associated with better heat tolerance.

Conversely, most Indian Ocean fathers produced offspring that were less able to survive heat stress, and were less likely to have gene variants associated with heat tolerance.

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Gene editing is revealing how corals respond to warming waters. It could transform how we manage our reefs

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Survival of the fittest

Encouragingly, gene variants associated with heat tolerance were not exclusive to Persian Gulf corals. Two fathers from the Indian Ocean produced offspring with unexpectedly high survival under heat stress, and had some of the same tolerance-associated gene variants that are prevalent in Persian Gulf corals.

This suggests that some populations have genetic variation upon which natural selection can act as the world’s oceans grow hotter. Selective breeding might be able to accelerate this process.

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Heat-tolerant corals can create nurseries that are resistant to bleaching

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We are now assessing the genetic basis for heat tolerance in the same species of coral on the Great Barrier Reef and in Western Australia. We want to find out what gene variants are associated with heat tolerance, how these variants are distributed within and among reefs, and whether they are the same as those that allow corals in the Persian Gulf to survive such extreme temperatures.

This knowledge will help us understand the potential for Australian corals to adapt to rapid warming.

Although our study shows selective breeding can significantly improve the resilience of corals to ocean warming, we don’t yet know whether there are any trade-offs between thermal tolerance and other important traits, and whether there are significant genetic risks involved in such breeding.

Platygyra larvae. It remains to be seen whether the genetic benefits of heat-tolerance genes persist throughout life.
Emily Howells, Author provided

Our study was done on coral larvae without the algae that live in close harmony with corals after they settle on reefs. So it will also be important to examine whether the genetic improvements to heat tolerance continue into the corals’ later life stages, when they team up with these algae.

Of course, saving corals from the perils of ocean warming will require action on multiple fronts — there is no silver bullet. Selective breeding might provide some respite to particular coral populations, but it won’t be enough to protect entire ecosystems, and nor is it a substitute for the urgent reduction of greenhouse emissions needed to limit the oceans’ warming.

Emily Howells, Senior Research Fellow in Marine Biology, Southern Cross University and David Abrego, Lecturer, National Marine Science Centre, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Lights out! Clownfish can only hatch in the dark – which light pollution is taking away

Some 22% of the worlds’ coastlines are exposed to artificial light at night.
Emily Fobert, Author provided

Emily Fobert, Flinders University

Clownfish achieved worldwide fame following Finding Nemo, but it turns out these fish don’t do so well in the spotlight.

Our research, published in Biology Letters, found when clownfish eggs were exposed to low levels of light at night – as they would be if laid near a coastal town – not a single egg hatched.

This finding adds to the growing body of research on the health affects of light pollution, a rapidly spreading ecological problem.

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Read more:
Light pollution: the dark side of keeping the lights on

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What is light pollution?

Light pollution occurs when artificial light interferes with ecological systems or processes, usually at night.

Natural light at night, produced by the moon, stars, and other celestial bodies, is minimal. A full moon creates only 0.05-0.1 lux, which pales in comparison to the artificial light produced by humans, which can range from around 10 lux from an LED or low-pressure sodium streetlight, up to 2,000 lux from something like stadium lighting.

Clownfish were exposed to artificial light to see what effect it would have on their reproduction.
Emily Fobert, Author provided

Because nearly all organisms on Earth have evolved with a stable day-night, light and dark cycle, many biological events are now highly attuned to the daily, lunar, and seasonal changes in light produced by the reliable movements of the Earth and Moon around the Sun.

But artificial light can mask these natural light rhythms and interfere with the behaviour and physiology of individual creatures, and ecosystems as a whole.

The ocean is not exempt from these problems. Light pollution is spreading to marine habitats through urbanised coastlines and increasing marine infrastructure such as piers, harbours, cruise ships, and tropical island resorts where bungalows extend out into the lagoon, directly above coral reefs.

Why are clownfish at risk?

Clownfish, like many reef fish, are particularly vulnerable to light pollution because they don’t move around much in their adult stage. Clownfish can travel long distances in the first 2 weeks after hatching, but at the end of this period the young fish will settle in a suitable sea anemone that becomes their forever-home.

Once clownfish find a suitable anemone they stay put forever.
Emily Fobert, Author provided

This means that if a fish chooses an anemone on a shallow reef in an area that is heavily lit at night, they will experience chronic exposure to light pollution throughout their life; they won’t just move away.

Clownfish also lay their eggs attached to rock or other hard surfaces, so in areas exposed to light pollution the eggs will experience continuous artificial light (as opposed to many fish that lay and fertilise eggs in open water, so they are immediately carried away by ocean currents).

What we found

To test how artificial light affects clownfish reproduction, we examined the common clownfish (Amphiprion ocellaris) in a lab experiment.

Five breeding pairs of fish experienced a normal 12-hour daylight, 12-hour dark cycle, while another five pairs of fish had their “night” period replaced with 12 hours of light at 26.5 lux, mimicking light pollution from an average coastal town.

For 60 days, we monitored how often the fish spawned, how many eggs were fertilised, and how many eggs hatched. While we saw no difference in spawning frequency or fertilisation rates between the two groups of fish, the impact of the artificial light treatment on hatch rate was staggering. None of the eggs hatched, compared with an average of 86% in the control group.

Clownfish attach their eggs to rocks or other hard surfaces, leaving them at the mercy of their immediate environmental conditions.
Emily Frobert, Author provided

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Why does Nemo the clownfish have three white stripes? The riddle solved at last

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At the end of the experiment we removed the artificial light and monitored the fish for another 60 days to see how they would recover. As soon as the light at night was removed, eggs resumed hatching at normal rates.

Clownfish, like many reef fish, have evolved to hatch after dusk to avoid the threat of being eaten. Newly hatched baby clownfish, like most coral reef fish, are small (about 5mm long) and transparent. Hatching in darkness likely means they are less visible to predators as they emerge from their eggs.

Our findings show that the presence of artificial light, even at relatively low levels, can disrupt this crucial process, by masking the environmental cue – darkness – that triggers hatching. As many reef fish share similar reproductive behaviours to clownfish, it is likely artificial light will similarly interfere with the ability of other fish species to produce viable offspring.

Healthy, fertilised clownfish eggs did not hatch in the presence of artificial light.
Emily Frobert, Author provided

The larger problem

Light pollution is one of the most pervasive forms of environmental change. An estimated 23% of land surface (excluding the poles) and 22% of coastal regions are exposed to light pollution.

And the problem is only growing. The reach of light pollution across all land and sea is expanding at an estimated rate of 2.2% per year, and this will only increase with the rising global human population.

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Read more:
Saving Nemo: how climate change threatens anemonefish and their homes

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Although research on the ecological impacts of light pollution is arguably only in its infancy, the evidence for negative consequences for a range of insects, birds, amphibians, reptiles, and mammals, including humans, is stacking up.

Our new research adds another species to the list, and highlights the importance of finding ways to manage or reduce artificial light, on land and below the waves.

Emily Fobert, Research Associate, Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

‘Give us a sniff, love’: giving marsupials scents from suitors helps breeding programs

A baby eastern barred bandicoot pokes its head out of its mother’s pouch.
M. Parrott, Zoos Victoria, Author provided

Marissa Parrott, University of Melbourne

Smell is a vital part of sexual attraction for all kinds of animals (including humans). We may be able to use smell to improve breeding programs by giving the female animal a sample sniff of potential mates and letting her choose the best one before introducing them.

Our new research found female marsupials paired with the male of their choice in captive breeding programs had a higher chance of becoming pregnant, a shorter time to pregnancy and may produce healthier young.

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Read more:
Curious Kids: How do we smell?

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Ladies’ choice

Zoos and breeding institutions traditionally pair animals based on their relatedness and pedigree so they can manage the overall genetic health of the population. It’s expensive and often not possible to transport multiple males just to give a female some options – but if she refuses her solitary suitor when he arrives, it can cause major problems.

Our research shows that presenting the female with a range of scent samples and letting her pick her favourite dramatically increased compatibility.

This simple 10-minute test more than doubled the number of pregnancies and shortened the time to becoming pregnant in a small carnivorous marsupial, the stripe-faced dunnart.

Marissa Parrott with a captive-bred mountain pygmy-possum released to the wild.
Author provided

Using the same technique in the critically endangered mountain pygmy-possum at Healesville Sanctuary, we showed that females had significantly higher breeding success with males they liked during their choice tests. We have shown a similar effect of increasing breeding success and shortening the time to pregnancy in the endangered eastern barred bandicoot at Zoos Victoria through scent and interactions.

How are female marsupials choosing mates?

Put simply, they are following their noses. We gave females a choice of male smell and allowed her to sniff out the best mate.

In the first published study of marsupial mate choice, we found female agile antechinus chose the most genetically suitable male based on his smell. Females preferred males that were genetically dissimilar to themselves (avoiding in-breeding), but not too dissimilar (avoiding genetic out-breeding).

There is a sweet spot to female choice. If you can provide a female with a suite of males, they can choose their most compatible suitor, which in turn is likely to produce the healthiest and fittest young.

Better yet, females are choosing males compared with their own genes, so each female may like a different male, which is good for managing the overall population. However, care must be taken with sisters, as they are likely to have the same choices.

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Swingers’ hookup program can find the right match for endangered species

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This information is particularly helpful for global programs that have endangered species spread across different institutions and zoos, such as tree kangaroos.

In the dunnarts, we found that freezing and storing the scents of males for up to 40 days did not affect a female’s choice or interest in a scent. Thus, if you have a female tree kangaroo at Melbourne Zoo and are uncertain which male should be sent from overseas, you could freeze scents from eligible bachelors and send them to her in advance for her approval. This could reduce the stress, time and cost associated with sending males between zoos, especially if the male you sent ended up being the wrong choice!

A stripe-faced dunnart in the captive breeding colony at the University of Melbourne.
M Parrott, Author provided

But why focus on females?

In marsupials, females provide the majority of the care of the young. In the extreme case of the antechinus, all males die after mating, leaving the females with all the work raising the offspring. Thus, females are generally the choosier sex, ensuring they get the maximum benefit from appropriate mate choice.

In other species, such as the critically endangered plains wanderer whose females lay eggs and leave them with stay-at-home fathers, you may expect the male bird’s choice to be more important. He is providing the care to the growing chicks and thus will want to maximise their success through choosing the best mate.

Can people learn from the marsupial approach?

Female mate choice is a perennial issue for many humans. A study that supplied 49 women with T-shirts worn by different men found the women could sniff out the men in their genetic “sweet spot” – not too similar or dissimilar – and found those scents most attractive.

We are not so different to the endangered marsupials we are working to recover. Perhaps in the future, instead of swiping right on an image, we can be sent a palette of smells to choose a potential suitor. Instead of speed dating, could we use smell dating?

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Tasmanian devils reared in captivity show they can thrive in the wild

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Certainly, when used in conservation breeding programs, allowing a female to choose her own mate can help find the best pairings, reduce the time to produce young and hopefully help produce the healthiest offspring to fight extinction for their species.

Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

‘Renewable energy breeding’ can stop Australia blowing the carbon budget – if we’re quick

Mark Diesendorf, UNSW

Moving to a future powered mainly by renewable energy will be crucial if we are to stay within the global warming limits set out by the Paris Agreement. But building all of this new renewable energy will initially require fossil fuels to help power all of the necessary mining, construction and decommissioning. This raises the question as to whether the energy transition itself will be pointless.

But new research by a group at UNSW (Bahareh Sara Howard, Nick Hamilton, Tommy Wiedmann and myself) shows that it is theoretically possible for Australia to move to a renewable energy future without blowing its share of the carbon budget.

Actually doing it will require two things: prompt, decisive action, and a reliance on “renewable energy breeding” – the process by which mining the raw materials and manufacturing technologies such as solar cells and wind turbines are themselves powered by renewables rather than fossil fuels.

Already under way

This renewable energy breeding is already under way in some places. Tesla’s solar panel factory in Nevada, known as Gigafactory 1, will itself run on solar power. In South Australia, Liberty OneSteel, the new owner of the Whyalla steelworks, is planning solar power, pumped hydro, batteries and demand management to reduce energy costs and greenhouse emissions. In Western Australia, Sandfire Resources’ DeGrussa gold and copper mine and Galaxy Resources’ lithium mine are both going solar.

These are encouraging developments. But will they be enough? The world has only a limited emissions budget left to keep global warming below the Paris Agreement’s 2℃ limit, and an even smaller budget for the agreement’s more ambitious 1.5℃ goal.

As Australia is responsible for about 1% of global emissions and its electricity industry is responsible for about one-third of that, we have assumed that the country’s carbon budget for electricity generation is about one-third of 1% of the global carbon budget. Overall, then, this gives us a total carbon budget for Australia’s electricity sector of 3.3 gigatonnes of carbon dioxide equivalent (post-2011) for the 2℃ target, and 1.3 gigatonnes for the 1.5℃ target. For comparison, Australia’s annual carbon dioxide equivalent emissions are over half a gigatonne (actually 0.55 gigatonnes), so we are only three years away from overshooting the 1.5℃ target.

Even these budgets are generous, because Australia is one of the biggest per capita carbon dioxide emitters in the world and has enormous renewable energy resources.

What’s more, electricity is the easiest part of the energy sector to move to renewable energy – heating and transport are more difficult prospects. This means that if we are to move to an entirely renewable energy future, most heating and transport will need to be electrified. Therefore, electricity should have a greater emissions reduction target than other sectors.

Making the transition

Our study, which builds on earlier research, looked at 22 possible scenarios for transitioning Australia’s electricity sector to predominantly renewable energy. Some were developed by us, and some by other research groups.

Crucially, our study factored in the “life-cycle” emissions of these energy generation technologies – that is, the total greenhouse emissions including those released during the manufacture of the technologies themselves. And we looked explicitly at renewable energy breeding as part of that analysis.

Our scenarios also assume that overall electricity demand will either stabilise or decline, despite the move towards electrifying transport and heating. This is because Australia is well placed to make huge improvements in energy efficiency.

Rapid action needed

The principal findings of our research include the good news that the life-cycle greenhouse emissions from manufacturing renewable energy technologies such as solar panels and wind turbines are tiny, compared with the emissions saved by using them as substitutes for fossil fuels.

With the help of renewable energy breeding, the overall life-cycle emissions savings can be substantial – more than 90%, in some of the scenarios we examined. Therefore, manufacturers of renewable energy systems should use renewable energy to power their production lines.

The bad news is that, in every scenario we investigated, Australia nevertheless fails to achieve its share of the ambitious emissions reductions needed to limit global warming to 1.5℃ with 66% probability. Furthermore, 9 of our 22 scenarios also fail the more lenient 2℃ target.

Cumulative emissions for 2011-50 for 22 different pathways for a renewable energy transition in Australia. Green shaded area represents pathways that are within Australia’s share of the global carbon budget for 2℃ of warming; red shaded area represents pathways that exceed it.
Howard et al., 2018

The main reason for this is the legacy of CO₂ emissions from fossil fuel use before the renewable energy transition. In most of our scenarios, the benefits of renewable energy breeding to the cumulative emissions become significant only beyond 2040.

The scenario (S8a, labelled V in the graph above) that comes closest to achieving the 1.5℃ target involves a 98% transition to renewable electricity and a 35% reduction in electricity demand by 2030 – a very rapid transition indeed!

The scenarios that deliver on the 2℃ target have rapid and high penetrations of renewable energy into the market, and high contributions from energy efficiency.

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Rapid transition to clean energy will take massive social change

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While it may already be too late for Australia to make a fair contribution to keeping global warming at 1.5℃, our results show that we can stay within our share of the carbon budget for 2℃ – provided we have the political will to move fast.

What’s more, if we implement policies that incentivise renewable energy breeding, there is no reason to suppose that moving to 100% renewable energy would necessarily entail a large increase in emissions to produce the necessary technologies.

But the overriding message is that time is of the essence, if we want to come anywhere close to limiting dangerous climate change. Our various scenarios suggest that even if we implement a rapid, effective response, we are likely to have to take CO₂ back out of the atmosphere in the future, to compensate for the likely overshoot on our share of the global carbon budget.

Mark Diesendorf, Honorary Associate Professor, UNSW

This article was originally published on The Conversation. Read the original article.

Australia’s rarest insect goes global: Lord Howe Island stick insect breeding colonies now in US, UK and Canada

Susan Lawler, La Trobe University

If you haven’t heard of the Lord Howe Island stick insect, you have missed out on one of the most remarkable conservation stories of the decade.

This week’s news is that breeding colonies of Australia’s rarest insect will soon be established in zoos at San Diego, Toronto and Bristol. These new colonies will join those at the Melbourne Zoo and the Lord Howe Island Museum to ensure the future of this unique species.

The remarkable story of these stick insects (which are also called phasmids or land lobsters) started when rats escaped from a shipwreck in 1918 and proceeded to eat every last stick insect on Lord Howe Island. The species was thought to be extinct until a few live specimens were discovered on Balls Pyramid in 2001. The news headline in the Sydney Morning Herald at the time proclaimed: “Joy as ancient ‘walking sausage’ found alive.”

This remote and almost inaccessible population was the key to survival for the phasmids, but presented enormous difficulties for scientists who wanted to study them. Eventually an expedition was arranged to collect live specimens, which had to be done at night when the insects are out of their burrows and active.

The story of the captive breeding program is almost heart-stopping with many twists and turns. The original pair held at the Melbourne zoo were named Adam and Eve and because almost nothing was known of their lifestyle and habits, trial and error and careful observation were needed to provide them with appropriate care. At one point Eve nearly died but was revived when zookeeper Patrick Rohan carefully dropped a mixture of sugar, calcium and ground melaleuca leaves into her mouth.

Eve’s first egg hatched on Threatened Species Day on 2003, and although this wasn’t the end of the challenges facing Melbourne Zoo staff, it turned out to be the beginning of hope for the species’ successful captive breeding program.

I became personally acquainted with these insects when the zoo allowed selected schools to hatch some eggs and one of the babies spent time at my house. A film of her first steps and the story of our excitement was published here in 2012.

Sticks that spoon: juvenile Lord Howe Stick Insects hatched at Tallangatta Secondary School in 2012.
Geoff Edney

The Lord Howe stick insects start out small and green but grow up fat and black. They spend their days curled up together in burrows and head out at night to feed. Their story has caught the attention of David Attenborough and Jane Goodall.

New books about Lord Howe Stick Insects

If you want to know all about the story of the Lord Howe Stick Insects, two recent books are ready for you to devour.

For adults, Return of the Phasmid: Australia’s rarest insect fights back from the brink of extinction, by Rick Wilkinson provides a comprehensive and fascinating summary of the history, geology and human drama involved in this story, complete with great photos and personal accounts. Anyone who wants to understand what it takes to bring a species back from the brink will find it great reading.

Additionally and delightfully, the invertebrate zookeeper Rohan Cleave has released a children’s book, Phasmid: Saving the Lord Howe Stick Insect, with lovely watercolour illustrations that bring phasmids to life for young hearts.

Soon these books will become important in a global context, as people in San Diego, Toronto and Bristol get to meet our very own ‘walking sausages’.

Susan Lawler, Senior Lecturer, Department of Ecology, Environment and Evolution, La Trobe University

This article was originally published on The Conversation. Read the original article.

Article: Devil’s Ark

The link below is to an article reporting on the breeding success with Tasmanian Devils at Devil’s Ark in the Barrington Tops, NSW, Australia.

For more visit:
http://www.australiangeographic.com.au/journal/40-tasmanian-devil-babies-boost-insurance-population.htm

Australia: Western Australia – More on Gouldian Finches

Australian Geographic has posted an article on the discovery of the breeding colony of Gouldian Finches I mentioned in a post a few days ago (https://kevinswildside.wordpress.com/2012/01/22/australia-western-australia-gouldian-finch/). This article is also worth a read.

For more info visit:
http://www.australiangeographic.com.au/journal/new-gouldian-finch-population-found-in-kimberley.htm

Australia: Western Australia – Gouldian Finch

A new breeding population of the extremely rare Gouldian Finch has been found in the Kimberley region of Western Australia.

For More Visit:
http://au.news.yahoo.com/a/-/latest/12658787/rare-bird-find-in-wa-s-north-boosts-hopes/

Kenya: Mountain Bongo Facing Extinction

With less than 120 individuals left in Kenya, the world’s largest antelope is facing extinction in the wild within a matter of years. Kenya is the only country in the world where Mountain Bongo exist in the wild. They are threatened by poachers, habitat destruction and a collapsing gene pool.

There is possible good news for the Mountain Bongo, with increasing captive populations, including a growing breeding population in Kenya which may one day be reintroduced to the wild.

For more visit:
http://www.scientificamerican.com/blog/post.cfm?id=mountain-bongo-faces-extinction-aft-2011-04-15