Those who help each other can invade harsher environments

Date: February 20, 2017

Source: Lund University

Through cooperation, animals are able to colonize harsher living environments that would otherwise be inaccessible, according to a new study from Lund University in Sweden, together with researchers in England and USA. The research community has long believed this was the other way around -- that species in tough environments had to cooperate to survive. As a result the established view of why animals cooperate is turned upside-down.

Some species of birds cooperate closely in the rearing of offspring. The older siblings appear to selflessly help their parents rear the youngest brood. This phenomenon is most common in species that live in harsh environments, where the climate is hot and rain is scarce.

For a long time, researchers believed that the harsh conditions have forced individuals to help because they can't breed on their own. It seems, however, the opposite is true -- that the cooperation evolves first, and this gives species a chance of successfully invading and surviving in more barren places.

"Cooperation appears to be an important prerequisite to colonization of arid habitats," says Charlie Cornwallis, biologist at the Faculty of Science at Lund University.

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How cathedral termites got to Australia to build their 'sky-scrapers'

February 21, 2017

They build among the tallest non-human structures (proportionately speaking) in the world and now it's been discovered the termites that live in Australia's remote Top End originated from overseas - rafting vast distances and migrating from tree-tops to the ground, as humans later did. 

 
Referred to as "cathedral" termites, the Nasutitermes triodiae build huge mounds up to eight metres high in the Northern Territory, Western Australia and Queensland - representing some of the tallest non-human animal structures in the world. 

 
DNA sequencing found the forebearers, called nasute termites, colonised Australia three times in the past 20 million years or so and evolved from wood to grass-feeding as they adapted to significant environmental changes, including increasingly arid conditions and the conversion of woodlands to grassland habitats in subtropical savannahs and central Australia.
Now a prominent feature of the arid landscape "Down Under", the mounds house millions of termites; this study is the first comprehensive investigation of the evolution of the nesting and feeding of the extended family of termites, through the Australian refugee descendants. 

 
The findings of the international research are published today in the Royal Society journal Biology Letters. 

 
Co-lead author of the paper from the University of Sydney, Associate Professor Nathan Lo, said although much was known about the functions of termite mounds - which include protection from predators - little had been known about their evolutionary origins. 

 
"We found that the ancestors of Australia's fortress-building termites were coastal tree-dwellers, which arrived in Australia by rafting long distances over the oceans from either Asia or South America," Associate Professor Lo said. 

 
"Once in Australia, they continued to build their nests in trees, but later descended and began building mounds on the ground instead, paralleling the evolution of the other great architects of the world - human beings, whose ancestors lived in the tree tops some millions of years ago."
Associate Professor Lo, from the University of Sydney's School of Life and Environmental Sciences, said the mounds are an engineering feat when considered in comparison to the tallest structure on Earth - Dubai's skyscraper the Burj Khalifas.
"Given that a worker termite stands about 3mm in height, these mounds are in human terms the equivalent of four Burj Khalifas stacked on top of each other," he said.
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How did legless worm-lizards cross the Atlantic? – via Herp Digest

How did a tiny, reclusive, underground animal colonize so much of the world? The answer to this and other unexpected animal migrations could be “rafting”

by Elsa Panciroli, The Guardian, 7/13/16

Biogeography is the study of the geographic distribution of living things. As you can imagine, when you stick “palaeo” in front of it and apply it to fossils, not only will you win at scrabble, but produce a science often confounded by a patchy fossil record, as well as the changing configuration of the continents, natural disasters, and many other biological and geographical phenomena. So how do palaeobiogeographers explain how an animal that is tiny, burrows underground, and has no legs, lives on multiple continents separated by the Atlantic Ocean?

When two or more populations of a terrestrial animal group are found in vastly separated parts of the world, two explanations are most often proposed. Firstly, that they spread by land from one place to the other, then the populations in-between went extinct, leaving two geographically distant populations. This is called dispersal. Another explanation is plate tectonics: as the continents split they carried animals with them, physically separating populations. This is an example of vicariance. Dispersal and vicariance are the common and over-arching explanations that account for the patterns of life on earth that take place over vast periods of time.

Dispersal and vicariance are sometimes seen to be at odds. Scientists can tend to favour one explanation over the other as being the most important and frequent cause of animal distribution patterns. For palaeontologists, there could be a tendency to view life in terms of vicariance, particularly driven by the ancient distribution of continents and plate-tectonic shifts. It makes sense to favour this when you spend your career thinking in millions of years.

However, there are instances of animal occurrence that continental drift can’t explain. If you look at terrestrial life on earth and assume it could only disperse by walking from one place to the next when the continents were connected, you get some pretty silly estimates for splits between major animal groups. To take advantage of land bridges to explain their dispersal, the first land animals would have to have evolved millions of years before the Cambrian. As we know from fossils, the first complex life on earth was only just evolving in our seas at that time. Cambrian animals didn’t even have backbones, let alone a leg to stand on.

What if land animals frequently “rafted” across seas and oceans to their new destinations?

Sound far-fetched? Well this proposal is broadly accepted as the mechanism for several animal dispersals. For example the distribution of mammals across the islands of the Caribbean from mainland South America, such as monkeys and rodents. This series of small jumps is also called island-hopping, and occurs when animals find themselves on rafts of floating tangled vegetation, swept out to sea. Flyers fly, swimmers swim, and it appears that land-lubbers that cannot swim across oceans, raft.

It’s all very well to imagine this may happen between island chains; it is amazing but not impossible. Could the same thing happen across an entire ocean? What about between Africa and the Americas? That’s exactly what the worm-lizards have done. Not just once, but twice.

The worm-lizards, Amphisbaenia, are mostly legless squamates related to other lizards and snakes. Amphisbaenians lost their legs independently of the snake lineage and belong to their own distinct part of the squamate tree. Most species of worm-lizard still retain remnants of their pelvis and pectoral girdle (hips and shoulders), but only four species from Mexico out of the 180 currently known around the world still have functioning forelimbs. The group as a whole gets its name from Amphisbaena, the Greek serpent that had a head at each end. This is because the first specimens to become known scientifically had a very similar tail and head, ending bluntly and somewhat worm-like. They are vertebrates, and so have skulls with varying numbers of teeth (they are carnivorous and insectivorous) in a jawed mouth. They also have deeply recessed eyes that can discern light from dark. They may look like earthworms, but inside they are still every bit reptilian, with two lungs, one of which is squeezed and elongated while the other is greatly reduced. 

If you want to go looking for these strange legless lizards, you’ll have your work cut out. Although they are found all across South America, most of Africa, parts of the Middle East, North America and Europe, they live underground, rarely surfacing from their burrows. Most are less than 15cm long. This begs the question: how does such a reclusive underground animal colonise so much of the world?

When both the DNA and fossil evidence are studied together, it turns out that the ancestral subterranean legless lizards first began splitting into different families around 109 million years ago in North America, where they are likely to have originated. There was another major diversification between North American and European amphisbaenians 40-56 million years ago. Finally the African and South American forms split around 40 million years ago. These dates matter because the Atlantic Ocean had fully formed by the time all of these splits took place. To get from North America to Europe, then Africa to South America, these animals must have crossed the ocean.

Worm-lizards therefore must have “rafted” across the Atlantic. Natural erosion and storm events can loosen large sections of soil, often bound together with tree roots, and wash it out to sea. Some unsuspecting worm-lizards were set adrift this way, and the natural direction of ocean currents and prevailing winds carried their life rafts to shores new. Being able to survive without food for weeks, some of these sailors became colonists. 

Worm-lizards are not the only group that have dispersed this way. But you have to wonder: what are the chances? How could enough of any one species make it to new shores to breed and survive in the long term? It just seems so improbable. For an animal like us, who lives to around 100 years of age if they are lucky, we struggle to grasp probability over longer time spans.

You often hear the phrase “a once in a lifetime event” being used to describe huge natural disasters, such as the tragic Boxing Day tsunami in 2004. After this event, natural and man-made debris washed across the Pacific Ocean, reaching American coastlines. For arguments sake, let’s assume something on that scale happens once in a hundred years. Multiply that by the span of all modern humans, around 140,000 years. That means humans have experienced this kind of natural disaster around one and a half thousand times. Multiply this by geological time, and you have millions of disasters befalling populations of humans and other animals.

Japanese tsunami sweeps dock to Oregon beach

A cheery thought, no? The point is that as unlikely as it seems for a legless lizard to be washed unharmed to sea, float across the Atlantic for weeks, and make it to the next continent only to find another legless lizard waiting for them to mate (either from a previous journey, or from the same raft of earth as them), the chances are actually pretty good given enough time. Of course, nature doesn’t evenly space these events out, so two or three “once in a lifetime” events may happen within the life-span of a single legless lizard.

So when it comes to the question of dispersal versus vicariance, it would seem that the answer is a complex interplay of both. No one explanation is “better” than the other, we must instead look at the fossil and genetic evidence together, and work out for each group of animals what the most likely explanation is for their distribution across our little globe. In doing so, let’s not underestimate the role of vast amounts of time on the likelihood of seemingly improbably events. Call it serendipity if you will. If the chances are a million to one, on a geological timescale I’ll take those odds.

References

Longrich, N. R., Vinter, J., Pyron, A., Pisani, D. and Gauthier, J. A. (2015) Biogeography of worm lizards (Amphisbaenia) driven by end-Cretaceous mass extinction. Proceedings of the Royal Society B, 282, http://dx.doi.org/10.1098/rspb.2014.3034

Naish, D. (2014) Worm Lizards: Lifestyles of the Limbless. Tetrapod zoology blog for Scientific American http://blogs.scientificamerican.com/tetrapod-zoology/worm-lizards-lifestyles-of-the-limbless/

Parade of Creatures Colonized Land After Dinosaur Demise

By Charles Q. Choi, Live Science Contributor | June 10, 2014 07:05pm ET

The cataclysm that ended the Age of Dinosaurs not only drove land animals to migrate into the water, but also pushed aquatic creatures to colonize the land, a new study reveals.

The shifts between land and water in the animal kingdom are among the most pivotal in evolution. The most famous example is that of fish that made the switch from water to land — the first tetrapods, or four-legged animals, which gave rise to amphibians, reptiles, birds and mammals. Animals also moved from land to water — for example, the ancestors of seafaring whales appear to have been deerlike ungulates, or hoofed mammals.

Scientists reason the shifts between the aquatic and terrestrial realms might relate to environmental upheaval. For instance, mass extinctions usually leave many open roles within ecosystems, niches that survivors might evolve to fill. 

Continued

Exotic migrant butterflies colonise the UK

The Long-tailed Blue, a rare migrant butterfly from Europe, has raised broods at several sites across the south coast of England. Photo credit Neil Hulme/Butterfly Conservation.

Long-tailed blue butterfly and unusual moths here in numbers

October 2013. UKIP and the Mail would not be happy; some foreigners have been arriving here in large numbers. Exotic butterflies and moths from the Continent are attempting to colonise the UK following this year's warm summer and mild autumn.

Long-tailed Blue butterfly

The Long-tailed Blue, a rare migrant butterfly from Europe, has raised broods at several sites across the south coast of England, and some very rare migrant moths such as the Clifden Nonpareil and Rosy Underwing have been seen in increasing numbers in recent weeks across several southern counties.

Autumn moths

These sightings suggest that all three species may be attempting to colonise southern England and come as the autumn moth migration gets into full swing bringing rarities such as the Crimson Speckled and the Vestal to our shores from Southern Europe.

UK brood

Long-tailed Blues migrated to the south coast in August and in the last fortnight the first home-grown British adults have emerged with the butterflies seen at sites including Dover and Margate in Kent and Newhaven in Sussex and a site in Wiltshire. The butterfly has bred in the UK on a handful of occasions before but this summer is the first time the Long-tailed Blue has raised young over such a considerable area.

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Mink have colonised large areas of coastline

By John Ross


AGGRESSIVE mink have colonised most of the coastline of Skye and Lochalsh posing a risk to ground-nesting birds, according to volunteers carrying out a monitoring project.

Hotspots have been found in Kyle, Kylerhea, Loch Bracadale and North Trotternish as well as the islands in the Sound of Raasay, the Skye and Lochalsh, Environment Forum's Mink Survey says.


About 50 people have now reported mink sightings, including those that have been trapped, killed on the roads or had footprints recorded in tunnels set with clay pads.

Scores of volunteers, including crofters and members of conservation bodies and fishing organisations, have helped gather the information for the survey, which is funded by Scottish Natural Heritage, the Highland Council and the European Leader programme.

The aim is to develop a policy to help protect native wildlife and biodiversity from the alien species.

Mink were introduced into Britain as a farmed animal for their fur, but escaped, or were released into the wild, where they compete with otters and others of the weasel family. They feed on fish, ground-nesting birds, eggs, and small mammals, and often take poultry from hen houses and runs.

Mammal Society member Roger Cottis welcomed the recent results: "This is an important element in the continuing fight to help indigenous Scottish wildlife under threat."

A project has been removing mink from the Western Isles for ten years during which time almost 1,500 animals have been cleared from the islands.

http://news.scotsman.com/nature/Mink-have-colonised-large-areas.6657245.jp