Creation of an island: The extinction of animals on Zanzibar

Date: February 23, 2016

Source: University of York

Researchers at the University of York have been part of the first comprehensive study of how Zanzibar was formed, charting the extinction of various animals from the island.

In a collaborative project between environmental scientists and archaeologists, a team charted the history of sea level change by examining mangrove sediments, and conducting analysis on animal remains found in Kuumbi Cave -- an important archaeological site.

Focusing on evidence from three distinct time periods -- the end of the last Ice Age, the stage when Zanzibar became an island 11,000 years ago, and the time of being an island -- researchers found that numerous large mammals had disappeared by the latter stage.

Analysing over 6000 bone specimens, it was found that large fauna such as zebra, buffalo, waterbuck and gazelle were present in the time of island formation. However, after sea levels had risen and the island had been inhabited by coastal cultures, they disappeared. Other small fauna, such as porcupines and hares, were also no longer present.

Insights into sea level changes, combined with archaeological data on the history of the island's fauna through excavation, has never been done before in charting Zanzibar's history. This unique interdisciplinary approach provides a new, accurate account of the island's prehistory and defaunation.

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The castaway: New monitor lizard fills top-order predator role on remote Pacific island

Date: February 24, 2016

Source: Pensoft Publishers

Separated by several hundred kilometres from its next of kin, a new species of blue-tailed monitor lizard unique to the remote Mussau Island has been described. Unknown to science until recently and formally termed the "isolated," it is the only large-sized land-living predator and scavenger native to the island.

Dubbed a "biogeographical oddity" by its discoverers, led by Valter Weijola, a graduate student from the University of Turku, Finland, the lizard species is also the first new monitor lizard to be described from the country of Papua New Guinea in over twenty years. The finding was published in the open-access journal ZooKeys.

Monitors play an important ecological role in many island ecosystems in the southwest Pacific. Predatory mammals have never colonized the region due to the isolation of these islands. Instead, these large, active and intelligent lizards fill the role of top-predators and scavengers. The Pacific monitor lineage to which the new species belongs have been so successful at oversea dispersal that a number of different species now occupy almost every island from the Moluccas in Indonesia to the eastern Solomon Islands and even Micronesia.

The new endemic species was observed and studied during fieldwork by Weijola and local assistants in the relatively dry coastal vegetation of Mussau, but it is likely that it also persist in the remnants of intact forest in the interior of the island.

The formally described female lizard, or holotype, measures 1 m with the tail being one and and a half times the length of the dominantly black-coloured body covered with yellow and orange markings. The tail of the adults shows varying degrees of turquoise to bluish pigmentation. Another distinctive feature for the species is the pale yellow tongue, which is a trait shared only by three other species of Pacific monitors. The new species is known to eat crabs, other reptiles and their eggs, and small birds.

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Fish of dinosaur era with unique 'hook-shaped sail' on its back

 Large tuna-like fish named in honor of North Texas amateur fossil hunter who discovered the 90-million-year-old specimen in Dallas County and donated it to the Perot Museum of Nature and Science

Date: February 22, 2016

Source: Perot Museum of Nature and Science

A 90-million-year-old fossil fish, which has been on display at the Perot Museum of Nature and Science in Dallas, turns out to be a new species. Research conducted by Kenshu Shimada, Ph.D., professor at DePaul University in Chicago and research associate of the Sternberg Museum in Kansas, reveals the 5.5-foot-long fossil fish to possess a tuna-like body with a unique 'hook-shaped sail' on its back. The fish has been given a new species name, Pentanogmius fritschi, in honor of Joseph Fritsch, a local amateur collector who discovered the fossil, dug it up with the help of another avid fossil collector, Kris Howe, and donated it to the Perot Museum.

"At first glance, the specimen looked like a known Pentanogmius species, but when I began to trace the curved dorsal fin, its front half kept extending backwards far beyond where I thought it would end relative to its rear half. That's when I realized I have something new to science," said Dr. Shimada.

The fossil fish is a nearly complete skeleton from the Britton Formation of the Eagle Ford Shale in Dallas County. Dr. Shimada's study suggests that Pentanogmius fritschi was an active fish in open ocean environments that possibly fed on a variety of small animals like squid and other fish.

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Genomic evidence sheds new light on our understanding of spider evolution

Date: February 23, 2016

Source: PeerJ

After a burst of work in the 1980s, it was believed that science had a sound understanding of the evolution of spiders. However, in a new study employing cutting edge bioinformatics and next generation sequencing techniques, scientists have reconstructed the spider 'tree of life' to come to intriguing new conclusions about the evolution of the web, something which has important implications for the overall story of spider evolution.

The arachnid order to which spiders belong, Araneae, is an incredibly ancient and diverse group comprising over 45,000 described species with nearly three times as many awaiting discovery; by all counts they are the largest known animal group that is exclusively predatory. In addition to remarkable diversity, ecology, and abundance, spiders are known for some extraordinary biomolecules , such as venoms and silks. Although few spider venoms are dangerous to humans, they hold enormous medical promise as insecticides and therapeutics. And, no other animal can claim a more varied and elegant use of silk -- a super strong material being used to create biometic material such as artificial nerve constructs, implant coatings, and drug delivery systems.

Despite their amazing diversity, and important biomolecules, our understanding of spider evolution has long been an open question. The orb web, the spiral wheel shaped web made by many spider species, once considered "the crowning achievement of aerial spiders" has captured the imagination of evolutionary biologists for over a century as a consequence of its intricate beauty. Initially thought to have evolved independently at least twice across the group's evolutionary history, complex associated morphologies and behaviors studied extensively in the 1980s suggested otherwise, sparking a shift in thinking that ultimately concluded that the orb web and the taxa that spin it all shared a common ancestor. Subsequent evolutionary changes in thread chemistry along with a vertically oriented orb web were thought to have sparked a tremendous bout of species diversification.

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Magnetoreception molecule found in the eyes of dogs, primates

Dog-like carnivores, some primate species may have a magnetic compass similar to that of birds

Date: February 25, 2016

Source: Max-Planck-Gesellschaft

The magnetic sense in migratory birds has been studied in considerable detail: unlike a boy scout's compass, which shows the compass direction, a bird's compass recognizes the inclination of the magnetic field lines relative to Earth's surface. Now scientists report that dog-like carnivores and some primate species may have a magnetic compass similar to that of birds.

Cryptochromes are light-sensitive molecules that exist in bacteria, plants and animals. In animals, they are involved in the control of the body's circadian rhythms. In birds, cryptochromes are also involved in the light-dependent magnetic orientation response based on Earth's magnetic field: cryptochrome 1a is located in photoreceptors in birds' eyes and is activated by the magnetic field. Now researchers from the Max Planck Institute for Brain Research in Frankfurt have also detected cryptochrome 1 in photoreceptors in several mammalian species. Therefore, it is possible that these animals also have a magnetic sense that is linked to their visual system.

The perception of Earth's magnetic field is used by many animal species for orientation and navigation. A magnetic sense is found in some insects, fish, reptiles, birds and mammals, whereas humans do not appear to be able to perceive Earth's magnetic field.

The magnetic sense in migratory birds has been studied in considerable detail: unlike a boy scout's compass, which shows the compass direction, a bird's compass recognizes the inclination of the magnetic field lines relative to Earth's surface. Surprisingly, this inclination compass in birds is linked to the visual system as the magnetic field activates the light-sensitive molecule cryptochrome 1a in the retina of the bird's eye. Cryptochrome 1a is located in the blue- to UV-sensitive cone photoreceptors and only reacts to the magnetic field if it is simultaneously excited by light.

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