Tag: biodiversity

Tiny thorn snail discovered in Panama’s backyard

*Close-up view of live individuals of the new species crawling on a leaf.*

Discoveries of biodiversity at the Lilliputian scale are more tedious than it is for larger animals like elephants, for example. Furthermore, an analysis producing a DNA barcode – a taxonomic method using a short snippet of an organism’s DNA – is not enough to adequately identify it to the species level.

In the case of tiny thorn snails – appearing as minute white flecks grazing in moist, decomposing leaf litter – it is the shell that provides additional and reliable information needed to verify or question molecular assessment of these otherwise, nondescript critters.

*Broadleaf forest litter with white arrows indicating the newly described species on the leaves.*

However, at 2 mm, thorn snails are too small and fragile to handle and the few, if any, tangible details on the outside of the shells can only be seen using a high-powered microscope and computed tomographic (CT) images.

This is exactly how the interdisciplinary team of Dr Adrienne Jochum, Naturhistorisches Museum der Burgergemeinde Bern (NMBE) and University of Bern, Dr. Bernhard Ruthensteiner, Zoologische Staatssammlung Muenchen, Germany, Dr. Marian Kampschulte, University Hospital of Giessen and Marburg, Gunhild Martels, Justus-Liebig University Giessen, Jeannette Kneubühler, NMBE and University of Bern, and Dr. Adrien Favre, Senckenberg Research Institute and Natural History Museum Frankfurt, managed to clarify the identity of a new Panamanian species. Their study is published in the open-access journal ZooKeys.

Even though the molecular analysis flagged what it was later to be named as the new to science species, Carychium panamaense, the examination left no shell for the description of the new snail to be completed, let alone to serve as tangible, voucher material in a museum collection available to future researchers. The mini forest compost-grazer had to wait for another five years and Dr. A. Favre, who collected fresh material while traveling in Panama.

The new snail is currently the second member of the family Carychiidae to be discovered in Panama. The first Panamanian, and southern-most member of its kind in the Western Hemisphere, is C. zarzaae, which was also described by Dr. A. Jochum and her team along with two sister species from North and Central America. The study was published in ZooKeys last year.

Much like X-rays showing the degree of damage in a broken bone, CT images visualise the degree of sinuosity of the potato chip-like wedge (lamella) along the spindle-like mast (columella) inside the thorn snail’s shell. These structures provide stability and surface area on which the snail exerts muscular traction while manoeuvring the unwieldy and pointed, signature thorn-like shell into tight nooks and crannies. The alignment and degree of waviness of the lamella on the columella is also used by malacologists (mollusc specialists) to differentiate the species.

*These are computed tomographic (CT) images of the new thorn snail species.*

Normally, a study of a thorn snail’s shell would require drilling out minute ‘windows’ in the shell by using a fine needle under a high microscope magnification.

“This miserable method requires much patience and dexterity and all too often, the shell springs open into oblivion or disintegrates into dust under pressure,” explains Dr. A. Jochum. “By exposing the delicate lamella using non-manipulative CT imaging, valuable shell material is conserved and unknown diversity in thorn snails becomes widely accessible for further study and subsequent conservation measures.”

The authors are hopeful that C. panamaense and C. zarzaae, which both inhabit the La Amistad International Park, Chiriquí, will remain a conservation priority along with other animalian treasures including the Resplendent Quetzal, Three-Wattled Bellbird and the Crested Eagles.

The park is considered the 1st bi-national biosphere reserve, as it occupies land in both Costa Rica and Panama, and constitutes a UNESCO World Heritage Site since 1990.

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Original Source:

Jochum A, Ruthensteiner B, Kampschulte M, Martels G, Kneubühler J, Favre A (2018) Fulfilling the taxonomic consequence after DNA Barcoding: Carychium panamaense sp. n. (Eupulmonata, Ellobioidea, Carychiidae) from Panama is described using computed tomographic (CT) imaging. ZooKeys 795: 1-12. https://doi.org/10.3897/zookeys.795.29339

Bee diversity and richness decline as anthropogenic activity increases, confirm scientists

The researchers compared wild bee communities in the tropical dry forest of Mexico living in three habitat conditions: preserved vegetation, agricultural sites and urbanised areas

Changes in land use negatively affect bee species richness and diversity, and cause major shifts in species composition, reports a recent study of native wild bees, conducted at the Sierra de Quila Flora and Fauna Protection Area and its influence zone in Mexico.

Having registered a total of 14,054 individual bees representing 160 species, 52 genera, and five families over the span of a year, the scientists conclude that the studied preserved areas demonstrated “significantly greater” richness and diversity.

In their paper, published in the open-access Journal of Hymenoptera Research, a research team from the University of Guadalajara, Mexico, led by Alejandro Muñoz-Urias, compare three conditions within the tropical dry forest study site: preserved vegetation, an agricultural area with crops and livestock, and an urbanised area.

This bee species (*Aztecanthidium xochipillium*) is known exclusively from Mexico.

The researchers confirm earlier information that an increase in anthropogenic disturbances leads to a decrease in bee richness and diversity. While availability of food and nesting sites are the key factors for bee communities, changes in land use negatively impact flower richness and floral diversity. Thereby, turning habitats into urbanised or agricultural sites significantly diminishes the populations of the bees which rely on specific plants for nectar and pollen. These are the species whose populations are threatened with severe declines up to the point of local extinction.

According to their data, about half of the bees recorded were Western honey bees (49.9%), whereas polyester bees turned out to be the least abundant (1.2 %).

On the other hand, some generalist bees, which feed on a wide range of plants, seem to thrive in urbanised areas, as they take advantage of people watering wild and ornamental plants at times where draughts might be eradicating native vegetation.

“That is the reason why bees that can use a wide variety of resources are often able to compensate when circumstances change, although some species disappear due to land use changes,” explain the scientists.

This is a tropical dry forest in the dry (left) and rainy season (right).

In conclusion, the authors recommend that the tropical dry forests of both the study area and Mexico in general need to be protected in order for these essential pollinators to be conserved.

“Pollinators are a key component for global biodiversity, because they assist in the sexual reproduction of many plant species and play a crucial role in maintaining terrestrial ecosystems and food security for human beings,” they remind.

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Original source:

Razo-León AE, Vásquez-Bolaños M, Muñoz-Urias A, Huerta-Martínez FM (2018) Changes in bee community structure (Hymenoptera, Apoidea) under three different land-use conditions. Journal of Hymenoptera Research 66: 23-38. https://doi.org/10.3897/jhr.66.27367

World’s largest campodeid dipluran named after the mythological giant Daidarabotchi

*The giant newly described species Pacificampa daidarabotchi, discovered in the Mejiro-do cave, Kyushu, Japan. Photo by Rodrigo Lopes Ferreira.*

The insect-like animal is also the first subterranean representative of its family in Japan

Amongst the fauna thriving in the subterranean spaces below the surface of the earth’s crust, the insect-like diplurans and, precisely, those in the campodeid family are one of the best-known groups, currently comprising almost 150 species. However, not a single subterranean member of the family had been known from Japan until very recently.

As part of a project at the National Council of Technological and Scientific Development, the research team of Dr. Rodrigo Lopes Ferreira, Universidade Federal de Lavras, Brasil, and Dr. Kazunori Yoshizawa, Hokkaido University, Japan, conducted an expedition to a total of 11 carbonate caves in the southern Japanese islands of Kyushu and Shikoku. Out of these, they managed to collect dipluran specimens from three touristic sites and sent them to Dr. Alberto Sendra from the Research group in Soil Biology and Subterranean Ecosystems at Alcala University, Spain, for identification.

*The Mejiro-do cave, Kyushu Island, Japan: the type locality of the newly discovered record-breaking species Pacificampa daidarabotchi. Photo by Rodrigo Lopes Ferreira.*

To the amazement of the scientists, it turned out that they had collected specimens of two previously unrecognised species of well-adapted subterranean campodeid diplurans.

Moreover, one of the new species (Pacificampa daidarabotchi), identified exclusively from the Mejiro-do cave located near an active quarry in Kyushu, proved to be the largest known dipluran in the family Campodeidae. Measuring about 10 mm in length, the creature looks gigantic next to any other campodeid, which, most often, are only half as big.

Inspired by the peculiar size of the former, the researchers decided to name it after the giant yökai creature Daidarabotchi, known from Japanese mythology. According to one of the legends, Daidarabotchi once lifted up the mountains of Fuji and Tsukuba in order to weigh them. By accident, he split the peak of Tsukuba in the process.

Another remarkable finding from the same study is that the genus, where both new species were assigned – Pacificampa – serves as yet another example of the former physical connection between Asia and America some millennia ago. In their paper, the scientists note that the genus demonstrates close affinities with a genus known from North America.

“We hope that this discovery could stop the destruction of the land nearby and preserve for the future the subterranean habitat of these remarkable gigantic species,” say the researchers in conclusion.

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Last year, lead author Dr. Alberto Sendra and his colleagues Prof. Boris Sket, University of Ljubljana, and Prof. Pavel Stoev, National Museum of Natural History, Bulgaria, described another cave-dwelling campodeid dipluran to the world’s amazement.

Discovered in Eastern Turkmenistan, the species, whose name (Turkmenocampa mirabilis) refers to its wondrous peculiarity, was the first of in the order Diplura found in Central Asia. Further, it was the first strictly subterranean terrestrial creature recorded in the country.

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Original source:

Sendra A, Yoshizawa K, Ferreira RL (2018) New oversize troglobitic species of Campodeidae in Japan (Diplura). Subterranean Biology 27: 53-73. https://doi.org/10.3897/subtbiol.27.28575

Wildlife on the highway to hell: Roadkill in the largest wetland, Pantanal region, Brazil

*Adult individual of Erythrolamprus aesculapii captured in roadside habitats of BR-262. Photo by Michel Passos*

Scientists provide crucial data to prompt further conservation and safety measures at the notorious BR-262 highway

Having systematically monitored wild animals killed on the Brazilian federal highway BR-262, which passes through the Pantanal region, a research team from the Federal University of Mato Grosso do Sul, Brazil, published their data concerning birds and reptiles in the open access journal Check List.

Apart from information crucial for future conservation activities, the paper provides new and unexpected roadkill records, including the Black-and-white hawk-eagle.

Authored by Wagner Fischer and his colleagues Raquel Faria de Godoi and Antonio Conceição Paranhos Filho, the article is part of the first dataset of vertebrate mortality in the region. A separate paper of theirs is planned to present the data concerning mammals gathered during the same survey, which took place between 1996 and 2000.

*An adult individual of Xenodon matogrossensis captured in roadside habitats of BR-262. Photo by Cyntia Santos.*

Having mapped bird and reptile roadkill on the highway between the cities of Campo Grande and Corumbá in the Brazilian savannah, the team reports a total of 930 animals representing 29 reptile and 47 bird species. In addition, the data provide the first regional geographic record of the colubrid snake Hydrodynastes bicinctus.

The researchers conclude that the species richness observed in the road-killed animals clearly confirms earlier concerns about wildlife-vehicle collisions in the Pantanal region. Such accidents lead to long-term and chronic impact on both wildlife and road safety.

“Mitigation of wildlife-vehicle collisions on this road continues to claim urgency for biodiversity conservation and for human and animal safety and care,” say the authors.

“For managers, the main goal should be to determine target species of greatest concern, focusing on those vulnerable to local extinction or those which represent major risks of serious accidents.”

In the past, the team’s dataset had already been used as a guide to road fauna management. In particular, it was used by government road managers when planning animal overpassess and underpassess equipped with roadside fences as part of the long-term project Programa Estrada Viva: BR-262. So far, however, only some of the less efficient safety methods, such as road signs and lowered speed limits, have been applied at the most critical points.

Over the past several years, a few independent studies have been conducted to monitor roadkill in a similar manner. Two of them (2010 and 2017) looked into mammal-vehicle collisions, while the third recorded reptiles and birds as well. All of them serve to demonstrate that BR-262 continues to be a major cause for the regional wildlife mortality, which in turn increases the risks of serious accidents.

“BR-262 keeps its inglorious fame as a highway to hell for human and wild lives,” points out lead author Wagner Fischer.

*Roadkill on the BR-262 highway, Pantanal region, Brazil. Photos by Ricardo Fraga and Wagner Fischer.*

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Original source:

Fischer W, Godoi RF, Filho ACP (2018) Roadkill records of reptiles and birds in Cerrado and Pantanal landscapes. Check List 14(5): 845-876. https://doi.org/10.15560/14.5.845

Large-sized fossilised lacewings prove remarkable species diversity during Middle Jurassic

Middle Jurassic has always been considered as a mysterious ancient period full of ‘magical’ dinosaurs, pterosaurs and plants. However, when we think about the Jurassic landscape, we should take insects into consideration as well.

The lacewings, for example, are a graceful group famous for the lovely net-like veins on their wings, beautiful enough to stand the test of time, preserved as fossils. In addition, the wing spots on their wings form various patterns, which serve to tell us more about their adaptation to the particular environment.

Having carefully studied several pieces of compressed fossils of the large and distinct insects they found in Dohugou village, Inner Mongolia, Chinese scientists Hui Fang, Dong Ren, Jiaxi Liu and Yongjie Wang, College of Life Science, Capital Normal University, Beijing, discovered two species new to science.

Due to their complex, one-of-a-kind wing venations, all three of them were placed in the same genus (Laccosmylus) in the family Saucrosmylidae. Their descriptions, along with the redescription of another previously known species, are published in the open access journal ZooKeys.

“Fossil lacewing insects are much more abundant compared to living ones,” comment the authors.

“These large-sized fossil lacewing species reflect a high lacewing diversity in Middle Jurassic. Soon, they will help us reconstruct the wonderful environment of the Jurassic world.”

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Original source:

Fang H, Ren D, Liu J, Wang Y (2018) Revision of the lacewing genus Laccosmylus with two new species from the Middle Jurassic of China (Insecta, Neuroptera, Saucrosmylidae). ZooKeys 790: 115-126. https://doi.org/10.3897/zookeys.790.28286

Newly discovered moth named Icarus sports a flame-shaped mark and prefers high elevations

The paper describing the new species is part of a special issue dedicated to macro moths of the New World published in the open-access journal ZooKeys

Newly-recognized species of owlet moth recently discovered to inhabit high-elevation mountains in western North America was named after the Greek mythological character Icarus. From now on, scientists will be referring to the new insect as Admetovis icarus.

In their paper, Dr Lars Crabo, Washington State University, USA, and Dr Christian Schmidt, Agriculture and Agri-Food Canada, explain that the combination of the distinct flame-shaped mark on the moth’s forewing and its high-elevation habitat were quick to remind them of Icarus, who is said to have died after flying so close to the sun that his wings made of wax and feathers caught fire.

The study is part of the seventh volume of the “Contributions to the systematics of New World macro-moths” series, where all previous volumes have also been published as special issues in ZooKeys.

Found in the town of Nederland, Colorado, the moth was collected at an elevation of 2,896 m above sea level. The species has also been recorded all the way from central Utah and central Colorado to the Selkirk Mountains of southeastern British Columbia, including a record from northeastern Oregon. It can be spotted between June and August at night.

In fact, it turns out that the moth has been collected during surveys in the past on multiple occasions, but has been misidentified with another closely related species: Admetovis oxymorus.

While the flame mark is a characteristic feature in all three species known in the genus (Admetovis), in the newly described species it is darker. When compared, the wings of the Icarus moth are also more mottled.

Despite the biology of the larvae being currently unknown, the scientists believe they are climbing cutworms and feed on woody shrubs, similarly to the species Admetovis oxymorus.

“Finding undiscovered moths is not that unusual, even though scientists have been naming insects since the eighteenth century,” says lead author Dr Lars Crabo.

“The Contributions series, edited by Don Lafontaine and Chris Schmidt, in which this discovery is published, really encourages professional and citizen scientists alike to go through the steps necessary to properly name the species that they have discovered. This series of seven volumes also includes a new check list for the United States and Canada, which has led to a re-kindling of interest in moths during the last decade.”

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Original source:

Crabo LG, Schmidt BC (2018) A revision of Admetovis Grote, with the description of a new species from western North America (Noctuidae, Noctuinae, Hadenini). In: Schmidt BC, Lafontaine JD (Eds) Contributions to the systematics of New World macro-moths VII. ZooKeys788: 167-181. https://doi.org/10.3897/zookeys.788.26480

The first drywood termite known to use snapping stick-like mandibles to defend its colony

Tasked to defend the colony from attackers, the specialised soldier caste in some termite species has evolved various impressive mechanisms, including plug-like heads – meant to block intruding ants trying to invade their lairs, and mouthparts designed to bite and pierce.

Still, there are even more spectacular soldiers, such as a recently discovered drywood termite species, whose unique long and slender, stick-like snapping mandibles produce one of the highest acceleration speeds measured in a living organism. Rather than bite, these peculiar ‘jaws’ deliver powerful strikes at enemies bold enough to stand in the way of the soldier termite and its colony.

The scientists describe the new termite’s specialty in detail:

“Roisinitermes employs a unique strategy of snapping, achieved by long and slender mandibles pressed against each other in a defensive encounter. When this potential energy is released, the left mandible springs over the right and the resultant snap is forced onto the opponent if it is in the path of the strike.”

Discovered in Cameroon, this striking species is the first drywood termite found to rely on snapping mandibles as a defense strategy. Given that until now there had been a single subfamily (Termitinae) known to have developed such, the very existence of the new insect poses a whole new set of questions before scientists. Have snapping mandibles evolved independently in two evolutionary lineages? Or, is it that these groups share a distant kin relationship which has gone unnoticed for that long?

The new drywood termite, which is also assigned to a new genus, is named Roisinitermes ebogoensis, and is described in the open access journal ZooKeys by an international team of researchers, led by Dr Rudolf Scheffrahn of the Institute for Food and Agricultural Sciences at University of Florida, Davie, USA. Although this particular species is not thought to be a pest, some drywood termites cause serious damage to wooden structures around the world.

Both colonies studied by the scientists were found near the Ebogo II village, which also stands behind the name of the species. The first unusual colony to draw the attention of the scientists was collected from a forest on an island in the Nyong River, where it lived in a thin (3 cm) and long (over 3 m) broad-leaf tree branch suspended from a canopy. The second one – in a 15-mm thick dead liana branch hanging from a tree in a nearly pristine rainforest.

The team expects that future research will shed more light on the origins and evolution of the newly discovered termite.

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Original source:

Scheffrahn RH, Bourguignon T, Akama PD, Sillam-Dussès D, Šobotník J (2018) Roisinitermes ebogoensis gen. & sp. n., an outstanding drywood termite with snapping soldiers from Cameroon (Isoptera, Kalotermitidae). ZooKeys 787: 91-105. https://doi.org/10.3897/zookeys.787.28195

Scientific divers from the California Academy of Sciences discover new species of dazzling, neon-colored fish

Post originally published by the California Academy of Sciences

Named for Aphrodite, Greek goddess of love and beauty, a new species of fish enchants Academy scientists

On a recent expedition to the remote Brazilian archipelago of St. Paul’s Rocks, a new species of reef fish—striped a vivid pink and yellow—enchanted its diving discoverers from the California Academy of Sciences.

First spotted at a depth of 400 feet beneath the ocean’s surface, this cryptic fish inhabits rocky crevices of twilight zone reefs and is found nowhere else in the world. Upon discovery, the deep-diving team was so captivated by their finned find that they didn’t notice a massive sixgill shark hovering above them in an exciting moment captured on camera. The new fish description published today in Zookeys.

“This is one of the most beautiful fishes I’ve ever seen,” says Dr. Luiz Rocha, the Academy’s Curator of Fishes and co-leader of the Hope for Reefs initiative. “It was so enchanting it made us ignore everything around it.”

The sixgill shark stretched nearly ten feet long and cruised overhead as Rocha and post-doctoral fellow Dr. Hudson Pinheiro delicately collected the fish for further study back at the Academy. Behind the camera, the team’s diving officer Mauritius Bell enthusiastically announced the behemoth visitor to the duo, but to no avail. Aptly named, Tosanoides aphrodite enchanted its discoverers much like Aphrodite, Greek goddess of love and beauty, enchanted the ancient Greek gods.

“Fishes from the twilight zone tend to be pink or reddish in color,” says Pinheiro. “Red light doesn’t penetrate to these dark depths, rendering the fishes invisible unless illuminated by a light like the one we carry while diving.”

Back at the Academy, laboratory and collections manager Claudia Rocha helped the diving duo describe the new species: Males are outfitted with alternating pink and yellow stripes while females sport a solid, blood-orange color. Using a microscope, the team counted fins and measured spine length; DNA analysis revealed the new species is the first Atlantic-dwelling member of its genus.

*Male specimen of the new species (Tosanoides aphrodite). Photo by LA Rocha.*

The new denizen of the deep is a remarkable testament to the vast ocean habitats that still remain unexplored. Rocha and Pinheiro are part of a deep-diving research team that ventures to twilight zone reefs—mysterious coral habitats stretching across a narrow band of ocean 200 – 500 feet beneath the surface. In these deep reefs, animals live in partial darkness—beyond recreational diving limits, yet above the deep trenches patrolled by submarines and ROVs. As part of its Hope for Reefs initiative, the Academy team and their collaborators are exploring this unknown frontier with the help of high-tech equipment like closed-circuit rebreathers that allow scientists to extend their research time underwater.

Nearly 600 miles offshore the coast of Brazil, St. Paul’s Rocks is so remote that it required the team to utilize the research vessel M/V Alucia as their homebase to explore the archipelago. The rocky outcroppings are extensions of the Mid-Atlantic Ridge—an active, tectonic plate boundary—puncturing the ocean’s surface. Given the region’s unique geology and isolated location, many of the species that live there are found nowhere else on Earth. Through their research, the Hope for Reefs team is finding that twilight zone habitats also host many location-specific species.

In a recent landmark paper, the team found that twilight zone reefs are unique ecosystems bursting with life and are just as vulnerable to climate change threats as their shallow counterparts. Their findings upended the long-standing assumption that species might migrate between habitats to avoid human-related stressors. As documented in the footage from this new fish’s discovery, a piece of fishing line can be seen streaming behind the sixgill shark—evidence that human impacts extend to depth too.

“In a time of global crisis for coral reefs, learning more about unexplored reef habitats and their colorful residents is critical to our understanding of how to protect them,” says Rocha. “We aim to highlight the ocean’s vast and unexplored wonders and inspire a new generation of sustainability champions.”

Research article:

Pinheiro HT, Rocha C, Rocha LA (2018) Tosanoides aphrodite, a new species from mesophotic coral ecosystems of St. Paul’s Rocks, Mid Atlantic Ridge (Perciformes, Serranidae, Anthiadinae). ZooKeys 786: 105-115. https://doi.org/10.3897/zookeys.786.27382

Two fish a day keep the mantid coming back to prey: The 1st fishing praying mantis

Commonly known to predate on insects, praying mantises have occasionally been observed to feed on vertebrates, including small birds, lizards, frogs, newts, mice, snakes and turtles. Mostly, such records have either not been scientifically validated or have occurred under induced and human-manipulated circumstances.

Nevertheless, no scientific data of mantises preying on fish existed until the recent study of Roberto Battiston, Musei del Canal di Brenta, Rajesh Puttaswamaiah, Bat Conservation India Trust, and Nayak Manjunath, published in the open access Journal of Orthoptera Research.

Last year, the team observed an adult male hunting and devouring guppies in a pond located in a private roof garden in Karnataka, India. Curiously enough, the predator came back five days in a row and caught a total of nine fish (a minimum of two a day). To reach its prey, the insect would walk on the leaves of water lilies and water cabbage growing on the surface of the pond.

*The artificial pond with the praying mantis sitting on a leaf visible to the right.*

Apart from being a curious first-of-its-kind, the observation raises three new discussion points worthy of further study, point out the researchers.

Firstly, the fact that praying mantises hunt on vertebrates outside cages in labs confirms that a single invertebrate species is indeed capable of having an impact on a whole ecosystem. In this case, a mantis preys on guppies which, in their turn, feed on aquatic insects.

*The mantis eating a guppy starting from the tail, while the fish is still alive and breathing in the water.*

Secondly, the discovery questions previous knowledge about the visual abilities of mantises. While the structure of their eyes clearly indicates that they have evolved to prey in daylight, the studied male specimen proved to be an excellent hunter in the dark. The insect managed to catch all nine fish either at sunset or late at night.

Besides visual, mantises might have evolved impressive learning abilities too. The researchers speculate that the observed repetitive behaviour might have been the result of personal experience, utilised to navigate the specimen. Sophisticated cognitive skills, on the other hand, might have allowed the mantis to develop its hunting strategies.

“Remembering the prey’s abundance in a particular site, in relation to their ease of capture and their nutritional content, could be one important factor of this choice and indirectly influence the individual predator’s fitness,” comment the scientists. “This should be investigated in further studies.”

Original source:

Battiston R, Puttaswamaiah R, Manjunath N (2018) The fishing mantid: predation on fish as a new adaptive strategy for praying mantids (Insecta: Mantodea). Journal of Orthoptera Research27(2): 155-158. https://doi.org/10.3897/jor.27.28067

New light on the controversial question of species abundance and population density

Inspired by the negative results in the recently published largest-scale analysis of the relation between population density and positions in geographic ranges and environmental niches, Drs Jorge Soberon and Andrew Townsend Peterson of the University of Kansas, USA, teamed up with Luis Osorio-Olvera, National University of Mexico (UNAM), and identified several issues in the methodology used, able to turn the tables in the ongoing debate. Their findings are published in the innovative open access journal Rethinking Ecology.

Both empirical work and theoretical arguments published and cited over the last several years suggest that if someone was to take the distributional range of a species – be it animal or plant – and draw lines starting at the edges of the space inwards, they would find the species’ populations densest at the intersection of those lines. However, when the team of Tad Dallas, University of Helsinki, Finland, analysed a large dataset of 118,000 populations, equating to over 1,400 species of birds, mammals, and trees, they found no such relationship.

Having analysed the analysis, the American-Mexican team concluded that despite being based on an unprecedented volume of data, the earlier study was missing out some important points.

Firstly, the largest dataset used by Tad and his team comprises observational data which had not required a certain sampling protocol or a plan. Without any standard in use, it is easy to imagine that the observations would be predominantly coming from people around and near cities, hence strongly biased.

Additionally, the scientists note that the analysis largely disregards parts of species’ geographic distributions for which there were no abundant data. As a result, the range of a species could be narrowed down significantly and its centroid – misplaced. Meanwhile, the population would appear denser on what appears to be the periphery of the area.

Similar issue is identified in the localisation of populations in the environmental space, where once again their range turned out to have been represented as significantly smaller, when compared to data available from the International Union for Conservation of Nature (IUCN) and the Global Biodiversity Information Facility (GBIF).

Further, a closer look into the supplementary materials provided revealed that the precision of the population-density data was not scalable with the climate data. As a result, it is likely that multiple abundance data falls within a single climate pixel.

In conclusion, the authors note that in order to comprehensively study the abundance of a species’ populations, one needs to take into consideration a number of factors lying beyond the scope of either of the papers, including human impact.

“We suggest that this important question remains far from settled,” they say.

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Original source:

Soberón J, Peterson TA, Osorio-Olvera L (2018) A comment on “Species are not most abundant in the centre of their geographic range or climatic niche”. Rethinking Ecology 3: 13-18. https://doi.org/10.3897/rethinkingecology.3.24827