Bright fireball meteor seen over Southern California.

The American Meteor Society has received reports of a bright fireball meteor being seen over much of southern California slightly at about 9.30 pm local time on Monday 23 April 2016 (about 4.30 am on Tuesday 24 April GMT). The fireball has been described as being greenish in colour, which may indicate it was caused by the explosion of a small meteorite with a high iron content, and was seen from the northern Baja California as far north as Mendocino County, and east to western Arizona, though the majority of sightings were in Southern California. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry.

 Fireball over Southern California on Monday 23 April 2016. CBS2.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. It is possible that this object will have produced meteorites that reached the surface (an object visible in the sky is a meteor, a rock that falls from the sky and can be physically held and examined is a meteorite).

Witness reports can help astronomers to understand these events. If you witnessed this fireball you can report it to the American Meteor Society here. 

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Bright 'fireball' meteor seen over much of England.                                                       The UK Meteor Observation Network has received reports of a bright fireball meteor being seen over much of southern England slightly after 3.15 am GMT...

Fireball seen over southern France and northern Italy.                                                  A bright fireball was seen over much of southeast France and northern Italy at about 6.20 pm local time on Wednesday 17...

Meteorite unlikely to have killed man in Tamil Nadu.                                                         Indian newspaper The Hindu carried a report on Sunday 7 February 2016 in which the death of a man and injury of three other people as well as causing damage to several nearby buildings at the campus of a college in Vellore, Tamil Nadu, were described as...

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Understanding the role of Bears in enabling a Cherry tree to migrate up mountains.

The Earth's climate is known to fluctuate over time, requiring animals and plants to move in order to find suitable habitats. For animals this is a fairly easy task, since most animals constantly move in search of the optimum environments during their lives, however for plants this is much more problematic, as they live the majority of their lives rooted to a single spot, with dispersal only occuring during the seed stage. One way to track optimum conditions in a changing climate without traveling vast distances is to move up and down slopes, since on average a 100 m rise in altitude coresponds to a -0.65 °C drop in temperature. However, while a seed can easily move downslope throgh gravity or water dispersal, seeds cannot fall upslope, requiring the plant to find more creative ways to move seeds uphill.

In a paper published in the journal Current Biology on 25 April 2016 a team of scientists led by Shoji Naoe of the Forestry and Forest Products Research Institute examine the dispersal of the seeds of the Hill Cherry, Prunus verecunda, in Central Japan via two animal vectors, the Asiatic Black Bear, Ursus thibetanus and the Japanese Marten, Martes melampus.

Oxygen isotope ratios in plant tissue can be closely related to altetude, enabling Naoe et al. to estimate the altitude at which the trees that produced Cherry stones found in Bear and Marten droppings had been growing. Surprisingly they found that both species preferentially moved the seeds upwards, with Bears moving them an average of 749.5 m upslope and Martens 460.5 m, close to the maximum distance a foraging member of each species would be expected to travel between eating the fruit and excreting their stones.

The Hill Cherry produces fruit in spring-to-summer, with trees lower on the slope producing flowers, fruit and leaves earlier in the season. Bears, which were responsible for moving 80.3% of the Cherry seeds, have previously been shown to move upslope over the season enabling them to access fruit throughout the season. Naoe et al. suggest that the preferential movement of Bears and Martend uphill between consuming Cherries and defacating may reflect a daily feeding cycle, with the animals feeding first on the fruit, then moving upslope to forrage on herbs and young vegetation that cannot be accessed beneath the canopy of fruiting trees.

Vertical seed dispersal toward the mountain tops by mammals that are following the springto summer plant phenology. The spring-to-summer plant phenology proceeds from the foot to the top of mountains. Cherry fruits and young vegetation are no longer available in low altitudes, ripe fruits are available but young vegetation is no longer available in middle altitudes, and ripe fruits are unavailable but young vegetation is available in high altitudes. Naoe et al. (2016).

See also...

Prunus kunmingensis: Peaches from the Late Pliocene of Yunnan Province.                 Peaches, Prunus persica, are widely grown and consumed fruit around the world today, with a total annual production of about 20 million tons. They have a long historical association with humans, particularly in East Asia, with the oldest known...

Changes in the diet of Brown Bears on Hokkaido.                                                           Expanding Human populations have been the major factor affecting almost all of the Earth’s ecosystems since the end of the last glaciation. Human activity has altered food...

Worker killed by Bear at Alberta oil sands site.                                                                   A worker was killed in an attack by a Bear at an oil sands excavation site operated by Suncor Oil, about 25 km north of Fort McMurray in Alberta Province, Canada, around mid-afternoon on Wednesday 7...

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Lacustrine Gastropods from the Late Miocene Turiec Basin of Slovakia.

The Turiec Basin of the Slovakian Carpathian mountains was home to a closed freshwater lake for several million years during the Late Miocene, a lake that developed in a half-graben system (an area where tectonic movements are drawing rocks apart at the surface, causing thining of the crust and subsidence) and which developed a unique flora and fauna of endemic species (species not found elsewhere). This has been studied since the nineteenth century, with some groups from the lake (such as Ostracods) being very well understood, while others are less well known. Mollsuscs from Lake Turiec were first recorded in the 1860s, and have been intermittently described ever since; however the group has been the subject of few systematic reviews and the work on it is known to contian many imprecise descriptions and misidentifications.

In a paper published in the journal Geologica Carpathia in April 2015, Thomas Nuebauer and Mathias Harzhauser of the Department of Geology & Paleontology at the Vienna Natural History Museum and Radovan Pipík of the Geological Institute of the Slovak Academy of Sciences review the Gastropods of Lake Turiec, in which they describe four new species.

The first new species described is placed in the genus Viviparus, a widespread group of freshwater Snails with a fossil record dating back to the Jurassic, and given the specific name pipiki, in honour of Radovan Pipík of the Slovak Academy of Sciences for his work on the geology of Lake Turiec. Snails assigned to the genus Viviparus have been described from the Lake Turied deposits since the 1920s (and Snails described earlier are now assigned to this genus today), but oppinions have varied as to the specific assignment of these Snails, which have been placed in a number of fossil and extant species, but which Nuebauer et al. conclude should be described as a unique species found only in the Turiec deposits.

(D-E) Viviparus pipiki, first specimen; (F-G) Viviparus pipiki, second specimen; (H-I) Viviparus pipiki, protoconchs; (J) Viviparus pipiki, juvenile specimen. All specimens from Martin Brickyard. Scale bars correspond to 100 μm (H-I), 1 mm (A-C, J), and 10 mm (D-G). Nuebauer et al. (2015).

Viviparus pipiki is broad and conical with a thick shell and up to six whorls. The shape of the shell changed considerably as they grew, with early whorls being broadly conical, weakly convex and having a wide, ovoid, apature, while later whorls are conical to weakly ovoid and strongly convex, with a tear-shaped appature with a small posterior notch.

The second new species described is placed in the genus Melanopsis, which is today found in Europe, Anatolia, North Africa and parts of Austrelasia and which first appeared in the Cretaceous, and given the specific name glaubrechti, in honour of Matthias Glaubrecht of the Museum für Naturkunde Berlin, an expert on Melanopsid Snails. This species is described from 30 whole and fragmentary specimens from the Martin Brickyard, which were described by Czech palaeontologist Remeš as specimens of Melanoptychia pseudoscalaria, a species known from the Early Miocene of Moravia, a diagnisis rejected by Nuebauer et al. Melanopsis glaubrechti has a slender drop-shaped shell with distinct ribs and up to nine whorls.

 (A, D) Melanopsis glaubrechti, specimen digitally recombined from two separate images; (B) Melanopsis glaubrechti, juvenile shell; (C) Melanopsis glaubrechti, holotype. Scale bars correspond to 1 mm (D), and 5 mm (A-C). Nuebauer et al. (2015).

The third new species described is placed in the genus Tournouerina, which previously contains a single Mio-Pliocene species, and is given the specific name turiecensis, meaninf 'from Turiec'. This species is described from 35 specimens from Martin Brickyard, previously assigned to the species Lithoglyphus nannus in 2012 by Nadežda Krstić, Ljubinko Savić, and Gordana Jovanović, a diagnosis again rejected by Nuebauer et al. Tournouerina turiecensis is a small Snail shell with up to six convex whorls separated by deep sutures. The final whorl has a large drop-shaped apature with a thickened posterior tip.

 (E) Tournouerina turiecensis, paratype 1; (F) Tournouerina turiecensis, holotype; (G) Tournouerina turiecensis, paratype 2; (H) Tournouerina turiecensis, paratype 3; (I) Tournouerina turiecensis, protoconch. Scale bars correspond to 100 μm (I) and 1 mm (E-H).  Nuebauer et al. (2015).

The fourth species described is placed in the genus Radix, airbreathing freshwater Snails found throughout the Northern Hemisphere today and known to have been present by the Miocene, and given the specific name kovaci, in honour of Michal Kováč of Univerzita Komenského, for his work on the sedimentary evolution and stratigraphy of the Pannonian Basin. The species is described from a series of previously undescribed specimens from different locations in the Turiec Basin (many from drill cores). The majority of these specimens are fragmentary, making a full description difficult, but this is a small shell with four whorls, the last of which expands rapidly to the appature, which is eliptical with a small notch at the base, where it contacts the penultimate whorl.

Radix kovaci. (A) Holotype, Mošovce; (B) Juvenile specimen, Horná Štubňa; (C) Paratype 1, Horná Štubňa; (D) Paratype 3, Mošovce; (E) Paratype 2, Horná Štubňa; (F) Sediment infills of apertures of two specimens, Mošovce. Scale bars correspond to 10 mm. Nuebauer et al. (2015).

In addition to the newly described species Nuebauer et al. refur several Gastropod specimens to the species Theodoxus postcrenulatus, transfer the species Kosovia compressa to the new genus Popovicia and specimens assigned to the genera Radix and Planorbis but which cannot be assigned to species level.

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Echinolittorina nielseni: A new species of Periwinkle from the Pleistocene-Holocene of northern Chile.                                    Periwinkles, Littorinidae, are abundant shallow marine Gastropods, the shells of which are familiar from neaches around the world...

Fossil Land Snails from the Late Pleistocene of south central Jamaica.                                     Jamaica is considered to be a biodiversity hotspot for Land Snails, with over 505 species considered to be endemic to the island (i.e. coming from the island...

Gastropod predation on Barnacles in the Late Pleistocene of southern South America. Muricid Gastropods (Murexes) are carnivorous Snails which...

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Asteroid 2016 HO passes the Earth.

Asteroid 2016 HO passed by the Earth at a distance of 808 600 km (2.10 times the average distance between the Earth and the Moon, or 0.54% of the average distance between the Earth and the Sun), slightly before 12.30 pm GMT on Sunday 24 April 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2016 HO has an estimated equivalent diameter of 14-45 m (i.e. it is estimated that a spherical object with the same volume would be 14-45  m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 28 and 10 km above the ground, with only fragmentary material reaching the Earth's surface.

 The calculated orbit of  2016 HO. JPL Small Body Database.

2016 HO was discovered on 24 April 2016 (the day of its closest approach to the Earth) by the Southern Observatory for Near Earth Asteroids Research (SONEAR) at Oliviera in Minas Gerais State, Brazil. The designation 2016 HO implies that it was the 14th asteroid (asteroid O) discovered in the second half of April 2016 (period 2016 H).

2016 HO has a 673 day orbital period and an eccentric orbit tilted at an angle of 1.56° to the plane of the Solar System that takes it from 1.01 AU from the Sun (i.e. 101 % of the average distance at which the Earth orbits the Sun) to 2.00 AU from the Sun (i.e. twice the average distance at which the Earth orbits the Sun, considerably outside the orbit of the planet Mars). It is therefore classed as an Amor Group Asteroid (an asteroid which comes close to the Earth, but which is always outside the Earth's orbit). This means that close encounters between the asteroid and Earth are fairly common, with the most recent having occurred in June 2005 next predicted in June 2027. 2016 HO also has occasional close encounters with the planet Mars, with the last such encounter calculated to have occured in October 1962 and the next predicted for April 2024.

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Asteroid 2016 GP221 passes the Earth. Asteroid 2016 GP221 passed by the Earth at a distance of 592 000 km (1.54 times the average distance between the Earth and the Moon, or 0.40% of the average distance between the Earth and the Sun), slightly after 6.20 am GMT on Monday 18 April...

Asteroid 2016 GO134 passes the Earth. Asteroid 2016 GO134 passed by the Earth at a distance of 332 000 km (0.86 times the average distance between the Earth and the Moon, or 0.22% of the average distance between the Earth and the Sun), slightly before 7.35 pm GMT on Friday 6 April...

Lyrid Meteors to be visible next week.        The Lyrid Meteors will be visible between Saturday 16 and Monday 25 April 2006, with peak acticity on Friday 22 April, when the number of meteors may exceed 20 per hour. However with the...

 

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Populus × jrtyschensis: Understanding the origin of a hybrid Poplar population from Xinjiang Province, China.

Hybridization between species is rare in animals, but a fairly common occurrence in many plants, with related plant species often having hybridization zones between populations of related parent species. How such hybridization zones occur without the two species is a subject of ongoing discussion among botanists, with three main theories having emerged. The Tension Zone theory suggests that the hybrids are less genetically fit than either parent species, but that the hybridization zone persists because there is no bar to hybridization between the two parent species, so that new hybrids are constantly produced, even if these do not thrive and reproduce. The Bounded Hybrid Superiority Theory suggests that the hybrids are unfit in the habitats favored by their parent species, but that they are more fit than their parents in the habitat where they occur, enabling them to thrive in a specific environment that the parents do not colonize; this theory allows for a thriving hybrid population even if the hybrids are sterile. Mosaic Hybridization is thought to occur where two species have an overlapping ranges containing a patchwork of different environments; in such circumstances a range of hybrid species can co-exist with the parents, each being suited to a different habitat.

In a paper published in the journal BMC Plant Biology on 18 April 2016, Dechun Jiang of the State Key Laboratory of Grassland Agro-Ecosystem at Lanzhou University, Jianju Feng, also of the State Key Laboratory of Grassland Agro-Ecosystem at Lanzhou University and of the College of Plant Sciences of the Xinjiang Production & Construction Corps and the Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin at Tarimu University, and Miao Dong, Guili Wu, Kangshan Mao and Jianquang Liu, all of the State Key Laboratory of Grassland Agro-Ecosystem at Lanzhou University, discuss the origin of a naturally occurring hybrid Poplar, Populus × jrtyschensis, from Xinjiang Province in northwest China.

Poplars, Populus spp., (also known as Aspens and Cottonwoods) are a widespread group of flowering trees in the Willow Family (Salicaceae), known for producing a range of hybrids, with a number of established trees in the genus also thought to have originated as hybrids. Hybridization in Poplars has previously been studied in Europe and North America, but the phenomenon has to date been little studied in Asia. Populus × jrtyschensis occurs naturally on the floodplains of the Erqis River in the north of Xinjiang Province, where it forms forests in which neither of its presumed parent species is present. The species is also widely planted along agricultural drainage channels, being easily cultivated as a clone from cuttings.

Foliage of Populus × jrtyschensis. eFlora/Flora of China.

It is thought to be a hybrid of two distantly related species, the Black Poplar, Populus nigra, which is found from Europe and northwest Africa east to Central Asia, and which favors wet slopes near rivers at altitudes of 400-1000 m, and the Laurel-leafed Poplar, Populus laurifolia, which is found in Northern Asia south into parts of Central Asia, and favors dry slopes in the mountainous parts of river valleys, occurring from 400-1800 m, these tow species co-concurring in parts of Xinjiang Province. Although these species prefer different environments, they flower at the same time of year, April-May, and are wind-pollinated as well as having wind-distributed seeds, leading to the possibility of both hybridization and the colonization of environments not favored by either parent by the resulting hybrid young.

A Black Poplar, Populus nigra. L'Orto botanico d'Italia.

Jiang et al. took chloroplast and nuclear DNA samples from 566 trees from 45 different populations of the three different species in order to determine their relationships. They found that the chloroplast DNA (which is passed only through the female line) of Populus nigra and Populus laurifolia were easily distinguished, with 94% of Populus × jrtyschensis trees having Populus laurifolia chloroplast DNA (indicating descent from a female Populus laurifolia plant) and the remaining 6% having Populus nigra chloroplast DNA. Sequencing of the nuclear DNA of Populus × jrtyschensis suggested that 84% of these trees were first generation hybrids between parents of the two other species, while 6% were crosses between first generation hybrids and one of the parent species, and 10% were more difficult to ascribe parental backgrounds. Two trees were found to be clones, suggesting that one or both had grown vegetatively from a detached part of a first generation hybrid.

A stand of Laurel-leafed Poplar, Populus laurifolia. Илья Смелянский/Определитель растени.

This suggests strongly that the population of Populus × jrtyschensis is maintained by a continuous supply of new hybrids between (usually male) Populus nigra and (usually female) Populus laurifolia flowers (Poplars usually produce separate male and female flowers on the same tree), with the trees themselves apparently having low fertility. However they had a distinct ecological niche, separate to that favored by either parent, growing on the floodplains of river valleys rather than higher on the side slopes. Examination of the sites where these trees grew revealed that the soil in which they grew also had far lower nitrogen levels than could normally be tolerated by either parent species, re-enforcing the idea that these trees have a unique ecological niche.

See also...

Prunus kunmingensis: Peaches from the Late Pliocene of Yunnan Province.                 Peaches, Prunus persica, are widely grown and consumed fruit around the world today, with a total annual production of about 20 million tons. They have a long historical association with humans, particularly in East Asia, with the oldest known...

Syzygium pyneei: A new species of Myrtle from Mauritius.                                                        The genus Syzygium is the largest within the Myrtle family, Myrtaceae, with over 1200 described species from across the tropical and subtropical regions of the Old World, including fifteen previously described species from Mauritius.

A new species of Rhododendron from Guizhou Province, China.              Rhododendrons, Rhododendronspp., are a large group of flowering shrubs and trees found in East and Southeast Asia and across Indonesia to northern Australia, and widely introduced elsewhere...

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Magnitude 4.6 Earthquake off the Atlantic Coast of Morcco.

The Centre Seismologique Euro-Méditeranéen  recorded a Magnitude 4.6 Earthquake at a depth of 2 km about a hundred km off the Atlantic Coast of Morocco slightly before 3.55 pm GMT on Sunday 24 April 2016. There are no reports of any damage or casualties associated with this event, which occurred too far from shore to present any real hazard, but people have reported feeling it on the Moroccan Coast from Casablanca as far south as Essaouira.

 The approximate location of the 24 April 2016 Atlantic Earthquake. Google Maps.

The Atlantic Coast of Morocco lies close to the boundary between the African and European plates to the east of the Mid-Atlantic Ridge. This is currently an area of expansion, with the two plates moving apart along this part of the boundary and new seafloor being created by the upwelling of magma from the mantle and its extrusion as a new area of crustal material, the Azores Microplate. This is not a smooth process, and can lead to occasional Earthquakes.

The location of Europe, Africa and the Azores relative to the Mid-Atlantic Ridge. (Martins et al. 2008)

Earthquakes around the Mediterranean Basin are most common in southeast Europe, but those in northwest Africa, while less frequent, are often larger and more deadly. In February 2004 a magnitude 6.4 quake on the north Moroccan coast destroyed over 2500 homes, killing at least 628 people and making over 15 000 homeless. 

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organization Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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Magnitude 4.7 Earthquake on the north Coast of Morocco.                                        The United States Geological Survey recorded a Magnitude 4.7 Earthquake at a depth of about 10 km...

Magnitude 6.1 Earthquake beneath the western Mediterranean.                                The United States Geological Survey recorded a Magnitude 6.1 Earthquake at a depth of about 10 km, off the northern coast of Morocco, slightly after 4.20...

Magnitude 4.3 Earthquake in the Tadla-Azilal Region of central Morocco.                         The United States Geological Survey recorded a Magnitude 4.3 Earthquake at a depth of 17.5 km, about 3 km north of the town of Isseki in the Tadla-Azilal...

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Eight confirmed deaths following Houston flooding.

Eight people have been confirmed dead following flooding in Houston, Texas this week, with around a thousand homes flooded and 70 000 more left without electricity. Houston has suffered a series of flooding events in the last year, but this weeks rains have been considered exceptional, with 44.7 cm of rain falling on the city on Monday 18 April 2016, and floodwaters in places twelve meters higher than the previous highest levels recorded.

Rescue workers helping evacuees in Houston, Texas, this week. David Philips/AP.

Rainfall in Texas is driven principally by evaporation of water from the Caribbean, an area which has been suffering exceptionally high temperatures this year. However the flooding has also been linked to rapid urban expansion in the Houston area, which is built on an area of historic coastal wetlands. Samuel Brody of the Center for Texas Beaches and Shores at Texas A&M University at Galveston has calculated that the area of soil covered by paving in Houston has expanded by 25% in the last 15 years, preventing rainwater from draining into the soil and raising the dangers of flooding in the city.

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Storms and floods kill at least 43 people in the US over Christmas period.                        AT least 43 people have died across the southern and midwest United States over the past week as the country has been hit by a series of severe floods and storm events. Multiple deaths have been recorded...

Flooding and winter storms thought to have killed at least fourteen in Texas, Oklahoma and Kansas.                                                   At least fourteen people are thought to have died as flooding and...

 Hurricane Patricia: The most severe storm ever recorded causes widespread flooding but relatively few casualties.                 Hurricane Patricia formed as a tropical depression over the eastern Pacific Basin in mid-October 2015, before increasing rapidly in intensity on 22 October...

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Sixteen dead after landslide in Arunachal Pradesh.

Sixteen construction workers working on a new hotel site have been confirmed dead after a landslide hit their camp at Phamia in the Tawang District of Arunachal Pradesh at about 3 am local time on Friday 22 April 2016. Three other men at the camp were dug out of the debris alive, though one of these is described as being in a serious condition.

Rescue operations at Phamia in Arunchal Pradesh following the 22 April 2016 landslide. Jansamachar.

The incident happened following several days of heavy rain in the region, marking the beginning of this years rainy season. Landslides are a common problem after severe weather, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. Arunchal Pradesh has a rainy season that begins around the end of April or benining of May and ends around September, bringing 2-4000 mm of rain to the region each year.

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At least seven dead following heavy rains in Guwahati, Assam.                                         At least seven people have died following torrential rainfall overnight in the city of Guwahati in Assam State, northeast India. Three people from one family...

Seven members of one family killed by landslide in Assam State, India.                Seven members of a single family have been killed by a landslide that struck their home in the village of Satkoragool in the Karimganj District of Assam...

Magnitude 4.4 Earthquake in eastern Tibet. The United States Geological Survey recorded a Magnitude 4.4 Earthquake at a depth of 10 km in the eastern Tibet Autonomous Region of China slightly after 8.05 am local time (slightly after 2.05 am GMT)...

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