Sunday, 23 February 2020

Populations of small Carnivores are becoming homoginised in the Niger Delta.

Carnivores are indicative of ecosystem health and integrity, and can potentially affect food web and community structure of lower trophic levels. Several studies of sympatric African Carnivore species have demonstrated that ecological separation is primarily related to dietary differences. As specialisation and resource selectivity is generally stronger in small carnivores than large ones, they may serve as useful indicator species of the state of an ecosystem. Thus, understanding the changes taking place in the assemblage and abundance of carnivores may allow the determination of the state of conservation of a particular habitat.

In a paper published in the African Journal of Ecology on November 2019, Glorious Onuegbu and Godfrey Akani of the Department of Animal & Environmental Biology at Rivers State University of Science and Technology, Luca Luiselli, also of the Department of Animal & Environmental Biology at Rivers State University of Science and Technology, and of the Institute for Development, Ecology, Conservation and Cooperation, and the Department of Zoology at the University of Lomé, Fabio Petrozzi of Ecologia Applicata Italia, Daniele Dendi also of the Department of Animal & Environmental Biology at Rivers State University of Science and Technology, the Institute for Development, Ecology, Conservation and Cooperation, and the Department of Zoology at the University of Lomé, John Fa of the Division of Biology and Conservation Ecology at Manchester Metropolitan University, and the Center for International Forestry Research, and Adaobi Ugbomeh and Ibiso Georgewill, again of the Department of Animal & Environmental Biology at Rivers State University of Science and Technology, describe the results of a study of small Carnivore diversity in the Niger Delta based upon animals being sold in bushmeat markets.

In the Niger Delta, members of four small carnivore families: Mustelidae (Weasels, Badgers, Otters, etc.) of which ther are two species, Viverridae (Civets and Genets), also two species, Nandiniidae (African Palm Civits), one species, and Herpestidae (Mongooses), three species. All are found in forest and forest‐derived habitats in the region. However, knowledge of their biology is still poorly understood primarily because of their secretive and nocturnal habits.

Small Carnivores are regularly consumed as bushmeat and sold in markets in West and Central Africa. Using records of species and individuals of small Carnivores sold in bushmeat markets, it is possible not just to uncover noteworthy aspects of their biology, but also determine whether hunting may be causing biotic homogenisation within the catchment supplying the markets. Onuegbu et al. use data from three markets in the surroundings of the city of Port Harcourt in Rivers State (Niger Delta, Nigeria) to evaluate whether a biotic homogenisation process on taxonomic, species richness diversity characteristics and perhaps substitution of species has occurred. They also compare their results with data from other markets in the same area and from other sites in southern Nigeria and neighbouring Benin Republic.

The study was carried out in the Rivers State, Nigeria. Rivers State has over 5 million inhabitants and a density of more than 630 persons/km². During the last 30 years, agricultural and industrial expansion throughout the region has caused severe fragmentation of the existing forests. The study area's climate is characterised by a long rainy season from April through to the end of September.

Map of Rivers State in southern Nigeria, showing the three sample stations. Onuegbu et al. (2019).

Onuegbu et al. monitored three bushmeat markets: Omagwa, Oyigbo and Mbiama. These study stations were chosen because they represent localities in which hunting, alongside traditional agriculture, provide important economic revenues for the resident rural population. These localities differ in terms of vegetation cover and human population density; the latter being significantly higher in Mbiama than in the other localities. Hunters living in bushland and forest patches, often more than 7 km away from the market, regularly supply a variety of animal carcasses for their sale.

In this study, Onuegbu et al. made the implicit assumption that small Carnivore abundance in bushmeat markets can be used as a proxy of small Carnivore abundance in the field. They surveyed bushmeat markets during the dry season (December 2017–March 2018) and in the wet season (May 2018–August 2018). Sampling effort was identical in the three market sites; they visited each market three times per week during 8 months (48 daily visits in each season). During each sampling day, Onuegbu et al. counted all animal carcasses on sale, including small Carnivores. All markets were visited between 7.00 am and 11.00 am, in order to be able to count and inspect carcasses as hunters dropped them with the bushmeat traders, and before traders dressed these (burning off the hairs/fur and butchering) making it more difficult to identify the species.

A total of 1206 carcasses of small Carnivores were recorded in the three study markets. The largest number (699) was observed at the Omagwa market, followed by Oyigbo (416) and Mbiama (91).

Onuegbu et al. recorded four different taxa, all Least Concern in the International Union for the Conservation of Nature's Red List of Threatened Species: the Flat‐headed Kusimanse, Cṛossarchus platycephalus, a member of the Herpestidae (1176), African Civet, Civettictis civetta (21), African Palm Civet, Nandinia binotata (6) and Genets, Genetta spp., possibly Genetta maculata (3). In all three markets, Cṛossarchus platycephalus accounted for over 97% of the total number of observed individuals, and the relative frequency of occurrence of the various species did not vary significantly among study areas.

The four observed small Carnivores: (a) Civettictis civetta (from Omagwa), (b) Genetta sp. (from Oyigbo), (c) Crossarchus platycephalus (from Omagwa) and (d) Nandinia binotata (from Omagwa). Onuegbo et al. (2019).

The number of carcasses was higher in the wet season than in the dry season, independently of the market and species. The increase in the number of traded carcasses from the dry months to the wet months was smooth and regular in the Oyigbo market, whereas numbers varied significantly in the other two markets. The number of carcasses was significantly positively correlated with monthly rainfall in all study markets.

Sex ratios were significantly skewed towards females in both Cṛossarchus platycephalus and Civettictis civetta, but sample sizes in Nandinia binotata and Genetta spp. were to small to assess. For Cṛossarchus platycephalus, the same female biased sex ratio was observed during both the dry and the wet seasons.

The basic premise of Onuegbu et al.'s study is that because hunters do not specifically target small Carnivores, the numbers appearing in the markets reflect their relative abundance in the market catchment areas. Using this data, they conclude that there is evidence that biotic homogenisation and species substitution is occurring in the eastern Niger Delta region.

Ongoing homogenisation process has already been shown for Snakes and Chelonians. Similarly, Onuegbu et al. demonstrate that there is evidence of impoverishment of the small Carnivore community in the Rivers State agro‐forestry systems from comparisons between their study area and more heavily forested areas in the central Niger Delta and in Benin. They show that in their study area, only four species were found compared with 5–7 taxa in the central Niger Delta and Benin. Notably, in the three studied markets, the smallest species (i.e., Cṛossarchus platycephalus) accounted for more than 95% of all individuals observed. This species is also the best adapted to forest‐derived grasslands as it feeds essentially on Rodents, which become an abundant food resource in such altered habitats. Thus, Onuegbu et al.'s data suggest a process of functional similarity of biotas over time, associated with the establishment of species that have similar 'roles' in the ecosystem and with the loss of those possessing unique functional 'roles'.

Comparison of our results with data obtained for the same area about a decade ago shows that although only three species were recorded then, their relative abundances were more equilibrated than in the present study. There were also significant differences in the frequency of occurrence of the various species, particularly the dramatic increase in the relative abundance of Cṛossarchus platycephalus; in 2009, the species was not observed. This is a clear signal of an ongoing species substitution process, which mirrors data on Cobras from the same area, where Naja nigricollis (a mainly savannah species) was clearly substituting Naja melanoleuca (a mainly forest species) in almost every suitable habitat in the region. Analogous to the patterns observed for Cobras, Cṛossarchus platycephalus, a small group‐living species typical in deforested and heavily altered landscapes, is taking over This species is nowadays very common in the deforested grasslands and plantations of the Port Harcourt region, possibly due to the greater abundance of rodents (their main food type) in these habitats.

Onuegbu et al.'s study also confirmed the occurrence of Nandinia binotata in the surroundings of Port Harcourt, though this species was not considered present in the Niger Delta in 2007. This species is also one of the most intensively traded Carnivore species in African forests.

In Onuegbu et al.'s study, they show there is clear seasonal pattern in the number of carcasses of Cṛossarchus platycephalus that peaked during the rainy months. Although for the other three species the sample was too small for any statistical analysis, in the Niger Delta, Nandinia binotata was previously recorded slightly more often during the wet season with no significant inter‐seasonal difference. In Gabon, Nandinia binotata females gave birth to young from June to January each year (that is in both dry and wet seasons), which is apparently linked to fruiting seasonality as this species is mainly frugivorous.

Finally, in two of the species recorded (Cṛossarchus platycephalus and Civettictis civetta) the sex ratio of the traded individuals was significantly female‐skewed. Data on sex ratios of African small carnivores are very scanty, and thus, comparisons are problematic. Female‐skewed sex ratio was also observed in Nandinia binotata in Gabon. but sex ratio was even in Nigerian Nandinia binotata and Civettictis civetta, or males were significantly more numerous than females in other small Carnivore species of bushmeat markets in Nigeria, including Genetta sp..

See also...

https://sciencythoughts.blogspot.com/2020/02/macrogalidia-musschenbroekii-surveyinh.htmlhttps://sciencythoughts.blogspot.com/2019/11/eygyptologists-uncover-trove-of-new.html
https://sciencythoughts.blogspot.com/2019/08/leptarctus-primus-determining-diet-of.htmlhttps://sciencythoughts.blogspot.com/2019/08/aonyx-capensis-genetic-diversity-of.html
https://sciencythoughts.blogspot.com/2017/01/siamogale-melilutra-new-species-of.htmlhttps://sciencythoughts.blogspot.com/2014/10/a-new-species-of-leopard-cat-from-brazil.html
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Friday, 21 February 2020

Macrogalidia musschenbroekii: Surveying populations of the Sulawesi Civet on North Sulawesi using camera traps.

The Indonesian island of Sulawesi, located in the Wallacea biodiversity hotspot, has exceptionally high levels of endemism. For example, 62% of its 127 species of Mammal are endemic. This includes several ground-dwelling endemic Ungulates: the Babirusa, Babyrousa celebensis, Sulawesi Warty Pig, Sus celebensis, and Anoas, Bubalus depressicornis and Bubalus quarlesi. Yet despite this potentially rich prey base, the island’s apex Mammalian predator is the native Sulawesi Civet, Macrogalidia musschenbroekii, weighing only 4-6 kg. Excluding feral Dogs and Cats,\the other Mammalian carnivore species known from Sulawesi are the Malay Civet, Viverra tangalunga, and Common Palm Civet, Paradoxurus hermaphrodites, both introduced to the island in the 19th century. The latter is rare on the island and may not be fully established. The Sulawesi Civet is a little known carnivore species named in 1877 when a specimen was brought to Leiden Museum, Netherlands. It was nearly a century later, however, before studies on captured individuals, from central Sulawesi, provided the first insights into its behaviour and diet, which include \Rodents and fruit (e.g. Arenga and Pandanus), and indicated a preference for primary forest.The Sulawesi Civet is categorized as Vulnerable on the International Union for the Conservation of Nature's Red List of Threatened Species because of a presumed population decline, precipitated by loss of primary forest. There are, however, no recent and reliable population data, as reflected by the patchy International Union for the Conservation of Nature species range map that depicts four unconnected distribution polygons in various parts of the island, probably a reflection of the low sampling effort for this species. Whether this civet is able to survive outside primary forest is unknown because of the low survey effort in other potential habitat types, a matter that applies to most of Sulawesi’s Mammals.

In a paper published in the journal Orynx on 17 December 2019, Iwan Honowu, Alfons Patadung and Wulan Pusparini of the Wildlife Conservation Society's Indonesia Program, Isabel Danismend of Dobbs Ferry High School, Andi Cahyana, also of the Wildlife Conservation Society's Indonesia Program, Syahril Abdullah of Bogani Nani Wartabone National Park, Caspian Johnson and Harry Hilser of Selamatkan Yaki, Rivo Rahasia also of Selamatkan Yaki, and of Balai Konservasi Sumber Daya Alam, Jenli Gawina, also of Balai Konservasi Sumber Daya Alam, and Matthew Linkie, again of the Wildlife Conservation Society's Indonesia Program, discuss the results of a camera-trap study of Sulawesi Civits on North Sulawesi.

Honowu et al. conducted camera-trap surveys to investigate Mammalian assemblages across North Sulawesi province, focusing on the province’s two main protected areas (Bogani Nani Wartabone National Park, formerly known as Dumoga Bone National Park, and Tangkoko Nature Reserve), and potentially suitable habitat in areas between them. One of our aims was to determine the presence and habitat preferences of the Sulawesi civet across its North Sulawesi range. Survey data from the National Park buffer zone were also collected, to inform a local non-governmental organisation partner’s land purchase scheme, which aims to secure unprotected biodiversity-rich forest corridors, for which the Sulawesi Civet is one of several priority species.

Camera traps were employed on a 4 km² grid cell system with single cameras, set by four-person teams from the Wildlife Conservation Society, Selamatkan Yaki, Ministry of Environment and Forestry, and the community. The placement of cameras was systematic random in a checkerboard pattern in the National Park and Nature Reserve, and random in patches of potentially suitable habitat elsewhere, including in the small Nature Reserve of Gunung Ambang (about 80 m²). The mean distance between cameras was 3 km. Camera traps were fixed to a tree about 45 cm above ground and 4-6 m from trails, without bait, and were continuously active. The landscape included the National Park and its buffer zone, with 60 camera stations set during September 2016–April 2017, generating 4669 trap nights over 669.8 km² from altitudes of 25-1260 m. The entire 85 km² Tangkoko Nature Reserve was surveyed with 27 camera stations set during July–October 2017, generating 1766 trap nights over 76.9 km² from altitudes of 21-1146 m. Forty-nine camera stations were set in forest patches between the National Park and Tangkoko Nature Reserve during March–July 2018, generating 3936 trap nights over 212 km² from altitudes of 149-1492 m. Field teams checked cameras and retrieved data monthly. Eleven cameras malfunctioned or disappeared and were not included in the analysis. The data for the Sulawesi Civet from the National Park were supplemented by an opportunistic camera trap record, and subsequent release of a snared individual.

Camera-trap data were compiled for all civet species, with time, date and location recorded. ArcGIS 10.4 was used to construct a geospatial database for the camera-trap stations. A land cover map was created using government data for 2015, onto which records of the Sulawesi and Malay Civets were overlain, and species encounter rates were calculated (photographs separated by.over 30 minutes per 100 trap nights).

The high trapping effort but low detection rate for the Sulawesi Civet (17) yielded a low encounter rate in the National Park (0.28 records per 100 trap nights), Tangkoko Nature Reserve (0.11) and other forest patches (0.05, including Gunung Ambang Nature Reserve).Malay Civet detections (24) yielded a higher encounter rate in the Tangkoko Nature Reserve (0.51) and other forest patches (0.36), than in the National Park (0.02). Honowu et al. recorded the Sulawesi Civet in more locations (12) than the Malay civet (8).

An earlier study captured three Sulawesi Civet images in Southeast Sulawesi province from 979 camera trap nights (0.30) but none from Central (8645 camera-trap nights and 302 km of transect surveys) or North Sulawesi province (5187 trap nights and 683 km). Additionally, this study recorded one Malay Civet and no Common Palm Civets. Another study did not record the Sulawesi Civet in 1065 camera-trap nights in Tangkoko Nature Reserve but did record the Malay Civet. Thus the Sulawesi Civet may be rare and/or ground traps set for a semi-arboreal Civet may have a low detection probability.

Honowu et al. recorded the Sulawesi Civet 13 times at eight stations in the National Park, and with two opportunistic records from two locations. These records were from altitudes of 271-1093 m, from primary forest (three of 21 stations), secondary forest (three of seventeen stations) and farmland (teo of nine stations). From the Tangkoko Nature Reserve there were two Sulawesi Civet records from farmland (two of five stations), 85 and 450 m from forest, including one recorded at the same station as a Malay Civet. Honowu et al.'s study is the first to confirm the presence of the Sulawesi Civet with photographic records in both Bogani Nani Wartabone National Park and Tangkoko Nature Reserve (previous records were from tracks and scats). Amongst the other forest patches surveyed, the Sulawesi Civet was recorded in primary (one of eleven stations) and secondary forest (one of 24 stations) inside Gunung Ambang Nature Reserve, and the Malay Civet from secondary forest (three of forteen stations) and open land (one of four stations).

Locations of camera-trap records of the Sulawesi Civet, Macrogalidia musschenbroekii, (19 records in 14 locations) and Malay Civet, Viverra tangalunga, (24 records in 8 locations) in Tangkoko Nature Reserve and Bogani Nani Wartabone National Park, and areas between, including in Gunung Ambang Nature Reserve, North Sulawesi province, Indonesia. Honowu et al. (2019).

Despite the relatively low number of records, Honowu et al.'s data reveal diverse habitat use by the Sulawesi Civet and confirm the observation that the species is not restricted by elevation or forest disturbance. Their results showed widespread presence of the Sulawesi Civet in Bogani Nani Wartabone National Park, with the single Malay Civet record from a shrub-mixed dryland farm 11 km from the Park’s border. In its native range of Sumatra, Kalimantan, Malaysia, presumably Brunei, and probably introduced into the Philippines, the Malay Civet occupies a variety of habitat types, such as encroached areas and was more widespread in Tangkoko Nature Reserve than the Sulawesi Civet, with both species recorded in the same forest patches between the two protected areas.

Camera-trapped (a) Sulawesi Civet, Macrogalidia musschenbroekii, in primary forest in Bogani Nani Wartabone National Park, showing its characteristic striped tail (February 2017), and (b) Malay Civet, Viverra tangalunga, (August 2017) in Tangkoko Natural Reserve, and (c) snared Sulawesi Civet found by a National Park ranger patrol team (March 2018), and (d) examples of bushmeat seen at a road-block patrol for monitoring wildlife trade in Maelang (from left to right Sulawesi Civet, Black-crested Macaque, Macaca nigra, and Babirusa, Babyrousa celebensis, in 2013. Homowu et al. (2019).

Forest loss is a potential threat to the Sulawesi Civet. During 2000-2015 forest cover declined by 2.2% in Bogani Nani Wartabone National Park and 17.4% in Tangkoko Nature Reserve, with increased accessibility being the main explanatory factor. Roads and fragmented forest increase access for poachers. Honowu et al. released one Sulawesi Civet from a snare trap, which was probably set for Wild Pigs. Bushmeat consumption is widespread in North Sulawesi province. A market survey conducted in 2002-2003 recorded 96 586 wild mammal specimens on sale, including the Sulawesi Civet. Nevertheless, new conservation measures are being implemented in the protected areas that Honowu et al. studied, with ranger patrol teams and local informant networks, and law enforcement agency partnerships have implemented an integrated site-based protection strategy since 2017. Camera trapping is now being extended into neighbouring Gorontalo province, which could provide additional information on the Sulawesi Civet and help guide the conservation of this species.

See also...

https://sciencythoughts.blogspot.com/2019/12/leopard-kills-five-year-old-boy-in.htmlhttps://sciencythoughts.blogspot.com/2019/12/indonesian-authoriteis-arrest-five.html
https://sciencythoughts.blogspot.com/2019/11/eygyptologists-uncover-trove-of-new.htmlhttps://sciencythoughts.blogspot.com/2019/10/notorious-tiger-poacher-arrested-in.html
https://sciencythoughts.blogspot.com/2019/09/assessing-how-wildlife-attacks-upon.htmlhttps://sciencythoughts.blogspot.com/2019/09/leopard-killed-by-villagers-near-town.html
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Balaenoptera physalus: Fin Whale dies after becoming stranded on Lizard Peninsula, Cornwall.

An eighteen metre long Fin Whale, Balaenoptera physalus, has died after becoming stranded on a beach on the Lizard Peninsula in Cornwall, England, on Friday 14 February 2020. The animal, identified as a subadult female, was seen swimming in the area before it became stranded by the receding tide, and proved to be too large for Human volunteers to refloat before it died. A necropsy carried out by the Cetacean Strandings Investigation Programme ruled out plastic ingestion as a cause of death, and it is believed the Whale died as a result of its own bodymass crushing its lungs, as such large Whales are poorly adapted to life out of the water.

The body of a Fin Whale, Balaenoptera physalus, which died after becoming stranded on a beach in Cornwall, England, on 14 February 2020. Cornwall Live.

Fin Whales are the second largest Whale species, reaching about 27 m in length with an estimated maximum mass of about 114 tonnes. Fin Whales were hunted heavily until 1989, when it was given full protection by the International Whaling Commission. Since the introduction of the moratorium on Whaling the species has recovered well and is now only considered to be Vulnerable under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species (one step short of 'Least Concern').  The reporting of greater numbers of dead Whales on our shores is often distressing, and can appear to be sign of more Whales dying in inshore waters, but in fact this greater number of dead Whales reflects a larger population of living Whales being present offshore, and is a symptom of recovering populations.

See also...

https://sciencythoughts.blogspot.com/2020/01/humpback-whale-dies-after-becoming.htmlhttps://sciencythoughts.blogspot.com/2019/12/balaenoptera-acutorostrata-northern.html
https://sciencythoughts.blogspot.com/2019/10/humpback-whale-spotted-im-thames-estuary.htmlhttps://sciencythoughts.blogspot.com/2019/09/humpback-whale-washes-up-on.html
https://sciencythoughts.blogspot.com/2019/09/immature-blue-whale-washes-up-dead-on.htmlhttps://sciencythoughts.blogspot.com/2019/09/megaptera-novaeangliae-how-kermadec.html
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Magnitude 1.4 Earthquake beneath Doncaster, South Yorkshire.

The British Geological Survey recorded a Magnitude 1.4 Earthquake at a depth of 6 km beneath the town of Doncaster in South Yorkshire, England slightly after slightly after 3.25 am GMT on Thursday 20 February 2020. There are no reports of any injuries associated with this event, though it may have been felt locally.
 
The approximate location of the 20 February 2020 Doncaster Earthquake.Google Maps.
 
Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England. However, while quakes in southern England are less frequent, they are often larger than events in the north, as tectonic presures tend to build up for longer periods of time between events, so that when they occur more pressure is released.
 
The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.
 
Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process.
 
(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.
   
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here. 
 
See also...
 
https://sciencythoughts.blogspot.com/2015/06/magnitude-18-earthquake-in-south.htmlhttps://sciencythoughts.blogspot.com/2013/09/magnitude-17-earthquake-in-south.html
https://sciencythoughts.blogspot.com/2013/06/earthquake-near-doncaster.htmlhttps://sciencythoughts.blogspot.com/2012/05/earthquake-in-south-yorkshire.html
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Thursday, 20 February 2020

Asteroid 2020 DU passes the Earth.

Asteroid 2020 DU passed by the Earth at a distance of about 324 900 km (0.85 times the average  distance between the Earth and the Moon, or 0.22% of the distance between the Earth and the Sun), slightly before 1.20 pm GMT on Thursday 13 February 2020. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2020 DU has an estimated equivalent diameter of 3-11 m (i.e. it is estimated that a spherical object with the same volume would be 3-11 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 more than 30 km above the ground, with only fragmentary material reaching the Earth's surface.
 
The calculated orbit of 2020 DU. JPL Small Body Database.

2020 DU was discovered on 16 February 2020 (the day before its closest encounter with the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2020 DU implies that the asteroid was the twentieth object (asteroid A - in numbering asteroids the letters A-Y, excluding I, are assigned numbers from 1 to 24, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 25, A2 = 49, etc, which means that U = 20) discovered in the second half of February 2020 (period 2020 D).

2020 DU has a 901 day (2.47 year) orbital period, with an elliptical orbit tilted at an angle of 1.57° to the plain of the Solar System which takes in to 0.90 AU from the Sun (90% of the distance at which the Earth orbits the Sun) and out to 2.75 AU (275% of the distance at which the Earth orbits the sun and almost twice as far from the Sun as the planet Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer).

See also...

https://sciencythoughts.blogspot.com/2020/02/fireball-meteor-over-arizona.htmlhttps://sciencythoughts.blogspot.com/2020/02/fireball-meteor-over-southern-north-sea.html
https://sciencythoughts.blogspot.com/2020/02/fireball-meteor-over-alberta.htmlhttps://sciencythoughts.blogspot.com/2020/02/asteroid-2020-ca-passes-earth.html
https://sciencythoughts.blogspot.com/2020/02/the-alpha-centaurid-meteor-shower.htmlhttps://sciencythoughts.blogspot.com/2020/02/asteroid-2016-xo23-passes-earth.html
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Sepiella japonica: Paternity testing reveals polyandry in the Japanese Spineless Cuttlefish.

The Japanese Spineless Cuttlefish, Sepiella japonica, is a commercially important marine species in China. Production from wild stocks reached 60 000 tons in Zhejiang Province and accounted for more than 9.3% of provincial fishing catches in 1957. The wild population of Sepiella japonica has declined since the 1980s due to over-fishing and pollution. To enhance production, artificial breeding methods are being developed in China and successful aquaculture techniques have been established in recent years. However, studies have revealed that the populations and individual genetic diversity in this species has declined under artificial conditions.An important factor that affects the genetic diversity of a population is the effective population size which in turn is greatly influenced by the mating system of a species. The mating system influences effective population size through changing the number of individuals contributing to subsequent generations. In a polyandrous mating system, females mate with several males within a single reproductive cycle in which the clustered offspring are descended from multiple males. In such a mating system, effective population size increases, and, as a result, maximizes the genetic diversity of the offspring within a single reproductive season. Some studies have confirmed that a polyandrous mating system is frequent in marine Cephalopods including the  Common Octopus, Octopus vulgaris, Deep-sea Octopus, Graneledone boreopacifica, the Southern Reef Squid, Sepioteuthis australis, the Giant Cuttlefish, Sepia apama, the Longfin Inshore Squid, Loligo pealeii, and the Spear Sqiuid, Loligo bleekeri. The female of all these species carries stored sperm from more than one male, and the effective population size is therefore significantly higher. Previous studies have shown that female Sepiella japonica store sperm in the seminal receptacle found in the buccal membrane. All else being equal, long-term sperm storage enhances the opportunity for multiple matings of this species. Moreover, multiple matings of female Sepiella japonica has actually been observed. Polyandry, coupled with sperm storage, is therefore potentially an important reproductive strategy for maximizing the genetic diversity of offspring in Sepiella japonica.

In a paper published in the journal ZooKeys on 14 October 2019, Liqin Liu of the National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization and the National Engineering Research Center for Facilitated Marine Aquaculture at Zhejiang Ocean University, Yao Zhang and Xiaoyu Hu, also of the National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhenming Lü, also of the National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization and the National Engineering Research Center for Facilitated Marine Aquaculture, Bingjian Liu, again of the National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Li Hua Jiang, again of the National Engineering Research Center for Facilitated Marine Aquaculture, and Li Gong, once again of the National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, examine the mating system of Sepiella japonica experimentally, in order to understand the role of polyandry in maintaining effective population size.

In recent years, multiple paternity in several marine species has been documented using different genetic markers including allozymes, DNA fingerprinting, Random Amplification of Polymorphic DNA, and microsatellites. Microsatellites are the preferred marker because they are widely distributed in the genomes of most organisms and are highly polymorphic. Paternity studies based on microsatellites have become increasingly common, and the number of studies using microsatellites has increased. Several microsatellite markers have been isolated and characterized for Sepiella japonica and used to evaluate the genetic structure of its populations. Liu et al. used the previously described microsatellite markers to investigate whether multiple paternity occurs in Sepiella japonica.

Sexually mature adult Sepiella japonica were obtained from the Fujian Shacheng Harbor Cultivation Base in Fujian Province, China. A sample of 200 wild adults was captured using traps and kept mixed into a cage (9 m3). Seawater parameters were continuously maintained at 25–27 °C and 23‰ salinity. From this sample, seven mating pairs were randomly chosen as breeders to produce the next generation. All behavioral interactions were recorded using closed-circuit television with infrared to observe individual animals. Each mating pair was gently captured and placed in a spawning tank until oviposition. Egg strings derived from each clutch were transferred to a hatchery tank. After hatching, 280 offspring were randomly collected for population genotyping, maintained in a tank until they reached a pre-determined age.

Total genomic DNA was isolated from each offspring and from the muscular tissue of the respective parents. Three microsatellite loci, chosen from four loci (CL168, CL327, CL3354, CL904) developed specifically for Sepiella japonica were used to study genotypes for parents and their offspring.

Parents and their offspring were genotyped by determining alleles at three of the four microsatellite loci. Liu et al. considered evidence from at least two loci to be necessary for estimation of multiple paternity, because evidence from one locus may have been caused by mutations or genotyping error. They determined paternal alleles through subtracting the maternal alleles from offspring in a brood. The minimum number of sires for a clutch was assigned by counting the number of paternal alleles at each locus. Any instance of more than two possible paternal alleles at any loci indicated multiple paternity in a clutch.

Mating behavior in Sepiella japonica involves courtship of a female by a male, and females may copulate with multiple males. Mating pairs mated in the head-to-head position during which males transfer spermatophores to the buccal membrane of the females or to an internal seminal receptacle. The spermatophores that are deposited around the buccal area extrude the sperm mass to form spermatangium. Then the spermatangia attach to the buccal membrane where slowly released sperm are used for fertilization. Liu et al. found that the male flushed water strongly when he was close to the female buccal area prior to mating with the female. This behavior is thought to dislodge sperm from previous males. They also found obvious courtship rituals and agonistic behaviors after sexual maturity. Males are generally capable of mating early in life (3–6 months maturity) and will continue to mate until senescence. However, the females do not generally lay eggs after copulating until fully mature. The duration of spawning in Sepiella japonica varied from 21 to 30 days. Females lay multiple eggs (from tens to hundreds of thousands) by extruding them from the ovary and then they die shortly after spawning.

Sepiella japonica mating in the head-to-head position. Liu et al. (2019).

Three of the four microsatellite markers were chosen to test paternity in seven offspring clutches. These loci exhibited three or more alleles and were polymorphic in each individual. Lui et al. chose the locus which followed Mendelian inheritance to analyze paternity. Two hundred and eighty-seven individuals were genotyped at three loci, seven adult females and 280 offspring. The analysis was highly reproducible. Lui et al. analyzed paternity including sampled males and non-sampled males that had copulated with females prior to capture.

Almost all females were heterozygous at these loci (CL168, CL327, CL3354, CL904), except for CL327 in the clutch B female. For clutches A and E, three different alleles which the father contributed were observed at the three chosen loci, suggesting that these two clutches had been sired by at least two males. The offspring of four females (B, C, D, and F) had three or four paternal alleles in each locus, and three paternal genotypes were observed in all loci. The number of paternal genotypes at these three loci indicated that females B, C, D, and F had mated with three different males. Within clutch G, five different alleles were detected at loci CL168 and CL3354, two of which were from maternal alleles. Clutch G showed four alleles for the locus CL904 in addition to the two alleles detected in the female. Four different paternal genotypes were estimated in clutch G, suggesting the female G was fertilized by at least four different males.

Lui et al. observed female Sepiella japonica mating with different males during the reproductive period, a behavior also recorded in other species of Cephalopods. The benefits of multiple mating not only may raise the potential for genetic diversity but also increases the possibility of offspring survival. It has previously been shown that female Southern Dumpling Squid, Euprymna tasmanica, that mated with different males had larger eggs than those that mated with one male, indicating that females may obtain nourishment from the seminal fluid of several males. Male Cephalopods exhibit 'flushing behavior' in which they remove fresh spermatangia from previous males. In the Golden Cuttlefish, Sepia esculenta, the males remove sperm by using the hectocotylus (a modified arm used by some male Cephalopods to transfer sperm to the female) instead of flushing water. The males in Lui et al.'s study also exhibited such behavior, flushing the buccal area of the female with water, when mating with a previously mated female.

Microsatellite markers are particularly useful in paternity studies because of their polymorphism, codominance, and repeatability. Cephalopod biologists have determined multiple paternity in many species, including Squid and the Deep-sea Octopus, Graneledone boreopacifica. In this study, at least three paternal allele genotypes were found in all seven clutches indicating that at least two males were responsible for each brood. This result was in accordance with previous studies where multiple paternity was also found in the Giant Cuttlefish, Sepia apama. Multiple paternity in Sepiella japonica offspring indicates that sperm from different males must be mixed within the female’s reproductive tract. These sperm deposited around the buccal mass were used differentially to fertilize eggs, after a process of sperm competition or mediation by female choice.

Despite the prevalence of multiple paternity in cephalopod species, these studies show widely differing incidences of multiple paternity. In Lui et al.'s study, multiple paternity was demonstrated in all sampled clutches (100%). In the Giant Cuttlefish, Sepia apama, one-third of the females mated with multiple males and 67% of females’ eggs had multiple sires. Several factors have been confirmed to be related to the variance in incidence of multiple paternity observed in cephalopod species, e.g., sperm allocation, mating systems, sperm competition, and female choice. Moreover, as suggested for the Spear Squid, Loligo bleekeri, males who were the last to mate fertilized 85–100% eggs in four broods tested. However, in the multiple paternity study of the Longfin Inshore Squid Loligo pealeii, the mate order is not the most important factor in determining paternity; however, no clear hypothesis has yet emerged to explain which factor is essential in the multiple paternity of Sepiella japonica. Further work should be carried out to understand paternity patterns and to investigate different factors affecting multiple paternity in this species.

See also...

https://sciencythoughts.blogspot.com/2020/02/evidence-for-predation-of-soft-bodied.htmlhttps://sciencythoughts.blogspot.com/2019/10/eromangateuthis-soniae-large-fossil.html
https://sciencythoughts.blogspot.com/2019/08/washington-woman-hospitalised-by.htmlhttps://sciencythoughts.blogspot.com/2019/07/royal-canadian-mounted-police.html
https://sciencythoughts.blogspot.com/2019/06/architeuthis-dux-giant-squid-captured.htmlhttps://sciencythoughts.blogspot.com/2018/02/declining-ammanoid-diversity-before-end.html
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