Alien Species - Science topic

PLEASE, please, please NEVER introduce any exotic species into wild lands areas, ANYWHERE on our beautiful planet.

In California the European people who arrived here, introduced over 1,000 exotic plants in only 10 generations, and now our whole State is covered 99.99% by these horrible flammable weeds that are causing our whole California ecosystem to become Endangered.

Seemed like a good idea to introduce the exotics, but it worked TOO well, and now instead of living in CALIFORNIA, we are living in a completely transplanted piece of Europe and Australia.

The exotics will ALWAYS harm the native ecosystems, because every square meter they grow on, means on that square meter the local ecosystem will be extinct for eternity. Will destroy your ecosystem better than a point blank atomic weapon, because at the Trinity Site in New Mexico, the natives have grown back at Ground Zero.

I have Native American heritage, and it is really painful to see the destruction of the ecosystems that we consider Sacred, that is why my work is to restore them, and get the exotics off of them, so they can thrive again. Do not make the mistake we did here in California, please.

Learn how to use your native plants, if you are in Egypt, you have 2,302 native flowering plants, and they could become your best friends, if you take the time and put together the annual budgets to get to know them.

Start in tiny test plots, only one by two meters for each treatment. Sow seeds at different sowing rates, do soil tests and add different amounts of organic fertilizers and organic matter in each treatment.

And once you can get 100% native cover in one year for each species with natural rainfall, then you can expand to a hectare, then several hectares, etc.

Picture of my project here at the Kite Hill Preserve in Woodside, across from 144 Alta Mesa.

And two more from the same location:

The previous comments well summarize some of the reasons the breakthrough doesn't indicate something that can address the climate problem. I listened Monday to Miles O'Brien, PBS's science expert, on the PBS News Hour discussing the fusion announcement. He ended a good description by saying an old physics joke was the statement:

Unfortunately, I believe this is correct. When I came to Los Alamos in 1969 there was a magnetic confinement division called SYLLAC. There is now a related effort using a Tokamak machine in Europe, ITER, which is now about to go on line.

Several decades ago there was a LASER FUSION effort at LanL, smaller than NIF but a similar approach. The group leader of the group studying the theory involved was my best friend. This group was in one of my group's buildings. He told me they felt they had proved that the laser on a D-T pellet would not work in a practical energy production.

Hybrid of two non-native species, must be considered non-native. My reason is simple, that the parents were not supposed to be found in the non-native area, then how can you agree their offsprings to be native. If you say that the hybrid is native, then the seeds of normal non-native species occurring in non-native place should be considered native too, which is wrong.

ANOVA can be done depending which variables you select for rows and columns

I enjoy it. Hence, the research.

Hello,

In times of Drake it was not known, that exoplanetary systems differs completely from ours. Space biology understanding is problematic. And so on.

Invasive species can cause great economic and environmental harm to the new area. Not all non-native species are invasive. For example, most of the food crops grown in the United States, including popular varieties of wheat, tomatoes, and rice, are not native to the region.

You could try https://www.gbif.org/ (The Global Biodiversity Information Facility). It is also accessible via R (package rgbif) and allows several filters. It might allow selecting only alien or non-native species.

One should consider Environmental limiting factor along with resources.

Dr. Vinaya Tari

I'm sure this has already been resolved, but in case not; always contact zoos directly if you find an animal like this. Attika Zoological Park is an EAZA-accredited zoological institution, and most of their birds are tagged, like the one in the above picture. They could quickly determine if it is their bird, and if it is not, they will almost certainly help determine whose bird it is.

M. Cooper's responses above provide great details and protocols for how zoos take action on animals that escape from their facilities. I think the difficulty you've run into is how, as an academic, do you respond when being on the other end of discovering escaped wildlife, and is there a general protocol for such events? My simple answer is this: Always contact your local accredited zoological institution. Otherwise, contact local wildlife and/or rehabilitation centers. All of the above will make sure any animal, especially those that are tagged, are brought back to their home facilities.

Before addressing the proposed topic, which incidentally, we have been studying for years with other pandemics and epizootics in my laboratory, it should be noted that the hypotheses to understand their origin in humans have a lot to do with the thought of the landscape ecology.

These hypotheses, structured as landscape sciences do, but under the thought of rhizomatic ecology, tell us about how all animals are connected; hypotheses that serve to remind us of our animal condition and that shout at us, because they cannot say it louder, that as much as we live in artificial environments, we continue and will continue to be animals on the planet; a planet called earth which is our holistic environment.

Regardless of the origin or the time we have been together, some animals with others, the pandemic is the result of a zoonosis that may well be direct or indirect, in this case, as of May 2020, the way in which we are transmitted: Hypothesis 1: bats transported to the Guangzhou market were the original source for direct transmission of CoVid-19 to humans; Hypothesis 2: Pangolins (the most trafficked animal on the illegal market worldwide and widely consumed in China and other Asian regions) or a domestic animal such as dromedary or cat, could have been infected with CoVid-19 by bats and be the intermediary vectors of the virus to reach humans; Hypothesis 3: Pangolins could have directly infected the human. As can be seen, the crazy conspiracy idea that it was a virus created in the laboratory by either North Americans or Chinese and deliberately released or accidentally escaped into the environment is discarded biochemically.

Now, to understand this pandemic, we must remember that rhizomatic ecology tells us that humans are immersed in an ecosystem (holon) within larger ecosystems until they reach the Holo (Earth), and that each system has subsystems that directly influence adjacent or remote holons.

Bats are a very special group of mammals because their ability to fly allows them to have very high thermal regulation. Its temperature rises a lot during flight and drops considerably during rest. Their metabolism is more intense than that of the rest of the mammals and their immune system is much stronger, in such a way that they can have viruses, bacteria and parasites without causing apparent damage, but transport them long distances (zoocoria). The tangle of the rhizome extends indefinitely since where the bat reaches, it can infect endemic organisms such as the pangolin or dromedary, or common domestic animals, such as cats. It can even infect people when they are crowded into a market to trade and move more from there; huddled in a refugee camp or crowding into migratory groups to escape environmental catastrophes, dictatorships, famine, for example.

The natural migrations of fauna are becoming more extensive every day in the sense that the borders and the breeding or feeding sites are widening, covering more geographic area, interacting more with humans. A human population from a site that, if it did not previously have contact with said animal, can be infected more easily than people from populations that have lived with this animal for centuries. Likewise, consequences of the recent climate change and the illegal trafficking of species is the favor of this dispersion of pathogens, since the trafficked animals lack a clinical certificate, are transported in poor conditions, increase their stress, and therefore are more susceptible to suffer more pathogens and infect the fauna that accompanies them on their journey and final destination, including humans, of course, since we are also accompanying fauna. Climate change, on the other hand, encourages migratory behaviors in animals that are increasingly longer in their days of searching for places to reproduce, feed, hibernate, etc. The rhizome of the Earth has no territorial beginning or end, lacks a center and has nodes with vanishing lines and nodes with convergence lines, which can change, appear more or disappear; They can also modify their arms and nodal extensions, but it will always remind us that the whole planet is oneself and that humanity belongs to this planet as well as a bat or a pangolin, caring for them is caring for ourselves.

Avoiding the introduction and translocation of biological species is a pending subject of landscape ecology that now tries to give us the same teaching as in the time of the black plague (1347-1353), of cholera (1817), of the Spanish flu ( 1918) or the Asian flu (1957), the numerous cholera pandemics (1961, 1991, 1992 ...), swine flu (1976, 2009 ...), avian flu (1878, 1997, 2003, 2005, 2006 ...) and of course, by CoVid (2003-2004).

Hi João ,

The crab rings are widely used in brackish waters of India, especially from south-west coast for mud crab. Since this fishery is sustenance level, reports is very limited. Currently, we working on traps and pots of India, a review article on this underway. I'll share you once its published.

Best wishes,

Chinna

Quite an appealing discussion! Any postulates on the topic can be only speculative until we finally meet an alien race. However, literature, and more specifically, SF, has contributed some invaluable ideas. The Encyclopedia of Fictional and Fantastic Languages by Tim Conley and Stephen Cain gather loads of such examples.

For instance, Ted Chiang's Heptapod A, and Heptapod B. The former, as described in the novella, sounds like "a wet dog shaking the water out of its fur" (119), that is, an unpronounceable sound for human physiology. The latter, in turn, was so different that enabled its speakers to realise time in a non-linear way.

There are also cases like the Kesh language, describe in Ursula Le Guin's Always Coming Home that is more phonetically similar to human languages but quite distinct when it comes to grammar, which also happens because of physiological differences between humans and the aliens.

Most of the cases to point into one direction: if the alien species are physiologically similar to humans, so are their languages; whereas if the aliens' physical buildup is different, so is their language. As Michael W. Marek has mentioned, the unimaginably different culture the alien races might have developed over millennia of existence may cause quasi-untranslatable languages - we can already see similar cases in human languages. That makes total sense, in my opinion.

Thank you for the answer Andrew. I am not surprised by the lack of efficacy at the tested rates. In my region we use 20% tebuthiuron at 12 to 15 kg/ha to achieve effective control of other woody weeds such Vachellia nilotica. I would expect Prosopis spp. to require about the same latter rate for good efficacy but I have not heard of any field results.

Hello,

Usually, in literature, it is said to inject 1-2x10e6 cells suspended in 100ul PBS. Even if in vitro the cells grow very fast, in vivo are some differences. Here in our lab we use 1x10e6 cells/ 100ul PBS

Is this the kind of thing you're looking for ?

Mesopredator Management: Effects of Red Fox Control on the Abundance, Diet and Use of Space by Feral Cats. Robyn Molsher, Alan E. Newsome, Thomas M. Newsome, Christopher R. Dickman. 2017. https://doi.org/10.1371/journal.pone.016846

There's quite a lot of literature on this combination (cats and foxes in Australia) and also foxes and dingo. This paper will get you into that literature.

This kind of question is a bit tricky as it tends to answer itself. Something is successful because it is successful. Therefore any aspect of it is seen to be successful as well. Success 'explains' success.

Thanks Arne! I will go through the suggested articles.

Dear Philip thanks for your interest in the Channid Snakeheads of Europe. They could enter, spread, invade.  I have been reading up on them. But its not too late to stop them if bans on aquarium trade, live-food trade, aquaculture etc are put in place and implemented. They could spread in the southern half of Europe - in the cold-winter eastern half Channa argus did not spread - even though the USSR russians made many attempts (even in Slovak and Czech republics). So fortunately the situation is not like in the US.

Keep fish'n,

Stam 

 Showing the damage caused by invasive species can educate and convince many people.

I work as technician in the conservation project LimnoPirineus (http://www.lifelimnopirineus.eu/en). We are removing invasive fish from eight high mountain lakes in the Pyrenees. After three years of work we are getting some nice results such as the recovering of the natural transparency and the increase of abundance or the natural recolonization of many species of amphibians, invertebrates and crustaceans.

I have experienced that showing these milestones to the local people and pupils in local schools and high schools is convincing most of the audience.

Also, I have to recognize that a few people is not convinced anyway. However, I can see a very good progress at community scale.

Dear Jørgen. In this case the intended dosis (cutting depth) is variable from tree to tree. It depends on the cambium depth and it cannot be seen unless the bark is removed. This is why we want to apply this modified analysis, apart from a sensibility-specificity analysis.

The term alien species is synonym of introduced, exotic, non-indigenous, or non-native species. Refers to a species living outside its native distributional range, which has arrived there by human activity, either deliberate or accidental. Non-native species can have various effects on the local ecosystem. Introduced species that become established and spread beyond the place of introduction are called invasive species.

Hi.

As pointed out Filip Verloove, this species is an invading plant in some islands of the Canaries, like Tenerife. In any case, I have found C. grandiflorum growing here mostly in disturbed places (e.g. close to urban areas) and in the edges of secondary natural vegetation, but not inside well-preserved communities, e.g. of Euphorbia spp. and other succulent plants. This implies that probably it's difficult for this plant to grow in sites without some kind of human activities. On the other hand, at least in Tenerife its distribution is not too wide (for the moment), being more or less local. 

Best regards.

Thank you Paulo,

für the information

regards 

bernd

Dear Daniel, in my opinion rare species criteria depend of the group. It Is not the same a rare mammal than an invertebrate. Difficult in collecting, scarsety information available, history documentation, etc must be took account. Some species are cryptic, nocturnal, etc for their nature and could be considered as Rare for the difficult to be collected. For example for me, Solenodon cubanus is Rare species but that condition have been present always from the time of thier description. Some time is needed to compare with other species. S.cubanus is more rare that S. paradoxus for Hispaniola, that have been collected 3-4 times more historically than the Cuban species. Some time the species is RARE for scientist and is not rare for local people....

The draw back my be in that this energy use may create voids in the background energy densities and cause ripple affects that we do not know what it will mean.  This could also be good as there may be ways to send information using this kind of voids but it could also be bad as we are not sure if live is dependent on the state of the quantum energy being the way it is???

There is much to be discovered.  I would love to help with that kind of research.. 

"radiation potential of interchange between biogeographic regions (i.e. alien species)". Probably hybridization and introgression among previously isolated (by habitat, by geography) populations and species are important outcomes of globalization. Outcome is an increase in genetic diversity.  

Dear Khaled, try to send it to the Turkish Journal of Zoology. Publication has no cost, and the Journal has free access. It will be published online. in 2016. http://journals.tubitak.gov.tr/zoology/index.htm#

Although not very high, it has an impact factor of ca. 0.6. 

Have a look. Sometimes the point is to simply publish your results if their are original and shall be accessed easily by a wider community.

best regards,

alexandra

Ophisurus serpens (Linnaeus, 1758)  

(http://marinespecies.org/aphia.php?p=taxdetails&id=126317)

Hi Lorenzo,

I agree with Paulo--the Continuous Boyce Index is probably better than the normal Boyce Index.  FYI, I created R code to calculate the CBI (http://www.earthskysea.org/r-code/). 

And yes, it does make sense to use k-folding with this test statistic and with most others.  However, if you're using CBI to weight individual models to create an ensemble, be aware that CBI can be negative (meaning worse than random), so these models should not be included in an ensemble.  Better yet, if you're using the same algorithm, compute a series of models with k-fold splits and calculate the test statistics.  Then, use all of the presence sites to calculate an "all-points" model.  The latter will most likely be as accurate or even more than the individual k-fold models because it uses more data.

By the way, do you mean you're using the BIOCLIM model?  It's very easy to interpret and conceptualize, but it's often one of the worst-performing models.  You might try some of the other models available in dismo, especially Maxent or generalized additive models.

Dear Armando:

I think it is an species of Codium, it is similar to C. decorticatum, which type locality is the Mediterranean Sea. Check if the thallus is spongy, with an external palisade of vesicles called utricles.

Good luck with the determination.

Eugenia 

The animal is certainly of the genus Pilummnus. If the animal has in the walking legs a distal thorn in the carpus, it is Pilumnus villosissimus (Rafinesque, 1814).

Introns will be more different than exons among the different genomes (the three wheat genomes plus the barley or rice chromosomes), so you will get better chances not to amplify homoeologous sequences.

As you said, there are many papers describing Apis, Bombus and Megachile as invasive species. But "official" national or regional  lists of invasive species rarely contain bees, firstly because they usually contain few insects (these are more often listed as quarantine pests in the plant health sector) and also possibly because non-native bees also have positive sides, which makes their classification as invasive species more controversial than non-native ants or mosquitoes. However , some bees are officially listed here and there. For example, Bombus terrestris is listed in the Invasive Alien Species Act in Japan, where it is introduced, and it is also an official quarantine pest in several countries worldwide. In Australia, it is introduced in Tasmania but is considered a quarantine pest in the whole country, and. New South Wales qualifies it officially as a “Key Threatening Process”. The Africanized honeybee, Apis mellifera scutellata, has also been -and is still- listed in various sorts of States or local invasive species acts or quarantine lists during its spread in the Americas.

Thank you David Lorence and Alexsandra Maljkovic.

Indeed I consulted these suggested publication and I was able to get some of the information I needed.

Regards

Recently I was also searching for papers about Osmia taurus But I  do not found. But I have some papers about  Osmia cornifrons & Anthidium manicatum.

Here are the papers: http://www.fileconvoy.com/dfl.php?id=g5e409f029bffec3b999601638ccc002ecf7dfd84b

Dear Nancy.You must contact with Dr.Juán José Lopez Gappa.He works at Museo Argentino de Ciencias Naturales "Bernardino Rivadavia".Buenos Aires.Argentina.His mail is lgappa@mail.retina.ar.

<p>He is specialist in Briozoa and maybe he can help you.</p>

Dear Sujan,

Yes, there are georeferenced and nongeoreferenced species occurrence records for  Procambarus clarkii (2 records) and Orconectes virilis (2 records) in the state of Virginia, available for download from the US Geological Survey's Biodiversity Information Serving Our Nation (BISON - http://bison.usgs.ornl.gov) online species occurrence mapping system. Use the Refine Your Search panel to narrow your search down to only include records for Virginia. BISON does contain records for Orconectes rusticus but none occur in Virginia. Consider also searching BISON for occurrence records for other introduced crayfish species as well as for species that are impacted by introduced crayfish.

Best regards, Liz

Dear Sooraj,

First, MaxEnt is a presence-background model not presence-absence, and also BIOCLIM is a presence-only model. The presence-absence models are a different group of modeling approaches such as CART, MARS, SVM, GAM, GLM, etc.  

Second, I suggest you trying OpenModeler Desktop which the last version I think is 1.1.0, in this platform you could find more than 10 modeling approaches for your study.

I hope it would be useful for your project.

All the best wishes,

Ali

Aloha Carlos,

In response to your question I think there are many examples form all over the world.  In Hawaii, fountain grass (Pennisetum setaceum), for example, is a highly invasive plant that has caused massive fire risks in many dry areas. People would love to eradicate it but the extent of itʻs spread and percent cover (often times the ONLY species covering huge areas) makes it nearly impossible.

However, I think that the concept you are looking at is becoming increasingly rare (at least in the US) due, primarily, to biological control.  In Hawaii strawberry guava (Psidium cattleianum) was battled for many years as an invasive plant to rare Hawaiian wet forests using physical and chemical controls. After some 20 years of fighting it on the ground those efforts have been mostly abandoned because the Strawberry guava was simply too aggressive. But a couple years later a biological control agent was introduced to reduce the fruiting potential. 

But many invasive species have been given up on their control in Hawaii, even in the most sensitive habitats.  The Kahili ginger (Hedychium gardnerianum) is another good example.  While in some select areas they still fight it with huge amounts of volunteer labor, overall the costs of fighting it are simply too high.

As Robert and Truman allude to the answer to your questions requires a clearer definition, or perhaps just a clearer goal, of the environmental restoration. Some restoration efforts are focused on restoring native species or a particular form of ecosystem (sometimes even manmade ones), others on ecosystem function or services.

The question to ask, I think, is does removing the alien species move you towards your goals of ecosystem restoration? Even stated like this the answer is not always clear. For example in attempting to restore native species, many people assume universally that removing alien species is a good thing. However rapid removal of alien species can often open up an ecosystem to further, or even worse, invasions. Likewise when discussing ecosystem function sometime alien species have replaced native species to play a key role in supporting the overall functioning of the ecosytem.

I would argue that there is not a blanket answer, and that it will be situation ally depended on the goals, species, level on invasion, resources, use of the area, etc.

I was definitely wrong. This is another Malvaceae quite similar: Phymosia umbellata (Cav.) Kearney.

I appreciate all the information you have provided me.

My opinion is...don't fix what isn't broken

These papers could be helpful:

Ecological Monographs, 74(4), 2004, pp. 635–662: MULTIPLE TRAIT ASSOCIATIONS IN RELATION TO HABITAT DIFFERENTIATION AMONG 17 FLORIDIAN OAK SPECIES

Plant, Cell & Environment Volume 34, Issue 9, pages 1536–1547, September 2011: Morphological and physiological differentiation of seedlings between dry and wet habitats in a tropical dry forest

Annals of Botany 110: 1429 – 1438, 2012: Seedling traits, plasticity and local differentiation as strategies of invasive species of Impatiens in central Europe

I would start with ordinations to see if there are differences in species composition between habitats. Then I'd search for the subset of species, which is best at separating the habitats. From these species I'd then take the traits and run a PCA.

See also my account of the genus on alienplantsbelgium.be: http://alienplantsbelgium.be/content/parthenocissus

I confirm the above, except that the leaflet character (stalked or not) seems to have been inversed!

Hello Filip,

part of my research is to determine impact of Robinia pseudoacacia on vegetation and physical-chemical soil characteristics (see Vítková et Kolbek 2010, Phytocoenologia 40:205-241; full text in my profile). Currently, I'm writing an article about black locust adaptability to soil conditions based on my previous research on behavior of black locust in different habitats of the Czech Republic. 15 years ago, I also founded permanent plots on a transect across mesophilous and xerophilous black locust and pine stands to find out seasonal dynamics of chosen soil characteristics (soil moisture, pH, exchangeable cations, ammonium, nitrates, total C, N, extractable phosphorus, net N mineralisation, and nitrification rate) and differences in herb layer composition among plots. I repeated my measurements last year, but I have not evaluated all results yet. During last couple days I started to study decomposition of leaves of alien and native woody species – Robinia pseudoacacia, Quercus rubra, Prunus serotina, Quercus petraea, Fagus sylvatica, and Acer platanoides. I'm planning to collaborate with Microbiological Institute. Dealing with allelopathic potential of black locust would be very useful. I think, only evidences from the laboratory conditions are available (e. g. Nasir et al., 2005).

Hi Azubuike, a most striking example is the introduction of Red Swamp Crayfish Procambarus clarkii to Lake Naivasha and other places in East Africa, first introduced to provide forage for introduced large-mouth bass, with devastating consequences for the aquatic vegetation and Tilapia fisheries, and subsequent collapse of the crayfish. The developing situation has been described in by David Harper et al. 2003 and by John Foster & David Harper 2007 in Francesca Gherardi's edited 'Biological Invaders in Inland Waters'. David Harper has written other papers about the situation. The latest crayfish problem has been the introduction of parthenogenetic Marbled Crayfish Procambarus fallax f. virginalis to Madagascar where they are expanding rapidly. References in my 2012 book 'Management of freshwater biodiversity - crayfish as bioindicators'. With the amazing biodiversity of West Africa, including indigenous river prawns, it's worth trying to keep Nigeria crayfish-free. Cheers, Julian

i found high populations of this species in potato crops of buenos Aires province, Argentina, in in years 2008-2009. i olso frecuently found in wheat crops. (crops without insecticides)

Dear Josè, as far as i know there is not so much info on the invasive status of Casuarina equisetifolia in Europe. C. equisetifolia is planted as ornamental in many Med. countries. The MEPA Guidelines on managing non-native plant invaders and restoring native plant communities in terrestrial settings in the Maltese Islands promotes actions to control C. equisetifolia. You might also try to contact expert from Cyprus and Azores, but I do not know if published literature is already available on that. C. equisetifolia is cited also by Ramon Vallejo in his work(s) on Restoring Mediterranean Forests. Another useful info source is the EPPO site, in the EPPO reporting service and on ISSG on-line data-base. Hope it helps, best wishes, Giuseppe

What Weed Risk Assessment method are you using Rubén?

If its the Australian designed system the outcomes are simple enough, a score of 6 or more means it is a Weed, less than one and its not a Weed and from 1-5 the outcome is indeterminate. You cannot compare scores between species with this model. They just provide you with an outcome, that's it. You can find plenty of assistance in answering the questions in the Australian WRA system in this paper,

Gordon, D.R., Mitterdorfer, B., Pheloung, P.C., Ansari, S., Buddenhagen, C., Chimera, C., Daehler, C.C., Dawson, W., Denslow, J.S., LaRosa, A., Nishida, T., Onderdonk, D.A., Panetta, F.D., Pyšek, P., Randall, R.P., Richardson, D.M., Tshidada, N.J., Virtue, J.G., Williams, P.A. (2010) Guidance for addressing the Australian Weed Risk Assessment questions. Plant Protection Quarterly 25 (2) pp:56-74.

You can download a copy from my list of publications on this site.

If you wish to rank these species you need to use another system entirely such as one like this...

Randall, R.P. (2000). “Which are my worst weeds?” A simple ranking system for prioritizing weeds. Plant Protection Quarterly. 15 (3) 109-115.

Again a copy is available on this site...

cheers, r

Thanks Victor and Javier, I have been monitoring Hydrilla invasion for the past three years and have identified factors influencing its expansion. But the general feeling was that the surveys are no longer yielding new results, I rather monitor control operations which are not yet exercised and its not clear when they will be exercised. Do you have examples of similar studies showing the benefits for long term monitoring?

P.S. Visual inspection for the disease is unreliable. You may look for melanised spots but these are general immune response and are not necessarily associated with infection by A. astaci. Thus, some individuals with melanisation are actually uninfected, and the pathogen DNA may be detected also in animals where macroscopic melanisation is not apparent.