The Coronavirus Thread

[JimC]

The species concept is rather difficult to apply to a virus...

actually, I'm yet to fully understand the definition of distinctive speciation in higher animals and plants. my rule of thumb understanding is interfertility, like I differenciate dialects from acctual languages at the intercomprehension line, but I know that's a layman's attitude, and not necessarily the correct understanding.

That is actually the basis for one of the more important definitions of species, at least for most animals IMO. The best way to envision it is to imagine 2 populations of the original species, separated geographically by something like a mountain uplift, or a new sea, for a considerable period of time. Inevitably the 2 gene pools will become gradually more different. The test for whether they have truly become separate species comes when a change allows the 2 populations to meet again. If insufficient genetic change has occurred, then they will successfully interbreed, and merge into one breeding population. If they are no longer inter fertile, they remain separate, and can be legitimately classified as 2 separate species. Now, there are certainly a variety of situations where this concept is hard to apply, but it still remains a useful guide.

but could the intensely differentiated birds Darwin found in the Galapagos still breed between different types?

They differentiated on different islands, to a degree. In the situation where more than differentiated species exists together on the same island, then it is safe to call them separate species - they have probably evolved differences in courtship behaviour which make cross breeding unlikely. In the case of similar looking finch populations on different islands, one could put them together in an aviary and experimentally test their ability to cross breed.

Back in the day, when I worked on frogs, the group of frog researchers could test this quite easily, by mixing sperm from a male and eggs from a gravid female, sometimes from populations assumed to be different species, in a petri dish, then following the development (if any) of the tadpoles and then froglets.

[JimC]

Not surprising, but tangentially relevant:

'Bat "super immunity" may explain how bats carry coronaviruses, study finds'

A University of Saskatchewan (USask) research team has uncovered how bats can carry the Middle East respiratory syndrome (MERS) coronavirus without getting sick -- research that could shed light on how coronaviruses make the jump to humans and other animals.

Coronaviruses such as MERS, Severe Acute Respiratory Syndrome (SARS), and more recently the COVID19-causing SARS-CoV-2 virus, are thought to have originated in bats. While these viruses can cause serious and often fatal disease in people, for reasons not previously well understood, bats seem unharmed.

"The bats don't get rid of the virus and yet don't get sick. We wanted to understand why the MERS virus doesn't shut down the bat immune responses as it does in humans," said USask microbiologist Vikram Misra.

In research just published in Scientific Reports, the team has demonstrated for the first time that cells from an insect-eating brown bat can be persistently infected with MERS coronavirus for months, due to important adaptations from both the bat and the virus working together.

"Instead of killing bat cells as the virus does with human cells, the MERS coronavirus enters a long-term relationship with the host, maintained by the bat's unique 'super' immune system," said Misra, corresponding author on the paper. "SARS-CoV-2 is thought to operate in the same way."

Misra says the team's work suggests that stresses on bats -- such as wet markets, other diseases, and possibly habitat loss -- may have a role in coronavirus spilling over to other species.

"When a bat experiences stress to their immune system, it disrupts this immune system-virus balance and allows the virus to multiply," he said.

There seems to be a reasonable rule of thumb in such cases; the longer a host and virus have been together, the less virulent the effect. Often people assume that this is mainly due to evolution towards lower lethality in the virus, as premature death reduces success in spreading. The suggestion in this research seems to suggest parallel evolution in the bats, in terms of their immune system becoming more able at dealing with the virus in question. This may well be so, but it is likely that the rate of evolution of the virus population is orders of magnitude greater than any metazoan host.

[JimC]

https://www.abc.net.au/news/2020-05-14/ ... e/12243694

Health officials are advising residents to avoid contact with wild birds after three people test positive for a potentially dangerous bacterial infection.

The Nepean Blue Mountains Local Health District (NBMLHD) issued the advice to residents of Blue Mountains and Lithgow, New South Wales, after several locals were recently diagnosed with psittacosis, also known as parrot fever.

If it's not bats, its parrots!

It's a biotic conspiracy!

[Svartalf]

psittacosis still can be a problem? fraggit, and I thought it had been beaten more than 50 years ago.
and don't mix conspiracies up, bats want to sicken us with viruses, while birds us bacteria.

[Cunt]

So virus, bacteria...what's next? Fucking toad-rain?

[pErvinalia]

Just recently there was a study released describing the effects of interbreeding between two species of Galapagos finches.

'How gene flow between species influences the evolution of Darwin's finches'

Despite the traditional view that species do not exchange genes by hybridisation, recent studies show that gene flow between closely related species is more common than previously thought. A team of scientists from Uppsala University and Princeton University now reports how gene flow between two species of Darwin's finches has affected their beak morphology. The study is published today [May 4, 2020] in Nature Ecology and Evolution.

Similarly there was gene exchange between sapiens and neanderthalensis, and denisovans(?)

[L'Emmerdeur]

Yes, 'species' is a useful concept but it's also to some extent amorphous. You're right about the Denisovans being in there, mostly their contribution is seen in Asia and the Pacific. There is also another group called 'super-archaics' (left largely undefined) that interbred with Neanderthals and Denisovans.

'Earliest Interbreeding Event Between Ancient Human Populations Discovered'

[Tero]

Supplies to remote places:
https://www.kios.org/post/14-hours-and- ... n-pandemic

[JimC]

Yes, 'species' is a useful concept but it's also to some extent amorphous. You're right about the Denisovans being in there, mostly their contribution is seen in Asia and the Pacific. There is also another group called 'super-archaics' (left largely undefined) that interbred with Neanderthals and Denisovans.

'Earliest Interbreeding Event Between Ancient Human Populations Discovered'

Early in the divergence of species some gene flow could occur, so in that sense, the species concept has fuzzy edges at certain stages. But when the genetic divergence has reached a stage where interbreeding produces less than viable offspring, there tends to be the evolution of various pre-mating isolation mechanisms, which shuts the flow down. In the case of early humans, that stage may not have been reached before the various other populations died out, and/or were absorbed into one species.

[Brian Peacock]

Our county has some 600 cases. It's taking an awful lot of time for viruses to disappear from tested people:
As of Wednesday afternoon, the Lancaster County COVID-19 dashboard shows 688 people have tested positive for COVID-19, four people have died, and 63 have recovered. Twenty-three new cases of the coronavirus were reported Wednesday in Lancaster County.

That's a mortality rate of c.10%. That's pretty high on the face of it, but it does rather depend on the number of people being tested.

Well no, all we know is that 10% have recovered and can go back to normal life. Of the 688 only 4 have died. Less than a percent. But more will die as deaths lag the newly infected.

Ah, my bad. I got the figures round the wong way. Mortality around Europe has been converging around c.5%.

[Brian Peacock]

Yes, 'species' is a useful concept but it's also to some extent amorphous. You're right about the Denisovans being in there, mostly their contribution is seen in Asia and the Pacific. There is also another group called 'super-archaics' (left largely undefined) that interbred with Neanderthals and Denisovans.

'Earliest Interbreeding Event Between Ancient Human Populations Discovered'

Early in the divergence of species some gene flow could occur, so in that sense, the species concept has fuzzy edges at certain stages. But when the genetic divergence has reached a stage where interbreeding produces less than viable offspring, there tends to be the evolution of various pre-mating isolation mechanisms, which shuts the flow down. In the case of early humans, that stage may not have been reached before the various other populations died out, and/or were absorbed into one species.

When you say 'various pre-mating isolation mechanisms' what you mean is 'we ate all the Neanderthals' don't you?

[JimC]

Actually, some of the best examples come from frogs, where both male calls and female responses can diverge to the point where mating will not happen. Courtship displays in birds, and various pheromones are other examples. Mating with individuals who are too genetically different to form viable offspring is a major waste of resources (particularly for females), and so is a negative driver in the evolution of any such mechanisms...

[L'Emmerdeur]

Early in the divergence of species some gene flow could occur, so in that sense, the species concept has fuzzy edges at certain stages. But when the genetic divergence has reached a stage where interbreeding produces less than viable offspring, there tends to be the evolution of various pre-mating isolation mechanisms, which shuts the flow down. In the case of early humans, that stage may not have been reached before the various other populations died out, and/or were absorbed into one species.

Seems like humans are fairly stable, genetically. In the article they describe an interbreeding between the super-archaics (who split off from other human groups two million years ago) and the ancestors of Neanderthals and Denisovans, over a million years after the split. We're messing with evolution now, so if we survive we may diverge genetically through our own doing.

[rainbow]

When you say 'various pre-mating isolation mechanisms' what you mean is 'we ate all the Neanderthals' don't you?

Something just so obvious

[NineBerry]

First, the data suggests that fewer people die in economic trouble. This seems counterintuitive, but that's reality.
https://www.nature.com/articles/d41586-019-00210-0

The suicide rate in Japan fell by 20% in April compared with the same time last year, the biggest drop in five years, despite fears the coronavirus pandemic would cause increased stress and many prevention helplines were either not operating or short-staffed.

People spending more time at home with their families, fewer people were commuting to work and delays to the start of the school year are seen as factors in the fall.

https://amp.theguardian.com/world/2020/ ... ss-factors