Until recently, museums weren't particularly trying to preserve DNA. Sometimes you can get DNA from museum specimens, but they aren't specifically great for it (still better than nothing, though).

But for dodos specifically, there are only 2 or 3 specimins in the world that were collected when the species was alive, and only one of those has any soft tissue

https://blogs.ucl.ac.uk/museums/2013/09/19/the-best-natural-history-specimen-in-the-world/

Yes

Generally speaking you see a big increase in height between malnourished parents and their children who have plenty of food, so if there is an effect it doesn't dominate the effect of food availability that you have yourself during critical growth periods.

Plasma just means the substance is mostly charged particles rather than being mostly neutral. In practice, this means a lot of hydrogen and helium nuclei that have been separated from their electrons. We know where it is on the periodic table, it's just ionized.

This isn't too surprising. Most of the matter in the universe is in stars or dispersed in near vacuum, both of which are conducive to plasma formation.

Also, this means 99% of the visible ordinary matter in the universe.

Nursing frequency and birth spacing in Kung hunter-gatherers

citation for long birth intervals in !Kung

Foraging and Menstruation in the Hadza of Tanzania

citation for shorter, but still 2.5 yr birth intervals for Hazda

Analysis of Factors Involved in Lactational Amenorrhea

citation for big variation in how long infertility lasts during nursing, depending on specific situation...in other words, you can't safely assume that the same thing applies to people with totally different nursing habits and totally different nutritional profiles.

Birth spacing in hunter gatherers is 3-4 years, and it's the same or higher in great apes. Generally speaking, they all tend not to get pregnant while still nursing the previous offspring.

2% DNA doesn't mean 2% interspecies reproduction....there's not a direct relationship between numbers like that. You can get to 2% DNA from a relative handful of crosses. As this paper shows only a few hundred crosses, basically one a generation across the whole range overlap, could account for the observed level of Neanderthal DNA in our genomes.

>But at the same time, if there isn't any other explanation, it's highly unlikely there aren't any nearthental women in this chain for any alive human being today.

Not really. It's very easy for mitochondrial DNA lineages to go extinct. For any particular lineage to stick around, it's like tossing a coin and coming up heads every single generation in a row. Even in the large population of humans, it's not surprising random chance would eliminate all neanderthal mitochondria.

To get Neanderthal mitochondria today, you need an unbroken chain of mother-daughter ancestry going all the way back to the Neanderthal. At no point in that entire chain could there be a mother who had only sons, because then the mitochondrial line would be lost.

So we can't really tell much by the absence of mitochondrial dna....it's just too easy to lose by pure chance.

>They didn't have the dramatic gender dimorphism of humans

Hm? Humans have less sexual dimorphism than the other great apes, and H. erectus had more sexual dimorphism than humans (but not as much as other apes)

https://www.nature.com/articles/s41598-019-44060-2

>and were about half again as big as humans

H. erectus were larger than previous hominids but they weren't larger than modern humans! If anything they were marginally smaller.

>Did they have a monthly reproductive cycle like in humans or was it seasonal?

Very few primates have seasonal reproduction, so we can guess this is similar to humans and other primates

>How long did it take them to reach sexual maturity?

It's not entirely clear but H. erectus seems to have matured a little faster, or at least grown a little faster

https://royalsocietypublishing.org/doi/10.1098/rstb.2015.0234

> (humans reach this in about a dozen years though the ability to carry a child successfully and safely to term can take another few years)

Age of first birth tends to be around 19-20 in modern hunter gatherers. It's around 15 in chimps, so H. erectus was probably somewhere in the range between the two, though I couldn't find actual data for it

> homo erectus would likely have been able to have children faster than the 1 year average people tend towards.

This is not a realistic birth spacing, for humans or H. erectus. Hunter gatherers show a birth spacing of 3-4 years, and the other great apes have longer birth intervals. It's only in sedentary societies with abundant food and no need to carry offspring while foraging that humans can come close to a birth rate of 1 per year, and it's unusual even then. Actually producing 15-30 babies is even more unusual.

I wouldn't expect H. erectus to produce any more offspring than modern humans. Probably a bit fewer actually, considering the way modern humans displaced other hominids and seem to have had higher populations when they did so.

https://www.jstor.org/stable/10.1086/667591 table 1 has birth interval and age at first birth data

Birth spacing for other great apes is even wider

https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.1330830207

> a swan shrink wrapped

This is from the excellent book All Yesterdays, a book of paleoart. The point of those images wasn't to represent issues with well done reconstructions, but instead to reimagine modern animals if we shrink wrapped them the same way that is (and especially was) done with dinosaur reconstructions in the past...trim muscles, no body fat, no feathers or fur of any sort, no fleshy bits. And then monsterize them a bit because they are dinosaurs after all. A Jurassic Park raptor probably isn't much closer to true life appearance than that swan. And there are plenty of older reconstructions that are further off.

It's not clear to me how a size change would be possible

Minimum viable population is less of a rule and more of a guideline. Specifically speaking, it's usually defined as something like "the minimum population to have a 95% chance of survival for 100 years, in a population that isn't being specifically managed by people."

95% is a pretty high percentage, so there's a lot of "room" below it. Maybe 4 moose only have a (to pull a number out of the air) 25% chance of survival....but that's common enough that it isn't surprising to see it happened.

And furthermore, populations can have big advantages that mean their actual odds of survival are higher than the given percentage. For example, moose introduced onto an island with no competitors and no predators can expect to have a greater fraction of their offspring survive. And that means their population will more rapidly grow out of the danger zone.

>the lost civilization as interlopers

Although it was actually the Pueblo who had been there longer, and the Navajo who were part of a migration that came down from the north.

Well, it's the same as Pando for example. Or coral heads. People don't usually count bananas because they aren't all connected to each other, but the fungus probably is (there's probably no way to verify that, but it's what you would expect)

Having the same DNA is pretty much the thing that defines what makes up a fungus organism.

Fungal colonies are big networks of filaments that spread through the soil (or something else) and grow by cells dividing and making more fungal cells. So if you get the same genetic signature, you know the cells must be different branches of that same fungal network. There's not really "individual organisms" in these fungus the way there is in animals, it's just what is genetically a part of the original colony, or what's a new colony produced by sexual reproduction.

In the old days, they'd take samples from different areas and see if they fuse in a a petri dish, which indicates they are the same individual. These days genetic testing is faster and easier though.

So basically you take samples from different areas and map out where the fungus matches out as genetically identical. Once you get an idea of the amount of ground surface it covers, you can estimate total mass by figuring how much fungus mass is in a given square meter of soil (or whatever) and multiplying by the total area.

generally speaking, if populations aren't isolated then mutations will eventually spread across the whole species, so you don't get divergence between different populations.

The dirt the colony is in will be more wet after a rain, but the colony itself isn't going to flood with water during a normal rain event. Water poured on the ground tends to soak into the ground...in places where it actually forms puddles, you tend not to get ant nests.

How long ago were they stocked with the other fish? My bet is that you had a few juvenile flathead sneak in with the other fish when they were stocked. It takes them 4-5 years to mature, and it might take a few generations before the ponds had enough in them for them to be noticeable.

This will probably make more sense if you look at extinct ungulates. When comparing a horse and a deer or antelope, you are comparing animals that have converged on similar solutions to similar problems, while whales have gone off and done something totally different. But if you look at the ancestors you can better see what's going on.

Also important is the details of the anatomy of these species. Horses may look like moose in many ways, but how they get to that final result is rather different even if that isn't always visible at a causal glance.

Early whale ancestors like indohyus and pakicetus looked less like whales and more like early hippos (the closest living relatives of whales).

>How do fishes get into isolated inland lakes in the first place?

For random small ponds and lakes, there are two main ways that fish get into seemingly isolated bodies of water: people, and flood events.

I cannot emphasize this enough, people are absolutely obsessed with putting fish in all sorts of bodies of water. Fishermen want fish to fish for, and nobody wants mosquitoes. People go to extreme lengths to get fish into everything from their farm ponds to remote lakes in the middle of nowhere in the mountains. In the old days, this meant packing milk cans full of trout fry out on mules, nowdays it means airdropping them.

If the fish you see is any sort of trout, bluegill or other freshwater sunfish, a bass, common carp or goldfish, golden shiners, fathead minnows, mosquitofish, or tilapia, there's a very good chance it was stocked in the body of water by a person. These fish have all been spread all over the place outside of their native range by people. (this is a North America-centric list, other places will have their own commonly stocked fish)

The second method of fish dispersal is flood events. When there's a big flood, all the water flowing into an "isolated" pond has to flow out. The exit may not be obvious most of the time, and it may not have water in it most of the time, but during floods there's a lot of water moving on the land and that lets fish move around to places you wouldn't expect. There are relatively few isolated bodies of water that are truly isolated. This is even more true if you take the long view...there were enormous floods at various points toward the end of the last ice age, and as recently as the 1800's we've had megafloods in the central valley of California, for instance.

Now, I know people always bring up birds, but I'm not at all convinced that is a major method of fish dispersal. The first option is a bird carrying an adult fish and dropping it in a new lake. I find this an extremely unlikely method of fish dispersal, because nearly all fish are external fertilizers. Which means you need a male and a female to be present, you can't just have a pregnant female carrying fertile eggs. The odds that birds would happen to drop two separate fish in the same pond, after carrying them (and you'd have to carry them alive a long way) are just too small for it to happen regularly.

There's a better case for birds consuming fish eggs, but it's still only proven for a few fish species that the eggs can survive passage through a duck digestive tract, and a great many fish don't lay eggs in places where birds might eat them anyway. Probably happens sometimes.

But it doesn't happen very often, and we know that because historically there have been a lot of lakes without fish in them. Especially in high mountains or areas in the north, lots of lakes just...didn't have fish. These often housed unusual or unique ecosystems with amphibians and insects found in few other places. And also it's very common for fish to be found in one watershed and not neighboring watersheds, even if other fish lived in those other watersheds. So it's clear that most fish aren't getting airlifted to nearby streams or lakes, because we know they just weren't in those streams or lakes.

Of course, as I mentioned before, people are absolutely mad for moving around fish so nowadays nearly all of those previously fishless lakes have fish in them thanks to historic stocking efforts.

>and why don't we see more divergent evolution / speciation given the separation of each group of fishes from each other?

Ponds and lakes are usually very short lived, on a geological or evolutionary time scale. Ponds usually come and go over the course of a few hundred or few thousand years, they just don't stick around long enough for speciation to happen. Lakes come and go too, the Great Lakes only appeared at the end of the last ice age, for example. And of course many of the "lakes" people know about are actually reservoirs built by humans in the past hundred years or so and stocked with a mix of human chosen fish.

Old lakes do have a bunch of unique species: the rift lakes in Africa and Lake Baikal are two excellent examples of this phenomenon. And in general, freshwater does cause a bunch of speciation...there are almost as many freshwater fish species as marine species, despite the total volume of freshwater habitat being enormously smaller. This is because isolation in different watersheds causes speciation. But you won't necessarily see that diversity because if you are fishing, you are probably catching and seeing the very handful of fish species that people have stocked in ponds and lakes all over the place.

I think I am not doing a great job explaining, its hard without pictures

Think about what it means for the moon to be visible in the sky...that side of the planet has to face the moon. Which means the planet has to take the same time to spin around once as the moon takes to travel around the planet once. Otherwise that side of the planet would get ahead of the moon or get left behind it.

The moon takes a month to go around the earth. If one side of the the earth faces the moon, it must therefore also take a month to rotate.

Granted, a "month" might be much shorter on some other planet if the moon was much closer. For example, pluto's moon charon faces only one side of the planet, but it only takes 6.4 days to orbit.