Wikipedia describes the last super-continent as
Pangaea or Pangea (/pænˈdʒiːə/) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 million years ago. In contrast to the present Earth and its distribution of continental mass, Pangaea was centred on the Equator and surrounded by the superoceanPanthalassa. Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists.Wikipedia: “Pangaea“
However that last statement isn’t really correct. Humans have created the most recent virtual super-continent. At least as far as species movement has been concerned world wide. We’ve picked up species from around the world and transplanted them almost everywhere else.
My dinner last night consisted of a beef steak (probably from domestication of wild aurochs in the mid-east) , Kumara (originally from South America), and broccoli (probably originally the Mediterranean). All were carried to New Zealand by humans. The Māori brought a kumara with then, and then took up the much larger cultivars after European settlement. The rest of my delicious meal (says the cook) were brought in by settlers.
Humans are effectively camping in NZ and outside of the natural ecology of our islands. Outside of survival exercises, in my 60 odd years living here, I’ve never eaten food that is native to NZ. Fern root is edible – but only if you’re starving. Native birds are protected because almost all of them can be regarded as close to extinction. With berries, between that native birds and the Australian possums, competition is too fierce for mere humans to get any.
New Zealand is probably an extreme example because of the way that the Zealandia continent plate is largely submerged and has been down to very small islands several times over the last 65 million years. Our ecological diversity is that of small islands.
Most of this is well known. What is less well obvious are the consequences at the micro-biological level – for humans and for entire genera of species.
For instance read a 2018 National Geographic article on frogs and other amphibians.
MANY OF THE world’s amphibians are staring down an existential threat: an ancient skin-eating fungus that can wipe out entire forests’ worth of frogs in a flash.
This ecological super-villain, the chytrid fungus Batrachochytrium dendrobatidis, has driven more than 200 amphibian species to extinction or near-extinction—radically rewiring ecosystems all over Earth.
“This is the worst pathogen in the history of the world, as far as we can tell, in terms of its impacts on biodiversity,” says Mat Fisher, an Imperial College London mycologist who studies the fungus.
Now, a global team of 58 researchers has uncovered the creature’s origin story. A groundbreaking study published in Science on Thursday reveals where and when the fungus most likely emerged: the Korean peninsula, sometime during the 1950s.
From there, scientists theorize that human activities inadvertently spread it far and wide—leading to amphibian die-offs across the Americas, Africa, Europe, and Australia.National Geographic: “Ground Zero of Amphibian ‘Apocalypse’ Finally Found“
The significance of this is that amphibians have a significiant but still poorly understood effect on local ecosystems. They were almost everywhere, so much part of the background that it took some time to realise that there was a massive dieback going on.
In person, Bd infestations can look like biblical plagues. Each August, adult midwife toads in the French Pyrenees climb out of their birth lakes for the first time. The infected toads barely make it to shore. “They’ll do one last hop, and then they’ll expire in your hands,” says Fisher, one of the study’s coauthors. “You can walk the lakes—it’s just carpets of dead frogs.”
Similar die-offs started popping up in the 1970s, but researchers didn’t realize these “enigmatic declines” were a global phenomenon until the 1990s. In 1997, researchers first described Bd, and within a decade, they had connected it to the slaughters. Meanwhile, Bd‘s killing spree continued. From 2004 to 2008, one site in Panama lost 41 percent of its amphibian species to the fungus.
Most of the once-mysterious slaughters are now attributed to the “Global Panzootic Lineage,” a lethal strain nicknamed BdGPL.National Geographic: “Ground Zero of Amphibian ‘Apocalypse’ Finally Found“
And there are potentially worse species of Bd from the same previously geographically limited area. There these diseases are in balance – probably because the affected species evolved alongside the pathogens. The problem is when they get moved by, usually by humans, into ecosystems that they didn’t evolve in and jump species.
In 2013, researchers identified B. salamandrivorans, a sister species of Bd known as Bsal. Its name translates to “salamander-devouring” for a reason. From 2009 to 2012, the fungus slashed Dutch fire salamander populations by more than 99 percent.National Geographic: “Ground Zero of Amphibian ‘Apocalypse’ Finally Found“
If all of this sounds horribly familiar to us these days – then it should. Humans are suffering the consequences of our virtual Pangaea super-continent of the rapid transit. A localised disease or one that jumps species gets spread by rapid travel and then causes pandemics.
The spread of species jumping Covid viruses across multiple species, including humans, is exactly the same wholesale killing process as Bd and happening for the same reasons. So far we have seen several closely related Covid diseases from SARS, MERS, and now Covid-19.
If this follows the course of pandemics in our history like smallpox or black death, we will probably see several more before the human population worldwide develops a population level immunity to that family of pathogens over the coming decades.
The problem is that there are a lot of families of viruses, fungi, bacteria, and prions around, and that is before getting into trying to count the species. As a species who appears to be committed to going everywhere and sticking our noses into everything, we’ve just been damn lucky over the last century.
Perhaps it is time to start thinking about what kinds of precautions we should be taking to prevent the currently inevitable pandemic repeats. Like getting really serious about border controls (and ignoring our tourism addictions). Or spending more money on preemptive discovery of potential threats.