I really do agree with your broader point here but that’s not how niches work. There’s no “lizard niches” those niches are already occupied and are already being utilized. Are you saying food is being left on the table? Nature doesn’t work like that. Tegus will necessarily be outcompeting native animals
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I don’t mean that they won’t be eating food that other animals would have eaten instead (though they are highly omnivorous, unlike our native lizards, but I also realize that just shifts the competition away from other lizards and towards birds). My point is that it’s odd that we don’t have any large species of lizard given our climate here in the South, and seems to just be an artifact of geological history.
If you look at similar places that weren’t as heavily affected by the ice ages, they do have such animals. Southern Argentina has areas with similar temperature extremes, and they have tegus, southeastern Australia has a similar if slightly milder and drier climate, and they have various monitor lizard species, and of course, the most similar, southeastern and central China, has Chinese water dragon, crocodile lizards, Chinese forest lizards, and the Asian water monitor, all of which far exceed the size of any native lizard in the South.
Now, in fairness, another similar climate can be found in parts of the Balkans, and there they also have no large native lizards. But Europe generally is far less species-rich and during the ice ages suffered far more biodiversity loss than even the US. It’s actually in the Balkans that they’ve found fossils of bald cypress and tulip poplar dating to just before the glaciation. And more on topic, if a bit weaker of an example, fossils of European versions of the Gila Monster have been found in France, though for them the fossil record is much less clear and not known to be as recent.
As a kind of reverse parallel we can talk about a species that recently went extinct. The South lacks a large-bodied woodpecker. Sure, the bugs that such a woodpecker would have eaten are now getting eaten by other birds, insects, mammals, etc. and yet people still talk about how longleaf pine savanna ecosystems are in some way incomplete after the loss of the ivory-billed woodpecker. Somehow bringing back the ivory-billed woodpecker would very much mean taking away food from other animals, and yet we can still talk about how those birds served a particular niche.
It’s not a perfect analogy, since the ivory-billed woodpecker was in some ways a keystone species, but the general idea should still be the same. And I’m not sure niche is even the best word to use, but it’s close enough to get the idea across.
That’s my $0.02 anyway. I think there’s a lot to learn about how an ecosystem can better function and support more diversity by looking at other, similar, ecosystems around the world instead of fixating on the tradition that the ecosystem ought to be whatever it looked like before the Pilgrims arrived and anything else is inferior (specifically the Pilgrims and other Europeans arrival, because Native American interference somehow don’t count as human interference… Yikes.). It’s well worth noting that almost every ecosystem in the northern hemisphere has been massively degraded and drained of biodiversity, both by humans and by recent geological events. Now we’re left holding the bag, the least we can do is not wed ourselves to just preserving whatever is left of the whichever random state of things existed in 1492.
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again, agree with pretty much everything here, the only difference in your analogy is time and that’s the important one. Bringing back some animal (or an equivalent role) that is filling a RECENTLY empty hole is totally different because everything else has been expecting that role to be filled. Likewise, there are tons and tons of native species expanding their range northward, I have no issue with this and tegus spreading north aren’t a concern for me. Now if they are transplanted without thousands of years of interactions between species this is how we get these imbalances that result in a net loss of productivity
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I mostly agree, though I’d put the timescales much longer, tens to hundreds of thousands of years being the lower limit.
I think I also put more emphasis on the extent to which our original ecosystems are already more or less completely destroyed. Whatever ecosystem balances we have discovered here in the US are mostly just recent equilibria that emerged after the extinction of North American megafauna and other major extinction events and climate shifts in near geological history.
Not that we should be heedless and just start bringing in whatever we want or eradicating whatever we don’t like. And of course preservation is still hugely important. I’m mostly just venting frustration that largely passive preservation work is pretty much the only thing that’s kosher. Even natural and assisted migration gets a a negative reaction most times.
Oh, and there’s of course the major caveat that different climates have wildly different degrees of risk. Colder and drier places are just way more vulnerable to being significantly changed by the addition or absence of a single species.
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and those were actually just a recent equilibria of the thing before that and etc. Nothing is static, but this recent equibria (pre columbian) was just as robust as every other one before that. Yes american ecosystems are very degenerated, agree 100% tegus won’t help either.
I also understand the frustration at the totally passive approach, even some of the researchers who advocate for this view might not understand it comes from a place of ignorance much like “eat a well balanced diet”. If we could very very accurately simulate the major potential interactions and then the second and third order reactions from adding something new to the environment we should, in my opinion, be extremely active in our approaches (reintroductions, new introductions, and eradication campaigns).
But currently (probably 98% of the time) we don’t have ANY kind of idea of what will happen with any kind of granularity so we (and we’re batting at basically 0% having tried in the past) throw out hands up and say “it’s best to just leave things alone”
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Species moving around and then evolving into new species in new locations is a major part of why we have so many species today. If we could go back in time and stop species from moving around way back in the very beginning we wouldn’t have much today.
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Well I’m one who disagrees I just don’t care enough about native species. Grow up face the music you suck and you’re on the short list. Compete or die. Change is constant unstoppable and inevitable. What is it? 90% of all known species are extinct and nothing lasts forever. It’s just the way things are. I know a lot of people are nostalgic and upset when we lose a species. I’m not. What new species are we suppressing by holding up obsolete old species? It works both ways. Wolf-coyote hybrids are going to out compete and drive down the coyotes and wolves numbers. No matter what we do. Half my state used to be the bottom of the ocean and it will be again.
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That is funny because I hear and see tree frogs up here all the time. Sometimes I hear them as early as March into November.
We have the Italian wall lizard in Kansas too. They were introduced by a Herpetologist from Kansas University.
hang on. I remember reading a message you wrote about watching the ash trees die and how sad it made you. I watched it happen too, it sucked
Change IS inevitable. and humans HATE it. literally everything we do goes against change so why should animal management be any different
No shortage of lizards in New york!
Ok, I think I have a scenario I’d like to run by you to see what you think.
Say we decided to introduce a variety of cervids to the eastern US. For this example, we’ll use fallow deer, tufted deer, and marsh deer. Now, of course, the first question is why the heck would we do that? The reasoning is two-fold: to improve ecosystem diversity, and to protect white-tailed deer.
For ecosystem diversity, there’s the facile part in that we’d have more deer species. But there are those second-order effects you talked about. There is a compelling argument that woody and herbaceous plant species diversity would improve if we introduced those species. White-tailed deer, while gardeners feel like they eat anything and everything (and in the suburbs, where their population gets all out of whack, they do) are fairly picky about what and where they eat. They tend to browse in particular kinds of habit, and while generalists they do have certain species that they will hammer over and over to the point of local expatriation–in my area that’s euonymus and calycanthus. Meanwhile, white-tails rarely forage in water or really open sites and don’t typically consume grasses much. Fallow deer on the other hand are primarily grazers. The largest grazing herbivore in the east is the cottontail rabbit… So I think there’s a pretty good case to be made that there’s a hole in our ecology where a large, grass-eating mammal is supposed to be. And we know that regular grazing is critical for maintaining grassland and meadow diversity. Tufted deer are dual grazer-browsers, but they strongly prefer dense habit like thickets, unlike whitetails which use such habits mostly just for cover and bedding down. Once again, a big chunk of our ecosystem that is missing a key component of its food chain (which I suspect is part of why kudzu and muscadines manage to suppress late-successional trees so well). Then there’s marsh deer. It’s a South American relative of whitetail deer. Unlike whitetails, their preferred habit is marshlands and swamps, as the name suggests. And unlike whitetails, grasses are a major part of their diet. Grasses, and a pretty little plant called water hyacinth. Most of our native wetland herbivories, such as beavers and muskrats, eat woody and herbaceous plants, as does the invasive nutria. Once again, the biggest wetland grazing herbivore we have on the east coast is… the swamp rabbit. Clearly something’s missing.
So we’d get more deer diversity, but since they’d be filling out different roles/niches, we’d also just have more deer generally. And since they all have different browse and grazing habits, we’d expect to see an increase in overall plant diversity, both in those areas preferred by whitetail (which are currently over-pressured) and in those areas underserved by whitetails (which are currently under-pressured).
Then there’s the white tail deer themselves. They would almost certainly benefit from this scheme. The most direct reason being the combination of increased competition and increased predation (more deer overall would support more deer predators, ie coyotes and bears and to a lesser extent bobcats and to a much lesser extent few red wolves that are left and in theory the condors and mountain lions that I wish they’d bring back and Florida panthers I wish had enough habitat to spread back northwards) which would reduce their overall numbers. Why is that good? Because the current whitetail deer population is far in excess of healthy which has left them extremely vulnerable to diseases. And one disease in particular: chronic wasting disease. Yes, CWD does affect all cervids, but it only spreads in direct or close contact. All these different deer species would be largely non-interacting with each other, so spread between species would be infrequent, certainly less frequent than spread within whitetails. And the lower whitetail population and higher predation rates would reduce overall transmissivity of diseases and would more quickly cull diseased animals respectively. Currently, whitetail deer are in serious danger and are showing classic boom-and-bust behavior. To save the whitetails, and to enrich our ecosystem, we should introduce a bunch of other deer species.
What are your thoughts on this argument?
Is it necessary to run all the modeling and test second and third-order effects, or are the likely immediate benefits going to outweigh the possible negative effects? I’ll grant that there would be negative effects as well. But it seems to me a reasonable and fair estimation of the effects would be on balance positive. We already have a very negative ecosystem disfunction with whitetail deer, it’s not like we’re risking spoiling something that’s all fine and dandy.
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I would 100% be for field trialing these sorts of things, along with potentially some other contenders that may work. There would definitely be these second and third order consequences but, as you pointed out, it’s probably not going to be worse than the degradation that we’ve already seen on the east coast. But there’s no chance it would happen sadly
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Don’t forget the possibility of pre-historical human predation being the explanation for the lack of any particular type of biodiversity in basically any ecosystem that included humans. If there was some large lizard that doesn’t happen to be toxic or really good at running or hiding, it likely was on our dinner plate, and may not have survived long alongside us. Many extinct species of iguana are found in Caribbean coastal & island midden heaps. (I found samples of a few of them myself in a college archeology dig in the Turks and Caicos.)
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Already happened in the Chesapeake bay states, primarily Maryland. there was a island a guy turned into a game farm. in the 70’s a hurricane flooded it and brought some of the animals to the mainland. they have a hunting season for fallow and sitka deer now and they all coexist with a large whitetail population. sitka love the tall reed marshland there. there’s more sitka there now than in Japan. my brother took a nice bull sitka about 10 yrs ago there. they are tiny and spotted but neat looking.
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I read there are also fallow deer in a few places. Probably most notable is the largely albino population in a national park in Tennessee.
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