Showing posts with label Ecology. Show all posts
Showing posts with label Ecology. Show all posts

Monday, 20 June 2016

Where did the wild horse go?

Tarpan. Isn't it an evocative word? It brings to mind images of wild horses, untamed by man, of fierce stallions and galloping herds. When it comes to wild horses in Europe, "Tarpan" is the go to term. Unfortunately, it is also one shrouded in controversy, and for one simple reason: nobody really knows what it means. It seems simple enough - the Tarpan is another word for the European wild horse, right? Well... kinda. Sometimes. It is certainly true that the undomesticated horses which roamed Europe in prehistory are commonly referred to as Tarpans, but the problem is that the designation is not exclusively limited to them - nor necessarily should it be. If Tarpan is a word for the European wild horse, then it should apply to all members of that species, regardless of when they lived. The factor that complicates everything and throws this neat and tidy definition out of the window can be summarized neatly in one word: Interbreeding.

Europe has been home to domestic horses for a long time, and for the entirety of their time coexisting with their wild relatives, interbreeding has most likely occurred. Now, at first this was not an issue, since the populations of (mostly) pure wild horses were so larger that the genes of a few domestics did not have much of an impact. As time went on however, and the wild horse populations plummeted, this genetic balance was lost. Suddenly there were significantly more domestic horses than wild ones, and in times of war or simply due to accidents, domestics were often abandoned and left to their own devices, resulting in them becoming feral. This is where the boundary between wild horses and domestics becomes incredibly blurred, and where the word Tarpan really starts to grow sketchy. Historical observers from centuries passed were rarely detail-orientated enough to take note of the subtle morphological distinctions that separated wild horses and domestics, so whenever a herd of wild-living horses was spotted, these animals were simply referred to as wild, and sometimes, you guessed it, "Tarpans". This makes it very difficult to ascertain whether any given historical account of wild horses living in an area actually refer to true, undomesticated horses, or simply feral descendants of domestics. To make matters even more complicated, as mentioned before, extensive interbreeding took place, and in the latter years of the wild horse's existence, it is plausible if not almost certain that very nearly all populations of so-called Tarpans were either hybrids or pure domestic animals, with very few pure wild types remaining. This is often referred to as the only known picture of a Tarpan, but looking at its morphology, the animal shown is almost certainly either a hybrid or a pure domestic, as it bares very little resemblance to neither the skeletons we have of European wild horses, nor the extant and closely related Przewalski's horses.

To add one final layer of complexity and doubt to the word "Tarpan", today it is often used to refer to certain "primitive" breeds of domestic horses, particularly the Konik Polski. Koniks are one of several breeds often claimed to be either direct descendants of wild horses, or, in the Konik's case, a deliberate back-breeding attempt that incorporated hybrids of wild and domestic animals, thus resulting in a breed almost identical to the original wild horse. While the Konik is undeniably a sturdy and "wild"-looking breed, its morphology, like that of the animal in the picture claimed to be a Tarpan, and all other modern horse breeds, does not match that of the wild horse. Genetic tests have shown that it is no more closely related to wild horses than any other modern breed, and the story of it being a back-breeding attempt has been demonstrated to be a myth. In reality, the Konik is simply a particularly hardy breed originally used as draft animals in their native Poland, where the breed presumably originated, which just so happens to somewhat resemble the original wild horse. And yet, regardless of everything I just told you, the Konik is still often referred to as a Tarpan, including by organizations such as Rewilding Europe.

Pictured: Not Tarpans, but instead a herd of Przewalski's horses, the world's only still extant species of wild horse.


Thursday, 14 January 2016

Rebuilding Australia: How reintroductions and introduced species could help save a continent's wildlife

I am not from Australia, so I have no doubts that whatever I say will be dismissed by at least some people as just the ramblings of an uninformed foreigner. They may be right, but I would like to think that at least some subjects can be mostly, though not entirely, learned from reading and thinking. I have written about Australia before, and in fact I have something of a fascination with the continent for a variety of reasons. One is the most obvious; from a wildlife perspective, Australia is unlike any other continent on present day Earth. The marsupial faunas that (used to) dominate there are the last remaining on the planet, after South America's collision with North America essentially ended the age of marsupials there, and the general cooling of the global climate wiped them out on most continents. In this respect, it offers us something of a look back at earlier times, and gives us a window into the past diversity that marsupials once enjoyed across so much of the world. There is another reason for my fascination with Australia however. It is the only tropical first world country, and certainly the least densely populated one. The great majority of Australia is still wilderness in one form or another. A rich country with magnitudes of uncultivated wilderness and an iconic endemic fauna, that sounds like a great thing, doesn't it? Most of the problems facing wildlife in other tropical countries are at least partly a result of the widespread poverty and corruption in said countries, and while Australia cannot necessarily be completely cleared of the later, it is certainly nowhere near as extreme as in most countries with similar climatic conditions and quantities of wilderness. You would think that the Land Down Under would be an ideal place for nature, a country with a great fauna wealthy enough to protect it. So why is everything going so horribly?

With 11% of its mammalian fauna extinct within just the last few centuries, it has the highest rate of mammal extinctions in the world. On top of that, 15% of the remaining species are also endangered, with more yet more on the verge of being so. All in all, things are not going well for Australia's mammals. The typical explanation for this is that, as an isolated island continent, Australia's endemics are especially vulnerable to introduced species. It was the foxes, goats, and horses that did it, or so the story goes. In this post I will be arguing against that prevailing idea, and continuing on my previous post on Australia in arguing that invasive species are merely a symptom of a wider problem, and that a few of the introductions may in fact be part of the solution.

Australia: Land of marsupials, especially extinct ones.

Friday, 18 December 2015

A thought experiment in the Highlands

Much ink has been spilled over the merits and flaws of rewilding. It is a concept which I have come out in support of multiple times before, though I take issue with many of the claims and arguments made by some so-called "rewilders". One of the main points of disagreement between advocates and opponents of rewilding has been as to what impacts simply letting nature reassert itself would have. Some people say that it would be negative, that human activities are necessary for the preservation of our ecosystems, while others say that it is unquestionably a positive, that can only serve to better our wildlife. Both of these positions are of course extremes, and most people lie somewhere in between, but they give a  general idea of what the sides are. To actually answer the question is a difficult if not impossible task, as it would depend on a wide variety of factors. Whether reintroductions are considered a necessary part of rewilding, for instance, completely changes what results said process would have. In this post, I will indulge in a thought experiment of sorts, centered on the British highlands: What if all farming along with most other human activity everywhere in the uplands was stopped, and deer numbers were heavily culled and kept at bay. No reintroductions, no direct action aside from the culling, just a complete ceasing of all activities in the highlands. I do not actually advocate this scenario, nor do I find it remotely plausible, but it offers some idea of what the outcome of one extreme form of rewilding would be. As we will eventually see, it also shows why reintroductions are in fact necessary for rewilding and habitat restoration in the long term, and that "grazing bad, trees good" is not always true.

The British highlands as they appear today, beautiful but lifeless

Wednesday, 14 October 2015

Frozen in time: The illusion of stable ecological communities and the geological perspective

Evolution as a process is, at its most basic level, relatively easy to understand: Slow adaptation over many generations favoring forms more well suited to their environment. This is of course so overly simplified as to border on flat out inaccuracy, there are so many complicated processes at play in evolution that one could not possibly do them all justice in a brief summary. The point however stands that the general perception of what evolution broadly speaking is can be defined as an endless process of refinement. We tend to perceive the species that exist today as perfectly adapted to their environments, fully capable of persisting and surviving on their own. After all, if this was not the case, how could they even be here in the first place? This mindset is not necessarily wrong at face value, species must be competitive in order in order to persist. The issue here is the lack of perspective. Species and populations that may seem stable and self-sustaining in the short term may actually be in a state of chronic decline over a longer course of time. The lifespan of an individual person is so fleeting compared to the vastness of deep time, that perceiving such declines is essentially impossible without the benefit of hindsight.

When we look at a pristine forest, an un-managed oldgrowth, we see a vast and complex community of plants and animals, each fulfilling its own role in the ecosystem. Trees of varies species tower above us, often forming dense stands, seemingly impenetrable and ageless. Yet this is an illusion. Pollen cores and fossil evidence clearly shows that forests, and all other ecosystems for that matter, are in a state of constant flux, everchanging, but on a timescale too slow for us to perceive. The communities of trees that a person visiting a Himalayan forest today might see would be almost wholly different from that experienced by a person walking through the same area just a few thousand years prior. But this state of constant change is not just an endless reshuffling, many species once common are now gone, and many that we today would consider "staples" of the forests will no longer be here millennia in the future.

Thursday, 10 September 2015

Alien species and the future ecology of Australia

First off, the next post will be about prehistory, I promise, this is the last conservation related post for a while. With that said, buckle in, as this is going to be a long one.

Species disperse, this is an universally accepted part of ecology and evolution. Eventually animals will spread from one area to another, and if the conditions in this new habitat are different enough that they favor unique adaptations, evolution will occur, possibly resulting in the creation of a new subspecies. When animals naturally disperse, we tend not to have a problem with it, at least in most cases. Take for instance the Cattle egret. This small Heron has rapidly spread to colonize most of the world, while even just a century ago it was mostly restricted to Africa. This seems to have been completely by its own doing, and thus we have allowed it. Another example of this is the Turtle dove, which rapidly spread from western Asia to most of Europe within a few decades, though it is now declining again.

The Cattle egret, conqueror of the world