Pleistocene Animals / Population Dynamics

The Field Museum of Natural History was a “kid magnet” in my day; I’m sure it still is. I remember the Egyptian mummies, which I didn’t like to be around because the odor they gave off was repulsive. The big dioramas and paintings attracted me, especially the giant fauna of Ice Age animals, which were labeled “extinct”. Some were shown as being hunted by Paleo-Indians; it seemed preposterous (and terribly brave – or an act of desperation) for a human with a wooden spear and stone point to do such a thing. Then there were “cave” animals presented; they looked a lot like contemporary bears and big cats, but bigger and more ferocious. The word “cave” confused me. Being Asperger I took this literally: humans occupied caves, too – did they have to “evict” or kill all the animals living there before moving in? I’m still not sure, but it seems that “cave” doesn’t refer to the animal occupying the cave, but to species that humans depicted in cave paintings. (Language again! So non-specific…)

As a “real” hunting scene, this is idiotic! Wild boar are EXTREMELY dangerous animals! No one would crouch on the ground or stand a few feet in front of one of these fast charging and deadly animals… And what about those “coyote-looking” dogs on leashes? Hmmm… And all that tender white skin?

Diorama ID: Mas d’Azil cave in France. The scene shows two Azilian men armed with wooden spears with flint lance-points at close quarters with an enraged wild boar defending his mate and two young pigs. The dogs are held by rawhide straps and they are straining forward at the leash. The painted background shows the peaks of the Pyrenees in the distance.

For the story of this and other Field Museum “cave men” dioramas:

https://www.fieldmuseum.org/science/blog/what-happened-caveman-dioramas

Le Mas-d’Azil cave, southwestern France, is the typesite for the prehistoric Azilian culture. The Grotte du Mas d’Azil is a “supersite” for human habitation ca. 30,000 years ago, and is also a key site for the Magdalenian culture that preceded it. 

For lots more info & photos see also: http://donsmaps.com/masdazil.html

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Full PDF at: http://www.sciencedirect.com/science/article/pii/S0960982209013062

Ecological Change, Range Fluctuations and Population Dynamics during the Pleistocene

Apart from the current human-induced climate change, the Holocene is notable for its stable climate. In contrast, the preceding age, the Pleistocene, was a time of intensive climatic fluctuations, with temperature changes of up to 15°C occurring within a few decades. These climatic changes have substantially influenced both animal and plant populations. Until recently, the prevailing opinion about the effect of these climatic fluctuations on species in Europe was that populations survived glacial maxima in southern refugia and that populations died out outside these refugia. However, some of the latest studies of modern population genetics, the fossil record and especially ancient DNA reveal a more complex picture. There is now strong evidence for additional local northern refugia for a large number of species, including both plants and animals. Furthermore, population genetic analyses using ancient DNA have shown that genetic diversity and its geographical structure changed more often and in more unpredictable ways during the Pleistocene than had been inferred. Taken together, the Pleistocene is now seen as an extremely dynamic era, with rapid and large climatic fluctuations and correspondingly variable ecology. These changes were accompanied by similarly fast and sometimes dramatic changes in population size and extensive gene flow mediated by population movements. Thus, the Pleistocene is an excellent model case for the effects of rapid climate change, as we experience at the moment, on the ecology of plants and animals.

Excerpt: Clearly, these massive climatic and environmental changes significantly influenced the distribution and genetic diversity of plants and animals. The idea that, during times of adverse climate, species track their habitat goes back to Darwin [9], and the Pleistocene should represent an excellent opportunity to test this assumption. Generally, one would assume that Arctic species would expand their distribution southwards during colder times and that temperate species would expand northwards during warmer times. While this is straightforward in North America, with mountain chains, which represent partial barriers to range shifts, running from north to south, in Europe a level of complexity is added with mountain chains running from east to west and the available land mass becoming smaller to the south and being divided into several peninsulas bordering the Mediterranean. This geography, together with numerous studies that found geographical patterns in the genetic diversity of many species consistent with colonization of mid-latitude and northern Europe from the Iberian Peninsula, Italy and the Balkans (for review, see [10,11]) has resulted in the classical ‘refugium theory’, which proposes that temperate species survived the glacial maxima in southern refugia with little gene flow among them and colonized the more northern parts from there during interglacial times. While this model is theoretically sound and correct in many aspects, recent studies on both modern and, especially, ancient DNA diversity have shown that reality is much more complex and only very broadly follows a contraction–expansion model for population dynamics, with many additional processes complicating the picture [12–16].

Finally, the end of the Pleistocene is marked by a massive extinction of large land vertebrates across most of the world (Box 1), with the exception of Africa [17]. Although these extinctions have long been known, their causes remain controversial. While some authors blame humans [18], others deny any human influence, at least on the continents, although human-induced extinctions are widely accepted for islands [19]. Again, recent research has revealed a great deal about the timing and processes of these extinctions, showing that not only mammoths [20,21], but also giant deer (deceivingly known as Irish elk) [22] and some Caribbean ground sloths [23], survived into the Holocene. However, when it comes to the cause(s) of these extinctions, the verdict is still out.

Signature Pleistocene animals.

The Arctic fox (Alopex lagopus) is a small (smaller than the red fox) white or bluish-grey fox that lives today in the arctic northern hemisphere of the Holarctic from Greenland to Iceland and the Arctic regions of North America and Eurasia. During the Pleistocene it had a much wider distribution across the middle part of Europe and western Asia as well as in the large ice-free region of Beringia. It is primarily an inhabitant of the tundra and mountainous regions above the tree line, but it does penetrate into the taiga to some degree. Arctic foxes feed primarily on lemmings, but their diet also includes Arctic hare, eggs, and carrion scavenged from the leftovers of larger predators. A remarkable characteristic is their capability for long distance dispersal, with movements up to 2,000 km.

The brown bear (Ursus arctos) had and still has by far the largest habitat range of all living bear species. Formerly, its habitat extended across North Africa, Europe, the northern and middle parts of Asia and North America from Alaska down to Mexico. Due to intensive human persecution, it is now extinct in many of these areas, including North Africa, large parts of Europe and most of North America. Brown bears are very adaptable and can live on both a mostly herbivorous diet and a mostly carnivorous diet. They are very variable in size and other morphological traits which historically has led to the description of numerous subspecies and even species. Today, all brown bears are considered a single species with a number of subspecies.

Cave bears (Ursus spelaeus) are the close — and less fortunate — cousins of the brown bear. The two species diverged some 1.6 million years ago, with tooth and stable isotope analyses indicating that cave bears were mostly herbivorous. However, recently a population was discovered that shows a stable isotope signature indicating an omnivorous, or even carnivorous, diet. Although in Europe cave bear remains are much more numerous than those of the brown bear, cave bears went extinct some 25,000 years ago. It has recently been shown that cave bears also occurred in Asia up to north-eastern Siberia.

Cave hyenas (Crocuta crocuta spelaea) are close relatives of the living spotted hyenas from Africa. In fact, in mitochondrial DNA sequence trees, sequences of cave and spotted hyenas are quite intermingled, questioning any taxonomic distinction of them as a subspecies or even as a species. Judging by cave paintings, they were probably spotted like modern spotted hyenas in Africa. They lived in Eurasia throughout the Pleistocene and probably already during the late Pliocene, about 3 million years ago. The timing of their extinction is not well established, but may have taken place around the same time as the cave bear, some 25,000 years ago.

The giant deer (Megaloceros giganteus), or Irish elk, is the gigantic relative of the rather gracile fallow deer. Giant deer are not only remarkable for their large body size but also for their huge antlers which could span up to 3.5 meters. Giant deer are often seen as typical representatives of the Pleistocene, but recent research has shown that in the Urals, giant deer survived until at least 7,700 years ago, far into the Holocene.

The woolly mammoth (Mammuthus primigenius) is no doubt the most iconic of all extinct Pleistocene animals. However, the woolly mammoth is only the last representative of a long lineage that had its origin in Africa. The first European mammoth lived in southern Europe and only later did mammoths colonize the arctic regions. Woolly mammoths differ from their closest relatives, the living elephants, in many features, most conspicuously by their curved tusks, the long hair and their small ears and short tails. Tens of thousands of mammoth bones have been recovered from the northern permafrost regions and sometimes even complete frozen carcasses. Mammoths survived into the Holocene, with the last population disappearing from Wrangel Island only about 3,700 years ago.

The steppe bison (Bison priscus) must have been a very common species throughout the Arctic region, especially in Beringia, given the vast numbers of fossils that have been found. Steppe bison were very variable in their morphology, especially with regard to the size of their horns, which were much larger in some individuals than in modern bison. They went extinct in Eurasia, but genetic analyses have established that they were the ancestor of the modern American bison, Bison bison. Their relationship to the European bison, Bison bonasus, is not known.

In this review, we will discuss the dynamics of animal and plant populations during the Pleistocene, trying to outline how populations reacted to the rapid variations in climate. We will restrict our analyses to the northern hemisphere, as the majority of studies on Pleistocene DNA have been done on species from this region.

What kids see today: Neoteny is rampant in American entertainment and education! Thank-you Hollywood for making “creationism” look legitimate!

 

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