What Two Animals Did Darwin Observe While On The Islands
On July ane, 160 years ago (1858) Darwin and Wallace presented their theory on the development of species by the action of natural selection at the Linnean Society of London. Since then, many of the animals and plants they discovered and analyzed on their voyages and in their writings take been the object of numerous studies that accept clarified their evolutionary significance.
But some animals discovered or analyzed by Darwin and Wallace have refused to reveal their nature, even though they played an of import office in the construction of their theory. Amidst them are ii: the Macrauchenia , a strange, extinct giant mammal from South America constitute by Darwin; and the Babirusa , an unusual squealer (endemic to some islands in the Malaysian archipelago) analyzed past Wallace. The Macrauchenia is one of the most "chimerical" animals ever; while the Babirusa is an animal with an extremely strange anatomical feature. The application of a number of genetic and molecular techniques is at present at last clarifying their nature.
Darwin's extinct monsters
In 1834 Darwin discovered the fossilized bones of a strange giant mammal in Argentina and Uruguay during his voyage in the Beagle. This discovery, also as that of other fossils of large South American mammals such as glyptodonts, Megatheria and mylodons (related to the sloths or armadillos currently alive in these regions), helped him begin to call back for the offset time of the theory of development by natural selection, given that they demonstrated that species can vary over fourth dimension and even go extinct.
At Darwin's urging, Richard Owen, the most important zoologist of the time, christened this strange fossil equally Macrauchenia , higher up all because he idea that its long neck and the form of its trunk meant it was a large Camelid related to the South American llamas.
In fact, Macrauchenia ways "long-necked", with auchenia referring to the genus in which all the South American camelids (llamas, vicuñas, guanacos, alpacas, etc.) were included at the time. But later, since they also had features of other animals, like the long neck of a giraffe, and a skull and strange trunk similar to an elephant, their taxonomical position has been much debated.
Recent molecular studies of these animals have begun to resolve the enigma. In 2015, based on the fossilized bones of these animals that are more than 10,000 years erstwhile, an nearly consummate sequence has been obtained of the protein collagen, the main protein in the skin and bones of mammals (ane); and in 2017, the about consummate mitochondrial Deoxyribonucleic acid (2) sequence. Comparing these sequences with those of the rest of the ungulates (the group of mammals with hoofs to which they belong) proves that these mammals have a common ancestry with horses, hippopotami and tapirs, but are not related to camelids, elephants or armadillos and sloths. In add-on, the molecular information evidence that the ancestors of species and groups such as Macrauchenia originated more than 60 million years agone, possibly in the American department of the swell land mass of Gondwana, and that later, when the South American continent separated, evolved and proliferated there independently until some ten,000 years ago, when they became extinct – or maybe were made extinct by humans?
In the end, its strange mixture of morphological characteristics could be explained by convergent evolutionary processes, which are parallel with but independent of other mammals such equally elephants, giraffes, camelids, etc., with which they share some of their features.
Wallace'south fantastic pig
In his trips around the Malaysian Archipelago, which began in 1854 and lasted viii years, when he reached the Celebes-Sulawesi Islands (currently part of Indonesia), Wallace mentioned a strange endemic species of pig: the babirusa. According to him, it was a species that evolved from the pigs that arrived from the Asian continent to these islands at a time when the sea level had fallen (due to phenomena such as glaciations, telluric movements, etc.). Just when the bounding main level later rose, the ancestors of the babirusa may have become isolated on the Celebes, thus evolving in a different way from the ancestral species of pigs from which they came.
Since and then the babirusa has been an enigma in diverse ways. It is a strange wild sus scrofa for a number of reasons, not just considering of its appearance, which is different from other pigs from snout to trotters. In fact, in some cases it has been linked more to the hippopotamus than to pigs.
In particular, what is characteristic and practically unique in this fauna is that instead of growing downward as is normal, its upper canines grow upward and backward, and even affect its snout and sometimes perforate it. Given that at that place are deer on the Celebes islands that take developed tusks exterior the snout (but never backward and never to such an extent), the natives gave them the name babirusa, or "hog-deer".
Fiddling progress has been made on the origin and evolutionary meaning of these strange tusks since Wallace'southward time, although some folk explanations have survived: i native legend has it that the animals used them to hang from the trees while they slept and thus escape their predators. At any charge per unit, if they do serve any purpose, it is perhaps as protection for the snout when they fight, or even as an indicator of sexual prowess and the wellness status of the males.
In dissimilarity, numerous genetic and molecular studies are now examining Wallace's hypothesis on the origin of this species in depth. The sequencing of diverse genes and nuclear and mitochondrial proteins and even the consummate genomes of the babirusa and other Suidae (a group that as well includes a number of Asian/European species of pigs, wild boars, and other African species such as warthogs, giant wood hogs, red river hogs, etc.) accept demonstrated that this is the near differentiated of the Suidae: its ancestors separated earliest from the rest of its grouping in evolutionary terms – in fact, even before the divergence between the Eurasian and African species (3).
At the same time, these studies provide us with information that explain other biological characteristics that differentiate the babirusa from other pigs, such as its low reproductive rate or the different way its digestive, reproductive or cardiac systems are structured and operate. But that'south another story, in which it's also worth including two other points: that the babirusas are depicted in cavern paintings on the Celebes Islands dating back to well-nigh 40,000 years ago (4); and that thanks to modern techniques of reproduction and animal intendance it has been possible recently to reproduce a babirusa in a zoo (San Diego, USA), which opens up interesting possibilities in the fight to preclude its extinction.
Manuel Ruíz Rejón
Bibliography
- Welker, F. 2015. Aboriginal proteins resolve the evolutionary history of Darwin's S American ungulates. Nature .Jun 4, 522 (7554):81-84.
- Westburg M. et al. 2017. A mitogenomic time tree for Darwin enigmatic South American mammal Macrauchenia patachonica. Nature Commun. Jun 27, viii: 15951.
- Frantz, L. et al. 2016, The development of Suidae. Rev. Anim. Biosci. 4: 61-85.
- Aubert,Thou. et al. 2014. Pleistocene cavern art from Sulawesi, Indonesia. Nature, Oct. ix, 514 (7521): 223-227.
Source: https://www.bbvaopenmind.com/en/science/bioscience/darwin-fantastic-animals-and-where-to-find-them/
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