Table of Contents
Bats are mammals from the order Chiroptera and their forelimbs form webbed wings. This development makes them one of the only species of mammals that are capable of flight. The oldest fossils that came about around the eoscene era which was about fifty to sixty years ago show that bats still look very much similar to their current appearance. This was long before even humans began to evolve from the apes and yet bat ancestors had already developed mechanisms and adaptations to chase insects using echolocation. They are the only species that represent the ability of flight within the class of mammals. This paper investigates the background of bats from evolution to the present day providing reasons for any differences so far established.
Presently, the missing link between the non-flying element in mammals and flying mammals in evolution remains unknown to scientists. As a basic assumption, they believe that microchiroptera was the original ancestor for both types of mammals. The ancestor probably originated from small gliding mammals from the order of insectivora (The Wild Classroom 2011). At the present, this order continues being classified a small rodent resembling mammals that feed on insects like shrews and moles. There are two suborders of bats, which are the microchiroptera and megachiroptera. Both orders share many commonalities. However, there have some distinct characteristics identified by scientists making the two evolutions different.
The megachiroptera include the flying fox and the big brown bat while the little brown bat belongs to the microchiroptera order. First, the former suborder does not have a form of echolocation while the latter has. They also have different pulp grinding teeth. The megachiroptera teeth are designed differently as they are used to crush pulp from fruits. The latter suborder had teeth designed to crush insects, therefore meeting separate design objectives. The differences in these characteristics have made some experts believe that the two did not originate from a single ancestor.
Scientists believe that the fruit eating the variety of megachiroptera rather evolved from primates. This is unlikely because evolution into flight capability occurred in two instances if the claim is true. The insectivorous variety evolved in its own and the fruit eating kind evolved from a common ancestor. The folly here is that humans belong to the order of primates; therefore, they share a common ancestor with fruit bats, which is highly unlikely. At the same time, the prospect that flight in mammals happened twice in evolution to a certain extent is unlikely.
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Adaptations and Geographic Distributions
Currently, the theory that makes sense is that bats came from an order of insectivora and diverted to the present varieties of species. Diversion in the form of different ancestors does not seem feasible. Vicariance and environmental linkages have been described as some of the main reasons for variations and origins for bat species (Genoways et. al 2011). Researchers concluded after thoroughly surveying territories in the Caribbean that the oldest lineage of bats came from the region and its surroundings. These included the Brachyphylla and the Phyllonycteris. Vicariance provides a reason for the pre-existence of the Antillean vertebrate species.
There are many arguments made on the geographic distribution of species. Darwin for one argued that the geographic distribution of species made no sense if the species had been created separately (Wells 2009). There are cases that disputed his theory. Darwin gave examples of presences of bats, with absolutely no terrestrial life on them, in exotic oceanic islands as instances of inexplicable happenings in the scheme of creation. From another point of view, it seems that he did not want agree that he may have been wrong, and migration was a probable factor.
Darwin admitted that it was possible for bats to fly to new landmasses. Nonetheless, land animals were not part of this allowance. Darwin also knew that migration could not account for all the patterns of geographic forms of distribution. For example, the existence of plant life on a summit mountaintop separated from each other by lowlands where alpine species could not exist in a possible scheme of a striking case of the same species living at different points without the possibility of having migrated from one point to another. He went on to explain that the recent ice age could offer a reasonable explanation to this case.
There were arctic plants and animals that were nearly the same that flourished almost everywhere in Europe, as well as the Northern parts of America. Still, when the warmth came back, the same brand of species that had lived together in the lowlands found itself in the arctic summits of the old and the new worlds (Kunz 2003). They also found themselves on many isolated mountaintops far from each other. Seasons were responsible for this transformation of different environments. The fauna was moved by the changing weather. Similarly, the geographical movement and positioning contributed to it.
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It is then proven that not every geographic distribution is a by-product of migration, but that of vicariance. Splitting of the widespread and established populations of fauna in specific is the main reason behind the differences in scenery in these cases. Geographical distribution in the latitudinal variation as concerns the species ranges may have been a consequence of the differences among the species when it came to body mass. Many researchers have concluded that large bodied species have greater geographical ranges as compared to the smaller bodied types.
The conclusion thereof implies that the micro species were partial to enclosed regions while the mega order preferred a larger vicinity of the operation. There are hypotheses suggesting that the range sizes would go according to the body size in equal proportions. Even then, the eating habits may also have a hand in this issue. Microchiroptera are typically insect eaters and are most like key to inhabit one region more than they would in a larger continental region. They resemble a hive in their operations unlike the megachiroptera, which has the bigger body mass. Subsequently, they have a much higher probability to survive from longer migrations. In this case, the small varieties do not have the same probabilities of survival.
Bats have distributed themselves across the world in a fashion that would easily suggest weather or climate preferences. America holds the richest fraction of the groupings having at least 200 species of bats. The temperate regions, on the other hand, are quite impoverished. As a result, bats do not like the tropics and Africa being saddled with the latitudinal lines holds a few species of the group compared to other well-endowed continents (Altringham 1996). Only migration and climate change are two factors that are constantly changing their patterns.
There were areas previously populated with bats in the Pacific and Atlantic only to be left for another home. Other factors that may influence the pattern include the existence of deserts such as the Sahara in Northern parts of Africa. There are no bat inhabitants in these regions as compared to other areas of the same latitudes. The areas of South and Central America hold the richest populations. These regions did not have the climatic or environmental settings they have at the moment. Their development through time has had a hand in the migration to areas of new preference.