Pegasoferae

The Pegasoferae represents a hypothetical taxon within the Mammals (Mammalia ), which was proposed in June 2006 by Hidenori Nishihara, Masami Hasegawa and Norihiro Okada for the first time on the basis of a molecular biological analysis. It is a grouping of ferae ( carnivores and pangolins ), the odd-toed ungulates ( Perissodactyla ) and the bats ( Chiroptera ) in a common systematic group. Thus, it provides the hitherto accepted as plausible hypothesis of Fereuungulata, the summary of ferae and Perissodactyla with the Cetartiodactyla ( cloven-hoofed animals and whales ) against an alternative.

Summary of the observed animal groups

Due to the very different lifestyles and combinations of features combined within the Pegasoferae animal groups a general feature description is not possible, bringing together based only on matches in the genetic material. In the following, the considered taxa and highly regarded as a sister group Cetartiodactyla are briefly described accordingly, a detailed description can be found in the relevant articles:

The ferae consist of the species-poor group of pangolins ( Pholidota ) and the form- rich predators ( Carnivora ). With the exception of seals, these are to four-legged land animals that are distributed worldwide and have typically focused on a predatory lifestyle ( an exception for example, represents the giant panda ). The pangolins are highly specialized ant and termite eaters, most predators meat and fish eaters. The relationship of these two orders out as groups of animals is regarded as largely confirmed, although the pangolins are also often classified in the family of the Xenarthra.

The odd-toed ungulates ( Perissodactyla ) are a group of large herbivores. Above all, the horses are highly specialized runners who have adapted to the steppes. In addition, in this group include the tapir, and the rhinoceros. As a characterizing feature of the main axis is at all odd-toed ungulates, both the front and the rear feet by means of the center beam, and the third digit is therefore the largest of all types.

The Bats are the only mammals that are capable of active flight. According to the requirements of this way of life their limbs are modified and equipped with a flight skin. They feed partly by insects ( bats ) and partly of fruit ( fruit bats ). After the rodents they are the most species-rich order of mammals dar.

The Cetartiodactyla are composed of the even-toed ungulates ( Artiodactyla ) and the Whales ( Cetacea), which are combined to form a monophyletic taxon both by morphological and molecular biological characteristics. The Artiodactyla are similar to the odd-toed ungulates, large, four-legged herbivores, where the toes have developed due to an adjustment to a running lifestyle to hooves, but with them the central axis of a leg between the third and fourth toe is. In contrast, the whales make an animal group which has completely adapted to life in the sea ( marine mammals ). In this group, both hunting carnivores ( toothed whales feed on fish, squid, mammals and other sea animals ) and plankton filter feeders ( baleen whales ) contain. The grouping of whales in the relationship of cloven hoofed animals is mainly based on paleontological finds, within the Artiodactyla the hippos are considered to be closest relative of whales.

Method

Background: structure and function of the gene elements used

The basis for the compilation of the Pegasoferae were short sections of the genome, called Retroposonen, compared with representatives of all orders in the mammals and evaluated. Retroposonen are a special form of transposons ( jumping genes ) that are contained in the genome, and are characterized in that they can only be reproduced with the help of reverse transcription. To date, no mechanism is known that could cause a Distance ( reversion ) of a once integrated in the genome of retroposons. In addition, the multiple independent installation ( insertion) of a homologous retroposons to the same site is valid within a genome at different groups of animals as excluded. Retroposonen apply for this reason as insensitive to homoplasy or convergence, ie independently created multiple features, and provide a stable element within the genome represents, can be performed on the phylogenetic studies with high predictive value.

For the investigation of Nishihara et al. were used in representatives of all orders of mammals Long interspersed nuclear elements (LINE ) of the type L1. The L1 elements are among the most researched Retroposonen and make humans about 16 % of the total genome from. They are divided into about 50 different types due to their base pairing, and especially by the arrangement of nucleotides at the so-called 3 'end. Furthermore they differ in their length, which is about six kbp (6,000 base pairs) is on average, but can vary by several hundred base pairs. The variation is due to interruptions in the replication of DNA during the installation of the elements in the genome. Since the individual L1 elements are thereby actually unique in its design and its location in the genome, a homoplasy is completely excluded.

Selection and comparison of Retroposonen

To illustrate the phylogenetic relationships within the mammalian genome sequences of representatives of all orders of mammals with the exception of pangolins compared ( alignment ) and through the bootstrap method for plausible results were performed. Here, the working group focused on the described L1 elements and compared a total of 192 loci ( loci ) with each other, they in a pre- made ​​in silico screening for the comparison of already known gene sequences of human (Homo sapiens), the house mouse (Mus musculus ), the domestic dog (Canis lupus familiaris ) and the house cow (Bos taurus taurus) were able to identify.

Of these 44 loci have been identified as evidence for a phylogenetic relationship at the level of orders and used.

Result

By Nishihara et al. 2006 confirmed the general hypothesis developed great systematics within the higher mammals with the Afrotheria, Xenarthra to the Euarchontoglires and the Laurasiatheria. In addition, the studies support the taxon Scrotifera. Within this contradict their findings, however, the hitherto accepted as plausible taxon Fereuungulata by providing them the bats instead of Cetartiodactyla as a sister group of the Perissodactyla and ferae ( Zooamata ) are grouped and these form the taxon Pegasoferae. The Cetartiodactyla be considered as a sister group of the Pegasoferae:

Cetartiodactyla ( cloven-hoofed animals and whales)

Bats ( Chiroptera )

Perissodactyla

Ferae ( carnivores and pangolins )

Insectivores ( Eulipotyphla )

Was completely discarded the often still to be found in classical systematics grouping of Euungulata in which the Perissodactyla, Artiodactyla and whales form a taxon. The group of ungulates ( Ungulata ) to also contain the aardvarks, elephants, sea cows, and hyraxes next to the orders mentioned above and which is based solely on morphological characteristics, is also excluded.

Also in the placement of the bats based on morphological characteristics tests are not supported, this place in the relationship of the primates, giant slides and tree shrews and thus in the Archonta place in the Laurasiatheria. On a molecular basis, it can not confirm this; here were the bats so far either as a sister group of the Fereuungulata or as a sister group of the insectivores ( Eulipotyphla ), with which they then form the common taxon Insectiphillia considered.

Morphological and paleontological findings

On morphological basis allows all taxa within the mammals that were formed based on molecular genetic analyzes, very difficult or impossible to confirm. Especially within the Laurasiatheria in which the Pegasoferae are located, the morphological observation contradicts the findings of molecular biology. A problem of classification represent primarily the two classical to the ungulates ( Ungulata ) grouped orders Artiodactyla and Perissodactyla of. Both have a number of common features that are now considered to be convergent. This primarily involves the development of hooves as mitigation and adaptation appearance of the four limbs, especially fingers and toes rays.

Also paleontological can not support the molecular biological discovery, as it came to a rapid radiation of various mammalian forms within the early mammalian evolution. So can be from different mammalian orders though are in the early first representative, transitional forms, however, are rarely available. This applies to all groups within the Laurasiatheria to except the Cetartiodactyla where earlier findings allow an unambiguous assignment whales as sister group of cloven hoofed animals.

Naming

The name Pegasoferae consists of the already established name ferae (Latin: wild animals) for the existing of robbery and pangolins taxon and the root word Pegaso. Since it is in the other two groups of Pegasoferae to the flying bats and the odd-toed ungulates in which the horses make up the largest share, it refers to the Pegasus from Greek mythology. It is a flying horse, the name was suggested by Masami Hasegawa.