Tracheal animals
The division of living beings into systematics is a continuous subject of research. Different systematic classifications exist side by side and one after the other. The taxon treated here has become obsolete due to new research or is not part of the group systematics presented in the German-language Wikipedia.
As Tracheentiere (Tracheata), also Antennata or Atelocerata called is referred to within the arthropod , the summary of the matched to the country life (Arthropoda) millipedes (Myriapoda) and Sechsfüßer (Hexapoda), the main group, the insects are (Insecta). The tracheata are a controversial taxon. Most scholars today believe that the two groups summarized here are not sister groups.
features
The group owes the name Tracheentiere to a characteristic that is very important for rural life. They have a system of so-called tracheas . These are air channels that run through the body and thus supply all cells with oxygen and in some places open out through so-called stigmata. Since the trachea, like all arthropods, have an exoskeleton , breathing through the body surface is not possible. Despite the naming, the trachea do not form any of the possible autapomorphies of the group. The tracheas of different representatives in all probability arose convergent .
Another adaptation to life on land are the animals' excretory organs, the Malpighian vessels . Unlike the crustaceans (Crustacea), the trachea only have one pair of antennae. This corresponds to the first pair of antennas of the Crabs and this explains the other names of the group, all of which indicate the loss of the second antenna. Further differences to the crustacea are: mandibles without palpus, legs without articulated exopodites , midgut without branched diverticula. The inner skeleton of the head, the tentorium , has also been suggested as an autapomorphy.
Systematics of the tracheal animals
Classically, the tracheates are divided into two groups, as in the text, the hexapods , which are made up of the insects (Insecta), springtails (Collembola) and two more obscure groups, the double tails (Diplura) and leg probers (Protura), and the Millipede (Myriapoda). The hexipedes form a well-founded natural group, i.e. a monophylum . Contrary to numerous doubts that have arisen in the meantime, the millipedes are again predominantly considered to be monophylum.
The classic conception of family relationships would then look like this:
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As a result of more recent investigations into molecular phylogeny (by comparing homologous DNA sequences), the tracheatic hypothesis has lost some of its credibility and is no longer considered the most likely hypothesis of relationships (see e.g. in fact, there are now dozens of increasingly more sophisticated and numerous Genes from tests not confirmed in one case this grouping). Most research instead shows a closer relationship between the Hexapoda and the Crustacea, known as Pancrustacea (or more commonly: Tetraconata). It is very likely that the crustaceans are even paraphyletic with regard to the Hexapoda. This means that the Hexapoda would be a line of development within the Crustacea that had passed over to land life. This grouping is also supported by numerous morphological arguments about the fine structure of the eyes and the nervous system.
There are two more hypotheses about the actual relationship between the millipedes. They are either the closest relative of the Tetraconata; the common grouping is then called the mandibulata. Or, alternatively, they could be the Chelicerata's closest relative . More information on these hypotheses can be found in the article Arthropods and Millipedes .
According to this hypothesis, the relationships could look something like this:
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A taxon Tracheata would therefore not exist.
swell
- ^ Superclass Antennata (syn. Tracheata, Atelocerata) In: HE Gruner, M. Moritz, W. Dunger: Textbook of special zoology. Invertebrates, 4th part Arthropoda (without Insecta). 4th edition, 1993. Gustav Fischer Verlag, Jena.
- ^ C. Bitsch & J. Bitsch (2004): Phylogenetic relationships of basal hexapods among the mandibulate arthropods: a cladistic analysis based on comparative morphological characters. Zoologica Scripta 33: 511-550
- ↑ Stefan Koenemann, Ronald A. Jenner, Mario Hoenemann, Torben Stemme, Björn M. von Reumont (2010): Arthropod phylogeny revisited, with a focus on crustacean relationships. Arthropod Structure & Development 39: 88-110. doi : 10.1016 / j.asd.2009.10.003
- ↑ O. Rota-Stabelli, L. Campbell, H. Brinkmann, GD Edgecombe, SJ Longhorn, KJ Peterson, D. Pisani, H. Philippe, MJ Telford: A congruent solution to arthropod phylogeny: phylogenomics, microRNAs and morphology support monophyletic Mandibulata . In: Proceedings. Biological sciences / The Royal Society. Volume 278, number 1703, January 2011, pp. 298-306, doi : 10.1098 / rspb.2010.0590 , PMID 20702459 , PMC 3013382 (free full text).
- ^ Gregory D. Edgecombe (2010): Arthropod phylogeny: An overview from the perspectives of morphology, molecular data and the fossil record. Arthropod Structure & Development 39: 74-87. doi : 10.1016 / j.asd.2009.10.002