Hvirveldyr

Hvirveldyr
	Skelet af benfisk; Beryx decadactylus
Videnskabelig klassifikation
Rige	Animalia (Dyr)
Underrige	Deuterostomia
Række	Chordata (Chordater)
Underrække	Vertebrata
Klasser
	Agnatha; Chondrichthyes; Osteichthyes; Amphibia; Reptilia; Aves; Mammalia;
	Hjælp til læsning af taksobokse

Hvirveldyr (latin: Vertebrata) tilhører chordaterne. Hvirveldyrene har en rygsøjle, et akseskelet af brusk, ben eller forbenet brusk. De fleste hvirveldyr har udviklet to par lemmer samt en hjernekasse. Nogle hvirveldyr deler neurale kredsløb for mange forskellige typer af social adfærd. Det er undersøgt for frøer (krybdyr), fisk og mennesker.^[1]

Genetiske spor

Via sammenligning af mange hvirveldyrs DNA, har man fundet 3 brede distinkte perioder af evolutionære innovationsbølger:^[2]^[3]

Den første periode op til omkring 300 millioner år siden var domineret af regulatoriske innovationer, som vedrørte embryonisk udvikling (inkl. kropsudformning).
Den næste periode fra ca. 300 til 100 millioner år siden var domineret af celle-til-celle kommunikations innovationer.
De sidste 100 millioner år har været domineret af signaleringsvejs innovationer indeni cellen. Disse ændringer har optimeret den komplekse krydstale mellem molekyler, som koordinerer alle celle aktiviteter.

Systematik

Ifølge Tree of Life web projekt ser en delmængde af hvirveldyrs hierarki sådan ud (2003)^[4]:

Vertebrata (Hvirveldyr)
- Agnatha (Kæbeløse hvirveldyr)
  - Cyclostomata (Rundmundede fisk:,slimål, lampret.(Se evt. fisk)
  - Ostracoderms (uddød)
- Gnathostomata (Kæbebærende hvirveldyr)
  - Placodermi (Panserhajer, uddød)
  - Chondrichthyes (Bruskfisk, se evt. også fisk)
    - Elasmobranchii (tværmunde) (haj, rødhaj, sildehaj, den hvide haj, sømrokke, rokke, elrokke...)
    - Subterbranchialia (havmus m.fl.)
  - Teleostomi
    - Acanthodii (uddød)
    - Osteichthyes (Benfisk)
      - Actinopterygii (Strålefinnede fisk (se evt. også fisk): (torsk, søhest, hvilling, ål, søheste...)
      - Sarcopterygii (Kødfinnefisk (Se evt. også fisk))
        Crossopterygii (Kvastfinnefisk, f.eks. Coelacanth
        Dipnoi (Lungefisk)
        Tetrapoder (Krybdyr, Dinosaurer, Pattedyr, Fugle, Padder...)

Kilder/referencer

^ University of Texas at Austin (2012, May 31). Vertebrates share ancient neural circuitry for complex social behaviors, biologists find. ScienceDaily Citat: "...Humans, fish and frogs share neural circuits responsible for a diversity of social behavior, from flashy mating displays to aggression and monogamy, that have existed for more than 450 million years, biologists at The University of Texas at Austin found..."In these key brain regions, we found remarkable conservation of gene activity across species," said Hofmann..."
^ University of California – Santa Cruz (2011, August 18). Three waves of evolutionary innovation shaped diversity of vertebrates, genome analysis reveals. ScienceDaily
^ Tidligere: University Of California, Santa Cruz (2004, May 7). Surprising 'Ultra-conserved' Regions Discovered In Human Genome. ScienceDaily Citat: "..."As far as we can tell, most of these ultra-conserved elements showed up during the evolution of vertebrates, perhaps during the period when land animals emerged, or a bit earlier. But their early evolutionary history is still mysterious," Haussler said..."
^ "Tree of Life Web Project: Vertebrata, Animals with backbones". Arkiveret fra originalen 21. juni 2003. Hentet 1. juni 2003.

Eksterne henvisninger

2004-05-06, Sciencedaily: Scripps Scientists Look Deep Inside Sharks And Their High-performance Swimming System Citat: "..."Sharks and bony fishes have been separated for over 400 million years and yet we see one group of sharks and one group of bony fish that share a remarkable host of similarities in body form and function," said Donley..."
BBCNews, 9 May, 2003, Animals 'are moral beings' Citat: "..."But the weight of scientific opinion is that it's certainly right to give the benefit of the doubt to all vertebrates."..."
Markku Savela: Life (Omfattende).
Fishbase search ( 27,315 Species, 76,410 Synonyms, 137,515 Common names, 34,720 Pictures, 29,525 References, 930 Collaborators, 6.2 million Hits/month) (3/2003).

Litteraturhenvisninger

Nielsen, Claus: "Nyt om hvirveldyrenes oprindelse – Vender vi ryggen fremad?", Naturens Verden, nr. 6/1999, vol. 82, side 33-40.

[1] University of Texas at Austin (2012, May 31). Vertebrates share ancient neural circuitry for complex social behaviors, biologists find. ScienceDaily Citat: "...Humans, fish and frogs share neural circuits responsible for a diversity of social behavior, from flashy mating displays to aggression and monogamy, that have existed for more than 450 million years, biologists at The University of Texas at Austin found..."In these key brain regions, we found remarkable conservation of gene activity across species," said Hofmann..."

[2] University of California – Santa Cruz (2011, August 18). Three waves of evolutionary innovation shaped diversity of vertebrates, genome analysis reveals. ScienceDaily

[3] Tidligere: University Of California, Santa Cruz (2004, May 7). Surprising 'Ultra-conserved' Regions Discovered In Human Genome. ScienceDaily Citat: "..."As far as we can tell, most of these ultra-conserved elements showed up during the evolution of vertebrates, perhaps during the period when land animals emerged, or a bit earlier. But their early evolutionary history is still mysterious," Haussler said..."

[4] "Tree of Life Web Project: Vertebrata, Animals with backbones". Arkiveret fra originalen 21. juni 2003. Hentet 1. juni 2003.

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