Sipunculans and segmentation
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Sipunculans and segmentation. / Wanninger, Andreas; Kristof, Alen; Brinkmann, Nora.
In: Communicative & Integrative Biology, Vol. 2, No. 1, 01.2009, p. 56-59.Research output: Contribution to journal › Review › Research › peer-review
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TY - JOUR
T1 - Sipunculans and segmentation
AU - Wanninger, Andreas
AU - Kristof, Alen
AU - Brinkmann, Nora
N1 - Key words: Sipuncula, evolution, segmentation, seriality, annelid, Echiura, nervous system, development, phylogeny, bodyplan
PY - 2009/1
Y1 - 2009/1
N2 - Comparative molecular, developmental and morphogeneticanalyses show that the three major segmented animal groups-Lophotrochozoa, Ecdysozoa and Vertebrata-use a wide range ofontogenetic pathways to establish metameric body organization.Even in the life history of a single specimen, different mechanismsmay act on the level of gene expression, cell proliferation,tissue differentiation and organ system formation in individualsegments. Accordingly, in some polychaete annelids the first threepairs of segmental peripheral neurons arise synchronously, whilethe metameric commissures of the ventral nervous system form inanterior-posterior progression. Contrary to traditional belief, lossof segmentation may have occurred more often than commonlyassumed, as exemplified in the sipunculans, which show remnantsof segmentation in larval stages but are unsegmented as adults.The developmental plasticity and potential evolutionary lability ofsegmentation nourishes the controversy of a segmented bilaterianancestor versus multiple independent evolution of segmentation inrespective metazoan lineages.
AB - Comparative molecular, developmental and morphogeneticanalyses show that the three major segmented animal groups-Lophotrochozoa, Ecdysozoa and Vertebrata-use a wide range ofontogenetic pathways to establish metameric body organization.Even in the life history of a single specimen, different mechanismsmay act on the level of gene expression, cell proliferation,tissue differentiation and organ system formation in individualsegments. Accordingly, in some polychaete annelids the first threepairs of segmental peripheral neurons arise synchronously, whilethe metameric commissures of the ventral nervous system form inanterior-posterior progression. Contrary to traditional belief, lossof segmentation may have occurred more often than commonlyassumed, as exemplified in the sipunculans, which show remnantsof segmentation in larval stages but are unsegmented as adults.The developmental plasticity and potential evolutionary lability ofsegmentation nourishes the controversy of a segmented bilaterianancestor versus multiple independent evolution of segmentation inrespective metazoan lineages.
KW - Faculty of Science
KW - Sipuncula
KW - Evolution
KW - Neurogenesis
KW - Segmentation
KW - Annelida
KW - Phylogeny
U2 - 10.4161/cib.2.1.7505
DO - 10.4161/cib.2.1.7505
M3 - Review
VL - 2
SP - 56
EP - 59
JO - Communicative & Integrative Biology
JF - Communicative & Integrative Biology
SN - 1942-0889
IS - 1
ER -
ID: 9810337