Sipunculans and segmentation
Publikation: Bidrag til tidsskrift › Review › Forskning › fagfællebedømt
Comparative molecular, developmental and morphogenetic
analyses show that the three major segmented animal groups-
Lophotrochozoa, Ecdysozoa and Vertebrata-use a wide range of
ontogenetic pathways to establish metameric body organization.
Even in the life history of a single specimen, different mechanisms
may act on the level of gene expression, cell proliferation,
tissue differentiation and organ system formation in individual
segments. Accordingly, in some polychaete annelids the first three
pairs of segmental peripheral neurons arise synchronously, while
the metameric commissures of the ventral nervous system form in
anterior-posterior progression. Contrary to traditional belief, loss
of segmentation may have occurred more often than commonly
assumed, as exemplified in the sipunculans, which show remnants
of segmentation in larval stages but are unsegmented as adults.
The developmental plasticity and potential evolutionary lability of
segmentation nourishes the controversy of a segmented bilaterian
ancestor versus multiple independent evolution of segmentation in
respective metazoan lineages.
Originalsprog | Engelsk |
---|---|
Tidsskrift | Communicative & Integrative Biology |
Vol/bind | 2 |
Udgave nummer | 1 |
Sider (fra-til) | 56-59 |
Antal sider | 4 |
ISSN | 1942-0889 |
DOI | |
Status | Udgivet - jan. 2009 |
- Det Natur- og Biovidenskabelige Fakultet
Forskningsområder
ID: 9810337