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David E K Ferrier

Publications and source records attributed to David E K Ferrier.

9 recordsLinked to original sources
PubMed2006

The development of the larval nervous system, musculature and ciliary bands of Pomatoceros lamarckii (Annelida): heterochrony in polychaetes.

BACKGROUND: To understand the evolution of animals it is essential to have taxon sampling across a representative spread of the animal kingdom. With the recent rearrangement of most of the Bilateria into three major clades (Ecdysozoa, Lophotrochozoa and Deuterostomia) it has become clear that the Lophotrochozoa are relatively poorly represented in our knowledge of animal development, compared to the Ecdysozoa and Deuterostomia. We aim to contribute towards redressing this balance with data on the development of the muscular, nervous and ciliary systems of the annelid Pomatoceros lamarckii (Serpulidae). We compare our data with other lophotrochozoans. RESULTS: P. lamarckii develops locomotory and feeding structures that enable it to become a swimming, planktotrophic larva within 24 hours. Formation of the trochophore includes development of a prototroch, metatroch and neurotroch, development of apical and posterior nervous elements at similar times, and development of musculature around the ciliary bands and digestive tract prior to development of any body wall muscles. The adult nervous and muscular systems are essentially preformed in the late larva. Interestingly, the muscular systems of the larvae and juvenile worms do not include the circular muscles of the body wall, which are considered to be plesiomorphic for annelids, although the possibility that circular muscles develop after these stages cannot be ruled out at this point. CONCLUSION: A comparison between polychaetes shows variability in the timing (heterochrony) of development of body wall muscles and elements of the nervous system. These heterochronies are one route for evolution of different life history strategies, such as adaptations to feeding requirements.

Journal Article↗
PubMed2006

Hox genes are not always Colinear.

The deuterostomes are the clade of animals for which we have the most detailed understanding of Hox cluster organisation. With the Hox cluster of amphioxus (Branchiostoma floridae) we have the best prototypical, least derived Hox cluster for the group, whilst the urochordates present us with some of the most highly derived and disintegrated clusters. Combined with the detailed mechanistic understanding of vertebrate Hox regulation, the deuterostomes provide much of the most useful data for understanding Hox cluster evolution. Considering both the prototypical and derived deuterostome Hox clusters leads us to hypothesize that Temporal Colinearity is the main constraining force on Hox cluster organisation, but until we have a much deeper understanding of the mechanistic basis for this phenomenon, and know how widespread across the Bilateria the mechanism(s) is/are, then we cannot know how the Hox cluster of the last common bilaterian operated and what have been the major evolutionary forces operating upon the Hox gene cluster.

Animals↗
PubMed2004

Hox genes: Did the vertebrate ancestor have a Hox14?

A new group of vertebrate Hox genes, Hox14, has been discovered in two fish, the horn shark and the coelacanth. This reveals that ancestrally all jawed vertebrates may have had fourteen Hox paralogue groups rather than the thirteen groups of mammals and teleost fish.

Animals↗
PubMed2003

Evolution of the Hox/ParaHox gene clusters.

The Hox gene cluster is a guiding force within the field of Evolutionary Developmental Biology. In large part our understanding of this gene cluster comes from only a few model organisms in developmental biology. The situation is gradually changing. A comparative review of the organisation of the Hox and ParaHox gene clusters and, in particular, instances of cluster disintegration, leads us to the view that the phenomenon of Temporal Colinearity is the major constraining force in maintaining these gene clusters over such long evolutionary timespans.

Animals↗
PubMed2002

Gene duplications in the prototypical cephalochordate amphioxus.

The new discipline of Evolutionary Developmental Biology (Evo-Devo) is facing the fascinating paradox of explaining morphological evolution using conserved pieces or genes to build divergent animals. The cephalochordate amphioxus is the closest living relative to the vertebrates, with a simple, chordate body plan, and a genome directly descended from the ancestor prior to the genome-wide duplications that occurred close to the origin of vertebrates. Amphioxus morphology may have remained relatively invariant since the divergence from the vertebrate lineage, but the amphioxus genome has not escaped evolution. We report the isolation of a second Emx gene (AmphiEmxB) arising from an independent duplication in the amphioxus genome. We also argue that a tandem duplication probably occurred in the Posterior part of the Hox cluster in amphioxus, giving rise to AmphiHox14, and discuss the structure of the chordate and vertebrate ancestral clusters. Also, a tandem duplication of Evx in the amphioxus lineage produced a prototypical Evx gene (AmphiEvxA) and a divergent gene (AmphiEvxB), no longer involved in typical Evx functions. These examples of specific gene duplications in amphioxus, and other previously reported duplications summarized here, emphasize the fact that amphioxus is not the ancestor of the vertebrates but 'only' the closest living relative to the ancestor, with a mix of prototypical and amphioxus-specific features in its genome.

Amino Acid Sequence↗
PubMed2002

Ciona intestinalis ParaHox genes: evolution of Hox/ParaHox cluster integrity, developmental mode, and temporal colinearity.

The Hox gene cluster, and its evolutionary sister the ParaHox gene cluster, pattern the anterior-posterior axis of animals. The spatial and temporal regulation of the genes seems to be intimately linked to the gene order within the clusters. In some animals the tight organisation of the clusters has disintegrated. We note that these animals develop in a derived fashion relative to the norm of their respective lineages. Here we present the genomic organisation of the ParaHox genes of Ciona intestinalis, and note that tight clustering has been lost in evolution. We present a hypothesis that the Hox and ParaHox clusters are constrained as ordered clusters by the mechanisms producing temporal colinearity; when temporal colinearity is no longer needed or used during development, the clusters can fall apart. This disintegration may be mediated by the invasion of transposable elements into the clusters, and subsequent genomic rearrangements.

Animals↗