According to the recent genome map of Strigamia maritima
“The use of different evolutionary solutions to similar problems shows that myriapods and insects adapted to dry land independently of each other,” said Chipman. “For example, comparing the centipede and insect genomes shows that they independently evolved different solutions to the same problem shared by all land-dwelling creatures — that of living in dry air.”
According to Chipman, the study found that despite being closely related to insects, the centipede lacks the olfactory gene family used by insects to smell the air, and thus developed its own air-sniffing ability by expanding other gene families not present in insects.
In addition, Chipman said, this specific group of centipedes live underground and have lost their eyes, together with almost all vision genes and genes involved in the body’s internal clock. They maintain enhanced sensory capabilities enabling them to recognize their environment and capture prey.
Note: The vid below notes that the centipede lacks a body clock, the implication being that the clock developed later than 400 mya, to which the ‘pede is dated.
Caution advised: That might turn out to be correct, but it is also possible that it just lost the body clock along the way, the way some weeds appear to have just lost genetic information about growing apart from certain crop plants (if they in fact did lose it). (Weeds are smarter than people but, like the Luminarians, they keep that a secret. 😉 )
Here’s the abstract:
Myriapods (e.g., centipedes and millipedes) display a simple homonomous body plan relative to other arthropods. All members of the class are terrestrial, but they attained terrestriality independently of insects. Myriapoda is the only arthropod class not represented by a sequenced genome. We present an analysis of the genome of the centipede Strigamia maritima. It retains a compact genome that has undergone less gene loss and shuffling than previously sequenced arthropods, and many orthologues of genes conserved from the bilaterian ancestor that have been lost in insects. Our analysis locates many genes in conserved macro-synteny contexts, and many small-scale examples of gene clustering. We describe several examples where S. maritima shows different solutions from insects to similar problems. The insect olfactory receptor gene family is absent from S. maritima, and olfaction in air is likely effected by expansion of other receptor gene families. For some genes S. maritima has evolved paralogues to generate coding sequence diversity, where insects use alternate splicing. This is most striking for the Dscam gene, which in Drosophila generates more than 100,000 alternate splice forms, but in S. maritima is encoded by over 100 paralogues. We see an intriguing linkage between the absence of any known photosensory proteins in a blind organism and the additional absence of canonical circadian clock genes. The phylogenetic position of myriapods allows us to identify where in arthropod phylogeny several particular molecular mechanisms and traits emerged. For example, we conclude that juvenile hormone signalling evolved with the emergence of the exoskeleton in the arthropods and that RR-1 containing cuticle proteins evolved in the lineage leading to Mandibulata. We also identify when various gene expansions and losses occurred. The genome of S. maritima offers us a unique glimpse into the ancestral arthropod genome, while also displaying many adaptations to its specific life history. Open access – Chipman, Ariel D.; Ferrier, David E. K.; Brena, Carlo; et al. The First Myriapod Genome Sequence Reveals Conservative Arthropod Gene Content and Genome Organisation in the Centipede Strigamia maritima. PLoS Biology, November 25, 2014 DOI: 10.1371/journal.pbio.1002005
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