We study Evo-Devo and specifically, how variation in development within a species generates divergent morphology and behavior in young.  We study marine invertebrates that are poecilogonous and have the capacity to produce more than one morph of larva, often in a single spawning event.  On-going research in our lab focuses on three major questions.

1)What common themes occur in poecilogony, and what can these unusual species tell us about larval evolution?  We recently verified a new case of poecilogony, and are studying this species to examine the importance of maternal traits in determining larval development mode.

2)  What mechanisms shape alternate pathways of development within a species, and generate dimorphic larvae?  Recently, we found that epigenetic mechanisms influence both maternal and larval traits in poecilogony, providing a molecular link between environment and developmental plasticity.

3) What is the developmental origin of nurse eggs?  Variable larval development in many spionids is based on maternal provision of nurse eggs, which fuels rapid development in some offspring that hatch at an advanced stage of development.  We have found that nurse eggs develop through a form of programmed cell death, suggesting that they may be an adapted component of the maternal phenotype.

Image: Egg capsule of the polychaete Polydora cornuta, showing both small planktotrophic and large adelphophagic larvae in a single capsule. (Credit: A. McMillan).

Image: Confocal image of a larva of Polydora cornuta  that is immunolabeled to show the distribution of histone methylation.  (Credit: C. Hart).

Gibson, G. and D. Carver.  2013.  Effects of extra-embryonic provisioning on larval morphogenesis in

            Boccardia proboscidea (Annelida, Spionidae). Journal of Morphology 274: 11-23. DOI: 10.1002/jmor.

            20071

Gibson, G., C. Hart, C. Coulter and H. Xu.  2012. Nurse eggs form through an active process of apoptosis

            in the spionid Polydora cornuta (Annelida). Integrative and Comparative Biology 52: 151-160. DOI:

            10.1093/icb/ics054

Gibson, G., C. Hart and V. Lloyd.  2012. Ontogenetic survey of histone modifications in an annelid. 

            Genetics Research International 2012, 11 pages. DOI:10.1155/2012/392903. 

                                                       

Gibson, G., K. MacDonald and M. Dufton. 2010. Morphogenesis and phenotypic divergence in two

            developmental morphs of Streblospio benedicti (Polychaeta, Spionidae).  Invertebrate Biology. 129

            (4): 328-343.

Mercer, S., G. Gibson and M. Dadswell.  2008.  Life-history of the marine isopod Cyathura polita in the Saint John River Estuary, New Brunswick: a species at the northern extent of its range.  Canadian Field Naturalist 121-2: 168-177.

Reynolds, L.,  M. Bren, B. Wilson, G. Gibson, M. Shoichet and R. Murphy 2008. Transplantation of porous tubes following spinal cord transection improves hindlimb function in the rat. Spinal Cord 46(1):58-64. doi: 10.1038/sj.sc.3102063

Gibson, G. and H. Smith. 2004.  From embryos to juveniles: Morphogenesis in the spionid Boccardia proboscidea (Polychaeta).  Invertebrate Biology 123(2): 136-145.

Gibson, G. and J. Gibson.  2004.  Heterochrony and the evolution of poecilogony: Generating larval

            diversity. Evolution 58(12):2704-2717.

Everett, E., P. J. Williams, G. Gibson and D. Stewart.  2004.  Mitochondrial  DNA polymorphisms and sperm fitness in Mytilus edulis (Bivalvia: Mytilidae).  Journal of Experimental Zoology 301A:906-910.

Gibson, G. and I. Paterson. 2003.  Morphogenesis during sexual and asexual reproduction

in Amphipolydora vestalis (Polychaeta: Spionidae), New Zealand Journal of Marine and Freshwater Research 37:741-752.

Paterson, I. and G. Gibson. 2003.  A new species of Amphipolydora (Polychaeta, Spionidae) from New

        Zealand. New Zealand Journal of Marine and Freshwater Research 37:733-740. 

Gibson, G. 2003.  Larval development and metamorphosis in Pleurobranchaea maculata (Opisthobranchia, Notaspidea), with a review of development in the Notaspidea.  Biological        

            Bulletin, Woods Hole 205: 121-132.

Gibson, G. and J. Harvey. 2000.  Morphogenesis during asexual reproduction in Pygospio elegans

            Claparede (Polychaeta, Spionidae). Biol. Bull. 199: 41-49.

Gibson, G., I. Paterson, H. Taylor and B. Woolridge.  1999.  Molecular and morphological evidence of a

            single species, Boccardia proboscidea (Polychaeta) with multiple development modes.  Marine

            Biology, 134: 743-751.

MacKay, J. and G. Gibson. 1999. The influence of nurse eggs on variable larval development in Polydora

            cornuta (Polychaeta, Spionidae).  Invertebrate Reproduction and Development, 35(3): 167-176.

Smith, H. and G. Gibson.  1999. Nurse egg production in the polychaete Boccardia proboscidea

            (Spionidae). Invertebrate Reproduction and Development 35 (3): 177-185.

Image: Epifluorescence image of a Boccardia proboscidea nurse egg that has undergone fragmentation of the nucleus (blue, DAPI), as is typical of apoptosis.