I'm working on latitudinal diversity gradients in these taxa (copepods and cladoceran) and would like to know if it is safe to assume that speciation events have little effect on current diversity patterns in zooplankton across Canada.
See literature on Daphnia speciation due to glaciation events by Derek Taylor. Look at
Belyaeva M., Taylor D.J., 2009. Cryptic species within the Chydorus sphaericus species complex (Crustacea: Cladocera) revealed by molecular markers and sexual stage morphology. Molecular Phylogenetics and Evolution 50: 534-546.
Haney, R. A. & D. J. Taylor, 2003. Testing paleolimnological predictions with molecular data: the origins of Holarctic Eubosmina. Journal of Evolutionary Biology 16: 871-882.
Crease T.J., Omilian A.R., Costanzo K.S., Taylor D.J., 2012. Transcontinental phylogeography of the Daphnia pulex species complex. PLoS ONE 7(10): e46620. doi:10.1371/journal.pone.0046620
Taylor D.J. & Hebert, P. D. N., 1993. A reappraisal of phenotypic variation in Daphnia galeata mendotae: The role of interspecific hybridization. Canadian Journal of Fisheries and Aquatic Sciences 50 (10): 2137-2146.
Taylor D.J., Finston, T. L. & Hebert, P. D. N., 1998. Biogeography of a widespread freshwater crustacean: Pseudocongruence and cryptic endemism in the North American Daphnia laevis complex. Evolution 52 (6): 1648-1670.
Ishida S., Taylor D.J., 2007. Quaternary diversification in a sexual Holarctic zooplankter, Daphnia galeata. Molecular Ecology 16: 569-582.
Xu S., Hebert P.D.N. Kotov A.A., Cristescu M.E., 2009. The non-cosmopolitanism paradigm of freshwater zooplankton: insights from the global phylogeography of the predatory cladoceran Polyphemus pediculus (Crustacea, Onychopoda). Molecular Ecology 18 (24): 5161-5179.