Ontogenetic divergence of growth among rainbow smelt morphotypes

Abstract

Multiple, sympatric morphotypes of rainbow smelt (Osmerus mordax) are known in Lake Utopia, New Brunswick. The largest, 'giant' form is predominantly a piscivore, the smaller, 'dwarf' form are predominantly planktivores, and there is an intermediate body-sized form. The forms exhibit some genetic variability, but it is body size that best defines morphotypes, trophic status, and spawning behaviour. We compared egg size, spawning date, incubation time, size at hatching, and daily and annual growth to determine when divergence in body size occurs among morphotypes. Giant form larvae hatched earlier and grew faster during their first year. Dwarf and intermediate form larvae displayed interannual variability in degree of overlap and divergence in growth which occurred in their first growing season or at age 1+ or 2+. We conclude that earlier hatching, early growth trajectories, and later niche shifting are linked to the persistence of morphotypes, i.e., the process is controlled by the environment and sustained to some degree by spawning segregation.

The consequences of genomic architecture on ecological speciation in postglacial fishes

“…The melting and recession of glacier ice precipitated a terrestrial rebound of the earth resulting in the formation of several-hundred lake environments that were colonized in parallel by both marine and freshwater fish species at the end of the ice age. The evidence for distinct gene pools in species complexes that evolved within these new environments is widespread and includes Arctic charr (e.g., Jonsson 1993, Corrigan et al 2011), Atlantic salmon (e.g., Verspoor and Cole, 1989;Gilbey et al, 2006), sockeye salmon (e.g., Hamon and Foote, 2005;Pavey et al, 2010b), lake whitefish (e.g., Lindsey, 1963;Fenderson, 1964;Bodaly, 1979;Bernatchez and Dodson, 1990), rainbow smelt (e.g., Taylor and Bentzen, 1993;Shaw and Curry, 2011), stickleback (e.g., Lavin and McPhail, 1993;McPhail, 1993;Thompson et al, 1997;Taylor and McPhail, 1999) and some lampreys (e.g., Docker, 2009). In all of these species, parallel evolution in response to the environment has occurred in multiple environments (Table 1).…”

Otolith size differences during early life of dwarf and cannibal Arctic char (Salvelinus alpinus)

“…Cannibalism is a common strategy among numerous species of teleost fishes (Smith & Reay 1991): for example cod (Gadus morhua L.) (Yaragina et al 2009), perch (Perca fluviatilis L.) (Persson et al 2000), pike (Esox lucius L.) (Craig 2008), rainbow smelt (Osmerus mordax Mitchill) (Shaw & Curry 2011), lake trout (Salvelinus namaycush Walbaum) and Arctic char [Salvelinus alpinus (L.)] (Finstad & Berg 2004). Cannibalism is a common strategy among numerous species of teleost fishes (Smith & Reay 1991): for example cod (Gadus morhua L.) (Yaragina et al 2009), perch (Perca fluviatilis L.) (Persson et al 2000), pike (Esox lucius L.) (Craig 2008), rainbow smelt (Osmerus mordax Mitchill) (Shaw & Curry 2011), lake trout (Salvelinus namaycush Walbaum) and Arctic char [Salvelinus alpinus (L.)] (Finstad & Berg 2004).…”

“…A particular form of predation is cannibalism, a predation system where both prey and predator are of same species. Cannibalism is a common strategy among numerous species of teleost fishes (Smith & Reay 1991): for example cod (Gadus morhua L.) (Yaragina et al 2009), perch (Perca fluviatilis L.) (Persson et al 2000), pike (Esox lucius L.) (Craig 2008), rainbow smelt (Osmerus mordax Mitchill) (Shaw & Curry 2011), lake trout (Salvelinus namaycush Walbaum) and Arctic char [Salvelinus alpinus (L.)] (Finstad & Berg 2004). Predator-prey interactions are frequently size-dependent, especially in fishes who ingest their prey whole (Vucic-Pestic et al 2010).…”