Contemporary and historical patterns of connectivity among populations of an inland river fish species inferred from genetics and otolith chemistry

Abstract

Patterns of dispersal in riverine populations of Australian smelt ( Retropinna semoni ) were examined using otolith chemistry (Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca) and genetic markers (allozymes, mtDNA, microsatellite DNA). During a period of prolonged low flows, young-of-year smelt were collected from 13 streams within three catchments of the southern Murray–Darling Basin, Australia. Spatial differences in otolith core and edge chemical signatures and high levels of genetic assignment to sampling locations were observed, suggesting that most recruits were retained in natal areas after spawning. Following a subsequent period of hydrological connection, the same cohort was sampled as 1-year-olds. Maximum likelihood estimation using otolith core chemistry data from these fish suggested that retention in natal areas was highly variable between years and a similar, though less pronounced, pattern was evident in genetic assignments. Partitioning of genetic variation among catchments was not significant (FCT < 0.004) and probably reflects disequilibrium between migration and genetic drift due to an historical population expansion (~270 000 years ago). Taken together, otolith chemistry and genetic analyses suggest that contemporary dispersal of smelt within these catchments is relatively restricted and may be mediated by changes in hydrological connectivity.

Metapopulation structure of a semi-anadromous fish in a dynamic environment

“…This is in contrast with the wetter year of 2011 where CV individuals were found to disperse into the PN. Woods et al (2010) similarly used otolith chemistry and genetic tools to determine that catchment dispersal of Australian smelt (Retropinna semoni) was mediated by changes in hydrological connectivity. Habitat affinities of the two splittail populations suggest that a sustained salinity of approximately ≤12 is needed to form such a bridge.…”

Accurate systematic frameworks are vital to advance ecological and evolutionary studies, with an example from Australian freshwater fish (Hypseleotris)

“…In fact, we think that this broader holistic perspective has already begun and is accelerating, with the integration of multiple techniques evident within work on Australasian freshwater fishes. The life-history, reproductive biology, population biology and feeding ecology of various species have been explored with a combination of different genetic techniques and otolith microchemistry (Woods et al 2010), stable isotopes (Cook et al 2007;Villamarín et al 2016) and intraspecific trait distribution (Sternberg et al unpublished data). As suggested by Vilizzi and Kováč (2014), rainbowfish (Melanotaenia) have become a focus of research on potential plasticity, both for gross morphology (Lostrom et al 2015) and the molecular pathways that underpin variation (McCairns et al 2016).…”

Nursery sources and cohort strength of young‐of‐the‐year common carp (Cyprinus carpio) under differing flow regimes in a regulated floodplain river

“…Classification success to the sampling year was relatively high for all nurseries, ranging from 90% at Barmah Lake and Larissa Road to 64% at McDon- Table 1 for site codes. The use of natural chemical signatures in otoliths to identify nursery sources and the connections between these sources and adult populations are now wide-spread in studies of freshwater, estuarine and marine fishes (e.g., Hamer et al 2005;Woods et al 2010;Standish et al 2011). Data are percentages and numbers (in brackets) of fish captured from each nursery (rows) that are classified by the discriminant functions into the various nurseries (columns).…”