Extreme Genetic Structure in a Small-Bodied Freshwater Fish, the Purple Spotted Gudgeon, Mogurnda adspersa (Eleotridae)

Abstract

Freshwater fish are a group that is especially susceptible to biodiversity loss as they often exist naturally in small, fragmented populations that are vulnerable to habitat degradation, pollution and introduction of exotic species. Relatively little is known about spatial dynamics of unperturbed populations of small-bodied freshwater fish species. This study examined population genetic structure of the purple spotted gudgeon (Mogurnda adspersa, Eleotridae), a small-bodied freshwater fish that is widely distributed in eastern Australia. The species is threatened in parts of its range but is common in coastal streams of central Queensland where this study took place. Microsatellite (msat) and mitochondrial DNA (mtDNA) variation was assessed for nine sites from four stream sections in two drainage basins. Very high levels of among population structure were observed (msat F ST = 0.18; mtDNA ΦST = 0.85) and evidence for contemporary migration among populations was rare and limited to sites within the same section of stream. Hierarchical structuring of variation was best explained by stream section rather than by drainage basin. Estimates of contemporary effective population size for each site was low (range 28 – 63, Sibship method), but compared favorably with similar estimates for other freshwater fish species, and there was no genetic evidence for inbreeding or recent population bottlenecks. In conclusion, within a stable part of its range, M adspersa exists as a series of small, demographically stable populations that are highly isolated from one another. Complimentary patterns in microsatellites and mtDNA indicate this structuring is the result of long-term processes that have developed over a remarkably small spatial scale. High population structure and limited dispersal mean that recolonisation of locally extinct populations is only likely to occur from closely situated populations within stream sections. Limited potential for recolonisation should be considered as an important factor in conservation and management of this species.

Phylogeographical Analysis of a Cold-Temperate Freshwater Fish, the Amur Sleeper (Perccottus glenii) in the Amur and Liaohe River Basins of Northeast Asia

“…This extreme population genetic structure explained by highly restricted dispersal has also been reported in another freshwater gobioid species Mogurnda adspersa from eastern Australia (Hughes et al, 2012).…”

Landscape genetics informs mesohabitat preference and conservation priorities for a surrogate indicator species in a highly fragmented river system

“…Patterns of IBD may still exist within streams or within catchments where continuous distribution of the species remains in longer river reaches (for example, the Ovens River (Lintermans, 2007)). It is expected that genetic similarity between individuals persists only over the spatial scale of a stream, as predicted for a poor disperser (Hughes et al, 2012).…”

Genetic Diversity and Structure Analysis of Percocypris pingi (Cypriniformes: Cyprinidae): Implications for Conservation and Hatchery Release in the Yalong River

“…In contrast to the studies that detected higher genetic diversity in wild fish compared to that of hatchery ones [18,29], our findings were somewhat unexpected. Freshwater fish populations are particularly susceptible to habitat degradation and to the introduction of exotic species [59]. Anthropogenic activity such as hydroelectric development has been the primary cause of habitat alteration in many rivers.…”