Concordance between dispersal and mitochondrial gene flow: isolation by distance in a tropical teleost, Lates calcarifer (Australian barramundi)

Abstract

Patterns of population subdivision and the relationship between gene flow and geographical distance in the tropical estuarine fish Lates calcarifer (Centropomidae) were investigated using mtDNA control region sequences. Sixty-three putative haplotypes were resolved from a total of 270 individuals from nine localities within three geographical regions spanning the north Australian coastline. Despite a continuous estuarine distribution throughout the sampled range, no haplotypes were shared among regions. However, within regions, common haplotypes were often shared among localities. Both sequence-based (average ST = 0.328) and haplotype-based (average ST = 0.182) population subdivision analyses indicated strong geographical structuring. Depending on the method of calculation, geographical distance explained either 79 per cent (sequence-based) or 23 per cent (haplotype-based) of the variation in mitochondrial gene flow. Such relationships suggest that genetic differentiation of L. calcarifer has been generated via isolation-by-distance, possibly in a stepping-stone fashion. This pattern of genetic structure is concordant with expectations based on the life history of L. calcarifer and direct studies of its dispersal patterns. Mitochondrial DNA variation, although generally in agreement with patterns of allozyme variation, detected population subdivision at smaller spatial scales. Our analysis of mtDNA variation in L. calcarifer confirms that population genetic models can detect population structure of not only evolutionary significance but also of demographic significance. Further, it demonstrates the power of inferring such structure from hypervariable markers, which correspond to small effective population sizes.

Global and New Caledonian patterns of population genetic variation in the deep-sea splendid alfonsino, Beryx splendens, inferred from mtDNA

“…At these scales and despite high nucleotide (p) and haplotype (Hd) diversities, our results provided no genetic evidence of subdivision among samples, suggesting a genetic admixture. Moreover, limited dispersal is often accompanied by a pattern of isolation by distance (e.g., Hellberg 1994;Chenoweth et al 1998;Todd et al 1998;Wilke and Davis 2000;Palumbi 2003), although this was not the case within New Caledonian seamounts since our analysis of local isolation by distance was not significant, suggesting that dispersal is not severely limited.…”

The importance of identifying spatial population structure in restocking and stock enhancement programmes

“…They might also be expected to show along-shore genetic isolation by distance. Such patterns have been observed in several estuarine fishes (Chenoweth et al, 1998;Gold et al, 2001;Gold, 2004;Burridge et al, 2004). In the sparid black bream (Acanthopagrus butcheri) along the south-east Australian coast, the F ST values for allozymes and mtDNA were 0.012 and 0.263, respectively (Burridge et al, 2004).…”

Comparative phylogeography of two open forest frogs from eastern Australia

“…tasmaniensis (Slatkin, 1993). First, we regressed natural logarithms of pairwise geographic distances (km) and Nemf values against each other (Nemf is an estimate of the extent of female gene flow between a pair of populations ____ _ _ _ -~ (Slatkin, 19933;Chenoweth et al, 1998). Such regressions arc expected to be negative a n d significant if there is a n effect of isolation by distance on genetic population structuring.…”