MEPS 526:157-167 (2015)  -  DOI: https://doi.org/10.3354/meps11191

Contrasting signals of genetic diversity and historical demography between two recently diverged marine and estuarine fish species

Sophie von der Heyden1,*, Jessica A. Toms1, Peter R. Teske2, Stephen J. Lamberth3, Wouter Holleman

1Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
2Molecular Zoology Laboratory (Aquatic Division), Department of Zoology, University of Johannesburg, Auckland Park 2006, South Africa
3South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa
*Corresponding author:

ABSTRACT: Estuaries, at the confluence of marine and freshwater systems, are mostly of geologically recent origin and as such make excellent models for understanding recent speciation events. Using molecular approaches, we compared genetic diversity and demographic histories in 2 closely related southern African klipfish species, the marine Clinus superciliosus and the estuarine C. spatulatus. Strong genetic differentiation was identified using both mtDNA control region and nDNA S7 sequencing, despite some haplotype sharing. Coalescent-based modelling suggests that species divergence occurred during the Late Pleistocene or, more likely, during the Early Holocene, when present-day estuaries formed. Analyses of population demography suggest that C. superciliosus has undergone historical population expansion, whereas C. spatulatus is characterized by a population decline, potentially driven by repeated cycles of population crashes linked to the opening and closing of estuarine systems. This is also reflected in values of genetic diversity, which are almost an order of magnitude lower in the estuarine than in the marine species. Given the unique evolutionary history of C. spatulatus, a species that is restricted to only 2 South African estuaries, we highlight the need for a better understanding of the processes that have shaped the evolution of estuarine populations. The identification of unique genetic lineages in estuaries can help to better guide conservation and management efforts for some of South Africa’s most fragile habitats.


KEY WORDS: Connectivity · Estuarine systems · Anthropogenic impacts · Evolution · Adaptive divergence · Biodiversity · Conservation planning


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Cite this article as: von der Heyden S, Toms JA, Teske PR, Lamberth SJ, Holleman W (2015) Contrasting signals of genetic diversity and historical demography between two recently diverged marine and estuarine fish species. Mar Ecol Prog Ser 526:157-167. https://doi.org/10.3354/meps11191

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