Fine-scale biogeography: tidal elevation strongly affects population genetic structure and demographic history in intertidal fishes

Abstract

Numerous studies have demonstrated population genetic structuring in marine species, yet few have investigated the effect of vertical zonation on gene flow and population structure. Here we use three sympatric, closely related clinid species, Clinus cottoides, C. superciliosus and Muraenoclinus dorsalis, to test whether zonation on South African intertidal rocky shores affects phylogeographic patterns. We show that the high-shore restricted species has reduced gene flow and considerably higher F ST values (F ST = 0.9) than the mid-and low-shore species (F ST < 0.14). Additionally, we provide evidence for remarkably different demographic and evolutionary histories, ranging from extreme population bottlenecks to population persistence, which are probably linked to effective population size and habitat specialisation. This study further highlights the need for a multispecies approach to unravel the biological and evolutionary processes that drive extant population genetic patterns in marine species, as even closely related species with similar life histories show highly variable results.

Habitat Discontinuities Separate Genetically Divergent Populations of a Rocky Shore Marine Fish

“…Genetic breaks have usually been concordant with the location of strong historical oceanographic features and biogeographic breaks, reflecting the parallelism between the processes governing geographic and genealogical boundaries of the species [ 25 , 61 – 63 ]. Habitat discontinuity in relation to changes in bathymetry has been addressed to explain genetic breaks in a wide variety of rocky shore species [ 6 , 64 – 65 ]. However, examples of genetic breaks associated to the presence of sandy areas in rocky shore fish are scarce (but see [ 66 – 67 ]).…”

Molecular ecology and phylogenetics of the water beetle genus Ochthebius revealed multiple independent shifts to marine rockpools lifestyle

“…; Von der Heyden et al . ). These ecosystems usually experience marked phenomena of local populations’ size expansions and reductions, associated with cyclic phases of rising and lowering of sea level, sea waves, dominant winds, rainfalls, rockpool volume, evaporation and solar radiation.…”

Life in a rock pool: Radiation and population genetics of myxozoan parasites in hosts inhabiting restricted spaces

“…The number of samples obtained at each locality is shown in parentheses. Moreover, the major oceanographic features around the South African coastline, the Benguela and Agulhas Currents, that influence population structuring of Clinus cottoides are shown along with the barriers to gene flow (blue vertical lines) as HB1: Jacobs Bay–Sea Point (at Cape Town), HB2: Gaansbai–Cape Agulhas, HB3: Knysna–Port Alfred [ 11 , 12 ]. Agulhas ring eddies and the Agulhas counter-current are also highlighted.…”

“…This is in contrast to North and South American clinids which are oviparous [ 9 ]. Thus, the potential for free dispersal in South African live-bearing clinid fishes is highly reduced [ 10 ], creating more pronounced population genetic structures [ 6 , 11 , 12 ]. Clinus cottoides Valenciennes, 1836 (bluntnose klipfish) is a viviparous fish species with restricted dispersal capacity [ 10 ], which is endemic to South Africa and has a clear population structure with discontinuities along the oceanographic barriers that influence gene flow patterns.…”