Evolution of sympatric species: a case study of the coral reef fish genus Pomacanthus (Pomacanthidae)

Abstract

Aim To establish a spatial and temporal framework within which we can begin to investigate the role of geography in the evolution of Pomacanthus species. This study examines the phylogenetic relationships among Pomacanthus species, tests whether the degree of sympatry among sister taxa correlates with their age, and explores potential modes of diversification.Location Pan-tropical coral reef systems.Methods Three gene regions (12S rRNA, 16S rRNA and nuclear S7) from all 13 Pomacanthus species were used in conjunction with fossil calibration to reconstruct a chronogram. IUCN maps were used to evaluate geographical range overlap. Various age-range correlation (ARC) analyses were used to test for a correlation between range overlap and node age. Range-size symmetry and node age were also examined.Results Biogeographical splits within the phylogeny corroborated key biogeographical events well, suggesting a potential role for allopatric speciation in the evolutionary history of the genus. ARC analyses suggested that speciation leading to sympatry is widespread in Pomacanthus, with 80% of sister species showing complete or substantial (> 85%) range overlap. No significant relationship between degree of sympatry and node age was recovered, which demonstrates that, for this group, exceptional sympatry is not necessarily a result of relatively old lineages. Range-size symmetry analysis was consistent with models of peripatric speciation within a finite area. Main conclusionsWe present evidence consistent with allopatric speciation, while our ARC results are consistent with simulations of sympatric speciation, with the possibility of peripheral budding having led to the richness of sympatric species in the West Indian Ocean. We discuss how these processes can affect the interpretation of temporal and spatial analyses, and provide a basis for future investigations into the processes driving speciation.

Patterns and drivers of species diversity in the Indo‐Pacific red seaweed Portieria

“…Although for other Philippine Portieria species, nonoverlapping ranges, and significant population genetic structuring hints towards allopatric speciation within the archipelago (Payo et al., ), it is difficult to untangle sympatric speciation from allopatric divergence on small spatial scales, possibly followed by subsequent dispersal and colonization events or secondary sympatry (Andersen et al., ). Sympatric or parapatric speciation along ecological boundaries in the marine environment has been inferred from a growing body of phylogenetic, biogeographical and ecological data (Bowen et al., ; Hodge, Read, Bellwood, & van Herwerden, ; Tornabene et al., ). Sympatric speciation should not be ruled out for Portieria , and will need to be further studied using population genetic data, and ecological data including biotic interactions (e.g., Aplysia grazing) of co‐occurring species clades to evaluate the role of ecological partitioning in speciation on small geographical scales.…”

The geography of speciation in coral reef fishes: the relative importance of biogeographical barriers in separating sister‐species

“…a) and the East Pacific Barrier (EPB; ‘II’ in Fig. a) in the evolution and biogeography of marine organisms, including reef fishes (Bellwood et al ., , ; Bernardi et al ., ; Lessios & Robertson, ; Cowman & Bellwood, ; Hodge et al ., ), these barriers did not appear to play a major role in the vicariance of recently diverged extant species. The timing of the TTE (12–18 Ma; Steininger & Rögl, ) places its influence much deeper in the evolutionary history of reef fishes and away from vicariance of contemporary species whose ages typically range between 1 and 5 Ma (Hodge et al ., ).…”

“…The IOP is the most recent hard barrier to have separated populations of marine organisms, and the timing of its rise (3.1–16 Ma; Coates & Obando, ) falls within the range of extant reef fish species divergence (Hodge et al ., ). The IOP has been implicated in clade divergence for a number of reef fish genera (Barber & Bellwood, ; Hodge et al ., ). Thus, the detection of a vicariant signal across this barrier was not unexpected.…”

Tempo and mode of speciation in Holacanthus angelfishes based on RADseq markers

“…As was shown for other angelfishes (Hodge et al, 2013), Holacanthus illustrates different speciation modes. Results indicate that speciation within the TEP and TWA occurred approximately 1.5 Mya.…”