Phylogeography of the copper shark (Carcharhinus brachyurus) in the southern hemisphere: implications for the conservation of a coastal apex predator

Abstract

The copper or bronze whaler shark (Carcharhinus brachyurus) is a large, coastal top predator that is vulnerable to overexploitation. We test the null hypothesis that copper sharks are panmictic throughout the southern hemisphere. We analysed part of the mitochondrial control region (mtCR) in 120 individuals from eight sampling areas, defining 20 mtCR haplotypes (h = 0.76 ± 0.06, π = 0.016 ± 0.0007). Significant genetic structure was detected among the following three major coastal regions separated by oceanic habitat: Australia–New Zealand, South Africa–Namibia and Perú (AMOVA ΦST = 0.95, P < 0.000001). A major phylogeographic discontinuity exists across the Indian Ocean, indicating an absence of at least female-mediated gene flow for ~3 million years. We propose that this species originated in the Atlantic, experienced vicariant isolation of Pacific and Atlantic lineages by the rise of the Isthmus of Panama and, subsequently, dispersed across the Pacific to colonise Australasia. Oceanic expanses appear to be traversed over evolutionary but not ecological timescales, which means that regional copper-shark populations should be assessed and managed independently.

Population structure and cryptic speciation in bonnethead sharks Sphyrna tiburo in the south‐eastern U.S.A. and Caribbean

“…natal philopatry, Feldheim et al ., ) to give birth. Continuously distributed elasmobranchs may actually be composed of multiple genetically differentiated populations, although deep lineage diversification and cryptic speciation is more typically observed across discontinuities in their distribution (Pardini et al ., ; Richards et al ., ; Benavides et al ., ; Naylor et al ., ).…”

Sizing up the ecological role of sharks as predators

“…Many shark species have been labelled as apex predators, such as bull sharks (O'Connell et al 2007), copper sharks (Benavides et al 2011) and Carib bean reef sharks (Maljkovic & Cote 2011), and indeed whole shark assemblages are often labelled generically as 'apex', 'top predators' or 'great sharks' (e.g. Ceccarelli & Ayling 2010).…”

Genetic structure and diversity of two highly vulnerable carcharhinids in Australian waters

“…Carcharhiniformes are the most represented of the elasmobranchs in the population genetic literature, but few have been examined in any detail (Dudgeon et al 2012). These studies have typically focused on elucidating genetic structure over broad spatial scales, consistently demonstrating large oceanic expanses to be robust barriers to mitochondrial gene flow (Duncan et al 2006, Keeney & Heist 2006, Benavides et al 2011a, also in C. obscurus (Benavides et al 2011b) and C. plumbeus (Portnoy et al 2010). Genetic subdivision on finer scales has also been reported for some shark species, raising important implications for regional fisheries management (Keeney et al 2003, Tillett et al 2012a,b, Whitney et al 2012.…”