Phylogeography and population genetics of the cryptic bonnethead shark Sphyrna aff. tiburo in Brazil and the Caribbean inferred from mtDNA markers

Abstract

Resolving the identity, phylogeny and distribution of cryptic species within species complexes is an essential precursor to management. The bonnethead shark, Sphyrna tiburo, is a small coastal shark distributed in the Western Atlantic from North Carolina (U.S.A.) to southern Brazil. Genetic analyses based on mitochondrial markers revealed that bonnethead sharks comprise a species complex with at least two lineages in the Northwestern Atlantic and the Caribbean (S. tiburo and Sphyrna aff. tiburo, respectively). The phylogeographic and phylogenetic analysis of two mitochondrial markers [control region (mtCR) and cytochrome oxidase I (COI)] showed that bonnethead sharks from southeastern Brazil correspond to S. aff. tiburo, extending the distribution of this cryptic species >5000 km. Bonnethead shark populations are only managed in the U.S.A. and in the 2000s were considered to be regionally extinct or collapsed in southeast Brazil. The results indicate that there is significant genetic differentiation between S. aff. tiburo from Brazil and other populations from the Caribbean (ΦST = 0.9053, P < 0.000), which means that collapsed populations in the former are unlikely to be replenished from Caribbean immigration. The species identity of bonnethead sharks in the Southwest Atlantic and their relationship to North Atlantic and Caribbean populations still remains unresolved. Taxonomic revision and further sampling are required to reevaluate the status of the bonnethead shark complex through its distribution range.

First stable isotope and mercury assessment of bonnethead and Caribbean sharpnose sharks from a potential nursery ground in the Archipelago of Bocas del Toro, Panamanian Caribbean

“…The bonnethead shark is widely distributed along estuarine, coastal, and insular areas of the American continent (up 90 m depth) in both Atlantic and Pacific oceans, but limited to warm waters (Ebert et al, 2013). However, this species which likely represents a differentiated linage in the Caribbean and Southwestern Atlantic (Naylor et al, 2012;Sigovini et al, 2016;Dıáz-Jaimes et al, 2021;Gonzalez et al, 2021), also shows a restricted distribution in Bocas del Toro, where the population appears to be resident according to genetic data (Gonzalez et al, 2019). Our findings also indicated the absence of niche partitioning between female and male bonnethead sharks within the Archipelago.…”

“…Hence, it was recently listed in Appendix II in the last Conference of the Parties (CoP) to CITES (Cop19) and classified as endangered on the IUCN Red List, primarily due to fishing activities and habitat degradation (Pollom et al, 2021). Additionally, genetic and phylogenetic studies suggest the existence of at least one cryptic species in the Atlantic Ocean (e.g., Naylor et al, 2012;Sigovini et al, 2016;Dıáz-Jaimes et al, 2021;Gonzalez et al, 2021), with the Caribbean bonnethead shark (S. aff. tiburo) distributed from Belize to southern Brazil (Gonzalez et al, 2021).…”

“…Additionally, genetic and phylogenetic studies suggest the existence of at least one cryptic species in the Atlantic Ocean (e.g., Naylor et al, 2012;Sigovini et al, 2016;Dıáz-Jaimes et al, 2021;Gonzalez et al, 2021), with the Caribbean bonnethead shark (S. aff. tiburo) distributed from Belize to southern Brazil (Gonzalez et al, 2021). Therefore, while taxonomic identity of bonnethead sharks remain unresolved in the Atlantic basin, the identification of key areas for inclusion within MPAs is imperative to ensure the protection of their populations as well as other shark species.…”

Global genetic diversity and historical demography of the Bull Shark

“…While the Benguela Current is a strong barrier for many organisms (Teske et al., 2011), partial migration from the IPA to the WTA has already been documented in some sharks (Lesturgie, Lainé, et al., 2022; Lesturgie, Planes, & Mona, 2022). Strong barriers such as the Isthmus of Panama or the Eastern Pacific open ocean have promoted genetic differentiation and even speciation of shark populations (Gonzalez et al., 2021; Pazmiño et al., 2018). Based on mitochondrial DNA (mtDNA) data, coastal or demersal species tend to present genetic structuring at small geographic scales (Hirschfeld et al., 2021; Momigliano et al., 2017; Vignaud et al., 2014) while pelagic or semi‐pelagic species show low structuring between and within ocean basins (Bailleul et al., 2018; Pirog, Jaquemet, et al., 2019).…”

Reply to Soldo, A.; Lipej, L. Comment on “Balàka et al. Updated Checklist of Chondrichthyan Species in Croatia (Central Mediterranean Sea). Biology 2023, 12, 952”

“…Cryptic shark species are known to have relatively low levels of genetic differentiation [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ], which might be the reason why previous population genetic studies of C. canicula were cautious to suggest a species distinct to S. canicula , although all of them found strong genetic differentiation [ 27 , 37 , 38 ]. Future studies might require a whole-genome-wide sequencing approach to cover as much genetic depth as possible [ 34 ].…”