Hidden Diversity in Sardines: Genetic and Morphological Evidence for Cryptic Species in the Goldstripe Sardinella, Sardinella gibbosa (Bleeker, 1849)

Abstract

Cryptic species continue to be uncovered in many fish taxa, posing challenges for fisheries conservation and management. In Sardinella gibbosa, previous investigations revealed subtle intra-species variations, resulting in numerous synonyms and a controversial taxonomy for this sardine. Here, we tested for cryptic diversity within S. gibbosa using genetic data from two mitochondrial and one nuclear gene regions of 248 individuals of S. gibbosa, collected from eight locations across the Philippine archipelago. Deep genetic divergence and subsequent clustering was consistent across both mitochondrial and nuclear markers. Clade distribution is geographically limited: Clade 1 is widely distributed in the central Philippines, while Clade 2 is limited to the northernmost sampling site. In addition, morphometric analyses revealed a unique head shape that characterized each genetic clade. Hence, both genetic and morphological evidence strongly suggests a hidden diversity within this common and commercially-important sardine.

Christmas tree worms of Indo-Pacific coral reefs: untangling the Spirobranchus corniculatus (Grube, 1862) complex

“…However, reports of distinct morphospecies being attributed to a single, genetically homogeneous species are less common (Meyer et al 2008;Nygren et al 2011;Ahrens et al 2013). In marine systems in general, occurrences of cryptic speciation based on geographic distribution (Barroso et al 2010;Carr et al 2011;Thomas et al 2014) and ecological factors (Nygren et al 2011) are far more common. Our results do not support the morphological distinction among three species of S. corniculatus complex in the Indo-Pacific; instead, they re-affirm the older notion that S. corniculatus is a cohesive species broadly distributed across the Pacific Ocean.…”

Species are hypotheses: avoid connectivity assessments based on pillars of sand

“…A perhaps less appreciated issue is that even for abundant, commercially important or ecologically well-studied marine taxa, species were often described long ago, but are not necessarily adequately delineated (e.g. Uthicke et al 2010;Jaafar et al 2012;Mantelatto et al 2014; Thomas et al 2014). For instance, Ciona intestinalis (Linnaeus, 1767) is a model organism in evolutionary developmental biology and was among the first animals to have its genome fully sequenced (Dehal et al 2002).…”

“…Cryptic species are typically revealed by population genetic studies, phylogeographic analyses or barcoding (e.g. Uthicke et al 2010;Jaafar et al 2012;Mantelatto et al 2014;Thomas et al 2014). In fact, the patterns emerging from connectivity and species delimitation studies belong to the same divergence continuum because population and species divergence result from common ecological and micro-evolutionary processes.…”

Morphological divergence in Indian oil sardine, Sardinella longiceps Valenciennes, 1847- Does it imply adaptive variation?

“…Morphological differences have been reported in many marine pelagic species, especially in clupeids (Thomas et al., ). In Atlantic cod Gadus morhua , morphological differences were associated with behavioural and ecological differentiation (McAdam et al., ).…”