Intraspecific Morphological Variation in Two Common Marine Fish Species from South Africa

Abstract

Intraspecific morphological variation in fish is typically associated with sexual dimorphism, or one of three common environmental gradients: variation in intensity of predation, variation in water velocity, or variation in feeding niche. The preponderance of examples of environment-associated morphological variation within fish species has been documented in freshwater systems. It is not clear whether environment-associated intraspecific morphological variation is less common in marine fishes or whether there has just been a lack of investigation. We used geometric morphometric analysis to quantify shape variation in two species of South African marine fish commonly harvested for human consumption, Pterogymnus laniarius (panga), and Argyrosomus inodorus (silver kob). Neither species exhibited significant sexual dimorphism, but both species exhibited significant intraspecific morphological variation. This variation appears consistent with patterns expected from variation along the benthic-pelagic feeding niche continuum.

Some morphometric features and length - weight relationships of F1 hybrid juveniles (Umbrina cirrosa ♀ Χ Argyrosomus regius ♂)

“…Our morphometric measurements that were demonstrated in this study was a clear evidence of the hybrids' acquire of mix characteristics that came from both parent species (Majumder and Sharma, 1997). Mattson and Belk, (2013) presented different morphometric variations resulting from using different niches depending on the different resources in benthic and pelagic locations for A. inodorus which is a bento-pelagic species. Yet, gen flow is not an expected factor or is low effective for interspecies morphological variations for marine fish compared to fresh water fish (Mattson and Belk, 2013).…”

“…Mattson and Belk, (2013) presented different morphometric variations resulting from using different niches depending on the different resources in benthic and pelagic locations for A. inodorus which is a bento-pelagic species. Yet, gen flow is not an expected factor or is low effective for interspecies morphological variations for marine fish compared to fresh water fish (Mattson and Belk, 2013). In this case, morphologic variations between marine fish require more investigations.…”

“…There are significant morphological variations between the fish species that may point out ecological and evolutionary interests and sometimes heritable (Mattson and Belk, 2013). Morphometric measurements are used to determine similarities or differences between taxonomic categories and to demonstrate ontogenetic changes of body shape in the fisheries biology area (Turan, 1999;Dwivedi and Dubey, 2013).…”

“…Morphometric measurements are widely used to identify differences between fish populations and shape-based recognition can be performed to obtain size and species information (To and Ci, 2015). According to Mattson and Belk (2013), the formation of different morphologies within same species that are specified by using of different resources can be a great power for the evaluation of new species. Recently several studies that were focused on the some hybrid culture under aquaculture conditions.…”

Geometric morphometric analysis of morphological variation in Bogor and Solok populations of bony lip barb (Osteochilus vittatus)

“…Many studies have reported that morphological divergences were associated with selective pressure exerted by the habitat where the populations lived. Intraspecific morphological variation in fish is typically related to sexual dimorphism or one of three typical environmental gradients: variation in predation intensity, water velocity, or feeding niche [20]. Concerning feeding niches, for instance, fish that feed on benthos tend to have a downturned mouth.…”