Variability of tilapias (Oreochromis spp.) introduced in Mexico: morphometric, meristic and genetic characters

Abstract

In Mexico, the tilapia Oreochromis provides one of the most important sources of animal protein and income in a wide variety of communities throughout the country, however, their culture and production face severe problems because of lack of management information. Evaluated in the present study is the degree of morphological, meristic and allozyme variation of two tilapia strains, two species and one hybrid from two important reservoirs in Mexico, two tilapia fry production farms (TFPF) and an experimental production system (EPS), to diagnose the actual status and degree of variation among them. Twenty-two presumptive loci were utilized to determine the genetic variation, structuring and distances among samples. Multivariate analyses of 11 meristic and 33 morphometric characters were also evaluated, including the distance from the end of the mouth opening to the most anterior dorsal fin (0.9894), distance from the anal fin base to the anterior part of the caudal fin (0.9845) and the base length of the dorsal fin (0.9839) which contributed to the separation of groups. The canonical discriminant functions for the morphometric and meristic variables show that the correct classification of the organisms in percentages and in the sites of origin was on average 72%. The tilapia from the reservoirs and the experimental production system had higher genetic variations than tilapia from the fry production farms (average H e 0.310, 0.062, 0.151 for Metztitlan, Infiernillo and EPS, respectively, vs 0.024 and 0.000 for Los Amates and Zacatepec, respectively). The genetic data indicate that fishes of the TFPF should be monitored closely, as they are the main source of dispersion to the reservoirs. Present results show that these data could be a fast and reliable aid to the fisheries and management of tilapia in Mexico.

Characterization of morphological and meristic traits and their variations between two different populations (wild and cultured) of <i>Cichlasoma festae</i>, a species native to tropical Ecuadorian rivers

“…Solomon et al (2015) recorded significant differences in the ratio HL / SL in wild (23.7) and cultured (26.6) populations of C. gariepinus. Similarly, Vreven et al (1998) and Barriga-Sosa et al (2004) indicated that the biggest differences between wild and cultured populations were presented at the head. The value of this relationship and other relationships between morphometric characters is closely linked to the species, so it is not surprising that differences can be registered between studies.…”

“…Barriga-Sosa et al (2004), after analysing morphometric characters in natural and domesticated populations of Nile tilapia (Oreochromis niloticus), reported morphological differences among these populations. Likewise, Narváez et al (2005) found significant differences between the two populations (wild and cultured) of Oreochromis niloticus in northern Colombia; differences were attributed to food, environmental conditions and the type of habitat (wild and cultured).…”

Phenotype and genotype differentiation between flathead grey mullet [Mugil cephalus] and thinlip grey mullet [Liza ramada (Pisces: Mugilidae)]

“…Different methods are used for identification but phenotype based on morphometric and meristic is considered as earliest and authentic methods for the identification of fish species in fish biology to measure discreteness and relationships among various taxonomic categories. There are many well documented morphometric studies which provide evidence for stock discreteness (Avsar, 1994;Haddon and Willis, 1995;Bembo et al, 1996;Anene, 1999;Turan, 1999;Zafar et al, 2002;Barriga-Sosa et al, 2004;Doherty and McCarthy, 2004;Naesje et al, 2004). Morphometric is the external measurements of an organism, while meristic counts means serial counts of body elements (Talwar and Jhingran, 1992).…”

Impact of Environmental Contaminants on the Testes of Oreochromis niloticus with Special Reference to Ultrastructure of Spermatozoa in Lake Manzala (Egypt)

“…The importance of Nile tilapia, Oreochromis niloticus in aqua cultures is due to its spreading in most countries of the world [1]. It breads in captivity and wide variety of water conditions [2].…”