Genetic Differentiation Studies among Natural Populations of <i>Tilapia zillii</i>

Abstract

The population structure of Tilapia zillii (Gervais 1848) from three reservoirs in Nigeria, Osun State (Opa, Osu and Igun) was determined by employing morphological and molecular (Random Amplified Polymorphic DNA) methods. For morphological studies, 25 morphometric measurements and six meristic counts were recorded on 40 individuals within each population. Principal Component Analysis (PCA) was performed on the morphometric and meristic data using the PAST software. For RAPD studies, genomic DNA was extracted from caudal fin tissue using CTAB method and five primers were used to initiate PCR amplifications. All the clusters produced by the Principal components analysis (PCA) of the morphometric and meristic parameters overlapped indicating a low level of genetic differentiation between the three populations of T. zillii studied. The UPGMA cluster diagram from RAPD analysis identified two major genotypic groups with inter and intra group relationships. All individuals in the first cluster were from the Osu reservoir, while individuals from Opa and Igun reservoirs constituted the second cluster. Nei's unbiased measure of genetic distances was 0.8532, 0.7321 and 0.7111 for Osu, Igun and Opa populations respectively. This revealed that Opa and Igun populations were genetically closer, while Osu populations is distant from them. The results suggest that the RAPD technique could be used to differentiate populations of T. zillii. However, additional methods such as microsatellite and sequence analysis can be used to maximize the efficiency of genetic differentiation studies.

Morphological Characterization of Wild and Cultured <i>Clarias gariepinus</i> (Burchell 1822) using Principal Component and Cluster Analyses

“…However, Oladimeji et al (2015) found that lower jaw width was the character most responsible for variation among the three wide populations of T. zillii studied.…”

“…This is in contrast with the report by Solomon et al (2015) where the meristic counts on C. gariepinus overlapped so widely among the sexes from different culture environments, so that the populations could not have been discriminated by sex or by culture environment. Oladimeji et al (2015) also reported that the PCA diagram of the meristic counts done on Tilapia zillii showed no specific pattern of differentiation among three natural populations.…”

Phenotypic Diversities of Four Populations of Clarias Gariepinus (Siluriformes, Clariidae) Obtained from Ogun and Ondo State Waterbodies in South-Western Nigeria

“…Th e meristic counts, however, overlapped broadly showing no divergence among the populations. Also, Oladimeji et al (2015) reported that all the clusters produced by the Principal components analysis (PCA) on the morphometric and meristic characters of T. zillii, overlapped revealing a low level of diff erentiation among the three populations studied. Although the studied populations are the same species, little or no gene fl ow had occurred among them which may be due to their locations.…”

“…PCA on the morphometric and meristic data were evaluated. Population centroids with 95 % ellipses obtained from the PCA scatter diagram were used to observe relationships among populations (Turan et al, 2005;Oladimeji et al, 2015;Ola-Oladimeji et al, 2016). PCA loadings were used to show the traits with the highest variation within the population Ola-Oladimeji et al, 2016) using the unweighted Pair Group Method with Arithmetic mean for phenogram or dendrogram grouping reported by Sneath and Sokal (1973).…”

Morphometric, Meristic and Conditional Factor Characterization of Redbelly Tilapia (Coptodon zillii) in Lake Komadugu, Yobe State, Nigeria

“…According to Goncalves et al, [19], Froese and Pauly [20], Mohammed [21] and Mwanja et al, [22], morphological change and divergence within species are expected to take place when fishes are exposed to new developmental and evolutionary forces that determine their body forms. In Nigeria, reports on morphological diversity of fishes within populations of the same species includes studies by Omoniyi and Agbon [23]; Solomon et al [24]; Oladimeji et al [25]; Ukenye et al [26] etc. Length-weight relationship is a crucial growth index used by fishery biologists as a tool for sustainable fisheries management [27].…”