Estimation of genetic variation through isozyme analysis in freshwater sardines, Sardinella tawilis (Herre), from two different sites near Taal Lake: Lemery and Talisay, Batangas

Date

2011

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ma. Carmina C. Manuel

Abstract

Genetic variation in freshwater sardines, Sardinella tawilis (Herre), from two different sites near Taal Lake: Lemery and Talisay, was determined through isozyme analysis using four enzyme systems: acid phosphatase (ACP), alkaline phosphatase (ALP), esterase (EST), and malic enzyme (ME). Three organs were collected namely, eye, heart, and muscle tissues. Results revealed four presumptive loci in both populations (ACP-1, ALP-1, EST-1, ME-1). An interpopulation variation was noted between the eye and muscle tissues of the two populations in terms of EST-1. The degree of genetic variability within each population was determined by calculating the proportion of polymorphic loci (P), average number of alleles (A), and average heterozygosity (H). The genetic variation between organs and between populations was assessed through the estimates of genetic identity (IN), genetic distance (D), and genotypic similarity (IH). Among the organs, the heart showed the highest genetic variability based on the P (0.75), A (1.75), and H (0.369-0.371) values in both populations. The variation in isozyme expression in the organs could be attributed to the differences in their physiological functions. The computed IN, D, and IH showed the same trend in the two populations, wherein the eye tissues had greater relatedness with muscle tissues. The two populations when compared revealed the same values for P (0.75) and A (1.75). However, the average heterozygosity was slightly higher in the Talisay population (H=0.291) than the Lemery population (H=0.249). The computed values for IN (0.929), D (0.074), and IH (0.869) implied high relatedness between the two populations showing that the geographical distance between Lemery and Talisay is not enough to produce significant isozyme variation. Moreover, variation between these two populations may have not been fully shown by the four enzyme systems used.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Document Type

Thesis

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