In the present study, we assessed the genetic variation of three Clarias macrocephalus Gu¨nther populations collected from Kedah, Perlis and Kelantan (Peninsular Malaysia) using sequences of partial mitochondrial cytochrome b (Cyt b) and D-loop genes. A total of 57 individuals were sequenced and 1470 bp were obtained (1053 bp Cyt-b; 417 bp D-loop). The analysis revealed 21 haplotypes based on 81 polymorphic sites. Nucleotide diversity (p) was 0.003 in all populations while haplotype diversity ranged from 0.657 to 0.765. No significant genetic differentiation among the three populations was observed. Nevertheless, a number of private haplotypes was discovered, providing valuable information for selective breeding programs.

Mitochondrial cytochrome oxidase subunit I (COI) gene was utilized to assess the population genetics of the commercially important black scar oyster, Crassostrea iredalei among 11 populations throughout the west and east coasts Peninsular Malaysia and Sabah (Malaysian Borneo). Overall, populations of C. iredalei demonstrated low nucleotide diversity π (0.000-0.004) and low-to-high haplotype diversity h (0.000-0.795) levels. Genetic structuring was detected between the Peninsular Malaysia and Sabah populations as revealed by the FST analysis. However, the COI gene analyses showed minimal and non-significant (p > 0.05) population differentiation within the east and west coasts Peninsular Malaysia and Sabah regions. This was attributed to both high larval dispersal along the east and west coasts and human-driven spat translocation between the two coastlines due to C. iredalei cultivation practices. Phylogeographic relationships inferences were also conducted to further support these hypotheses. The neutrality and mismatch distribution analyses suggested that C. iredalei had experienced a/several bottleneck event(s), followed by population expansion. The molecular information obtained from this study could be incorporated in a pragmatic aquaculture management strategy of wild broodstock and the hatchery lines of C. iredalei in Malaysia.

Summary Oil palm breeding involves crossing dura and pisifera palms to produce tenera progeny with greatly improved oil yield. Oil yield is controlled by variant alleles of a type II MADS‐box gene, SHELL, that impact the presence and thickness of the endocarp, or shell, surrounding the fruit kernel. We identified six novel SHELL alleles in noncommercial African germplasm populations from the Malaysian Palm Oil Board. These populations provide extensive diversity to harness genetic, mechanistic and phenotypic variation associated with oil yield in a globally critical crop. We investigated phenotypes in heteroallelic combinations, as well as SHELL heterodimerization and subcellular localization by yeast two‐hybrid, bimolecular fluorescence complementation and gene expression analyses. Four novel SHELL alleles were associated with fruit form phenotype. Candidate heterodimerization partners were identified, and interactions with EgSEP3 and subcellular localization were SHELL allele‐specific. Our findings reveal allele‐specific mechanisms by which variant SHELL alleles impact yield, as well as speculative insights into the potential role of SHELL in single‐gene oil yield heterosis. Future field trials for combinability and introgression may further optimize yield and improve sustainability.

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Genetic diversities in two cultured oyster species, Crassostrea iredalei (Faustino 1932) and Crassostrea belcheri (Sowerby 1871) were assessed using a 581-nucleotide fragment of the mtDNA cytochrome oxidase subunit 1 (CO1) gene. A total of 103 C. iredalei individuals and 120 C. belcheri from 12 populations were sampled along the coast of Malaysia. Trees of unique haplotype samples generated based on Neighbor-Joining (NJ) algorithm revealed that many individuals had been misidentified and did not cluster with their presumed species based on morphological identification. BLAST results of DNA sequences showed presence of previously unreported C. madrasensis in Peninsular Malaysian waters (98% maximum identity). The true identity of the Muar (Crassostrea sp.) and Semporna (Saccostrea sp.) populations were unresolved by two BLAST search and showed less than 88% identity with other species in GenBank. Repeated analysis of these two populations using 487 bp of the mitochondrial 16S gene data showed only a maximum identity less than 97%. Hence, the identity of these specimens remains unclear. Evolutionary divergences within presumed species were 0.001-0.011 and 0.034-0.313 between species. Findings from this study have important implications for aquaculture, management and monitoring of cultured populations as well as conservation of wild oyster species in Malaysia.