The Siamese fighting fish (Betta splendens) is a well-known ornamental fish and emerging model species for studying animal morphology, physiology, and behavior. A key concern of betta inbreeding is the decline in genetic diversity resulting from commercial breeding programs. Therefore, it is essential to develop markers for understanding the genetic bases of the domestication and phenotypic diversification of this species. We utilized the previously assembled genome of Siamese fighting fish to identify and characterize microsatellites and compare their genomic organization across different species. We annotated 812,134 microsatellite loci spanning 30.70 Mb, accounting for 6.57% of the Siamese fighting fish genome. We performed in silico polymorphism screening of microsatellites in the Siamese fighting fish and related species and present these sequences as candidate markers for cross-species amplification. In addition, we successfully validated two microsatellite loci using PCR-based assays in different species, which can promote further genetic characterization of diverse betta lineages. The set of polymorphic markers identified in this study may facilitate the assessment of genetic diversity and population structure and marker-assisted selection, among other applications.

Knowledge of the genetic characteristics, origin, and local adaptation of chickens is essential to identify the traits required for chicken breeding programs. Chee Fah and Fah Luang are black-boned chicken breeds reared in Chiang Rai, Thailand. Chickens are an important part of the local economy and socio-culture; however, the genetic diversity, characteristics, and origins of these two breeds have been poorly studied. Here, we investigated the genetic diversity, gene pool, and origin of the Chee Fah and Fah Luang chickens using mitochondrial DNA D-loop (mtDNA D-loop) sequencing and microsatellite genotyping, as well as habitat suitability analysis using maximum entropy modeling. The MtDNA D-loop sequencing and microsatellite genotype analyses indicated that the Chee Fah and Fah Luang chickens shared haplogroups A, B, and CD with Chinese black-boned chickens. Gene pool analysis revealed that the Chee Fah and Fah Luang chickens have distinct genetic patterns compared to Thai domestic chickens and red junglefowl. Some gene pools of red junglefowl and other Thai domestic chickens were observed within the Chee Fah and Fah Luang chicken gene pool structures, suggesting genetic exchange. The data indicate that the Chee Fah and Fah Luang chickens originated from Chinese indigenous black-boned chicken breeds and experienced crossbreeding/hybridization and introgression with red junglefowl and other domestic breeds during domestication. Interestingly, the Chee Fah and Fah Luang chickens from Chiang Rai shared the same allelic gene pool, which was not shared with the Chee Fah and Fah Luang chickens from Mae Hong Son, suggesting at least two gene pool origins in the Chee Fah and Fah Luang chicken populations. Alternatively, different gene pools in the Chee Fah and Fah Luang chickens from different localities might be caused by differences in environmental factors, especially elevation.

Pseudoalteromonas is a genus widely distributed in the ocean and displays antibacterial and antifouling activities. We isolated a Pseudoalteromonas sp. strain (LC2018020214) from coastal water of Qingdao, China, and assembled its complete genome. The genome consists of two circular chromosomes with lengths of 3,700,777 bp and 817,517 bp, respectively, and 3,866 coding sequences.

Populations of Siamese crocodiles (Crocodylus siamensis) have severely declined because of hunting and habitat fragmentation, necessitating a reintroduction plan involving commercial captive-bred populations. However, hybridization between Siamese and saltwater crocodiles (C. porosus) has occurred in captivity. Siamese crocodiles commonly have post-occipital scutes (P.O.) with 4–6 scales, but 2–6 P.O. scales were found in captives on Thai farms. Here, the genetic diversity and population structure of Siamese crocodiles with large P.O. variations and saltwater crocodiles were analyzed using mitochondrial DNA D-loop and microsatellite genotyping. Possible crocodile hybrids or phenotypic variations were ascertained by comparison with our previous library from the Siam Crocodile Bioresource Project. Siamese crocodiles with <4 P.O. scales in a row exhibit normal species-level phenotypic variation. This evidence encourages the revised description of Siamese crocodiles. Moreover, the STRUCTURE plot revealed large distinct gene pools, suggesting crocodiles in each farm were derived from distinct lineages. However, combining both genetic approaches provides evidence of introgression for several individual crocodiles, suggesting possible hybridization between Siamese and saltwater crocodiles. We proposed a schematic protocol with patterns observed in phenotypic and molecular data to screen hybrids. Identifying non-hybrid and hybrid individuals is important for long-term in situ/ex situ conservation.