Comparative reproductive study of two Streptocephalus sirindhornae (Branchiopoda: Anostraca) populations and F1 hybrids: a laboratory study

We investigated the effects of inbreeding and crossbreeding on the reproductive biology of two populations of fairy shrimp Streptocephalus sirindhornae from Maha Sarakham (M) and Suphan Buri (S) provinces of Thailand. Four groups of the mature fairy shrimp were experimentally mated; S x S, M x M, M x S and S x M. The data on life span, age at first spawning, number of eggs per brood and total number of eggs per female of the inbred and crossbred parent generations (P) were not significantly different. The spawning frequency and capacity of the crossbred P were significantly more productive than those of the inbred. In both populations, the majority of P had the greatest egg numbers in the 8th to 14th broods. The hatching percentages of eggs and the survival percentages of nauplii from the 10th brood of the F (1) populations were significantly higher than those of the 20th and 1st broods. The inbreeding in F (1) had no effect on hatching and survival percentages, sex ratios of males to females, average weight, body length and specific growth percentages. Our findings suggest that the inbred populations in P and F (1) were able to yield eggs similar to the crossbred populations, with similar growth, hatching and survival percentages.