Evidence for Female-Biased Dispersal in the Protandrous Hermaphroditic Asian Seabass, Lates calcarifer

Abstract

Movement of individuals influences individual reproductive success, fitness, genetic diversity and relationships among individuals within populations and gene exchange among populations. Competition between males or females for mating opportunities and/or local resources predicts a female bias in taxa with monogamous mating systems and a male-biased dispersal in polygynous species. In birds and mammals, the patterns of dispersal between sexes are well explored, while dispersal patterns in protandrous hermaphroditic fish species have not been studied. We collected 549 adult individuals of Asian seabass (Lates calcarifer) from four locations in the South China Sea. To assess the difference in patterns of dispersal between sexes, we genotyped all individuals with 18 microsatellites. Significant genetic differentiation was detected among and within sampling locations. The parameters of population structure (F ST), relatedness (r) and the mean assignment index (mAIC), in combination with data on tagging-recapture, supplied strong evidences for female-biased dispersal in the Asian seabass. This result contradicts our initial hypothesis of no sex difference in dispersal. We suggest that inbreeding avoidance of females, female mate choice under the condition of low mate competition among males, and male resource competition create a female-biased dispersal. The bigger body size of females may be a cause of the female-biased movement. Studies of dispersal using data from DNA markers and tagging-recapture in hermaphroditic fish species could enhance our understanding of patterns of dispersal in fish.

Chromosomal-Level Assembly of the Asian Seabass Genome Using Long Sequence Reads and Multi-layered Scaffolding

“…Thus, the clear signs of admixture and high level of genomic diversity seen in the SE Asian population are due to secondary contacts, translocation and hybridisation with the Indian population. This pattern can possibly be attributed to unrecorded translocation of fishes from the Bay of Bengal/Andaman Sea to the South China Sea or due to migration, though its breadth needs to be established [ 8 , 73 ]. Thus, both nuclear and mitochondrial genome sequences point to L .…”

Vasa Identifies Germ Cells and Critical Stages of Oogenesis in the Asian Seabass

“…In these hermaphroditic organisms, sex development also involves sex reversal. One of such protandrous perches is the Asian seabass ( Lates calcarifer ), which undergoes male-to-female sex reversal under natural conditions: It matures as male and changes to female 12 . In this organism, sex reversal accompanies major morphological changes of the gonad but lacks an intermediate gonadal status of ovotestis, and testicular and ovarian tissues cannot be found in one and the same gonad 13 , Therefore, the seabass represents an excellent model to study the role and behavior of germ cells not only in sex determination and differentiation but also in sex reversal.…”

Barcoding of Asian seabass across its geographic range provides evidence for its bifurcation into two distinct species

“…In addition, the Asian seabass has a wide geographic distribution, its natural range being the tropical Indo-West Pacific region, including the whole of Southeast (SE) Asia, Taiwan stretching to Papua New Guinea and Northern Australia. On the other end, it is found in the Bay of Bengal to at least the Western part of India (Yue et al, 2012). It is an important fish species from an aquaculture perspective.…”