There is a number of evidences, that maternally-derived molecules are crucial for proper embryo development. However, developmental consequences purely maternal origin are poorly understood at both zootechnical and molecular levels . The current research involves comparative analysis of two extreme maternal phenotypes (wild vs. domesticated) as an original approach to delve into maternal factors , mediated by maternal effect genes, on larvae phenotype. Additionally, this research not only sheds light on the importance of maternal impacts in shaping larval traits but also provides insights into the broader implications of domestication on offspring development.
We established 12 experimental groups by crossing Eurasian perch (Perca fluviatilis ) females from both domesticated (D) and wild (W) origins with cryopreserved semen from the same wild males each time, resulting in two types of crosses: DW and WW (denoting the maternal lineage as the first letter ). After hatching, the larvae were reared for 30 days, during which zootechnical data (i.e., length, weight, swim bladder inflation rate, cannibalism rate, mortality) were recorded . Additionally, larvae at the mouth-opening stage were sampled for transcriptomic analysis. Obtained RNA-sequencing data were mapped to the reference genome P. fluviatilis and analyzed to detect differentially expressed genes between groups.
The zootechnical analysis revealed no significant differences (p > 0.05) in fertilization and deformity rates. Mortality rate was notably higher (p < 0.05) in WW larval group. Conversely, larvae from DW group showed increased cannibalism rate and more efficient swim bladder inflation rate ( p < 0.05) . At mouth opening stage , DW larvae were larger and heavier than WW larvae , but the latter exhibited compensatory growth, surpassing domesticated ones in size and length as development progressed. Transcriptome analysis between groups highlighted genes involved mostly in metabolic - related processes and muscle development and suggested perm1 , pgr and egln3 as potential maternal-origin markers of domestication.
The study found significant differences in larval performance based on maternal origin. Despite standardized rearing conditions, significant differences emerged between offspring from wild and domesticated females. Higher mortality rates in offspring from wild females indicate potential maternal effects on larval survival, while domesticated larvae displayed superior swim bladder inflation and increased cannibalism tendencies suggesting a maternal effect on behavior . However, compensatory growth observed in wild larvae suggests adaptive mechanisms to overcome initial disadvantages. Transcriptomic analysis revealed metabolic processes predominating among differentially expressed genes , indicating a maternal role in influencing offspring metabolism. These findings contribute valuable insights into the interplay between maternal origin, larval traits, and gene expression patterns, crucial for understanding the complex dynamics of fish domestication and its implications for aquaculture practices .