# Comparative Analysis of Genetic Structure and Diversity in Larimichthys polyactis, Larimichthys crocea, and Their Reciprocal Hybrids Based on Microsatellite Loci

## TL;DR

This study compares the genetic diversity and structure of two fish species and their hybrids, finding that one hybrid has higher genetic diversity and stability, making it a better candidate for aquaculture.

## Contribution

The study identifies LCP hybrids as superior breeding material due to their higher genetic diversity and stability compared to reciprocal hybrids.

## Key findings

- LCP hybrids showed significantly higher genetic diversity and stability compared to LPC hybrids.
- Approximately 50% of LCP individuals had unique genetic combinations from both parents.
- LCP is a valuable germplasm resource for improving the genetic quality of marine fish.

## Abstract

Hybrid breeding represents a promising strategy for enhancing fish germplasm resources. In this study, we examined two hybrid offspring combinations derived from small yellow croaker (Larimichthys polyactis) and large yellow croaker (Larimichthys crocea), aiming to identify superior hybrid materials suitable for aquaculture applications. Through genetic analysis, we discovered that the hybrid LCP (female large yellow croaker × male small yellow croaker) exhibited significantly higher genetic diversity and greater genetic stability compared to its reciprocal hybrid, LPC. Notably, approximately 50% of LCP individuals displayed unique genetic combinations inherited from both parental species, whereas LPC hybrids predominantly retained maternal genetic traits. These results indicate that the LCP hybrid is a valuable germplasm resource with considerable potential. Our findings provide valuable insights and practical guidance for selecting optimal hybrid lineages to enhance the genetic quality of these economically significant marine fishes.

In this study, we compared the genetic diversity and structure of small yellow croaker (Larimichthys polyactis, LP), large yellow croaker (Larimichthys crocea, LC), and their reciprocal hybrids (LP ♀ × LC ♂ (LCP) and LC ♀ × LP ♂ (LPC)) using 14 microsatellite loci. Our results revealed that genetic diversity was highest in LCP, followed by LP and LPC, with LC exhibiting the lowest level. Additionally, among the two hybrid progenies, the number of loci in LCP deviating from Hardy–Weinberg equilibrium was lower. This suggests that LCP is a more appropriate choice as breeding material and has the potential to enhance germplasm resources. Based on the analysis of 14 microsatellite loci, we observed that both hybrid species clustered with their respective maternal parents. Specifically, LPC exhibited a closer genetic relationship to its maternal parent than LCP did. Furthermore, the majority of genes in LPC were inherited from its maternal parent (LP). In the LCP population, approximately 63% of individuals possessed gene profiles similar to those observed in LPC, while the remaining individuals displayed a mix from both parents. This study provides a strategic direction for the efficient utilization and management of novel germplasm resources in hybrid yellow croaker. Hybrid yellow croaker serves as an intermediate breeding material, playing a significant role in the genetic improvement of Larimichthys crocea and Larimichthys polyactis.