Desenvolupament de marcadors moleculars per detectar hibridació entre dues espècies de peixos : Squalius laietanus i Squalius cephalus

Abstract

Squalius laietanus, commonly known as the Catalan chub, is a fish species endemic to Catalonia.

Its natural habitat spans rivers from the Ebro to Portbou and from the Tec to the Aglí, on

southeast of France. During the 1990s, populations of S. laietanus experienced significant

declines due to a combination of factors, including water pollution and the introduction of exotic

species. These threats have caused extensive habitat degradation and posed severe challenges

to the survival of the species. Effective protection measures are essential and must focus on

several critical areas: addressing water pollution, controlling unregulated fishing practices,

mitigating habitat loss, and managing the impact of invasive species.

This study aims to identify and utilize molecular markers for detecting the possible hybridization

between S. laietanus and Squalius cephalus. Hybridization poses a significant risk to the genetic

integrity of S. laietanus, potentially compromising its unique genetic makeup and adaptive traits.

The research involves the use of nuclear genes to assess genetic variability since it is in these

types of genes that hybridization can be detected. This genetic approach is crucial for

understanding the extent of hybridization and its impact on the genetic diversity of S. laietanus.

Therefore, maintaining genetic diversity is vital for the resilience and long-term survival of the

species, enabling it to adapt to changing environmental conditions and resist emerging threats.

The results of this study indicate that of the 8 candidate genes for molecular markers initially

considered, after an exhaustive bioinformatic analysis and subsequent laboratory work along

with extensive bibliographic research, the main candidates are the genes bmp4 and actb, since

they present polymorphisms that allow differentiating S. laietanus from S. cephalus. This same

process allowed the initial exclusion of the genes amh, rpl8, and ef1a. In the subsequent process,

the genes irbp, egr2, and rh were also excluded, comparing the results obtained with studies

conducted by other authors.

The conclusions obtained in this study are not only applicable to S. laietanus but also provide

valuable information for the conservation of other species within the genus. In conclusion, this

research underscores the importance of molecular tools in conservation biology