Abalon

Journal of Shellfish Research, Vol. 29, No. 3, 709–715, 2010.

GENETIC VARIABILITY OF CULTURED POPULATIONS OF RED ABALONE IN CHILE: AN APPROACH BASED ON HETEROLOGOUS MICROSATELLITES

´ FABIOLA LAFARGA DE LA CRUZ,1,2 MIGUEL ANGEL DEL RI´O–PORTILLA3 AND ´ RATE1* CRISTIAN GALLARDO-ESCA 1 Laboratorio de Biotecnologı´a Acuı´cola, Departamento de Oceanografı´a, Facultad de Ciencias Naturales yOceanogra´ficas, Centro de Biotecnologı´a, Universidad de Concepcio´n, Casilla 160-C, Concepcio´n, Chile; 2Facultad de Ciencias Agrono´micas, Universidad de Chile, Santa Rosa 11315, La Pintana, Santiago, Chile; 3Departamento de Acuicultura, Divisio´n de Oceanologı´a, CICESE, Carretera Tij-Eda Km 107. BC, Ensenada, Me´xico
ABSTRACT To evaluate the current genetic status of Chilean abalone hatcherypopulations, we tested 25 heterologous microsatellite loci in Haliotis rufescens Swainson 1822. Successful cross-amplification was obtained with 13 microsatellite loci, and 7 were used to estimate genetic variability in 4 separate hatchery populations: 2 located in Caldera, 1 in Coquimbo (northern Chile), and one more on Chiloe Island (southern Chile). The number of alleles per locus (NA) ranged from2–16, with an average of 8.86. Among populations, mean Ho and He values were 0.510 and 0.746, respectively, with significant deviations from HardyWeinberg equilibrium at 23–28 of the population loci analyzed (82.1%). The FIS values calculated showed no significant differences among the different hatcheries analyzed. However, FIS values from the Caldera populations were close to panmixia values, whereasCoquimbo and Chiloe populations showed a slight tendency to endogamy. According to the FST and RST values, there are genetic differences among the populations, with the 3 northern hatcheries from Caldera and Coquimbo more related than the abalone population of southern Chile. In addition, comparison between California wild and Chilean hatchery abalone populations showed a loss of genetic diversityevidenced by microsatellite markers. The current study contributes to the genetic knowledge of the Chilean red abalone aquaculture resource and reveals the necessity to perform genetic monitoring in hatchery populations. KEY WORDS: Haliotis rufescens, abalone, cultured populations, heterologous primers, microsatellite loci, genetic variability

INTRODUCTION

The red abalone Haliotis rufescensis a broadcast-spawning marine gastropod with a natural distribution from the north of California to Baja California, Mexico. In Chile, a broodstock of several red abalone was introduced during 1977 for experimental farms. After several years of research and development, the industry began in 1992, and Chile is currently the 5th country worldwide in production, with around 886 TM/y (SERNAPESCA2009). Currently present, the abalone aquaculture industry is carried out in land-based systems and in-water systems located in northern and southern Chile, respectively (Flores-Aguilar et al. 2007). The distance between both aquaculture zones is approximately 2,000 km, with the northern farms suppliers of abalone seed for the southern grow-out farms. Abalone-related research in Chile has beenmainly focused on the development of a formulated diet, production improvements of seed and juvenile, and in the production of hybrids ´ and monosex abalone (Enrı´ quez & Villagran 2008). From a genetic point of view, there are no reports available about the genetic status of the introduced abalone broodstock as well as the current genetic diversity of the hatchery populations. Furthermore, seed andjuvenile transportation among farms is a common practice that does not allow adequate records from the 25 operative commercial farms. On the other hand, red abalone seed is usually produced by the breeders using broodstock from the same populations, and also relatively few parents are required to generate the offspring. However, there is a consensus that genetic variability could be lost by...