Response to bidirectional selection for naupliar length in<i>Artemia franciscana</i>

Abstract

Bidirectional mass selection for naupliar length was practised in Artemia franciscana from Great Salt Lake, UT, USA, with the aim of developing two divergent lines, namely small naupliar size (SNS) and bigger naupliar size (BNS). A random-bred control line was also maintained to quantify the environmental effects. The mean naupliar length in the base population was 486.99±2.11 μm in males and 490.58±1.82 μm in females. Six generations of selection for smaller naupliar size in the SNS line resulted in a phenotypic response of –45.32 μm and –37.52 μm decreases in naupliar size in males and females respectively. In the BNS line, responses (increase in size) from five generations of selection for bigger size were 8.59 μm and 35.80 μm respectively. The cumulative genetic gain in males and females of the SNS were –41.72 μm and –38.76 μm compared with 12.64 μm and 39.48 μm, respectively, in the BNS line.