Estimating genetic and
environmental components of variance using sexual and clonal Artemia
R.A. Browne, V. Moller, V.E. Forbes, M.H.
Depledge-2002
Journal of Experimental Marine Biology and Ecology,
267(1): 107-119
Abstract:
Reproductive and life span traits were measured for
two obligately parthenogenetic (Artemia parthenogenetica) and three
sexual (two A. franciscana and one A. sinica) brine shrimp
populations. For each population, clonal lineages or single mating pairs
were followed through one life cycle. The relative contributions of
environmental and genetic components to total phenotypic variation for 10
life-history traits in response to environmental stress (0, 10, 25 ppb Cu)
were estimated. Within treatment variation (CVW) was 39% higher
for sexual populations than parthenogenetic populations, with significant (p<0.05)
differences in total number of offspring and number of nauplii. CVA
(the change in variance due to rearing in different environments), when
averaged for all traits and all populations, increased variability by 9.9%.
CVA was 44.2% higher for sexual than parthenogenetic populations,
with significant differences in number of broods, total number of offspring,
and number of nauplii. The average genetic component of variation for the 10
traits was 23.44%, ranging from 5.26% for number of cysts to 44.87% for
number of nauplii. For all traits, the environmental component of variance
is greater than the genetic component measured, but every trait has a
genetic component, which can potentially be acted upon by selection.
(Department of Biology, Wake Forest University,
Winston-Salem, NC 27109, USA, Tel.: +1-336-758-5569; fax: +1-336-758-6008,
e-mail: brownera@wfu.edu)