Partheletterogenetic tetraploid (*); Parthenogenetic diploid (+); bisexual (o)

Partheletterogenetic tetraploid (*); Parthenogenetic diploid (+); bisexual (o)
The brand new a dozen morphological parameters, mentioned throughout anybody (Dining table 1), were utilized to establish relationships of these communities courtesy discriminant data

Away from for every single populace a haphazard take to was pulled. Pets was indeed anesthetized which includes droplets from liquid over loaded which have chloroform and female, constantly more 20 (but LMT, and therefore underwent a premier mortality in the community) had been separated throughout the others. The next morphological parameters was indeed quantified inside the for each and every girls: full size; abdominal size; depth out-of 3rd intestinal segment; depth of ovisac; duration of furca; number of setae registered for each part of one’s furca; thickness from head; maximum diameter and you may length anywhere between compound sight; period of first antenna; in addition to proportion intestinal duration ? 100/overall size. Profile 2 depicts this type of above mentioned looks steps. In most instances, an identical amount of people for each length period are incorporated manageable not to ever prejudice performance from testing. Preadult individuals were regarded as well.

Several analyses was basically achieved: earliest, all of the findings was basically classified by particular populace (bisexual diploid, parthenogenetic diploid and you may parthenogenetic tetraploid); regarding the 2nd analysis, the fresh separation standards is the foundation of your own inhabitants

This multivariate procedure provides a series of variables (Z1, Z2,…), Which are linear functions of the morphological variables studied, with the form Zn = ?1X2+?2X2+… (Where ?s are the calculated discriminant coefficients and Xs the variables being considered). They maximize the ong different groups of observations defined a priori (Anderson, 1984). Thus, the first discriminant function is the equation of a line cutting across the intermixed cluster of points representing the different observations. This function is constructed in such a way that the different predefined groups will evaluate it as differently as possible. Obviously, this will not be accomplished if the number of groups is high, and subsequent discriminant functions will be needed. These analyses have been performed using a backward stepwise procedure that allows removing the different variables out of the model separately and ranking them for their relative importance in discriminating Artemia populations. Nevertheless, all described variables were kept in the model. These calculations have been performed with the help of the statistical package Statgraphics v. 3.0 (Statistical Graphics Corp., Rockville, MD) run on an IBM AT personal computer.

In Table II, the results obtained when the type of population was used as a separation factor are displayed. The two functions found give 100% separation, and both are statistically highly significant (P<0.001). Morphological characteristics allow a clear differentiation among the three groups considered (Table II, groups centroids). The morphological characteristics that most significantly contribute to the discrimination among the three groups are : lengh of first antenna, width of head and those related to the form and size of the head, the ratio abdominal length/total length in form of percentage and the width of ovisac and abdomen (Table II).

Results of the second analysis (factor of separation is population of origin) are shown in Table III and Figure 3. In this case, 12 discriminant functions are needed in order to separate thoroughly the 27 populations, but the first five of them give a cummulative separation percentage of (the four discriminant functions shown in Table III give a % cummulative separation). The first eight functions calculated are highly statistically significant (P,0.001), the ninth is also significant (P<0.05) and the last three are not significant. The morphological characteristics that most signifiantly contribute to separate the groups in this case are : distance between eyes, eye diameter, length of the first antenna and all variable related to the shape and size of the head and the length of the furca (Table III).

Deja un comentario

Tu dirección de correo electrónico no será publicada. Los campos obligatorios están marcados con *