Twenty-four populations of several species of the genus Tisbe (Copepoda, Harpacticoida) have been assayed for fourteen enzyme-systems by electrophoresis. The affinity index, calculated as the ratio between the mean number of concordant bands (same mobility) and the number of bands found in the reference sample (pattern with the highest number of bands), increases with the degree of taxonomical affinity. Evolutionary implications are discussed.
A study on the life cycle of the Copepod Tigriopus brevicornis has been carried out at three temperatures (9°C, 10°C, 27°C) and two salinities (17‰, 34‰). The results show that (a) temperature influences minimum generation time, duration of life and survival; (b) salinity affects sex ratio by a differential mortality of females at low concentrations; (c) both factors modify the fertility values. Moreover, the results indicate that this Copepod has a long life cycle and an exceptionally high adaptability...
Eleven gene-enzyme systems have been studied by means of gel electrophoresis in four laboratory populations of three sibling species: Tisbe biminiensis, T. cucumariae and T. gracilis, of the 'gracilis' group. On the average the degree of genetic variability is very low. This may be due to bottlenecks during the rearing. The values of the genetic similarity are in agreement with the data on chromosomal structure and indicate that T. gracilis and T. cucumariae are the species which resemble most the...
The difficulty of understanding the esterase patterns in the Amphipod Gammarus insensibilis, due to the differential activities for various bands, has been overcome by employing several inhibitors and substrates. Thus five loci coding for arylesterase, acetyl esterase, cholinesterase, carboxilesterase have been identified. The results of some crossing also show that the arylesterase locus is represented by three codominant alleles and that the enzyme has a dimeric subunit structure.
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