Generation time, length of life, instar duration and frequency of moulting, and their relationship to temperature in eight species of cladocera from the River Thames, reading
✍ Scribed by Howard H. Bottrell
- Publisher
- Springer-Verlag
- Year
- 1975
- Tongue
- English
- Weight
- 792 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0029-8549
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✦ Synopsis
Data on generation time, length of life, instar duration and frequency of moulting at a range of constant temperatures are given for eight species of epiphytic CIadocera from the l~iver Thames. For each species each of the above events was inversely related to temperature. The number of juvenile instars was constant for a particular species, but varied between species; large species tending to have more juvenile instars than small species. A similar size relationship was found for generation time. Juveniles moulted more frequently than adults. The duration of an adult instar was the same as the duration of egg development, except at low temperatures. The data are compared with published data on daphniids, and possible reasons for the basic differences discussed. l~egression analysis of the relationships between the various dependent variables and temperature required a logarithmic transformation. A reciprocal transformation was statistically inadequate for describing the relationship. H.H. Bottrell maximum development rates which the eight species investigated are capable of attaining.
Definition of Terms
Embryonic Period: the period from the laying of an egg to the release of the fully developed juvenile from the brood chamber (----duration of egg development).
Juvenile: individual that has been released from the brood chamber but has not yet reached sexual maturity:
Adult: individual that has reached sexual maturity, as shown by the presence of eggs in the brood chamber.
Postembryonic Period: the period between release from the brood chamber and the attainment of sexual maturity (= total time spent in juvenile stage).
Generation Time: the period from the laying of an egg to the time the individual which develops from that egg reaches sexual maturity (= embryonic + postembryonic period).
Length of Life: the period from the laying of an egg to the time the individual which develops from that egg dies.
Instar: the period between two successive moults.