Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration
Under seasonal conditions, Polydesmus angustus individuals born in the first part of the breeding season have a 1-year life cycle and those born later have a 2-year life cycle (cohort-splitting). In this study, 249 juveniles from four early broods (born in mid-July) and four late broods (born in Sep...
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| Format: | Article |
| Language: | English |
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Institute of Entomology, Biology Centre, Czech Academy of Science
2011-07-01
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| Series: | European Journal of Entomology |
| Subjects: | |
| Online Access: | https://www.eje.cz/artkey/eje-201103-0006_Cohort-splitting_in_the_millipede_Polydesmus_angustus_Diplopoda_Polydesmidae_No_evidence_for_maternal_effec.php |
| _version_ | 1818734016543588352 |
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| author | DAVID Jean-François Jean-Jacques GEOFFROY |
| author_facet | DAVID Jean-François Jean-Jacques GEOFFROY |
| author_sort | DAVID Jean-François |
| collection | DOAJ |
| description | Under seasonal conditions, Polydesmus angustus individuals born in the first part of the breeding season have a 1-year life cycle and those born later have a 2-year life cycle (cohort-splitting). In this study, 249 juveniles from four early broods (born in mid-July) and four late broods (born in September) were reared under similar laboratory conditions, to test for possible maternal influences on life-cycle duration. Development times of early- and late-born individuals were compared under four combinations of day length and temperature (16 h - 18°C, 16 h - 16°C, 12 h - 18°C and 12 h - 16°C). The results showed that development time varied significantly in response to day length, temperature and sex, but that of individuals in the early and late broods did not differ significantly (mean development times ± SE: 180 ± 6 and 183 ± 8 days, respectively). There were no significant interactions between birth period and other factors, indicating that the effects of day length, temperature and sex on development time were similar in early- and late-born individuals. This indicates that the extended life cycle of millipedes born late in the season is not maternally determined and that cohort-splitting is controlled entirely by the environmental conditions experienced by the offspring during their development. This conclusion is supported by the absence of significant variation in offspring live weight at birth measured at different times in the breeding season. The results are discussed in relation to the bet-hedging theory, which is often put forward to account for cohort-splitting in arthropods. In P. angustus, the results are consistent with either bet-hedging or adaptive plasticity, but further studies are required to decide which interpretation is correct. |
| first_indexed | 2024-12-17T23:58:39Z |
| format | Article |
| id | doaj.art-435106b2253240a59ba70f6f37a4f299 |
| institution | Directory Open Access Journal |
| issn | 1210-5759 1802-8829 |
| language | English |
| last_indexed | 2024-12-17T23:58:39Z |
| publishDate | 2011-07-01 |
| publisher | Institute of Entomology, Biology Centre, Czech Academy of Science |
| record_format | Article |
| series | European Journal of Entomology |
| spelling | doaj.art-435106b2253240a59ba70f6f37a4f2992022-12-21T21:28:00ZengInstitute of Entomology, Biology Centre, Czech Academy of ScienceEuropean Journal of Entomology1210-57591802-88292011-07-01108337137610.14411/eje.2011.046eje-201103-0006Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle durationDAVID Jean-François0Jean-Jacques GEOFFROY1Centre d'Ecologie Fonctionnelle & Evolutive, UMR 5175 CNRS, 1919 route de Mende, F-34293 Montpellier cedex 5, France; e-mail: jean-francois.david@cefe.cnrs.frMuseum National d'Histoire Naturelle, Département Ecologie & Gestion de la Biodiversité, UMR 7179 CNRS, 4 avenue du Petit Château, F-91800 Brunoy, FranceUnder seasonal conditions, Polydesmus angustus individuals born in the first part of the breeding season have a 1-year life cycle and those born later have a 2-year life cycle (cohort-splitting). In this study, 249 juveniles from four early broods (born in mid-July) and four late broods (born in September) were reared under similar laboratory conditions, to test for possible maternal influences on life-cycle duration. Development times of early- and late-born individuals were compared under four combinations of day length and temperature (16 h - 18°C, 16 h - 16°C, 12 h - 18°C and 12 h - 16°C). The results showed that development time varied significantly in response to day length, temperature and sex, but that of individuals in the early and late broods did not differ significantly (mean development times ± SE: 180 ± 6 and 183 ± 8 days, respectively). There were no significant interactions between birth period and other factors, indicating that the effects of day length, temperature and sex on development time were similar in early- and late-born individuals. This indicates that the extended life cycle of millipedes born late in the season is not maternally determined and that cohort-splitting is controlled entirely by the environmental conditions experienced by the offspring during their development. This conclusion is supported by the absence of significant variation in offspring live weight at birth measured at different times in the breeding season. The results are discussed in relation to the bet-hedging theory, which is often put forward to account for cohort-splitting in arthropods. In P. angustus, the results are consistent with either bet-hedging or adaptive plasticity, but further studies are required to decide which interpretation is correct.https://www.eje.cz/artkey/eje-201103-0006_Cohort-splitting_in_the_millipede_Polydesmus_angustus_Diplopoda_Polydesmidae_No_evidence_for_maternal_effec.phpdiplopodapolydesmus angustuslife cycledevelopment timediapausematernal effectbet-hedging |
| spellingShingle | DAVID Jean-François Jean-Jacques GEOFFROY Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration European Journal of Entomology diplopoda polydesmus angustus life cycle development time diapause maternal effect bet-hedging |
| title | Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration |
| title_full | Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration |
| title_fullStr | Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration |
| title_full_unstemmed | Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration |
| title_short | Cohort-splitting in the millipede Polydesmus angustus (Diplopoda: Polydesmidae): No evidence for maternal effects on life-cycle duration |
| title_sort | cohort splitting in the millipede polydesmus angustus diplopoda polydesmidae no evidence for maternal effects on life cycle duration |
| topic | diplopoda polydesmus angustus life cycle development time diapause maternal effect bet-hedging |
| url | https://www.eje.cz/artkey/eje-201103-0006_Cohort-splitting_in_the_millipede_Polydesmus_angustus_Diplopoda_Polydesmidae_No_evidence_for_maternal_effec.php |
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