Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio
Abstract Background Algal isomorphic biphasic life cycles alternate between free-living diploid (tetrasporophytes) and haploid (dioicious gametophytes) phases and the hypotheses explaining their maintenance are still debated. Classic models state that conditional differentiation between phases is re...
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| Format: | Article |
| Language: | English |
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BMC
2018-12-01
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| Series: | BMC Evolutionary Biology |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s12862-018-1287-x |
| _version_ | 1818353685923627008 |
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| author | Vasco M. N. C. S. Vieira Aschwin H. Engelen Oscar R. Huanel Marie-Laure Guillemin |
| author_facet | Vasco M. N. C. S. Vieira Aschwin H. Engelen Oscar R. Huanel Marie-Laure Guillemin |
| author_sort | Vasco M. N. C. S. Vieira |
| collection | DOAJ |
| description | Abstract Background Algal isomorphic biphasic life cycles alternate between free-living diploid (tetrasporophytes) and haploid (dioicious gametophytes) phases and the hypotheses explaining their maintenance are still debated. Classic models state that conditional differentiation between phases is required for the evolutionary stability of biphasic life cycles while other authors proposed that the uneven ploidy abundances observed in the field are explained by their cytological differences in spore production. Results We monitored the state and fate of individuals of the red seaweed Gracilaria chilensis periodically for 3 years in five intertidal pools from two sites with distinct conditions. We tested for differentiation in fecundity and spore survival among the gametophyte males and females (haploids) and the tetrasporophytes (diploids). We tested for the influence of fecundity and spore survival on the observed uneven ploidy abundances in recruits. The probability of a frond becoming fecund was size-dependent, highest for the haploid males and lowest for the haploid females, with the diploids displaying intermediate probabilities. Fecund diploids released more tetraspores than carpospores released by the haploid females. Spore survival depended on ploidy and on the local density of co-habiting adult fronds. An advantage of diploid over haploid germlings was observed at very low and very high adult fronds densities. Conclusions Neither spore production nor spore survival determined the highly variable ploidy ratio within G. chilensis recruits. This result invalidates the hypothesis of natural cytological differences in spore production as the only driver of uneven field ploidy abundances in this species. Diploid spores (carpospores) survived better than haploid spores (tetraspores), especially in locations and time periods that were associated with the occurrence of strong biotic and abiotic stressors. We hypothesise that carpospore survival is higher due to support by their haploid female progenitors passing-on nutrients and chemical compounds improving survival under stressful conditions. |
| first_indexed | 2024-12-13T19:13:28Z |
| format | Article |
| id | doaj.art-441a696d817f4cdca1a55aa386db3b65 |
| institution | Directory Open Access Journal |
| issn | 1471-2148 |
| language | English |
| last_indexed | 2024-12-13T19:13:28Z |
| publishDate | 2018-12-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Evolutionary Biology |
| spelling | doaj.art-441a696d817f4cdca1a55aa386db3b652022-12-21T23:34:21ZengBMCBMC Evolutionary Biology1471-21482018-12-0118111110.1186/s12862-018-1287-xDifferentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratioVasco M. N. C. S. Vieira0Aschwin H. Engelen1Oscar R. Huanel2Marie-Laure Guillemin3MARETEC, Instituto Superior Técnico, Universidade Técnica de LisboaCCMAR, Center of Marine Science, University of AlgarveInstituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de ChileInstituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de ChileAbstract Background Algal isomorphic biphasic life cycles alternate between free-living diploid (tetrasporophytes) and haploid (dioicious gametophytes) phases and the hypotheses explaining their maintenance are still debated. Classic models state that conditional differentiation between phases is required for the evolutionary stability of biphasic life cycles while other authors proposed that the uneven ploidy abundances observed in the field are explained by their cytological differences in spore production. Results We monitored the state and fate of individuals of the red seaweed Gracilaria chilensis periodically for 3 years in five intertidal pools from two sites with distinct conditions. We tested for differentiation in fecundity and spore survival among the gametophyte males and females (haploids) and the tetrasporophytes (diploids). We tested for the influence of fecundity and spore survival on the observed uneven ploidy abundances in recruits. The probability of a frond becoming fecund was size-dependent, highest for the haploid males and lowest for the haploid females, with the diploids displaying intermediate probabilities. Fecund diploids released more tetraspores than carpospores released by the haploid females. Spore survival depended on ploidy and on the local density of co-habiting adult fronds. An advantage of diploid over haploid germlings was observed at very low and very high adult fronds densities. Conclusions Neither spore production nor spore survival determined the highly variable ploidy ratio within G. chilensis recruits. This result invalidates the hypothesis of natural cytological differences in spore production as the only driver of uneven field ploidy abundances in this species. Diploid spores (carpospores) survived better than haploid spores (tetraspores), especially in locations and time periods that were associated with the occurrence of strong biotic and abiotic stressors. We hypothesise that carpospore survival is higher due to support by their haploid female progenitors passing-on nutrients and chemical compounds improving survival under stressful conditions.http://link.springer.com/article/10.1186/s12862-018-1287-xGametophyteTetrasporophyteIsomorphic biphasic life cyclePhase ratioPloidy ratioRecruitment |
| spellingShingle | Vasco M. N. C. S. Vieira Aschwin H. Engelen Oscar R. Huanel Marie-Laure Guillemin Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio BMC Evolutionary Biology Gametophyte Tetrasporophyte Isomorphic biphasic life cycle Phase ratio Ploidy ratio Recruitment |
| title | Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio |
| title_full | Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio |
| title_fullStr | Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio |
| title_full_unstemmed | Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio |
| title_short | Differentiation of haploid and diploid fertilities in Gracilaria chilensis affect ploidy ratio |
| title_sort | differentiation of haploid and diploid fertilities in gracilaria chilensis affect ploidy ratio |
| topic | Gametophyte Tetrasporophyte Isomorphic biphasic life cycle Phase ratio Ploidy ratio Recruitment |
| url | http://link.springer.com/article/10.1186/s12862-018-1287-x |
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