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Linan AG, Lowry Ii PP, Miller AJ, Schatz GE, Sevathian JC, Edwards CE. Interspecific hybridization and island colonization history, not rarity, most strongly affect the genetic diversity in a clade of Mascarene-endemic trees. J Hered 2022; 113:336-352. [PMID: 35192705 DOI: 10.1093/jhered/esac010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 02/21/2022] [Indexed: 11/14/2022] Open
Abstract
Many factors shape the genetic diversity of island-endemic trees, with important implications for conservation. Oceanic island-endemic lineages undergo an initial founding bottleneck during the colonization process and subsequently accumulate diversity following colonization. Moreover, many island endemics occur in small populations and are further threatened by anthropogenic factors that cause population declines, making them susceptible to losses in genetic diversity through genetic drift, inbreeding, and bottlenecks. However, life-history traits commonly found in trees, such as outcrossing mechanisms, long lifespans, and a propensity for interspecific hybridization, may help buffer against losses of genetic variation. To assess the relative importance of colonization history, rarity, and distribution in shaping genetic diversity of island-endemic trees, we conducted a comparative population genomic analysis of 13 species of Diospyros (Ebenaceae) endemic to the Mascarene Islands that differ in island colonization history, distribution, population size, and IUCN threat status. We genotyped 328 individuals across the islands using 2b-RADseq, compared genetic diversity both among and within species, and assessed patterns of genetic structure. Genetic diversity did not vary significantly by IUCN status, but we found that species that co-occur with others on the same intermediate-aged island (Mauritius) had much greater genetic diversity than those that occur solitarily on an island (Réunion and Rodrigues), likely because of greater interspecific hybridization among species with overlapping distributions and processes related to time since island colonization. Results presented here were used to determine priority localities for in situ and ex situ conservation efforts to maximize the genetic diversity of each Mascarene Diospyros species.
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Affiliation(s)
- Alexander G Linan
- Center for Conservation and Sustainable Development, Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110, USA.,Department of Biology, Saint Louis University, Macelwane Hall, 3507 Laclede Avenue, St. Louis, MO 63103, USA
| | - Porter P Lowry Ii
- Africa and Madagascar Program, Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110, USA.,Institut de Systématique, Évolution et Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, École Pratique des Hautes Études, Université des Antilles, C.P. 39, 57 rue Cuvier, 75005 Paris, France
| | - Allison J Miller
- Department of Biology, Saint Louis University, Macelwane Hall, 3507 Laclede Avenue, St. Louis, MO 63103, USA.,Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
| | - George E Schatz
- Africa and Madagascar Program, Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110, USA
| | - Jean Claude Sevathian
- Botanist, Sustainability Consultant and Landscape Care and Maintenance Service, 20 Bis Morcellement La Confiance, Beau Bassin 71504, Mauritius
| | - Christine E Edwards
- Center for Conservation and Sustainable Development, Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110, USA
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Mairal M, Caujapé-Castells J, Pellissier L, Jaén-Molina R, Álvarez N, Heuertz M, Sanmartín I. A tale of two forests: ongoing aridification drives population decline and genetic diversity loss at continental scale in Afro-Macaronesian evergreen-forest archipelago endemics. ANNALS OF BOTANY 2018; 122:1005-1017. [PMID: 29905771 PMCID: PMC6266103 DOI: 10.1093/aob/mcy107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 05/25/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS Various studies and conservationist reports have warned about the contraction of the last subtropical Afro-Macaronesian forests. These relict vegetation zones have been restricted to a few oceanic and continental islands around the edges of Africa, due to aridification. Previous studies on relict species have generally focused on glacial effects on narrow endemics; however, little is known about the effects of aridification on the fates of previously widespread subtropical lineages. METHODS Nuclear microsatellites and ecological niche modelling were used to understand observed patterns of genetic diversity in two emblematic species, widely distributed in these ecosystems: Canarina eminii (a palaeoendemic of the eastern Afromontane forests) and Canarina canariensis (a palaeoendemic of the Canarian laurel forests). The software DIYABC was used to test alternative demographic scenarios and an ensemble method was employed to model potential distributions of the selected plants from the end of the deglaciation to the present. KEY RESULTS All the populations assessed experienced a strong and recent population decline, revealing that locally widespread endemisms may also be alarmingly threatened. CONCLUSIONS The detected extinction debt, as well as the extinction spiral to which these populations are subjected, demands urgent conservation measures for the unique, biodiversity-rich ecosystems that they inhabit.
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Affiliation(s)
- Mario Mairal
- Real Jardín Botánico (RJB), CSIC, Plaza de Murillo, Madrid, Spain
- Departamento de Biodiversidad Molecular y Banco de ADN, Jardín Botánico ‘Viera y Clavijo’ – Unidad Asociada CSIC (Cabildo de Gran Canaria), Las Palmas de Gran Canaria, Spain
| | - Juli Caujapé-Castells
- Departamento de Biodiversidad Molecular y Banco de ADN, Jardín Botánico ‘Viera y Clavijo’ – Unidad Asociada CSIC (Cabildo de Gran Canaria), Las Palmas de Gran Canaria, Spain
| | - Loïc Pellissier
- Landscape Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland
- Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
| | - Ruth Jaén-Molina
- Departamento de Biodiversidad Molecular y Banco de ADN, Jardín Botánico ‘Viera y Clavijo’ – Unidad Asociada CSIC (Cabildo de Gran Canaria), Las Palmas de Gran Canaria, Spain
| | - Nadir Álvarez
- Department of Ecology and Evolution, Institute of Biology, University of Lausanne, Biophore Dorigny, Lausanne, Switzerland
| | | | - Isabel Sanmartín
- Real Jardín Botánico (RJB), CSIC, Plaza de Murillo, Madrid, Spain
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Rodríguez-Rodríguez P, Pérez de Paz PL, Sosa PA. Species delimitation and conservation genetics of the Canarian endemic Bethencourtia (Asteraceae). Genetica 2018; 146:199-210. [PMID: 29435702 DOI: 10.1007/s10709-018-0013-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 02/06/2018] [Indexed: 10/18/2022]
Abstract
Bethencourtia Choisy ex Link is an endemic genus of the Canary Islands and comprises three species. Bethencourtia hermosae and Bethencourtia rupicola are restricted to La Gomera, while Bethencourtia palmensis is present in Tenerife and La Palma. Despite the morphological differences previously found between the species, there are still taxonomic incongruities in the group, with evident consequences for its monitoring and conservation. The objectives of this study were to define the species differentiation, perform population genetic analysis and propose conservation strategies for Bethencourtia. To achieve these objectives, we characterized 10 polymorphic SSR markers. Eleven natural populations (276 individuals) were analyzed (three for B. hermosae, five for B. rupicola and three for B. palmensis). The results obtained by AMOVA, PCoA and Bayesian analysis on STRUCTURE confirmed the evidence of well-structured groups corresponding to the three species. At the intra-specific level, B. hermosae and B. rupicola did not show a clear population structure, while B. palmensis was aggregated according to island of origin. This is consistent with self-incompatibility in the group and high gene flow within species. Overall, the genetic diversity of the three species was low, with expected heterozygosity values of 0.302 (B. hermosae), 0.382 (B. rupicola) and 0.454 (B. palmensis). Recent bottleneck events and a low number of individuals per population are probably the causes of the low genetic diversity. We consider that they are naturally rare species associated with specific habitats. The results given in this article will provide useful information to assist in conservation genetics programs for this endemic genus.
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Affiliation(s)
- Priscila Rodríguez-Rodríguez
- Instituto Universitario de Estudios Ambientales y Recursos Naturales (IUNAT), Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Canary Islands, Spain.
| | - Pedro Luis Pérez de Paz
- Departamento de Botánica, Ecología y Fisiología Vegetal, Universidad de La Laguna, 38071, La Laguna, Canary Islands, Spain
| | - Pedro A Sosa
- Instituto Universitario de Estudios Ambientales y Recursos Naturales (IUNAT), Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Canary Islands, Spain
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Peripatric speciation in an endemic Macaronesian plant after recent divergence from a widespread relative. PLoS One 2017; 12:e0178459. [PMID: 28575081 PMCID: PMC5456078 DOI: 10.1371/journal.pone.0178459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 05/12/2017] [Indexed: 11/19/2022] Open
Abstract
The Macaronesian Scrophularia lowei is hypothesized to have arisen from the widespread S. arguta on the basis of several phylogenetic studies of the genus, but sampling has been limited. Although these two annual species are morphologically distinct, the origin of S. lowei is unclear because genetic studies focused on this Macaronesian species are lacking. We studied 5 S. lowei and 25 S. arguta populations to determine the relationship of both species and to infer the geographical origin of S. lowei. The timing of S. lowei divergence and differentiation was inferred by dating analysis of the ITS region. A phylogenetic analysis of two nuclear (ITS and ETS) and two chloroplast (psbJ–petA and psbA–trnH) DNA regions was performed to study the relationship between the two species, and genetic differentiation was analysed by AMOVA. Haplotype network construction and Bayesian phylogeographic analysis were conducted using chloroplast DNA regions and a spatial clustering analysis was carried out on a combined dataset of all studied regions. Our results indicate that both species constitute a well-supported clade that diverged in the Miocene and differentiated in the Late Miocene-Pleistocene. Although S. lowei constitutes a well-supported clade according to nDNA, cpDNA revealed a close relationship between S. lowei and western Canarian S. arguta, a finding supported by the spatial clustering analysis. Both species have strong population structure, with most genetic variability explained by inter-population differences. Our study therefore supports a recent peripatric speciation of S. lowei—a taxon that differs morphologically and genetically at the nDNA level from its closest relative, S. arguta, but not according to cpDNA, from the closest Macaronesian populations of that species. In addition, a recent dispersal of S. arguta to Madeira from Canary Islands or Selvagens Islands and a rapid morphological differentiation after the colonization to generate S. lowei is the most likely hypothesis to explain the origin of the last taxon.
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Jia HM, Jiao Y, Wang GY, Li YH, Jia HJ, Wu HX, Chai CY, Dong X, Guo Y, Zhang L, Gao QK, Chen W, Song LJ, van de Weg E, Gao ZS. Genetic diversity of male and female Chinese bayberry (Myrica rubra) populations and identification of sex-associated markers. BMC Genomics 2015; 16:394. [PMID: 25986380 PMCID: PMC4436740 DOI: 10.1186/s12864-015-1602-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 05/01/2015] [Indexed: 11/25/2022] Open
Abstract
Background Chinese bayberry (Myrica rubra Sieb. & Zucc.) is an important subtropical evergreen fruit tree in southern China. Generally dioecious, the female plants are cultivated for fruit and have been studied extensively, but male plants have received very little attention. Knowledge of males may have a major impact on conservation and genetic improvement as well as on breeding. Using 84 polymorphic SSRs, we genotyped 213 M. rubra individuals (99 male individuals, 113 female varieties and 1 monoecious) and compared the difference in genetic diversity between the female and the male populations. Results Neighbour-joining cluster analysis separated M. rubra from three related species, and the male from female populations within M. rubra. By structure analysis, 178 M. rubra accessions were assigned to two subpopulations: Male dominated (98) and Female dominated (80). The well-known cultivars ‘Biqi’ and ‘Dongkui’, and the landraces ‘Fenhong’ are derived from three different gene pools. Female population had a slightly higher values of genetic diversity parameters (such as number of alleles and heterozygosity) than the male population, but not significantly different. The SSR loci ZJU062 and ZJU130 showed an empirical Fst value of 0.455 and 0.333, respectively, which are significantly above the 95 % confidence level, indicating that they are outlier loci related to sex separation. Conclusion The male and female populations of Chinese bayberry have similar genetic diversity in terms of average number of alleles and level of heterozygosity, but were clearly separated by genetic structure analysis due to two markers associated with sex type, ZJU062 and ZJU130. Zhejiang Province China could be the centre of diversity of M. rubra in China, with wide genetic diversity coverage; and the two representative cultivars ‘Biqi’ and ‘Dongkui’, and one landrace ‘Fenhong’ in three female subpopulations. This research provides genetic information on male and female Chinese bayberry and will act as a reference for breeding programs. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1602-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hui-min Jia
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Yun Jiao
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Guo-yun Wang
- Fruit Research Institute, 315400, Yuyao, Ningbo, PR China.
| | - Ying-hui Li
- The National Key Facility for Crop Gene Resources and Genetic Improvement (NFCRI)/Key Lab of Germplasm Utilization (MOA), Chinese Academy of Agricultural Sciences, Institute of Crop Science, 100081, Beijing, China.
| | - Hui-juan Jia
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Hong-xia Wu
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Chun-yan Chai
- Forestry Technology Extension Center, 315300, Cixi, Ningbo, China.
| | - Xiao Dong
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Yanping Guo
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Liping Zhang
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
| | - Qi-kang Gao
- Bio-Macromolecules Analysis Lab, Analysis Center of Agrobiology, Environmental Sciences of Zhejiang University, 310058, Hangzhou, China.
| | - Wei Chen
- Zhejiang Institute of Subtropical Crops, Wenzhou, 325005, China.
| | - Li-Juan Song
- Wenzhou Vocational and Technical College, 325035, Wenzhou, China.
| | - Eric van de Weg
- Plant Breeding-Wageningen University and Research Centre, P.O. Box 16, 6700 AA, Wageningen, The Netherlands.
| | - Zhong-shan Gao
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
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Genetic diversity and population structure of the endemic Azorean juniper, Juniperus brevifolia (Seub.) Antoine, inferred from SSRs and ISSR markers. BIOCHEM SYST ECOL 2015. [DOI: 10.1016/j.bse.2015.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Wang X, Zhang QW, Liufu YQ, Lu YB, Zhan T, Tang SQ. Comparative analysis of genetic diversity and population genetic structure in Abies chensiensis and Abies fargesii inferred from microsatellite markers. BIOCHEM SYST ECOL 2014. [DOI: 10.1016/j.bse.2014.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Jaén-Molina R, Marrero-Rodríguez Á, Reyes-Betancort JA, Santos-Guerra A, Naranjo-Suárez J, Caujapé-Castells J. Molecular taxonomic identification in the absence of a ‘barcoding gap’: a test with the endemic flora of the Canarian oceanic hotspot. Mol Ecol Resour 2014; 15:42-56. [DOI: 10.1111/1755-0998.12292] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 05/22/2014] [Accepted: 06/04/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Ruth Jaén-Molina
- Jardín Botánico Canario “Viera y Clavijo”-Unidad Asociada CSIC; Cabildo de Gran Canaria; Apartado de correos 14 de Tafira Alta 35017 Las Palmas de Gran Canaria Spain
- Fundación Canaria Amurga Maspalomas; Avda. Tirajana 39, II 6 35100 San Bartolomé de Tirajana Spain
| | - Águedo Marrero-Rodríguez
- Jardín Botánico Canario “Viera y Clavijo”-Unidad Asociada CSIC; Cabildo de Gran Canaria; Apartado de correos 14 de Tafira Alta 35017 Las Palmas de Gran Canaria Spain
| | - J. Alfredo Reyes-Betancort
- Unidad de Botánica Aplicada; Jardín de Aclimatación de La Orotava (ICIA); c/Retama 2 38400 Puerto de la Cruz, Tenerife Spain
| | - Arnoldo Santos-Guerra
- Unidad de Botánica Aplicada; Jardín de Aclimatación de La Orotava (ICIA); c/Retama 2 38400 Puerto de la Cruz, Tenerife Spain
| | - José Naranjo-Suárez
- Jardín Botánico Canario “Viera y Clavijo”-Unidad Asociada CSIC; Cabildo de Gran Canaria; Apartado de correos 14 de Tafira Alta 35017 Las Palmas de Gran Canaria Spain
| | - Juli Caujapé-Castells
- Jardín Botánico Canario “Viera y Clavijo”-Unidad Asociada CSIC; Cabildo de Gran Canaria; Apartado de correos 14 de Tafira Alta 35017 Las Palmas de Gran Canaria Spain
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Lopes MS, Mendonça D, Bettencourt SX, Borba AR, Melo C, Baptista C, da Câmara Machado A. Genetic diversity of an Azorean endemic and endangered plant species inferred from inter-simple sequence repeat markers. AOB PLANTS 2014; 6:plu034. [PMID: 24969504 PMCID: PMC4124485 DOI: 10.1093/aobpla/plu034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/28/2014] [Indexed: 05/03/2023]
Abstract
Knowledge of the levels and distribution of genetic diversity is important for designing conservation strategies for threatened and endangered species so as to guarantee sustainable survival of populations and to preserve their evolutionary potential. Picconia azorica is a valuable Azorean endemic species recently classified as endangered. To contribute with information useful for the establishment of conservation programmes, the genetic variability and differentiation among 230 samples from 11 populations collected in three Azorean islands was accessed with eight inter-simple sequence repeat markers. A total of 64 polymorphic loci were detected. The majority of genetic variability was found within populations and no genetic structure was detected between populations and between islands. Also the coefficient of genetic differentiation and the level of gene flow indicate that geographical distances do not act as barriers for gene flow. In order to ensure the survival of populations in situ and ex situ management practices should be considered, including artificial propagation through the use of plant tissue culture techniques, not only for the restoration of habitat but also for the sustainable use of its valuable wood.
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Affiliation(s)
- Maria S Lopes
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
| | - Duarte Mendonça
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
| | - Sílvia X Bettencourt
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
| | - Ana R Borba
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
| | - Catarina Melo
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
| | - Cláudio Baptista
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
| | - Artur da Câmara Machado
- Biotechnology Centre of Azores, Associated Laboratory Institute for Biotechnology and Bioengineering, University of Azores, Rua Capitão João D'Ávila, 9700-042 Angra do Heroísmo, Portugal
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Grubb PJ, Bellingham PJ, Kohyama TS, Piper FI, Valido A. Disturbance regimes, gap-demanding trees and seed mass related to tree height in warm temperate rain forests worldwide. Biol Rev Camb Philos Soc 2013; 88:701-44. [PMID: 23506298 PMCID: PMC7161821 DOI: 10.1111/brv.12029] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 01/19/2013] [Accepted: 01/25/2013] [Indexed: 12/02/2022]
Abstract
For tropical lowland rain forests, Denslow (1987) hypothesized that in areas with large-scale disturbances tree species with a high demand for light make up a larger proportion of the flora; results of tests have been inconsistent. There has been no test for warm temperate rain forests (WTRFs), but they offer a promising testing ground because they differ widely in the extent of disturbance. WTRF is dominated by microphylls sensu Raunkiaer and has a simpler structure and range of physiognomy than tropical or subtropical rain forests. It occurs in six parts of the world: eastern Asia, New Zealand, Chile, South Africa, SE Australia and the Azores. On the Azores it has been mostly destroyed, so we studied instead the subtropical montane rain forest (STMRF) on the Canary Islands which also represents a relict of the kind of WTRF that once stretched across southern Eurasia. We sought to find whether in these six regions the proportion of tree species needing canopy gaps for establishment reflects the frequency and/or extent of canopy disturbance by wind, landslide, volcanic eruptions (lava flow and ash fall), flood or fire. We used standard floras and ecological accounts to draw up lists of core tree species commonly reaching 5 m height. We excluded species which are very rare, very localized in distribution, or confined to special habitats, e.g. coastal forests or rocky sites. We used published accounts and our own experience to classify species into three groups: (1) needing canopy gaps for establishment; (2) needing either light shade throughout or a canopy gap relatively soon (a few months or years) after establishment; and (3) variously more shade-tolerant. Group 1 species were divided according the kind of canopy opening needed: tree-fall gap, landslide, lava flow, flood or fire. Only some of the significant differences in proportion of Group 1 species were consistent with differences in the extent of disturbance; even in some of those cases other factors seem likely to have had a major determining influence during evolution. We also sought to determine whether the species that are at least 'short-term persistent' in the soil seed bank (lasting 2-4 years) are all species needing canopy gaps for establishment. The answer was negative; large numbers of seeds of some shade-tolerants accumulate in the soil, and these species are able to benefit from soil disturbance in deep shade. We found a significant and strong positive relationship in Japan between mean seed mass and mature tree height, a weak positive relationship in New Zealand and no relationship in any of the other four regions. When comparing the seed mass values of Group 1 and Group 3 species we obtained different answers depending on whether or not we confined ourselves to taxonomically controlled contrasts. In only two of the four regions with an appreciable number of species in Group 1 is the mean seed mass of such species significantly lower than that of Group 3 species when taxonomic relatedness is ignored.
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Affiliation(s)
- Peter J Grubb
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
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Sosa PA, González-Pérez MA, Moreno C, Clarke JB. Conservation genetics of the endangered endemic Sambucus palmensis Link (Sambucaceae) from the Canary Islands. CONSERV GENET 2010. [DOI: 10.1007/s10592-010-0122-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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