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Reproductive biology and population structure of the endangered shrub Grevillea bedggoodiana (Proteaceae). CONSERV GENET 2022. [DOI: 10.1007/s10592-022-01480-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractNarrowly endemic species are particularly vulnerable to catastrophic events. Compared to widespread species, they may also be less capable of adapting to shifts in environmental pressures as a result of specialisation on a narrow range of local condition and limited ability to disperse. However, life-history traits, such as preferential outcrossing and high fecundity can maintain genetic diversity and evolutionary potential, and boost species resilience. The endangered Grevillea bedggoodiana (Enfield Grevillea) is an understorey shrub restricted to an area of ca. 150 km2 in south-eastern Australia with a legacy of large-scale anthropogenic disturbance. Prior to this study little was known about its biology and population structure. Here, its breeding system was assessed through a controlled pollination experiment at one of its central populations, and eight populations were sampled for genetic analysis with microsatellite markers. The species was found to be preferentially outcrossing, with no evidence of pollination limitation. In most populations, allelic richness, observed heterozygosity and gene diversity were high (Ar: 3.8–6.3; Ho: 0.45–0.65, He: 0.60 − 0.75). However, the inbreeding coefficients were significant in at least four populations, ranging from Fi -0.061 to 0.259 despite high outcrossing rates. Estimated reproductive rates varied among sampled populations but were independent of gene diversity and inbreeding. Despite its small geographic range, the species’ populations showed moderate differentiation (AMOVA: FST = 0.123), which was largely attributable to isolation by distance. We interpret these results as suggesting that G. bedggoodiana is reproductively healthy and has maintained high levels of genetic diversity despite recent disturbance.
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Rosche C, Baasch A, Runge K, Brade P, Träger S, Parisod C, Hensen I. Tracking population genetic signatures of local extinction with herbarium specimens. ANNALS OF BOTANY 2022; 129:857-868. [PMID: 35670810 PMCID: PMC9292615 DOI: 10.1093/aob/mcac061] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Indexed: 05/29/2023]
Abstract
BACKGROUND AND AIMS Habitat degradation and landscape fragmentation dramatically lower population sizes of rare plant species. Decreasing population sizes may, in turn, negatively affect genetic diversity and reproductive fitness, which can ultimately lead to local extinction of populations. Although such extinction vortex dynamics have been postulated in theory and modelling for decades, empirical evidence from local extinctions of plant populations is scarce. In particular, comparisons between current vs. historical genetic diversity and differentiation are lacking despite their potential to guide conservation management. METHODS We studied the population genetic signatures of the local extinction of Biscutella laevigata subsp. gracilis populations in Central Germany. We used microsatellites to genotype individuals from 15 current populations, one ex situ population, and 81 herbarium samples from five extant and 22 extinct populations. In the current populations, we recorded population size and fitness proxies, collected seeds for a germination trial and conducted a vegetation survey. The latter served as a surrogate for habitat conditions to study how habitat dissimilarity affects functional connectivity among the current populations. KEY RESULTS Bayesian clustering revealed similar gene pool distribution in current and historical samples but also indicated that a distinct genetic cluster was significantly associated with extinction probability. Gene flow was affected by both the spatial distance and floristic composition of population sites, highlighting the potential of floristic composition as a powerful predictor of functional connectivity which may promote decision-making for reintroduction measures. For an extinct population, we found a negative relationship between sampling year and heterozygosity. Inbreeding negatively affected germination. CONCLUSIONS Our study illustrates the usefulness of historical DNA to study extinction vortices in threatened species. Our novel combination of classical population genetics together with data from herbarium specimens, an ex situ population and a germination trial underlines the need for genetic rescue measures to prevent extinction of B. laevigata in Central Germany.
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Affiliation(s)
| | | | - Karen Runge
- Anhalt University of Applied Sciences, Department of Agriculture, Ecotrophology and Landscape Development, Strenzfelder Allee 28, 06406 Bernburg (Saale), Germany
| | - Philipp Brade
- Anhalt University of Applied Sciences, Department of Agriculture, Ecotrophology and Landscape Development, Strenzfelder Allee 28, 06406 Bernburg (Saale), Germany
| | - Sabrina Träger
- Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden, Große Steinstraße 79/80, 06108 Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103 Leipzig, Germany
| | - Christian Parisod
- University of Fribourg, Department of Biology, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Isabell Hensen
- Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden, Große Steinstraße 79/80, 06108 Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103 Leipzig, Germany
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Wang J, Chen J, Huang S, Han D, Li J, Guo D. Investigating the Mechanism of Unilateral Cross Incompatibility in Longan ( Dimocarpus longan Lour.) Cultivars (Yiduo × Shixia). FRONTIERS IN PLANT SCIENCE 2022; 12:821147. [PMID: 35222456 PMCID: PMC8874016 DOI: 10.3389/fpls.2021.821147] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/30/2021] [Indexed: 06/14/2023]
Abstract
Longan (Dimocarpus longan Lour.) is an important subtropical fruit tree in China. Nearly 90% of longan fruit imports from Thailand are from the cultivar Yiduo. However, we have observed that there exists a unilateral cross incompatibility (UCI) when Yiduo is used as a female parent and Shixia (a famous Chinese cultivar) as a male parent. Here, we performed a comparative transcriptome analysis coupled with microscopy of pistils from two reciprocal pollination combinations [Shixia♂ × Yiduo♀(SY) and Yiduo♀ × Shixia♂(YS)] 4, 8, 12, and 24 h after pollination. We also explored endogenous jasmonic acid (JA) and jasmonyl isoleucine (JA-Ile) levels in pistils of the crosses. The microscopic observations showed that the UCI was sporophytic. The endogenous JA and JA-Ile levels were higher in YS than in SY at the studied time points. We found 7,251 differentially expressed genes from the transcriptome analysis. Our results highlighted that genes associated with JA biosynthesis and signaling, pollen tube growth, cell wall modification, starch and sucrose biosynthesis, and protein processing in endoplasmic reticulum pathways were differentially regulated between SY and YS. We discussed transcriptomic changes in the above-mentioned pathways regarding the observed microscopic and/or endogenous hormone levels. This is the first report on the elaboration of transcriptomic changes in longan reciprocal pollination combination showing UCI. The results presented here will enable the longan breeding community to better understand the mechanisms of UCI.
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Affiliation(s)
- Jing Wang
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Ji Chen
- College of Horticulture, South China Agricultural University, Guangzhou, China
| | - Shilian Huang
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Dongmei Han
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Jianguang Li
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Ministry of Agriculture and Rural Affairs, Guangzhou, China
| | - Dongliang Guo
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Ministry of Agriculture and Rural Affairs, Guangzhou, China
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Gavin‐Smyth N, Kramer AT, Urbina‐Casanova R, Vitt P, Fant JB. Genetic rescue reduces mate limitation in a threatened, clonal, and self‐incompatible plant species. Restor Ecol 2021. [DOI: 10.1111/rec.13458] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nora Gavin‐Smyth
- Plant Biology and Conservation Northwestern University Evanston IL 60201 U.S.A
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL 60022 U.S.A
| | - Andrea T. Kramer
- Plant Biology and Conservation Northwestern University Evanston IL 60201 U.S.A
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL 60022 U.S.A
| | - Rafael Urbina‐Casanova
- Plant Biology and Conservation Northwestern University Evanston IL 60201 U.S.A
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL 60022 U.S.A
| | - Pati Vitt
- Plant Biology and Conservation Northwestern University Evanston IL 60201 U.S.A
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL 60022 U.S.A
- Lake County Forest Preserve District 1899 W. Winchester Road, Libertyville IL 60048 U.S.A
| | - Jeremie B. Fant
- Plant Biology and Conservation Northwestern University Evanston IL 60201 U.S.A
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL 60022 U.S.A
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Hoffmann AA, Miller AD, Weeks AR. Genetic mixing for population management: From genetic rescue to provenancing. Evol Appl 2021; 14:634-652. [PMID: 33767740 PMCID: PMC7980264 DOI: 10.1111/eva.13154] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/10/2020] [Accepted: 10/14/2020] [Indexed: 12/21/2022] Open
Abstract
Animal and plant species around the world are being challenged by the deleterious effects of inbreeding, loss of genetic diversity, and maladaptation due to widespread habitat destruction and rapid climate change. In many cases, interventions will likely be needed to safeguard populations and species and to maintain functioning ecosystems. Strategies aimed at initiating, reinstating, or enhancing patterns of gene flow via the deliberate movement of genotypes around the environment are generating growing interest with broad applications in conservation and environmental management. These diverse strategies go by various names ranging from genetic or evolutionary rescue to provenancing and genetic resurrection. Our aim here is to provide some clarification around terminology and to how these strategies are connected and linked to underlying genetic processes. We draw on case studies from the literature and outline mechanisms that underlie how the various strategies aim to increase species fitness and impact the wider community. We argue that understanding mechanisms leading to species decline and community impact is a key to successful implementation of these strategies. We emphasize the need to consider the nature of source and recipient populations, as well as associated risks and trade-offs for the various strategies. This overview highlights where strategies are likely to have potential at population, species, and ecosystem scales, but also where they should probably not be attempted depending on the overall aims of the intervention. We advocate an approach where short- and long-term strategies are integrated into a decision framework that also considers nongenetic aspects of management.
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Affiliation(s)
- Ary A. Hoffmann
- School of BioSciencesBio21 InstituteThe University of MelbourneParkvilleVic.Australia
| | - Adam D. Miller
- School of Life and Environmental SciencesCentre for Integrative EcologyDeakin UniversityWarrnamboolVic.Australia
- Deakin Genomics CentreDeakin UniversityGeelongVic.Australia
| | - Andrew R. Weeks
- School of BioSciencesBio21 InstituteThe University of MelbourneParkvilleVic.Australia
- cesar Pty LtdParkvilleVic.Australia
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Li J, Gu J, Wang X, Zhang W, Jin Z. Pollen limitation in the endangered Chinese endemic species Sinocalycanthus chinensis. Ecol Evol 2020; 10:8439-8448. [PMID: 32788992 PMCID: PMC7417249 DOI: 10.1002/ece3.6550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/01/2020] [Accepted: 05/05/2020] [Indexed: 11/09/2022] Open
Abstract
Pollen limitation negatively impacts endangered and endemic plants with small fragmented populations, such as Sinocalycanthus chinensis, an endangered plant endemic to China. In this study, we analyzed the pollen limitation of the S. chinensis Damingshan (DMS) population in 2006, 2009, and 2010, and crossed plants with mates separated by different distances, both within and between populations. The DMS population exhibited strong pollen limitation in fruit set, seed set, and seeds per fruit in 2006, 2009, and 2010. The average accumulated pollen limitation (for fruit set times seeds per fruit) was 0.510 ± 0.180. Progeny crossed with pollen from intermediate neighboring plants within the same population (separated by 30-50 m from pollen recipients) had the lowest fitness. No optimal outcrossing distance was found within the DMS population. Progeny from crosses with the Shunxiwu (SXW) and Daleishan (DLS) populations performed relatively better, while those from crosses with Qingliangfeng (QLF) and Longxushan (LXS) populations performed worse. Compared with average reproductive success, outbreeding depression was found in progeny from crosses with the LXS and QLF populations. Reproductive success from pure self-pollination indicated S. chinensis is self-compatible. Geitonogamous selfing increased reproductive success. Based on geitonogamous selfing, the proportion of selfed offspring was relatively high. These results provide basic references for the conservation of this species.
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Affiliation(s)
- Junmin Li
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
- Institute of EcologyTaizhou UnivesityTaizhouChina
| | - Jingjing Gu
- Institute of EcologyTaizhou UnivesityTaizhouChina
- Xianju Branch of Ecological Environment Bureau of Taizhou CityTaizhouChina
| | - Xinglong Wang
- Institute of EcologyTaizhou UnivesityTaizhouChina
- Zhejiang Hangkang Testing Technology Co. Ltd.HangzhouChina
| | - Wenbiao Zhang
- Institute of EcologyTaizhou UnivesityTaizhouChina
- Plant Quarantine Station of Beilun DistrictNingbo CityChina
| | - Zexin Jin
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
- Institute of EcologyTaizhou UnivesityTaizhouChina
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Li J, Qi C, Gu J, Jin Z. Effect of sire population on the genetic diversity and fitness of F1 progeny in the endangered Chinese endemic Sinocalycanthus chinensis. Ecol Evol 2020; 10:4091-4103. [PMID: 32489633 PMCID: PMC7244809 DOI: 10.1002/ece3.6179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 11/23/2022] Open
Abstract
Sinocalycanthus chinensis Cheng et S. Y. Chang (Calycanthaceae), which has a unique systematic status, is listed as a national second-class protected plant of China. In this study, the genetic diversity, performance, and fitness of F1 progeny from crosses between the Damingshan (DMS) population of S. chinensis and pollen parents from the Daleishan (DLS) and Longxushan (LXS) populations were examined. The DLS population has a relatively small population size, low genetic diversity, and considerable geographical and genetic distances from the DMS population relative to the LXS population. Compared with naturally occurring seeds, DLS-sired seeds had the highest thousand-seed weight, starch content, fat content, germination rate, germination index, and emergence rate, but the lowest protein content. Naturally occurring, open-pollinated seeds had the lowest thousand-seed weight, starch content, and fat content, but the highest protein content. Compared with natural F1 progeny, DMS × DLS seedlings had the highest genetic diversity, photosynthetic parameters, and growth characteristics, except for leaf mass ratio and stem mass ratio. Under strong light, DMS × DLS seedlings exhibited a F v/F m value of 0.75, while the other two seedling types exhibited F v/F m values of 0.65. DLS-sired seeds had the most vigorous growth characteristics except for leaf mass ratio and stem mass ratio. These results suggest that genetic rescue by transplanting seedlings from the DLS population or hand pollination with pollen from the DLS population would be effective methods to reduce inbreeding depression and obtain strong offspring with high genetic diversity and fitness in the DMS population.
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Affiliation(s)
- Junmin Li
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
| | - Caihong Qi
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
- Traffic Patrol Headquarters of Public Security Bureau of Chongqing CityVehicle Management InstituteChongqinChina
| | - Jingjing Gu
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
- Xianju Branch of Ecological Environment Bureau of Taizhou CityTaizhouChina
| | - Zexin Jin
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
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Ayre BM, Roberts DG, Phillips RD, Hopper SD, Krauss SL. Near-neighbour optimal outcrossing in the bird-pollinated Anigozanthos manglesii. ANNALS OF BOTANY 2019; 124:423-436. [PMID: 31115446 PMCID: PMC6798840 DOI: 10.1093/aob/mcz091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 05/20/2019] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS In plants, the spatial and genetic distance between mates can influence reproductive success and offspring fitness. Negative fitness consequences associated with the extremes of inbreeding and outbreeding suggest that there will be an intermediate optimal outcrossing distance (OOD), the scale and drivers of which remain poorly understood. In the bird-pollinated Anigozanthos manglesii (Haemodoraceae) we tested (1) for the presence of within-population OOD, (2) over what scale it occurs, and (3) for OOD under biologically realistic scenarios of multi-donor deposition associated with pollination by nectar-feeding birds. METHODS We measured the impact of mate distance (spatial and genetic) on seed set, fruit size, seed mass, seed viability and germination success following hand pollination from (1) single donors across 0 m (self), <1 m, 1-3 m, 7-15 m and 50 m, and (2) a mix of eight donors. Microsatellite loci were used to quantify spatial genetic structure and test for the presence of an OOD by paternity assignment after multi-donor deposition. KEY RESULTS Inter-mate distance had a significant impact on single-donor reproductive success, with selfed and nearest-neighbour (<1 m) pollination resulting in only ~50 seeds per fruit, lower overall germination success and slower germination. Seed set was greatest for inter-mate distance of 1-3 m (148 seeds per fruit), thereafter plateauing at ~100 seeds per fruit. Lower seed set following nearest-neighbour mating was associated with significant spatial genetic autocorrelation at this scale. Paternal success following pollination with multiple sires showed a significantly negative association with increasing distance between mates. CONCLUSIONS Collectively, single- and multi-donor pollinations indicated evidence for a near-neighbour OOD within A. manglesii. A survey of the literature suggests that within-population OOD may be more characteristic of plants pollinated by birds than those pollinated by insects.
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Affiliation(s)
- Bronwyn M Ayre
- School of Biological Sciences, University of Western Australia, Perth, WA, Australia
- Kings Park Science, Department of Biodiversity, Conservation and Attractions, Perth, WA, Australia
| | - David G Roberts
- Kings Park Science, Department of Biodiversity, Conservation and Attractions, Perth, WA, Australia
- Centre for Excellence in Natural Resource Management, School of Agriculture and Environment, University of Western Australia, Albany, WA, Australia
| | - Ryan D Phillips
- Kings Park Science, Department of Biodiversity, Conservation and Attractions, Perth, WA, Australia
- Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, VIC, Australia
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Stephen D Hopper
- Centre for Excellence in Natural Resource Management, School of Agriculture and Environment, University of Western Australia, Albany, WA, Australia
| | - Siegfried L Krauss
- School of Biological Sciences, University of Western Australia, Perth, WA, Australia
- Kings Park Science, Department of Biodiversity, Conservation and Attractions, Perth, WA, Australia
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Michaels HJ, Cartwright CA, Wakeley Tomlinson EF. Relationships Among Population Size, Environmental Factors, and Reproduction in Lupinus perennis (Fabaceae). AMERICAN MIDLAND NATURALIST 2019. [DOI: 10.1674/0003-0031-182.2.160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Helen J. Michaels
- Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403
| | - Carrie A. Cartwright
- Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403
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Chen LN, Cui YZ, Wong KM, Li DZ, Yang HQ. Breeding system and pollination of two closely related bamboo species. AOB PLANTS 2017; 9:plx021. [PMID: 28685014 PMCID: PMC5493747 DOI: 10.1093/aobpla/plx021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 05/21/2017] [Accepted: 05/27/2017] [Indexed: 05/28/2023]
Abstract
An understanding of the breeding systems and pollination of agriculturally important plants is critical to germplasm improvement. Breeding system characteristics greatly influence the amount and spatial distribution of genetic variation within and amongst populations and influence the rarity and extinction vulnerability of plant species. Many woody bamboos have a long vegetative period (20-150 years) followed by gregarious monocarpy. Relatively, little is known about their pollination and breeding systems. We studied these characteristics in wild Dendrocalamus membranaceus populations and cultivated Dendrocalamus sinicus populations distributed in the Yunnan Province of China. Floral morphology, flower visitors and breeding system were studied from 2013 to 2015. Both bamboos were protogynous, but flowering periods of florets overlapped providing opportunities for self-pollination amongst florets, especially in D. membranaceus. There was no agamospermy in either species. Seed set of D. sinicus was low (0.42 ± 0.42 %) under natural pollination but higher (8.89 ± 2.55 %) after artificial xenogamy. Seed set of D. membranaceus was higher (7.49 ± 0.82 %) in mass flowering populations and 2.14 ± 0.25 % in sporadically flowering populations. The Asian honeybee Apis cerana could provide cross-pollination of D. membranaceus and D. sinicus, and flower visitation peaked at 1000-1200 h. Pollination limitation due to lack of pollinators or pollen was detected in the cultivated populations of D. sinicus and sporadically flowering populations of D. membranaceus. Pollination limitation was not obvious within mass flowering populations. Hand pollination could significantly increase seed set of these two bamboo species. Dendrocalamus membranaceus and D. sinicus were self-compatible and have a mixed-mating system with outcrossing being pre-dominant. Their seed production was limited by the quantity of pollen and pollinator activity. Honeybees were observed as effective pollinators.
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Affiliation(s)
- Ling-Na Chen
- Research Institute of Insect Resources, Chinese Academy of Forestry, Bailongsi, Panlong District, Kunming 650233, China
| | - Yong-Zhong Cui
- Research Institute of Insect Resources, Chinese Academy of Forestry, Bailongsi, Panlong District, Kunming 650233, China
| | - Khoon-Meng Wong
- Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569, Singapore
| | - De-Zhu Li
- Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, No. 132, Lanhei Road, Panlong District, Kunming 650201, China
| | - Han-Qi Yang
- Research Institute of Insect Resources, Chinese Academy of Forestry, Bailongsi, Panlong District, Kunming 650233, China
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Dayrell RLC, Garcia QS, Negreiros D, Baskin CC, Baskin JM, Silveira FAO. Phylogeny strongly drives seed dormancy and quality in a climatically buffered hotspot for plant endemism. ANNALS OF BOTANY 2017; 119:267-277. [PMID: 27568299 PMCID: PMC5321058 DOI: 10.1093/aob/mcw163] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 05/24/2016] [Accepted: 06/22/2016] [Indexed: 05/22/2023]
Abstract
BACKGROUND AND AIMS Models of costs and benefits of dormancy (D) predict that the evolutionarily stable strategy in long-term stable environments is for non-dormancy (ND), but this prediction remains to be tested empirically. We reviewed seed traits of species in the climatically buffered, geologically stable and nutrient-impoverished campo rupestre grasslands in Brazil to test the hypothesis that ND is favoured over D. We examined the relative importance of life-history traits and phylogeny in driving the evolution of D and assessed seed viability at the community level. METHODS Germination and viability data were retrieved from 67 publications and ND/D was determined for 168 species in 25 angiosperm families. We also obtained the percentage of embryoless, viable and dormant seeds for 74 species. Frequencies of species with dormant and non-dormant seeds were compared with global databases of dormancy distribution. KEY RESULTS The majority of campo rupestre taxa (62·5 %) had non-dormant seeds, and the ND/D ratio was the highest for any vegetation type on Earth. Dormancy was unrelated to other species life-history traits, suggesting that contemporary factors are poor predictors of D. We found a significant phylogenetic structure in the dormancy categorical trait. Dormancy diversity was highly skewed towards the root of the phylogenetic tree and there was a strong phylogenetic signal in the data, suggesting a major role of phylogeny in determining the evolution of D versus ND and seed viability. Quantitative analysis of the data revealed that at least half of the seeds produced by 46 % of the surveyed populations were embryoless and/or otherwise non-viable. CONCLUSIONS Our results support the view that long-term climatic and geological stability favour ND. Seed viability data show that campo rupestre species have a markedly low investment in regeneration from seeds, highlighting the need for specific in situ and ex situ conservation strategies to avoid loss of biodiversity.
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Affiliation(s)
- Roberta L C Dayrell
- Departamento de Botânica, ICB/UFMG, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270-110, Brazil
| | - Queila S Garcia
- Departamento de Botânica, ICB/UFMG, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270-110, Brazil
| | - Daniel Negreiros
- Instituto de Ciências Biológicas e Saúde, Centro Universitário UNA, Rua Guajajaras 175, 30180-100 Belo Horizonte, MG, Brazil
| | - Carol C Baskin
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA
| | - Jerry M Baskin
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Fernando A O Silveira
- Departamento de Botânica, ICB/UFMG, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270-110, Brazil
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Yardeni G, Tessler N, Imbert E, Sapir Y. Reproductive isolation between populations of Iris atropurpurea is associated with ecological differentiation. ANNALS OF BOTANY 2016; 118:971-982. [PMID: 27436798 PMCID: PMC5055820 DOI: 10.1093/aob/mcw139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 05/13/2016] [Accepted: 05/23/2016] [Indexed: 05/28/2023]
Abstract
Background and Aims Speciation is often described as a continuous dynamic process, expressed by different magnitudes of reproductive isolation (RI) among groups in different levels of divergence. Studying intraspecific partial RI can shed light on mechanisms underlying processes of population divergence. Intraspecific divergence can be driven by spatially stochastic accumulation of genetic differences following reduced gene flow, resulting in increased RI with increased geographical distance, or by local adaptation, resulting in increased RI with environmental difference. Methods We tested for RI as a function of both geographical distance and ecological differentiation in Iris atropurpurea, an endemic Israeli coastal plant. We crossed plants in the Netanya Iris Reserve population with plants from 14 populations across the species' full distribution, and calculated RI and reproductive success based on fruit set, seed set and fraction of seed viability. Key Results We found that total RI was not significantly associated with geographical distance, but significantly increased with ecological distance. Similarly, reproductive success of the crosses, estimated while controlling for the dependency of each component on the previous stage, significantly reduced with increased ecological distance. Conclusions Our results indicate that the rise of post-pollination reproductive barriers in I. atropurpurea is more affected by ecological differentiation between populations than by geographical distance, supporting the hypothesis that ecological differentiation is predominant over isolation by distance and by reduced gene flow in this species. These findings also affect conservation management, such as genetic rescue, in the highly fragmented and endangered I. atropurpurea.
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Affiliation(s)
- Gil Yardeni
- The Botanical Garden, Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Naama Tessler
- Department of Biology, University of Haifa, Oranim, Tivon, Israel
| | - Eric Imbert
- Institut des Sciences de l’Evolution CNRS, IRD, University Montpellier 2, Montpellier, France
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Ruane LG, Dickens ME, Wall ME. Fitness consequences of short- and long-distance pollinations in Phlox hirsuta, an endangered species. AMERICAN JOURNAL OF BOTANY 2015; 102:1659-1665. [PMID: 26437884 DOI: 10.3732/ajb.1500270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 09/01/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY The persistence of rare and endangered plant species may depend on the distance pollinators travel when dispersing pollen. Pollinations between adjacent plants, which are often genetically similar, can decrease seed set, germination, and/or progeny vigor due to shared S-alleles or inbreeding depression. Interpopulation pollen dispersal is often suggested as a management tool to increase genetic diversity; however, long-distance pollinations also have the potential to decrease fitness. METHODS We performed experimental hand pollinations in the field and germination experiments in a growth chamber to determine the effect of intrapopulation pollination distance (1 m, 10 m, and 100 m) on seed set, seed germination, progeny growth, and progeny reproduction in Phlox hirsuta. In addition, we included interpopulation pollinations (6740 m) to determine whether artificial gene flow is a viable management option for this endangered species. KEY RESULTS Although pollination distance did not affect the number of healthy seeds produced or the likelihood of radicle emergence, it did significantly affect the ability of germinating seeds to successfully produce cotyledons. Outbreeding depression was observed during seed germination and early seedling development. Seedlings resulting from interpopulation pollinations developed more slowly and were less likely to survive to produce cotyledons than seedlings resulting from all three intrapopulation pollination distances. CONCLUSIONS Our results suggest that the success of P. hirsuta does not depend on the distance pollinators travel within populations and that conservation strategies that involve transporting genes between populations can be counterproductive.
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Affiliation(s)
- Lauren G Ruane
- Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia 23606 USA
| | - Morgan E Dickens
- Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia 23606 USA
| | - Morgan E Wall
- Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia 23606 USA
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Assessing genetic structure in a rare clonal eucalypt as a basis for augmentation and introduction translocations. CONSERV GENET 2015. [DOI: 10.1007/s10592-015-0781-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Whiteley AR, Fitzpatrick SW, Funk WC, Tallmon DA. Genetic rescue to the rescue. Trends Ecol Evol 2015; 30:42-9. [DOI: 10.1016/j.tree.2014.10.009] [Citation(s) in RCA: 355] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 01/26/2023]
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The population biology of mitigation: impacts of habitat creation on an endangered plant species. CONSERV GENET 2014. [DOI: 10.1007/s10592-014-0569-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Mate limitation in populations of the endangered Convolvulus lineatus L.: A case for genetic rescue? J Nat Conserv 2013. [DOI: 10.1016/j.jnc.2013.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Severns PM, Bradford E, Liston A. Whole genome duplication in a threatened grassland plant and the efficacy of seed transfer zones. DIVERS DISTRIB 2012. [DOI: 10.1111/ddi.12004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
| | - Emma Bradford
- Department of Botany and Plant Pathology; Oregon State University; Corvallis; OR; USA
| | - Aaron Liston
- Department of Botany and Plant Pathology; Oregon State University; Corvallis; OR; USA
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Gross CL, Nelson PA, Haddadchi A, Fatemi M. Somatic mutations contribute to genotypic diversity in sterile and fertile populations of the threatened shrub, Grevillea rhizomatosa (Proteaceae). ANNALS OF BOTANY 2012; 109:331-42. [PMID: 22080138 PMCID: PMC3268532 DOI: 10.1093/aob/mcr283] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 10/20/2011] [Indexed: 05/22/2023]
Abstract
BACKGROUND AND AIMS Grevillea rhizomatosa is a spreading shrub which exhibits multiple breeding strategies within a narrow area in the fire-prone heathlands of eastern Australia. Reproductive strategies include self-compatibility, self-incompatibility and clonality (with and without sterility). The close proximity of contrasting breeding systems provides an opportunity to explore the evolution of sterility and to compare and contrast the origins of genotypic diversity (recombinant or somatic) against degrees of sexual expression. METHODS ISSR markers for 120 band positions (putative loci) were used to compare genetic diversity among five populations at a macro-scale of 5 m between samples (n = 244 shrubs), and at a micro-scale of nearest neighbours for all plants in five 25-m(2) quadrats with contrasting fertilities (n = 162 shrubs). Nearest-neighbour sampling included several clusters of connected ramets. Matrix incompatibility (MIC) analyses were used to evaluate the relative contribution of recombination and somatic mutation to genotype diversity. KEY RESULTS High levels of genotypic diversity were found in all populations regardless of fertilities (fertile populations, G/N ≥ 0·94; sterile populations, G/N ≥ 0·97) and most sterile populations had a unique genetic profile. Somatic mutations were detected along connected ramets in ten out of 42 ramet clusters. MIC analyses showed that somatic mutations have contributed to diversity in all populations and particularly so in sterile populations. CONCLUSIONS Somatic mutations contribute significantly to gene diversity in sterile populations of Grevillea rhizomatosa, the accumulation of which is the likely cause of male and female sterility. High levels of genetic diversity therefore may not always be synonymous with sexual fitness and genetic health. We hypothesize that frequent fires drive selection for clonal reproduction, at the cost of flowering such that sexual functions are not maintained through selection, and the build-up of somatic mutations in meristems results in high genotype diversity at the cost of pollen and ovule fertilities.
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Affiliation(s)
- C L Gross
- Ecosystem Management, University of New England, Armidale, NSW, Australia.
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Weeks AR, Sgro CM, Young AG, Frankham R, Mitchell NJ, Miller KA, Byrne M, Coates DJ, Eldridge MDB, Sunnucks P, Breed MF, James EA, Hoffmann AA. Assessing the benefits and risks of translocations in changing environments: a genetic perspective. Evol Appl 2011; 4:709-725. [PMID: 22287981 PMCID: PMC3265713 DOI: 10.1111/j.1752-4571.2011.00192.x] [Citation(s) in RCA: 405] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 05/11/2011] [Indexed: 11/28/2022] Open
Abstract
Translocations are being increasingly proposed as a way of conserving biodiversity, particularly in the management of threatened and keystone species, with the aims of maintaining biodiversity and ecosystem function under the combined pressures of habitat fragmentation and climate change. Evolutionary genetic considerations should be an important part of translocation strategies, but there is often confusion about concepts and goals. Here, we provide a classification of translocations based on specific genetic goals for both threatened species and ecological restoration, separating targets based on 'genetic rescue' of current population fitness from those focused on maintaining adaptive potential. We then provide a framework for assessing the genetic benefits and risks associated with translocations and provide guidelines for managers focused on conserving biodiversity and evolutionary processes. Case studies are developed to illustrate the framework.
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Forrest CN, Ottewell KM, Whelan RJ, Ayre DJ. Tests for inbreeding and outbreeding depression and estimation of population differentiation in the bird-pollinated shrub Grevillea mucronulata. ANNALS OF BOTANY 2011; 108:185-95. [PMID: 21546431 PMCID: PMC3119612 DOI: 10.1093/aob/mcr100] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Accepted: 03/10/2011] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS Plants show patterns of spatial genetic differentiation reflecting gene flow mediated by pollen and seed dispersal and genotype × environment interactions. If patterns of genetic structure are determined largely by gene flow then they may be useful in predicting the likelihood of inbreeding or outbreeding depression but should be less useful if there is strong site-specific selection. For many Australian plants little is known about either their population genetics or the effects on mating systems of variation in pollen transfer distances. Experimental pollinations were used to compare the reproductive success of bird-adapted Grevillea mucronulata plants mated with individuals from a range of spatial scales. A hierarchical survey of microsatellite DNA variation was also conducted to describe the scale of population differentiation for neutral markers. METHODS The effects of four pollen treatments on reproductive performance were compared. These treatments were characterized by transfer of pollen from (a) neighbouring adults; (b) an adjacent cluster of adults (30-50 m distant); (c) a distant cluster (>5 km distant); and (d) open pollination. Sets of 17·9 ± 3·3 leaves from each of 15 clusters of plants were genotyped and spatial autocorrelation and F statistics were used to describe patterns of genetic structure. KEY RESULTS Grevillea mucronulata displayed evidence of both inbreeding and outbreeding depression, with 'intermediate' pollen producing consistently superior outcomes for most aspects of fitness including seed set, seed size, germination and seedling growth. Significant genotypic structuring was detected within clusters (spatial autocorrelation) and among adjacent clusters and clusters separated by >5 km distance (F(ST) = 0·07 and 0·10). CONCLUSIONS The superior outcome of intermediate pollen transfer and genetic differentiation of adjacent clusters suggests that G. mucronulata selection disfavours matings among closely and distantly related neighbours. Moreover, the performance of open-pollinated seedlings was poor, implying that current mating patterns are suboptimal.
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Affiliation(s)
- Cairo N Forrest
- Institute for Conservation Biology and School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia.
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Severns PM, Liston A, Wilson MV. Habitat fragmentation, genetic diversity, and inbreeding depression in a threatened grassland legume: is genetic rescue necessary? CONSERV GENET 2011. [DOI: 10.1007/s10592-011-0191-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Sgrò CM, Lowe AJ, Hoffmann AA. Building evolutionary resilience for conserving biodiversity under climate change. Evol Appl 2010; 4:326-37. [PMID: 25567976 PMCID: PMC3352557 DOI: 10.1111/j.1752-4571.2010.00157.x] [Citation(s) in RCA: 371] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/07/2010] [Indexed: 11/27/2022] Open
Abstract
Evolution occurs rapidly and is an ongoing process in our environments. Evolutionary principles need to be built into conservation efforts, particularly given the stressful conditions organisms are increasingly likely to experience because of climate change and ongoing habitat fragmentation. The concept of evolutionary resilience is a way of emphasizing evolutionary processes in conservation and landscape planning. From an evolutionary perspective, landscapes need to allow in situ selection and capture high levels of genetic variation essential for responding to the direct and indirect effects of climate change. We summarize ideas that need to be considered in planning for evolutionary resilience and suggest how they might be incorporated into policy and management to ensure that resilience is maintained in the face of environmental degradation.
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Affiliation(s)
- Carla M Sgrò
- Centre for Environmental Stress & Adaptation Research (CESAR) and Australian Centre for Biodiversity, School of Biological Sciences, Monash University, Clayton Victoria, Australia
| | - Andrew J Lowe
- Australian Centre for Evolutionary Biology and Biodiversity (ACEBB), School of Earth and Environmental Science, University of Adelaide North Terrace, Adelaide, Australia ; Department for Environment and Heritage, State Herbarium of South Australia North Terrace, Adelaide, Australia
| | - Ary A Hoffmann
- Department of Zoology, Centre for Environmental Stress & Adaptation Research (CESAR), The University of Melbourne Parkville, Victoria, Australia
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Allendorf FW, Hohenlohe PA, Luikart G. Genomics and the future of conservation genetics. Nat Rev Genet 2010; 11:697-709. [DOI: 10.1038/nrg2844] [Citation(s) in RCA: 939] [Impact Index Per Article: 67.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Pinto-Torres E, Koptur S. Hanging by a coastal strand: breeding system of a federally endangered morning-glory of the south-eastern Florida coast, Jacquemontia reclinata. ANNALS OF BOTANY 2009; 104:1301-11. [PMID: 19797424 PMCID: PMC2778389 DOI: 10.1093/aob/mcp241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
BACKGROUND AND AIMS Coastal development has led to extensive habitat destruction and the near extinction of the beach clustervine, Jacquemontia reclinata (Convolvulaceae), an endangered, perennial vine endemic to dune and coastal strand communities in south-eastern Florida. We examined the breeding system of this rare species, and observed visitors to its flowers, as part of a larger effort to document its status and facilitate its recovery. METHODS Reproductively mature experimental plants were grown from seed collected from wild plants in two of the largest remaining populations. Controlled hand pollinations on potted plants were conducted to determine the level of compatibility of the species and to investigate compatibility within and between populations. Seeds from the hand pollinations were planted in soil, and they were monitored individually, recording time to seed germination (cotyledon emergence). Wild plants were observed in several of the remaining populations to determine which species visited the flowers. KEY RESULTS Hand pollination and seed planting experiments indicate that J. reclinata has a mixed mating system: flowers are able to set fruit with viable seeds with self-pollen, but outcross pollen produces significantly greater fruit and seed set than self-pollen (> or =50 % for crosses vs. <25 % for self-pollinations). Visitors included a wide array of insect species, primarily of the orders Diptera, Hymenoptera and Lepidoptera. All visitors captured and examined carried J. reclinata pollen, and usually several other types of pollen. CONCLUSIONS Remnant populations of beach clustervine will have greater reproductive success not only if floral visitor populations are maintained, but also if movement of either pollen or seed takes place between populations. Restoration efforts should include provisions for the establishment and maintenance of pollinator populations.
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Affiliation(s)
- Elena Pinto-Torres
- Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199, USA
- Fairchild Tropical Botanic Garden, Miami, FL 33156, USA
| | - Suzanne Koptur
- Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199, USA
- For correspondence. E-mail:
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Holmes GD, James EA, Hoffmann AA. Limitations to reproductive output and genetic rescue in populations of the rare shrub Grevillea repens (Proteaceae). ANNALS OF BOTANY 2008; 102:1031-41. [PMID: 18922849 PMCID: PMC2712411 DOI: 10.1093/aob/mcn195] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS When conserving rare plant species, managers are often faced with small and/or isolated populations displaying low levels of sexual reproduction and genetic variation. One option for reinvigorating these populations is the introduction of genetic material from other sites, but in some cases fitness may be reduced as a result of outbreeding depression. Here the pollination biology of the rare shrub Grevillea repens is studied across its natural range and reproductive responses following cross-pollination among populations are examined to determine factors that may be limiting sexual reproduction and the potential for genetic rescue. METHODS Pollen manipulation treatments (self-, autogamous self-, cross- and open pollination) were applied to flowers to examine the breeding system and fruit and seed production in five populations of G. repens. Pollen production, presentation and viability were investigated and interpopulation crosses of increasing genetic distance performed among the populations. KEY RESULTS The study species is self-incompatible and displayed very low natural seed set over two seasons, due partly to low pollen viability in one of the populations. Within-population crossing increased fruit and seed production at some sites, indicating pollinator limitation. Interpopulation crosses further increased reproductive output in one population, suggesting mate limitation, and for this site there was a positive relationship between genetic distance among populations and the size of genetic rescue benefits. However, in other populations there was a decrease in fruit and seed set with increasing genetic distance. CONCLUSIONS The results highlight that management strategies involving interpopulation crosses can improve reproductive output in small, isolated populations of rare plants, but guidelines need to be developed on a population by population basis.
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Affiliation(s)
- G D Holmes
- Centre for Environmental Stress and Adaptation Research (CESAR), Department of Genetics, Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia.
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