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Li M, Sui Y, Wang X, Ma Z, Luo Y, Aluthwattha ST, McKey D, Pujol B, Chen J, Zhang L. High outcrossing rates in a self-compatible and highly aggregated host-generalist mistletoe. Mol Ecol 2022; 31:6489-6504. [PMID: 36201456 DOI: 10.1111/mec.16720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/19/2022] [Accepted: 09/28/2022] [Indexed: 01/13/2023]
Abstract
Plants have evolved various strategies to avoid inbreeding, but the mass flowering displayed by many plants predisposes them to within-plant pollen movements and self-pollination. Mistletoes often aggregate at multiple spatial scales. Their bird pollinators often visit several flowers of the same individual and of others on the same host tree. We hypothesized that hermaphroditic mistletoes have self-incompatibility mechanisms that reduce or prevent selfing. Whether their spatial distribution, affected by host specificity, host distribution, and the behaviour of seed dispersers, influences their mating system and population genetic structure remains unclear. We studied how mating system and spatial distribution affect genetic structure in four populations of the host-generalist mistletoe Dendrophthoe pentandra in southwestern China using microsatellite markers and progeny arrays. We also characterized the fine-scale spatial genetic structure among 166 mistletoes from four host trees in one population. Prevalence and intensity of infection both appeared to vary among host species, strongly affecting the degree of aggregation. Host tree size had a strong effect on infection intensity. Surprisingly, manual pollination experiments indicated that D. pentandra is self-compatible, but genetic analyses revealed that outcrossing rates were higher than expected in all four populations (MLTR tm 0.83-1.20, Bayesian tm 0.772-0.952). Spatial genetic structure was associated with distance between host trees but not at shorter scales (within hosts). Our results demonstrate that the combination of bird pollination, bird-mediated seed dispersal, and post-dispersal processes result in outcrossing and maintain relatively high diversity in the presence of biparental inbreeding, despite very high local densities and possible self-compatibility.
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Affiliation(s)
- Manru Li
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yi Sui
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xuanni Wang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhanxia Ma
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yahuang Luo
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Sasith Tharanga Aluthwattha
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Doyle McKey
- CEFE, University of Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Benoit Pujol
- PSL Université Paris, EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan, France
| | - Jin Chen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Ling Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
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Walters SJ, Robinson TP, Byrne M, Wardell‐Johnson GW, Nevill P. Association of putatively adaptive genetic variation with climatic variables differs between a parasite and its host. Evol Appl 2021; 14:1732-1746. [PMID: 34295360 PMCID: PMC8288004 DOI: 10.1111/eva.13234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 03/13/2021] [Accepted: 03/15/2021] [Indexed: 11/28/2022] Open
Abstract
Parasitism is a pervasive phenomenon in nature with the relationship between species driving evolution in both parasite and host. Due to their host-dependent lifestyle, parasites may adapt to the abiotic environment in ways that differ from their hosts or from free-living relatives; yet rarely has this been assessed. Here, we test two competing hypotheses related to whether putatively adaptive genetic variation in a specialist mistletoe associates with the same, or different, climatic variables as its host species. We sampled 11 populations of the specialist mistletoe Amyema gibberula var. tatei (n = 154) and 10 populations of its associated host Hakea recurva subsp. recurva (n = 160). Reduced-representation sequencing was used to obtain genome-wide markers and putatively adaptive variation detected using genome scan methods. Climate associations were identified using generalized dissimilarity modelling, and these were mapped geographically to visualize the spatial patterns of genetic composition. Our results supported the hypothesis of parasites and host species responding differently to climatic variables. Temperature was relatively more important in predicting allelic turnover in the specialist mistletoe while precipitation was more important for the host. This suggests that parasitic plants and host species may respond differently to selective pressures, potentially as a result of differing nutrient acquisition strategies. Specifically, mistletoes acquire water from hosts (rather than the abiotic environment), which may provide a buffer to precipitation as a selective pressure. This work deepens and complements the physiological and other ecological studies of adaptation and provides a window into the evolutionary processes that underlie previously observed phenomena. Applying these methods to a comparative study in a host-parasite system has also highlighted factors that affect the study of selection pressure on nonmodel organisms, such as differing adaptation rates and lack of reference genomes.
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Affiliation(s)
- Sheree J. Walters
- ARC Centre for Mine Site RestorationSchool of Molecular and Life SciencesCurtin UniversityBentleyWAAustralia
| | - Todd P. Robinson
- School of Earth and Planetary ScienceCurtin UniversityBentleyWAAustralia
| | - Margaret Byrne
- Biodiversity and Conservation ScienceDepartment of Biodiversity, Conservation and AttractionsBentleyWAAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWAAustralia
| | - Grant W. Wardell‐Johnson
- ARC Centre for Mine Site RestorationSchool of Molecular and Life SciencesCurtin UniversityBentleyWAAustralia
| | - Paul Nevill
- ARC Centre for Mine Site RestorationSchool of Molecular and Life SciencesCurtin UniversityBentleyWAAustralia
- Trace and Environmental DNA LaboratorySchool of Molecular and Life SciencesCurtin UniversityBentleyWAAustralia
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Lara C, Xicohténcatl-Lara L, Ornelas JF. Differential reproductive responses to contrasting host species and localities in Psittacanthus calyculatus (Loranthaceae) mistletoes. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:603-611. [PMID: 33819386 DOI: 10.1111/plb.13266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
Host trees are immediate environments for multi-host mistletoes, so parasitizing different hosts implies exposure to varying environmental conditions between mistletoe generations. Therefore, to maximize reproductive fitness in heterogeneous environments (host species) mistletoes should adjust its reproductive responses in relation to circumstances. Here, we ask how reproductive traits of Psittacanthus calyculatus mistletoes vary on two host tree species (Crataegus mexicana, Prunus serotina) at three different localities. We followed individual mistletoes on each host species and at three localities through the flowering season to quantify traits related to reproductive effort and success, e.g. total number of buds, flowers and fruits produced. In buds about to open, we measured two anthers and quantified the number of pollen grains and their viability. Individual flowers were marked to obtain flower longevity data and were followed until fruit formation. At which time we measured and weighed the fruits and the seeds. Mistletoes from one locality produced more buds, flowers and fruits, and the flowers lasted longer, had larger anthers and produced more pollen as compared to the other two localities. However, mistletoes on Prunus serotina produced fewer floral buds, but their fruits were heaviest, longest and widest and ripened fastest across localities. The probability of fruit formation, percentage of fruits formed, and pollen viability were similar among the mistletoes, regardless of host species or locality. We propose that the observed differences in reproductive effort and success associated with host species or locality are plastic or adaptive in this mistletoe in response to varying conditions.
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Affiliation(s)
- C Lara
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico
| | - L Xicohténcatl-Lara
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico
| | - J F Ornelas
- Departamento de Biología Evolutiva, Instituto de Ecología, A.C. (INECOL), Veracruz, Mexico
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Nabity PD, Barron-Gafford GA, Whiteman NK. Intraspecific competition for host resources in a parasite. Curr Biol 2021; 31:1344-1350.e3. [PMID: 33626328 DOI: 10.1016/j.cub.2021.01.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/13/2020] [Accepted: 01/12/2021] [Indexed: 11/28/2022]
Abstract
Intraspecific competition among parasites should, in theory, increase virulence, but we lack clear evidence of this from nature.1-3 Parasitic plants, which are sessile and acquire carbon-based resources through both autotrophy (photosynthesis) and heterotrophy (obtaining carbon from the host), provide a unique opportunity to experimentally study the role of intraspecific competition for nutrients in shaping the biology of both parasite and host.4-6 Here, we manipulated the spatial position of naturally occurring individuals of desert mistletoe (Phoradendron californicum), a xylem hemiparasite, by removing parasites from co-infected branches of a common nitrogen-fixing host, velvet mesquite (Prosopsis velutina), in the Sonoran Desert. We measured physiological performance of both host and parasite individuals under differing competitive environments-parasite location along the xylem stream-through time. Performance was determined by measuring resource availability and use, given that resource demand changed with competitor removal and monsoon-driven amelioration of seasonal drought. Our principal finding was that intraspecific competition exists for xylem resources between mistletoe individuals, including host carbon. Host performance and seasonal climate variation altered the strength of competition and virulence. Hemiparasitic desert mistletoes demonstrated high heterotrophy, yet experimental removals revealed density- and location-dependent effects on the host through feedbacks that reduced mistletoe autotrophy and improved resource availability for the remaining mistletoe individual. Trophic flexibility tempered intraspecific competition for resources and reduced virulence. Mistletoe co-infections might therefore attenuate virulence to maintain access to resources in particularly stressful ecological environments. In summary, experimental field manipulations revealed evidence for intraspecific competition in a parasite species.
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Affiliation(s)
- Paul D Nabity
- Department of Botany and Plant Sciences, University of California, Riverside, 900 University Avenue, Riverside, CA 92125, USA.
| | - Greg A Barron-Gafford
- School of Geography, Development, and the Environment, University of Arizona, PO Box 210137, Tucson, AZ 85721, USA
| | - Noah K Whiteman
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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5
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Kairo G, Pioz M, Tchamitchian S, Pelissier M, Brunet JL, Belzunces LP. Efficiency of an air curtain as an anti-insect barrier: the honey bee as a model insect. PEST MANAGEMENT SCIENCE 2018; 74:2707-2715. [PMID: 29808535 DOI: 10.1002/ps.5090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/22/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Vector-borne diseases are of high concern for human, animal and plant health. In humans, such diseases are often transmitted by flying insects. Flying insects stop their flight when their kinetic energy cannot compensate for the wind speed. Here, the efficiency of an air curtain in preventing insects from entering a building was studied using the honey bee as a model. RESULTS Bees were trained to visit a food source placed in a building. The air curtain was tested with strongly motivated bees, when the visiting activity was very high. Airflow velocity was modulated by setting an air curtain device at different voltages. At the nominal voltage, the anti-insect efficiency was 99.9 ± 0.2% compared with both the number of bees at a given time in the absence of the air curtain and the number of bees before the activation of the air curtain. The efficiency decreased as the airflow velocity decreased. CONCLUSION The results show that an air curtain operating at an airflow velocity of 7.5 m s-1 may prevent a strong flyer with high kinetic energy, such as the honey bee, from entering a building. Thus, air curtains offer an alternative approach for combating vector-borne diseases. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Guillaume Kairo
- INRA, Laboratoire de Toxicologie Environnementale, UR 406 Abeilles & Environnement, Avignon, France
| | - Maryline Pioz
- INRA, Laboratoire de Toxicologie Environnementale, UR 406 Abeilles & Environnement, Avignon, France
| | - Sylvie Tchamitchian
- INRA, Laboratoire de Toxicologie Environnementale, UR 406 Abeilles & Environnement, Avignon, France
| | - Michel Pelissier
- INRA, Laboratoire de Toxicologie Environnementale, UR 406 Abeilles & Environnement, Avignon, France
| | - Jean-Luc Brunet
- INRA, Laboratoire de Toxicologie Environnementale, UR 406 Abeilles & Environnement, Avignon, France
| | - Luc P Belzunces
- INRA, Laboratoire de Toxicologie Environnementale, UR 406 Abeilles & Environnement, Avignon, France
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Hybridization and differential introgression associated with environmental shifts in a mistletoe species complex. Sci Rep 2018; 8:5591. [PMID: 29615778 PMCID: PMC5882953 DOI: 10.1038/s41598-018-23707-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/12/2018] [Indexed: 12/22/2022] Open
Abstract
Host specialization after host shifting is traditionally viewed as the pathway to speciation in parasitic plants. However, geographical and environmental changes can also influence parasite speciation, through hybridization processes. Here we investigated the impact of past climatic fluctuations, environment, and host shifts on the genetic structure and patterns of hybridization and gene flow between Psittacanthus calyculatus and P. schiedeanus, a Mesoamerican species complex. Using microsatellites (408 individuals), we document moderate genetic diversity but high genetic differentiation between widespread parental clusters, calyculatus in dry pine-oak forests and schiedeanus in cloud forests. Bayesian analyses identified a third cluster, with admixture between parental clusters in areas of xeric and tropical dry forests and high levels of migration rates following secondary contact. Coincidently host associations in these areas differ from those in areas of parental species, suggesting that past hybridization played a role in environmental and host shifts. Overall, the observed genetic and geographic patterns suggest that these Psittacanthus populations could have entered a distinct evolutionary pathway. The results provide evidence for highlights on the importance of the Pleistocene climate changes, habitat differences, and potential host shifts in the evolutionary history of Neotropical mistletoes.
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Yule KM, Bronstein JL. Reproductive ecology of a parasitic plant differs by host species: vector interactions and the maintenance of host races. Oecologia 2017; 186:471-482. [DOI: 10.1007/s00442-017-4038-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 12/04/2017] [Indexed: 12/21/2022]
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Ramírez-Barahona S, González C, González-Rodríguez A, Ornelas JF. The influence of climatic niche preferences on the population genetic structure of a mistletoe species complex. THE NEW PHYTOLOGIST 2017; 214:1751-1761. [PMID: 28205240 DOI: 10.1111/nph.14471] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 01/05/2017] [Indexed: 06/06/2023]
Abstract
The prevalent view on genetic structuring in parasitic plants is that host-race formation is caused by varying degrees of host specificity. However, the relative importance of ecological niche divergence and host specificity to population differentiation remains poorly understood. We evaluated the factors associated with population differentiation in mistletoes of the Psittacanthus schiedeanus complex (Loranthaceae) in Mexico. We used genetic data from chloroplast sequences and nuclear microsatellites to study population genetic structure and tested its association with host preferences and climatic niche variables. Pairwise genetic differentiation was associated with environmental and host preferences, independent of geography. However, environmental predictors appeared to be more important than host preferences to explain genetic structure, supporting the hypothesis that the occurrence of the parasite is largely determined by its own climatic niche and, to a lesser degree, by host specificity. Genetic structure is significant within this mistletoe species complex, but the processes associated with this structure appear to be more complex than previously thought. Although host specificity was not supported as the major determinant of population differentiation, we consider this to be part of a more comprehensive ecological model of mistletoe host-race formation that incorporates the effects of climatic niche evolution.
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Affiliation(s)
- Santiago Ramírez-Barahona
- Departamento de Biología Evolutiva, Instituto de Ecología, AC (INECOL), Carretera antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz, 91070, Mexico
| | - Clementina González
- CONACyT-Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo, Av. San Juanito Itzícuaro s/n, Nueva Esperanza, Morelia, Michoacán, 58330, Mexico
| | - Antonio González-Rodríguez
- Laboratorio de Genética de la Conservación, Instituto de Investigaciones en Ecosistemas y Sustentabilidad (IIES), UNAM, Antigua carretera a Pátzcuaro 8701, Ex Hacienda de San José de la Huerta, Morelia, Michoacán, 58190, Mexico
| | - Juan Francisco Ornelas
- Departamento de Biología Evolutiva, Instituto de Ecología, AC (INECOL), Carretera antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz, 91070, Mexico
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Pérez-Crespo MJ, Lara C, Ornelas JF. Uncorrelated mistletoe infection patterns and mating success with local host specialization in Psittacanthus calyculatus (Loranthaceae). Evol Ecol 2016. [DOI: 10.1007/s10682-016-9866-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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