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In a previous study, we showed that the geographic proximity of hybrid plants to the allopatric areas of parental species increases their morphological and genetic similarity with them. In the present work, we explored whether the endophagous fauna of hybrid plants show the same pattern. We studied the canopy species richness, diversity and composi...
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... Consequently, modifications in genetic, morphological, or chemical traits among genetic categories (hybrids and parental species) can potentially influence the communities of associated species [7]. In fact, several studies have demonstrated the effect of host species genetics on the structure of associated communities within hybrid zones [3,7,[28][29][30]. However, to date, most studies that have evaluated the effect of the genetics of the host plants involved in hybridization events on community structure have emphasized the response of organisms that feed directly on the plant as phytophagous insects. ...
... Previously, each of these species was characterized by leaf morphology and genetic markers (random amplified polymorphic DNA; RAPDs), and it was reported that the geographic proximity of hybrid plants to the allopatric site of a parental species increases their morphological and genetic similarity with the latter [26]. Also, Tovar-Sánchez and Oyama [29] determined that the composition, abundance, and diversity of the community of endophagous insects (gall-forming wasps and leaf miner moths) were affected by the host oak genetic categories (parental species or hybrid) and the genetic diversity at the stand level (HZ). In addition, the hybrid plants supported intermediate levels of infestation of gall-forming and leaf-mining insects compared to their putative parental species. ...
... In general, studies that have documented the effect of plant hybridization have focused on arthropod communities. For example, Tovar-Sánchez and Oyama evaluated the effect of hybridization of the Q. crassifolia × Q. crassipes complex on the community structure of endophagous [29] and ectophagous [30] insects. In both communities, they found significant differences in the insect species composition between parental species and hybrids, showing that these communities on each host taxa are significantly different from one another. ...
Lichens are organisms whose dynamics take place on terrestrial substrates such as rock, dead wood, living plants, and soil. Living trees are used for lichens as structural support to access light. However, little is known about how the genetic traits of a host tree influence which lichen species grow on it and, consequently, the community structure of this funga. In this study, we investigated how the genetic diversity GD of host oak taxa (Quercus crassifolia, Q. crassipes and their putative hybrid: Q. × dysophylla) influence the community structure of the associated epiphytic lichen community in two hybrid zones (HZs) in Central Mexico. The lichen community was composed of 76 species, 27 genera and 14 families. We found significant differences in lichen composition between genetically distinct individuals and oak taxa in each HZ. Lichen diversity in Q. × dysophylla was intermediate and significantly different between parents in both HZs. We conclude that genetic differences between host oaks promoted significantly different lichen communities and that hybrids may act as ecological islands, accumulating lichen species from both parental species and their own novel species. Consequently, the conservation of HZs due to their high GD may be a strategy to ensure biodiversity conservation of oak-associated lichen communities.
... . Also, some studies have shown that increasing genetic diversity within interbreeding plant systems (e.g., hybrids and single plant species) increases arthropod diversity and community structure [8,9]. Plant genetics play an important role in SMs production and plant architecture [10-13]. ...
... Oaks dominate the canopy of forest ecosystems and have an extensive and complex network of interactions with other organisms, such as epiphytic plants, mammals, birds, fungi and arthropods [24]. In particular, oak distribution, abundance and species richness have significantly influenced the distribution and species richness of oak gall wasps [8]. ...
... In total, 100 individuals belonging to four populations (two allopatric [20 trees/site, one for each parental species] and two sympatric sites [30 trees/site]) were analyzed (Table 1). We selected this sample size considering that previous studies have used similar sample sizes and found significant and robust results [8,9,18]. To minimize the influence of environmental and spatial variables on gall-inducing wasps and their parasitoid communities, all study sites shared the following characteristics: geological history (all localities belonged to the central part of Mexico, originating during the Pliocene-Quaternary [55]), weather (sub-humid temperate [56]), altitude (between 2318 and 2667 m), vegetation type (mature oak) and soil type (volcanic origin: histosol [57]). ...
The hybridization phenomenon increases genetic diversity and modifies recombinant individuals’ secondary metabolite (SMs) content, affecting the canopy-dependent community. Hybridization events occur when Quercus rugosa and Q. glabrescens oaks converge in sympatry. Here, we analyzed the effect of the genetic diversity (He) and SMs of Q. rugosa, Q. glabrescens and hybrids on the community of gall-inducing wasps (Cynipidae) and their parasitoids on 100 oak canopy trees in two allopatric and two hybrid zones. Eighteen gall wasp species belonging to six genera and six parasitoid genera contained in four families were identified. The most representative parasitoid genera belonged to the Chalcidoidea family. Abundance, infestation levels and richness of gall wasps and their parasitoids registered the next pattern: Q. rugosa higher than the hybrids, and the hybrids equal to Q. glabrescens. Oak host genetic diversity was the variable with the highest influence on the quantitative SMs expression, richness and abundance of gall wasps and their parasitoids. The influence of SMs on gall wasps and their parasitoids showed the next pattern: scopoletin > quercitrin > rutin = caffeic acid = quercetin glucoside. Our findings indicate that genetic diversity may be a key factor influencing the dynamics of tri-trophic interactions that involve oaks.
... Many different theories have also been proposed regarding the intensity of herbivory in hybrids and parental species and the possible role of herbivory in the maintenance of different plant species or in the selection of hybrid populations. Different studies have obtained inconsistent results, with higher herbivory in hybrids than in parental species ('Hybrid susceptibility hypothesis') (Mattson et al. 1996, Cuevas-Reyes et al. 2018, lower herbivory in hybrids ('Hybrid resistance hypothesis') (Boecklen and Spellenberg 1990), intermediate herbivory levels in hybrid plants ('Additive hypothesis') (Tovar-Sanchez and Oyama 2006;Pearse and Baty 2012) or no differences from both parents ('Hybrid no difference hypothesis') (Fritz et al. 1996, Cheng et al. 2011). This wide divergence in results for different species suggests that investigating the implications of herbivory on the fitness of hybrids probably requires case-by-case studies. ...
Insect herbivory has attracted enormous attention from researchers due to its effects on plant fitness. However, there remain questions such as what are the most important leaf traits that determine consumption levels, whether there are latitudinal gradients in herbivore pressure, or whether there are differences in susceptibility between hybrids and their parental species. In this work we address all these issues in two species of Mediterranean Quercus (Q. faginea and Q. pyrenaica) and their hybrids. Over two years, we analyzed leaf emergence and 11 leaf traits (biomechanical, chemical and morphological), as well as the levels of herbivory by insects in leaves of the three genetic groups in different locations distributed along a climatic gradient. The hybrids showed intermediate values between both species in leaf emergence, chemical traits and in structural reinforcement. By contrast, they were more similar to Q. faginea in leaf size and shape. Despite their intermediate leaf traits, hybrids always showed lower losses by consumption than both parental species, which suggests that they possess inherent higher resistance to herbivores, which cannot be explained by their dissimilarities in leaf traits. Within each genetic group, differences in leaf size were the most important determinant of differences in herbivory losses, which increased with leaf size. In turn, leaf size increased significantly with the increase in mean annual temperatures across the climatic gradient, in parallel with herbivory losses. In conclusion, contrary to our expectations, hybrids maintained lower levels of herbivory than their parent species. Given the potential negative effect of leaf herbivory on C fixation, this advantage of the hybrids would imply a threat to the persistence of both pure species. More research is needed to elucidate possible alternative mechanisms that allow maintaining species integrity in the absence of reproductive barriers.
... For instance, heritable phenotypes in fish (Poecilia reticulata) are thought to influence ecosystem processes, such as nutrient cycling, because fish phenotypes exhibit different patterns of diet selectivity and excretion rates (4). In addition, the genetic diversity of host plants (Quercus sp.) is thought to be positively associated with the diversity of endophagous insect communities because insect species are often specific to certain host species or hybrids (5). ...
Although detrimental genetic processes are known to adversely affect the viability of populations, little is known about how detrimental genetic processes in a keystone species can affect the functioning of ecosystems. Here, we assessed how changes in the genetic characteristics of a keystone predator, grey wolves, affected the ecosystem of Isle Royale National Park over two decades. Changes in the genetic characteristic of the wolf population associated with a genetic rescue event, followed by high levels of inbreeding, led to a rise and then fall in predation rates on moose, the primary prey of wolves and dominant mammalian herbivore in this system. Those changes in predation rate led to large fluctuations in moose abundance, which in turn affected browse rates on balsam fir, the dominant forage for moose during winter and an important boreal forest species. Thus, forest dynamics can be traced back to changes in the genetic characteristics of a predator population.
... Hybrid individuals represent a wide range of resources and conditions that can be exploited by their associated fauna (Fritz et al. 1999). This is due to increased resources, besides the high ecological and evolutionary activity that characterizes hybrid zones, as they may be generating new habitats for associated organisms (Tovar-Sánchez and Oyama 2006 (Hunter et al. 1997), architecture (Bangert et al. 2005), as well as secondary chemistry (Cheng et al. 2011). These characteristics may be associated with the preferences of insect herbivores, their development and distribution (Fritz et al. 1999;Hochwender and Fritz 2004;Bailey et al. 2009 Contrasting patterns with regard to the effect of hybridization on plants and their influence on the insect herbivore diversity have been found in several studies, ranging from higher, intermediate, lower, or even no difference in the composition of herbivores in hybrid plants (Fritz 1996;Floate et al. 2016;Pérez-López et al. 2016;Cuevas-Reyes et al. 2018). ...
Oak hybridization have important effects on the structure of herbivorous insect communities and associated natural enemies. We tested the effects of hybridization between Q. magnoliifolia and Q. resinosa on insect gallers trophic networks and their parasitoids. We characterized the genotypes of 35 individuals of Q. magnoliifolia, 30 of Q. resinosa, and 57 hybrids using eight nuclear microsatellite markers. We collected 6,798 galls from the oak hybrid complex distributed in 33 gall morphospecies on Q. magnoliifolia, 28 on Q. resinosa, and 42 on hybrid oaks. Galler-parasitoid networks were realized by 21 gall morphospecies and 21 parasitoid species for Q. magnoliifolia; 16 gall morphospecies and 30 parasitoid species for Q. resinosa; and 25 gall morphospecies and 23 parasitoid species for hybrids. Plant-galler networks were different among three oak groups, having the hybrid network higher values of diversity of interactions, nestedness and modularity and lower values of specialization than Q. magnoliifolia and Q. resinosa networks. Hybrid network of gallers and parasitoids had higher diversity of interactions, connectance and generality and lower modularity than Q. magnoliifolia and Q. resinosa networks. Hybrids are more vulnerable to insect galler incidence having low pressure by parasitoids, which allow more gall incidence in hybrid plants. Our study corroborated that hybridization generates changes in oak genetic composition influencing insect gallers trophic networks and their parasitoids. Our findings are also consistent with the rule of genetic similarity which suggest a relationship between plant genetics and the associated arthropod community, where genetically similar plants support similar arthropod communities.
... For instance, heritable phenotypes in fish (Poecilia reticulata) are thought to influence ecosystem processes, such as nutrient cycling, because fish phenotypes exhibit different patterns of diet selectivity and excretion rates (4). In addition, the genetic diversity of host plants (Quercus sp.) is thought to be positively associated with the diversity of endophagous insect communities because insect species are often specific to certain host species or hybrids (5). ...
Although loss of genetic fitness is known to be severely detrimental to the viability of populations, little is known about how changes in the genetic fitness of keystone species can impact the functioning of communities and ecosystems. Here we assessed how changes in the genetic fitness of a keystone predator, grey wolves, impacted the ecosystem of Isle Royale National Park over 2-decades. The decline and subsequent resurgence of inbreeding in the wolf population led to a rise and then fall in predation rates on moose, the primary prey of wolves and dominant mammalian herbivore in this system. Those changes in predation rate led to large fluctuations in moose abundance which in turn impacted browse rates on balsam fir, the dominant forage for moose during winter and an important species in the forest. Thus, forest dynamics can be traced back to changes in the genetic health of a predator population.
... Furthermore, introgression of genes from one species into another is an important source of novel genetic variation that can have adaptive benefits for living in both biotic and abiotic environments (e.g., Whitney et al., 2010). The prevalence of hybridization means that its influence on associated communities is likely frequent and widespread, as evidence suggests (e.g., Hochwender and Fritz 2004;Wimp et al., 2004;Tovar-S anchez and Oyama 2006). Therefore, understanding how communities are influenced by genetic gradients created through hybridization helps us understand how communities are structured and is a step towards understanding the interplay of ecological and evolutionary processes (Whitham et al., 1999;Genung et al., 2011). ...
... Each cross type had some distinct EMF community attributes that set it apart from other cross types, with intermediate hybrids potentially being most distinct in composition. This pattern suggests that EMF communities are in-part influenced by epistatic interactions between parental genomes, and similarly unique community phenotypes associated with hybrids have been shown with other plant-associated organisms such as foliar arthropods (e.g., Whitham et al., 1999;Hochwender and Fritz 2004;Tovar-S anchez and Oyama 2006). Although the mechanisms causing this pattern are unknown, a recent study with P. trichocarpa and P. deltoides, which are in the same sections of the Populus genus as P. angustifolia and P. fremontii, respectively, suggested that the differential expression of miRNAs explains colonization differences between the two Populus species by the EMF Laccaria bicolor (Mewalal et al., 2019). ...
Plant hybridization is common and important in ecological and economic contexts, however little is known about the impact of plant hybridization on ectomycorrhizal fungal (EMF) communities in natural habitats. We used a Populus hybrid system (P. angustifolia x P. fremontii) in a heterogeneous riparian landscape to address the hypothesis that EMF communities differ among hybrids and their parental species (cross types). Several key results emerged. (1) Cross type influenced EMF composition, with communities on hybrids being distinct from their parents. (2) Cross type influenced the composition of hyphal exploration types important for soil resource foraging, although contact and short distance exploration types were dominant on all cross types. (3) Cross type had a marginal influence on EMF colonization, with P. angustifolia highest and P. fremontii lowest. These results highlight the potential for tree hybridization to structure belowground communities in heterogeneous natural ecosystems.
... Furthermore, introgression of genes from one species into another is an important source of novel genetic variation that can have adaptive benefits for living in both biotic and abiotic environments (e.g., Whitney et al., 2010). The prevalence of hybridization means that its influence on associated communities is likely frequent and widespread, as evidence suggests (e.g., Hochwender and Fritz 2004;Wimp et al., 2004;Tovar-S anchez and Oyama 2006). Therefore, understanding how communities are influenced by genetic gradients created through hybridization helps us understand how communities are structured and is a step towards understanding the interplay of ecological and evolutionary processes (Whitham et al., 1999;Genung et al., 2011). ...
... Each cross type had some distinct EMF community attributes that set it apart from other cross types, with intermediate hybrids potentially being most distinct in composition. This pattern suggests that EMF communities are in-part influenced by epistatic interactions between parental genomes, and similarly unique community phenotypes associated with hybrids have been shown with other plant-associated organisms such as foliar arthropods (e.g., Whitham et al., 1999;Hochwender and Fritz 2004;Tovar-S anchez and Oyama 2006). Although the mechanisms causing this pattern are unknown, a recent study with P. trichocarpa and P. deltoides, which are in the same sections of the Populus genus as P. angustifolia and P. fremontii, respectively, suggested that the differential expression of miRNAs explains colonization differences between the two Populus species by the EMF Laccaria bicolor (Mewalal et al., 2019). ...
Plant hybridization is common and important in ecological and economic contexts, however little is known about the impact of plant hybridization on ectomycorrhizal fungal (EMF) communities in natural habitats. We used a Populus hybrid system (P. angustifolia x P. fremontii) in a heterogeneous riparian landscape to address the hypothesis that EMF communities differ among hybrids and their parental species (cross types). Several key results emerged. (1) Cross type influenced EMF composition, with communities on hybrids being distinct from their parents. (2) Cross type influenced the composition of hyphal exploration types important for soil resource foraging, although contact and short distance exploration types were dominant on all cross types. (3) Cross type had a marginal influence on EMF colonization, with P. angustifolia highest and P. fremontii lowest. These results highlight the potential for tree hybridization to structure belowground communities in heterogeneous natural ecosystems.
... In Mexico, coppice effects have been poorly studied (Mwampamba et al., 2013); analyses on diversity, structure and gene flow patterns at a molecular level are even scarcer (Martins et al., 2018;Oyama, Ramírez-Toro, Peñaloza-Ramírez, Pérez Pedraza, Torres-Miranda, Ruiz-Sánchez, & González-Rodríguez, 2018;Tovar-Sánchez & Oyama, 2006). In the present study, we asked if there is a loss of genetic diversity caused by coppice oak harvest in the Sierra de Zongolica. ...
Firewood and charcoal are used on a daily basis both in rural areas and in cities. This type of energy is produced by one of the most ancient traditional methods, known as coppice, which harvest tree sprouts. There is controversy about its effects on forests: it preserves populations and tree cover of species used, but reduces density, inhibits sexual reproduction and generates genetic erosion. We inquired if it was possible to identify a loss of genetic diversity in oak populations traditionally used for charcoal by the Zongolica Nahuas in Veracruz state, Mexico. We studied populations of Quercus laurina, Quercus calophylla and Quercus rugosa in three different altitudes. Molecular analysis with eight nuclear codominant microsatellites was performed to determine the diversity, structure and gene flow of these species. Results for Q. laurina were Na = 8.458, I = 1.766, Ho = 0.679, polymorphism = 100%, Fis = 0.079, with intraindividual variation of 81.55%. For Q. calophylla: Na = 7.250, I = 1.563, Ho = 0.646, polymorphism = 91.67%, Fis = 0.083, with intraindividual variation of 83.80%. For Q. rugosa: Na = 6.958, I = 1.510, Ho = 0.574, polymorphism = 91.67%, Fis = 0.204, with intraindividual variation of 81.99%; this species shows signals of an early genetic isolation process. Our findings indicate that Quercus genetic diversity for the three species is high and comparable with oak species in Mexico and worldwide. We conclude that at the present, coppice is preserving a historical diversity in adult trees kept alive through sprouting. Nonetheless, problems with coppice systems elsewhere, unregulated harvesting and expansion of pine plantation in the region suggest that further studies, hand in hand with a landscape management approach that improve charcoal and firewood production, may be valuable for Sierra de Zongolica genetic biodiversity conservation.
... Furthermore, we found a high diversity of arthropod orders, guilds and ontogenic stages, coexisting in hybrid plants. Our results suggest that hybrids include a greater niche diversity that could represent more potential sites to be colonized by arthropods (Martinsen and Whitham 1994;Wimp et al. 2005;Fritz et al. 1994;Strauss 1994;Tovar-Sánchez and Oyama 2006b). Particularly, guilds such as phytophages, predators, detritivores-saprophages and parasitoids presented higher abundance and species richness in hybrid plants. ...
Understanding the factors that influence the diversity and composition of arthropod communities is a major topic in ecology. Canopy arthropod communities are a major constituent of biodiversity and show great variation in time and space according to different factors. Recently, genetic variation within tree species has attracted attention as a significant factor determining the diversity and composition of canopy arthropod communities. A major source of genetic and phenotypic novelty in plant species is interspecific hybridization, and therefore it is of interest to evaluate how this process affects the communities of associated organisms. In this study, we used microsatellite markers and geometric morphometry of leaf shape to analyze genetic and morphological variation in 45 individuals in a local hybrid zone between the oaks Quercus affinis and Q. laurina in Mexico. Individual trees were assigned to one of the parental species or to the hybrid category. The percentage of leaf area removed by herbivores was quantified in each individual and the canopies of five individuals of each categeory (two parental species and hybrids) was fogged with insecticide to assess the diversity and composition of arthropod communities. Results indicated that hybrid trees experience higher levels of herbivory than parental species and also sustain a higher abundance and richness of canopy arthropods. In general, our study supports the “hybrid susceptibility hypothesis” that predicts a higher incidence of associated arthropods on hybrid plants than in their parental species as result of the disruption of co-adapted gene complexes associated to resistance traits.
