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Intra-versus intersectional hybridization between species of Populus in sections Tacamahaca and Aigeiros (modified from Gom and Rood 1999). Leaf shapes are characteristic of the indicated Populus species and their hybrids.
Contexts in source publication
Context 1
... determinations, however, are confounded by natural hybridization. Intrasectional hybrids arise between species in section Tacamahaca. Intersectional hybrids arise between species of Aigeiros and Tacamahaca (Fig. 3). The F 1 progeny of such crosses, in turn, may backcross to the parental species in sequential fashion to form a continuum of hybrid intermediates that blur the genetic and morphological differences between species. The extent of the continuum depends on the parental species. Genetic (Keim et al. 1989) and morphological (Floate 2004) ...
Context 2
... In contrast, F 1 hybrids of Tacamahaca and Aigeiros species backcross only to the Tacamahaca parent, that is, unidirectional introgression. Unidirectional introgression forms a continuum of hybrid intermediates between F 1 's and the Tacamahaca parent but leaves a gap in the continuum between F 1 's and the Aigeiros parent (e.g., see Fig. 3b in Floate 2004). Hybridization is common wherever members of sections Tacamahaca and Aigeiros overlap in distribution (Eckenwalder 1984a(Eckenwalder , 1996. The distributions of P. balsamifera and P. deltoides are sympatric on most of the grasslands, with these species and P. angustifolia overlapping in southern Alberta (Fig. ...
Context 3
... complex of Populus angustifolia, P. balsamifera, and P. deltoides (cont.). Fig. 10. Gall of Pemphigus populicaulis opened to show apterae within. Fig. 11. Gall of Pemphigus populiglobuli on Populus hybrid. Fig. 12. Gall of Pemphigus populiramulorum on woody shoot (left) and gall of Pemphigus populitransversus on petiole (right) of P. deltoides. Fig. 13. Abscising gall of P. populiramulorum showing formation of button-shaped scar on the woody shoot. Fig. 14. Gall of P. populitransversus on petiole of P. deltoides. Fig. 15. Spiral-shaped gall of Pemphigus spyrothecae on petiole of Populus nigra var. italica (photo courtesy of D. Gillespie, Agriculture and Agri-Food Canada). Photographs ...
Context 4
... mother and her offspring (Fig. 12). The exit opening is a narrow slit with slightly protruding lips. The location of galls on the woody tissues of the twig results in vacant galls frequently being retained on the tree during winter months. The point of attachment left by abscised galls is a characteristic flattened "button" region on the twig (Fig. 13). Galls in southern Alberta produced an average of 74 (range: 9-190) alatae, with gall exiting beginning in early to mid-July and being 90% complete by August 23 (Harper ...
Citations
... It feeds near the center of leaf petioles of Populus nigra L., especially on its variety "Italica". It induces a spiral-shaped gall (usually consisting of three spirals) that completely surrounds fundatrix and its offspring [6]. Galls of P. spyrothecae are induced only by a fundatrix which is an extremely specialized and conservative stage [7]. ...
Pemphigus spyrothecae Pass. which is a member of the subfamily Pemphiginae is one of the gall-inducing aphids that occurs on poplar trees. Phloem feeding of a founding mother on leaf petiole results in the formation of a new organ, i.e., the spiral gall. This study documents aphid development inside the galls during the growing season and the effect of their feeding on leaf architecture and physiology of the host plant. In particular, leaf length, width, and area were measured, as well as hydrogen peroxide (H2O2) content, electrolyte leakage (EL), malondialdehyde (MDA) concentration, and the activity of ascorbate (APX) and guaiacol peroxidase (GPX) were determined in galls and galled leaves. The presence of petiole galls significantly decreased the length, width, and leaf area. Aphid activity increased H2O2 concentration in galls and EL from galls and leaf tissues, which was accompanied by a strong decrease in MDA content and both peroxidase activities, especially in gall tissues. It can be suggested that P. spyrothecae can manipulate physiological machinery of the host plant for its own benefit.
... M. vagabunda has been recorded completing its life cycle on several species of Populus including P. deltoides and P. tremuloides (Floate, 2010). Although the aphid's life history has been documented, little is known about the influence of host plant genetics on gall formation or resistance to feeding (Floate, 2010;Ignoffo & Granovsky, 1961a). ...
... M. vagabunda has been recorded completing its life cycle on several species of Populus including P. deltoides and P. tremuloides (Floate, 2010). Although the aphid's life history has been documented, little is known about the influence of host plant genetics on gall formation or resistance to feeding (Floate, 2010;Ignoffo & Granovsky, 1961a). ...
Plants employ a diverse set of defense mechanisms to mediate interactions with insects and fungi. These relationships can leave lasting impacts on host plant genome structure such as rapid expansion of gene families through tandem duplication. These genomic signatures provide important clues about the complexities of plant/biotic stress interactions and evolution. We used a pseudo‐backcross hybrid family to identify quantitative trait loci (QTL) controlling associations between Populus trees and several common Populus diseases and insects. Using whole‐genome sequences from each parent, we identified candidate genes that may mediate these interactions. Candidates were partially validated using mass spectrometry to identify corresponding QTL for defensive compounds. We detected significant QTL for two interacting fungal pathogens and three insects. The QTL intervals contained candidate genes potentially involved in physical and chemical mechanisms of host–plant resistance and susceptibility. In particular, we identified adjoining QTLs for a phenolic glycoside and Phyllocolpa sawfly abundance. There was also significant enrichment of recent tandem duplications in the genomic intervals of the native parent, but not the exotic parent. Tandem gene duplication may be an important mechanism for rapid response to biotic stressors, enabling trees with long juvenile periods to reach maturity despite many coevolving biotic stressors. This work focuses on elucidating the host genetic drivers of community composition in a hybrid Populus family. We mapped quantitative trait loci for pathogenic fungi and leaf modifying insects in plantations and connected these to genomic intervals of the two host species. We found that tandemly duplicated genes were significantly enriched in the intervals and that these genes have functions that are consistent with rapid host co‐evolution with the interacting organisms.
... The final gall structure may be complex and present a refined tissue organisation with neoformations, while simpler galls are generally parenchymatic, have poor tissue organisation and are structurally similar to non-galled organs (Floate 2010). Some galls may present an intermediate complexity pattern with a refined metabolism. ...
Understanding factors that modulate plant development is still a challenging task in
plant biology. Although research has highlighted the role of abiotic and biotic factors
in determining final plant structure, we know little of how these factors combine to
produce specific developmental patterns. Here, we studied patterns of cell and tissue
organisation in galled and non-galled organs of Baccharis reticularia, a Neotropical
shrub that hosts over ten species of galling insects. We employed qualitative and
quantitative approaches to understand patterns of growth and differentiation in its
four most abundant gall morphotypes. We compared two leaf galls induced by
sap-sucking Hemiptera and stem galls induced by a Lepidopteran and a Dipteran,
Cecidomyiidae. The hypotheses tested were: (i) the more complex the galls, the more
distinct they are from their non-galled host; (ii) galls induced on less plastic host
organs, e.g. stems, develop under more morphogenetic constraints and, therefore,
should be more similar among themselves than galls induced on more plastic organs.
We also evaluated the plant sex preference of gall-inducing insects for oviposition.
Simple galls were qualitative and quantitatively more similar to non-galled organs
than complex galls, thereby supporting the first hypothesis. Unexpectedly, stem galls
had more similarities between them than to their host organ, hence only partially supporting
the second hypothesis. Similarity among stem galls may be caused by the
restrictive pattern of host stems. The opposite trend was observed for host leaves,
which generate either similar or distinct gall morphotypes due to their higher phenotypic
plasticity. The Relative Distance of Plasticity Index for non-galled stems and
stem galls ranged from 0.02 to 0.42. Our results strongly suggest that both tissue plasticity
and gall inducer identity interact to determine plant developmental patterns,
and therefore, final gall structure.
... A significant feature of the aphids of Pemphigus infesting poplars is the fact that most of them differ much more in terms of biology, including the galls they cause, than in morphology (Börner, 1952;Dunn, 1960;Lampel, 1960;Moran, 1990;Moran and Whitham, 1990;Wool, 2004;Floate, 2010) (Fig. 3). For this reason and to help most entomologists, particularly practitioners, to quickly and easily differentiate the species of Pemphigus occurring in Europe, the authors prepared a key based on their galls. ...
We reviewed the diversity and distribution of the gall-forming aphids of the genus Pemphigus developing on poplars in Eastern Siberia. As a result, the checklist of this group was compiled comprising of 13 species distributed in this macroregion that accounts about 29% of the world's known poplar-feeding Pemphigus species. Biogeographical and host plant data are provided for all listed species. Pemphigus birimatus Ivanovskaja, Pem. laurifoliae Dolgova and Pem. matsumurai Monzen were documented for the first time in the Republic of Tuva. Additionally the latter two species were also discovered in the Republic of Buryatia and Zabaikalskii Krai respectively. Two poplars Populus × sibirica and Pop. laurifolia were recorded as novel hosts for 3 Pemphigus species. The origin of Pem. passeki Börner, Pem. spyrothecae Passerini and Pem. microsetosus Aoki in Eastern Siberia remains unclear. Four species Pem. populi Courchet, Pem. bursarius (Linnaeus), Pem. matsumurai, and Pem. spyrothecae Lichtenstein cause noticeable damage to poplars in man-made plantations.
Studying a biological species, we are very often obliged to examine many other species which are directly or
indirectly related to the particular species in order to have broader perspective of its being. Interactions between
organisms can be perceived on various levels concerning biological study areas, such as ecology, physiology,
morphology etc. In this place, the authors have given some peculiar examples concerning parasitism. This
specific interaction is very common in the animal kingdom, having in mind that about a half of all known
organisms are parasitic. The importance of this phenomenon is reflected on many aspects of life, propelling
evolution and speciation of each member in the relation.
Key findings:
the degree of genetic relatedness among parental species determines whether hybridization is primarily bidirectional or unidirectional; host genotype and genetic similarity strongly affect the distributions of gall-forming species, individually and as a community. These effects were detected observationally in the wild and experimentally in common gardens; correlations between the diversity of host genotypes and their associated arthropods identify hybrid zones as centres of biodiversity and potential species interactions with important ecological and evolutionary consequences. These findings support both hybrid bridge and evolutionary novelty hypotheses. However, the lack of parallel genetic studies on gall-forming arthropods limits our ability to define the host of origin with their subsequent shift to other host species or their evolution on hybrids as their final destination.
