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Comparative anatomy of the needles of Abies koreana and its related species
Abstract
The morphological traits of the resin duct of the needle leaves of Abies koreana E.H.Wilson, an endemic species of Korea, and its related species were analysed. The quantitative traits of the resin ducts from 289 individuals were measured, and the observed resin duct types were compared with previous studies. As a result, each characteristic of the resin duct showed some clinal variations with latitude changes. The variations had extreme values in A. nephrolepis (Trautv.) Maxim. on Mt. Sikhote-Alin (Russia) and in A. koreana on Mt. Halla (Korea). In addition, it was difficult to suggest just one type of resin duct in some taxa. Thus, further studies on the type of resin duct will need to survey the entire distribution area of a taxon and analyse the quantitative traits to determine the range of morphological variation.
... Differences in leaf traits reflect the adaptability of species in complex habitats, as well as the evolutionary history of species (Eo and Hyun, 2013). Genetic differentiation and environment divergence promote the phenotypic variation within species (Li, 2013;Kitajima, 2012). ...
... RCN was positively correlated with altitude, but negatively correlated with longitude, annual mean temperature and precipitation. Resin canals were considered to be the first line of defense stress (Eo and Hyun, 2013). Increasing the number of resin canals could help increase stress resistance in habitats with higher altitude. ...
The morphological and anatomical traits of needles are important to evaluate geographic variation and population dynamics of conifer species. Variations of morphological and anatomical needle traits in coniferous species are considered to be the consequence of genetic evolution, and be used in geographic variation and ecological studies, etc. Pinus tabuliformis is a particular native coniferous species in northern and central China. For understanding its adaptive evolution in needle traits, the needle samplings of 10 geographic populations were collected from a 30yr provenience common garden trail that might eliminate site environment effect and show genetic variation among populations and 20 needle morphological and anatomical traits were involved. The results showed that variations among and within populations were significantly different over all the measured traits and the variance components within population were generally higher than that among populations in the most measured needle traits. Population heritabilities in all measured traits were higher than 0.7 in common garden sampling among populations. Needle traits were more significantly correlated with longitude than other factors. First five principal components accounted for 81.6% of the variation with eigenvalues greater than 1; the differences among populations were mainly dependent on needle width, stomatal density, section areas of vascular bundle, total resin canals, and mesophyll, as well as area ratio traits. Ten populations were divided into two categories by Euclidean distance. Variations in needle traits among the populations have shown systematic microevolution in terms of geographic impact on P. tabuliformis. This study would provide empirical data to characterize adaptation and genetic variation of P. tabuliformis, which should be more available for ecological studies.
... Differences in leaf traits reflect the adaptability of species in complex habitats, as well as the evolutionary history of species (Eo and Hyun 2013). Results from correlation analysis show that lots of needle traits are correlated with multiple environmental factors in different provenances ( Table 6). ...
... Resin canal traits were positively correlated with elevation and longitude, but negatively correlated with annual mean temperature and precipitation. Resin canals were considered to be the first line of defense stress (Eo and Hyun 2013). Increasing the number of resin canals could help increase stress resistance in habitats with higher elevation. ...
Pinus yunnanensis Franch. is an particular conifer tree species in Yunnan–Guizhou plateau in southwest China. The morphological and anatomical traits of needles are important to evaluate geographic variation and population dynamics of conifer species. Seedlings from seven populations of P. yunnanensis were analyzed, looking at 22 morphological and anatomical needle traits. The results showed that variations among and within populations were significantly different for all traits and the variance components within populations were generally higher than that among populations in the most tested needle traits. The proportions of three-needle fascicle were significantly different among populations. The traits related to needle size in both morphology and anatomy were positive with latitude and negative with annual temperature and precipitation. Ratio indices, including mesophyll area/vascular bundle area, mesophyll area/resin canals area, vascular bundle area/resin canals area and mesophyll area/(resin canals area and vascular bundle area), were negatively correlated with elevation and positively correlated with the annual mean temperature, showing some fitness feature for the populations. Needle traits were more significantly correlated with longitude than with other four environmental factors. Needle length was significantly correlated with almost all environmental factors. First four principal components accounted for 81.596 % of the variation with eigenvalues >1; the differences among populations were mainly dependent on needle width, stomatal density, section areas of vascular bundle, total resin canals, and mesophyll, as well as area ratio traits. Seven populations were divided into three categories by Euclidean distance. Variations in needle traits among the populations have shown systematic microevolution in terms of geographic impact on P. yunnanensis. This study would provide empirical data to characterize adaptation and genetic variation of P. yunnanensis, which would be helpful for management of genetic resources and reasonable utilization of them in future. © 2015 Northeast Forestry University and Springer-Verlag Berlin Heidelberg
... The RDD in A. alba in Belarus (120 µm) [42] is higher than in our studies (86.5 µm). The position of A. alba resin ducts in our studies is medial, which is also a characteristic of A. nephrolepis, but not always of A. koreana and A. veitchii, where sometimes their position is marginal or submarginal [43]. In our studies, the VBD of A. alba averaged 263.5 µm, which is less than in A. cilica (479-485 µm) and A. nordmannian (511-594 µm) [44]. ...
The survival of marginal/peripheral silver fir (Abies alba Mill.) populations in the broader region of Southeast Europe is endangered due to climate change and population decline. This study aimed to determine the level and pattern of variability for the anatomical traits of needles and the possibility of linking the pattern of phenotypic variability with environmental factors. In most of the analyzed needle traits, the statistically significant variability between populations was determined. According to the results of the multivariate principal component analysis, it is evident that the populations are distinct from each other, in three groups. The climatic factors Hargreaves reference evaporation, mean annual temperature, and growing degree-days, were statistically significantly correlated. The altitude and heating degree-days are statistically significantly correlated with the following three environmental factors: Hargreaves reference evaporation, mean annual temperature and growing degree-days, but negatively with others. The paper’s findings indicate significant moderate and high correlations between the anatomical traits of the needles’ central bundle diameter with the resin duct diameter, the distance between the vascular bundle and the resin duct and the epidermis thickness with cuticle, the resin duct diameter with the distance between the vascular bundle and the resin duct and the epidermis thickness with cuticle, as well as the distance between the vascular bundle and the resin duct with the hypodermis height and the epidermis thickness with cuticle. The results of agglomerative hierarchical clustering analysis, performed for anatomical and climatic traits, confirmed the existence of three groups of tested populations according to the altitude gradient. Research results provide knowledge on the diversity and structure of Abies alba populations of Southeast Europe, important for further research and guidelines for the species’ conservation and genetic variability preservation in the southern marginal distribution area and keeping in line with climate change projections.
... Furthermore, hybrid populations between A. sachalinensis and A. nephrolepis have been recognized based on recent molecular analysis (Semerikova et al., 2011). Potential hybridization between A. nephrolepis and A. koreana was proposed based on anatomical observations (Eo & Hyun, 2013). Speciation and divergence with interspecific gene flow through hybridization may play a major role in evolution by creating reticulate, rather than hierarchical lineages in plant species (Willyard et al., 2009). ...
Aim
Pinaceae have been noted for their tendency towards reticulation as a result of interspecific hybridization. Here, we demonstrated the phylogeographic dynamics of the native Northeast Asian sub‐alpine conifer, Abies nephrolepis species complex (ANSC), evolving in circular overlaps along the Northeast Asian landform, which functions as a corridor with the sea, thus acting as a geographic barrier.
Location
Northeast Asia: the Korean Peninsula, Japanese Archipelago, Russian Far East and northeastern China.
Taxon
Abies nephrolepis species complex (Family Pinaceae, Genus Abies , Section Balsamea , Abies nephrolepis, A. koreana, A. veitchii and A. sachalinensis ).
Methods
A total of 728 individuals from 38 ANSC populations were analysed using multiplexed inter‐simple sequence repeat genotyping by sequencing to capture variations in biparental nuclear genomes. Eight mitochondrial regions and eight chloroplast regions of each individual were sequenced using the MiSeq platform and Sanger sequencing. Species distribution models were generated.
Results
Bayesian clustering with 507 nuclear single nucleotide polymorphisms and the discrepancy between cytoplasmic and nuclear genome lineages implied contemporary and ancient connections between neighbouring species in the form of circular overlap. This genetic connectivity was supported by principal component analysis. Strong correlations between genetic distance and geographic distance were observed, suggesting that gene flow occurs through a continuous chain around the sea. We also found that gene flow direction and intensity changed over time, with support from palaeodistribution modelling.
Conclusion
Past hybridization events were captured in cytoplasmic genomes, generating heterogeneity across maternal ancestries. This intensive phylogeographic study demonstrates speciation with incomplete reproductive isolation (continuous gene flow) among neighbouring species with an alteration of the direction and intensity of gene flow due to climate change. The divergence of ANSC due to repeated isolation and reconnection caused by heterogenous physiological environments and climate fluctuation provides a model to solve evolutionary scenarios for reticulate evolution in Pinaceae and other plants.
... Al respecto, Sheue & al. (2014) plantean que tanto los canales dentro del haz vascular como los endonales tienen un fuerte control genético y son menos susceptibles a variaciones ambientales, a no ser que estén asociados a verdaderas adaptaciones microclimáticas y las variaciones son generalmente relativas al número de estos. Otros autores refieren que la clasificación de los canales es un buen carácter interespecífico (Knopf & al. 2012, Eo & Hyun, 2013, Ghimire & al. 2014; sin embargo, han documentado que este puede variar dentro de una especie, especialmente si hay fenómenos de introgresión e hibridación asociados (Sheue & al. 2014, Boratynska & al. 2003. En este estudio nunca se encontraron muestras que suscitaran ambigüedad en la adscripción a cada especie. ...
Las variaciones en la anatomía foliar pueden ser respuestas adaptativas o de aclimatación interpoblacional al estrés edafoclimático, sobre todo de especies que se desarrollan en ambientes extremos. Pinus caribaea var. caribaea y P. tropicalis se distribuyen en el occidente de Cuba, principalmente en la provincia de Pinar del Río donde forman poblaciones puras o en simpatría. Es objetivo de este trabajo comparar las características anatómicas distintivas de las acículas de ambos taxones en diferentes localidades donde se asocian simpátricamente. Para ello se realizaron cortes transversales de las acículas y se evaluaron 14 variables anatómicas. Los análisis estadísticos empleados permitieron diferenciar claramente los dos taxones y ambos presentan variaciones propias para adaptarse a un mismo ambiente. El análisis de componentes principales mostró que dentro de cada taxón las poblaciones se segregan en relación al edátopo donde se desarrollan. Para P. caribaea var. caribaea las variables anatómicas que más contribuyeron a la variación y ordenación fueron el número de estomas, grosor y número de capas de células de la hipodermis; en P. tropicalis el grosor de la cutícula y el parénquima clorofílico, y para ambos taxones el tipo de canal fue inequívocamente endonales y marginal.
... The distribution of A. nephrolepis was controlled by a MTWQ of 19.5°C, which was higher than that of A. koreana ( Fig. 1; S2). These results support the hypothesis that A. nephrolepis is more able to adapt to cold and dry climates than A. koreana, which is associated with the process of speciation (Eo and Hyun 2013). ...
To facilitate the adaptive management of subalpine ecosystems in the Korean Peninsula under climate change conditions, we identified the climatic factors that determine the distribution of two dominant subalpine firs (Abies koreana and A. nephrolepis). We also identified sustainable and vulnerable habitats for these species inside and outside of current protected areas under climate change scenarios. The minimum temperature of the coldest month, and the amount of precipitation in the warmest quarter were the most important climatic variables that determined the distribution of these two Abies species. Potential habitats for A. koreana and A. nephrolepis were predicted to decrease to 3.3% and 36.4% of the current areas due to climate change, irrespective of whether inside or outside the protected areas. It was predicted that the potential habitats for A. nephrolepis would be maintained in the northern part of the Korean Peninsula, and sustainable potential habitats outside the protected areas were predicted in central parts of the Korean Peninsula. The potential habitats for A. koreana were predicted to disappear from Is. Jeju and shrink significantly in the Korean Peninsula. These results suggest that, in central parts of the Korean Peninsula, revision of protected areas would be effective in preserving A. nephrolepis under conditions of future climate change. In contrast, revision of protected areas would be insufficient to conserve A. koreana due to their high vulnerability and limited populations. Active management is required to ensure the survival of A. koreana under future climate conditions.
... Frequent hybridization among Abies species (Isoda et al. 2000;Jiang et al. 2011;Semerikova et al. 2011) and high crossability between A. koreana and A. nephrolepis have been previously shown (Kormuťák et al. 2008). Clinal variation of morphological characteristics and maternally-inherited mitochondrial genotypes have been reported in A. koreana and A. nephrolepis (Eo and Hyun 2013;Yang et al. 2015), implying frequent gene flow through hybridization or introgression between these two species. The possibility of admixed ancestry of SB, as estimated with STRUCTURE and TESS, could be a sign of gene flow from A. nephrolepis or other related species (Fig. 2c, d). ...
To establish a management plan for endangered and rare species, genetic assessment must first be conducted. The genetic characteristics of plant species are affected by demographic history, reproductive strategy, and distributional range as well as anthropological effects. Abies koreana E. H. Wilson (Pinaceae), Korean fir, is endemic to Korea and found only in sub-alpine areas of the southern Korean Peninsula and Jejudo Island. This species has been designated as critically endangered by the International Union for Conservation of Nature due to a continuous decline in its range and population fragmentation. We genotyped 176 individuals from seven natural populations and two afforested populations on the Korean Peninsula using 19 microsatellite loci. STRUCTURE analysis revealed two genetic clusters in natural populations (Fst = 0.040 and Rst = 0.040) despite low differentiation. We did not detect a significant reduction in genetic diversity or the signature of a genetic bottleneck despite population fragmentation and small population size. We deduced that this species exhibits a metapopulation structure, with the population on Jirisan Mountain acting as a source of genetic diversity for other local small populations on the Korean Peninsula, through contemporary asymmetric gene flow. However, the majority of afforested individuals on the Korean Peninsula originated from a different gene cluster. Thus, we recommend a conservation strategy that maintains two genetically unique clusters.
... In addition, these two species are geographically parapatric. A. nephrolepis occurs in the central and northern parts of Korea, Manchuria, and Siberia. Although these two species are distinguished by leaf length, bark roughness, and the direction of bract-scales (i.e., downward or otherwise; Wilson, 1920;Chang et al., 1997), none of these characteristics are clearly distinct between the species (Chang et al., 1997;Eo and Hyun, 2013). Several molecular studies have explored the genetic diversity of A. nephrolepis (Woo et al., 2008a) as well as the genetic relationship between A. koreana and A. nephrolepis (Kormutak et al., 2007;Hong et al., 2011). ...
Abies koreana is an endemic and rare species from Korea and is classified as endangered by the International Union for Conservation of Nature. Although the genetic diversity assessment for current population of A. koreana needs to be performed urgently, no microsatellite markers have been developed for this species. In the present study, we developed 22 novel polymorphic microsatellite loci and the characteristics of these loci were determined in A. koreana as well as in Abies nephrolepis, the most closely related species, and these loci were compared with previously reported microsatellite markers developed for the Abies genus. Genomic sequence (161 Mbp; 325,776 reads) was obtained from one individual of A. koreana using Roche 454 GS-FLX Titanium sequencing and 19,258 repeat motifs were identified from it. A total of 288 primer pairs with high copy numbers of di-repeat motifs were evaluated for amplification in A. koreana and A. nephrolepis. A total of 71 primer pairs successfully amplified fragments, of which 22 showed polymorphisms in A. koreana and A. nephrolepis. The average expected diversity was 0.767 and 0.717 in A. koreana and A. nephrolepis, respectively; these heterozygosity levels were moderate compared to the previously reported microsatellite loci from Abies species. This is the first set of microsatellite markers developed for A. koreana as well as A. nephrolepis and further population genetic studies of both species and genetic delimitation can be carried out for the species conservation and management.
... On the other hand, both Balsamea species included in this study, A. koreana and A. nephrolepis, had two medial resin ducts. Eo & Hyun (2013) described a similar position to this study for resin ducts in A. nephrolepis but found both marginal and medial ducts for A. koreana. They also presumed that the movement of resin ducts from the marginal to the medial position is latitude-dependent, with samples of lower latitude having marginal ducts and samples of higher latitude having medial ducts. ...
A number of conifer species are still lacking anatomical data, which is significant because morphological and anatomical data are essential for systematic study. Leaf anatomy was studied in selected species of Abies and Picea using light and scanning electron microscopy. Both genera were found to have typical coniferous and highly xerophytic leaves with sunken stomata and an epidermis covered by a thick cuticle. In the genus Abies, species can be differentiated by the nature of the lignified hypodermis and the number and position of resin ducts. Abies firma and A. holophylla have a continuous hypodermis whereas in A. koreana and A. nephrolepis the hypodermis is discontinuous and represented by isolated cells or groups of four or five cells. On the other hand, in Picea leaf shape, stomata arrangement, and number, position, and nature of resin ducts are the key features for species differentiation. Picea jezoensis has a flattened leaf with stomata distributed on the adaxial surface whereas P. abies and P. koraiensis have a rectangular leaf with stomata found on surfaces.
... Comparative wood anatomy consists of two main efforts: wood identification and evolutionary studies. Evolutionary studies can be divided into two main areas: systematic wood anatomy and ecological wood anatomy (Olson, 2005;Tiwari et al. 2012;Eo & Hyun 2012;Güvenç & Kendir 2012). ...
In this study, comparative wood anatomy of European (Rhodothamnus chamaecistus (L.) Reichb.) and Anatolian (Rhodothamnus sessilifolius P.H.Davis) species of Rhodothamnus were studied. The wood anatomy of the taxa shows evidence of adaptation to growing in alpine habitats. The woods of the species exhibit primitive wood anatomical characteristics and share similar qualitative anatomical features. However some of the quantitative anatomical characteristics of the taxa show significant differences such as the distinctness of the growth ring and the bar number of scalariform perforation plate. The present study describes and compares the anatomical properties of the wood of Rhodothamnus species.
L’objectif de cette thèse vise l’identification des caractères morphologiques et
anatomiques adaptatifs permettant de discriminer entre les populations du cèdre Marocaines distantes géographiquement.
The object of this study was the climate change sensitivity assessment of Korean Fir and Khinghan Fir as a representative subalpine plant in South Korea. Using species distribution models, we predicted the probability of current and future species distribution. According to this study, potential distribution that have been predicted based on the threshold (MTSS) is, Khinghan Fir was higher loss rate than Korean Fir. And in the climate change sensitivity assessment using the scalar sensitivity weight (W_{is}), W_{is} of Korean Fir was higher relatively than the sensitivity of Khinghan Fir. When using the species distribution models as shown in this study may vary depending on the probability of presence data and spatial variables. Therefore should be prior decision studies on the ecological environment of the study species. Based on this study, if it is domestic applicable climate change sensitivity assessment method is developed. it would be important decision-making to climate change and biological diversity of adaptation policy.
To understand the compatibility of xylem with dry climates, wood anatomy similarities and differences of four shrubs were investigated in dry and cold region of Sarab (Azarbaijan sharghi province). These shrubs were: Pteropyrum olivieri, Rosa canina, Tamarix gallica, and Rhamnus pallasii, while the wood anatomy of Pteropyrum sp. is reported for the first time, in this research. After preparing microscopic sections of mature xylem and staining them, wood anatomy of studied species were reported and compared. The results showed that Pteropyrum olivieri and Rosa canina are the most similar in terms of wood anatomy while Rhamnus pallasii and Tamarix gallica have the least similarities with each other. Those anatomical features which compensate the drought stress were different in these shrubs according to local distribution of studied species; among them was the occurrence and intensity of spiral thickenings in vessels, the presence of vascular / vasicentric tracheids, and the size and grouping of vessels. Tamarix gallica which were grown only near the lake had the least adaptation to drought in its stem while Rhamnus pallasii which could distribute in the harshest conditions were equipped with the best adaptive traits.
A recent analysis of quantitative variation in cone and needle characteristics indicated that Abies balsamea and A. lasiocarpa from western Canada are not well differentiated morphologically. To further investigate the relationship of A. balsamea to A. lasiocarpa, 10 populations of firs collected from western Saskatchewan to central British Columbia were compared on the basis of their needle flavonoids. Easternmost populations of A. balsamea were distinct from the westernmost samples of A. lasiocarpa; the easternmost firs contain additional flavonoid derivatives including diglycosides, flavones, and dihydroflavonols that were not found in the westernmost samples of A. lasiocarpa. Flavonoid patterns of geographically intermediate populations formed a continuum from east to west beginning in the lower foothills of the east slope of the Rocky Mountains in Alberta and extending to the interior of British Columbia. Although no sharp boundary separating the two species could be detected based on flavonoid results, the observed clinal pattern was steepest at the Rocky Mountain crest. In addition, the populations on either side of the crest were more variable than the 5 mixed-wood populations to the east of the mountains. This pattern of variation suggests that genetic inter-change has occurred between A. balsamea and A. lasiocarpa to each side of the Rocky Mountain crest following post-glacial migration.
This morphometric study of the geographic variation in the Abies religiosa–hickelii–guatemalensis complex is based on samples from 15 Guatemalan and 12 Mexican populations, two populations of A. religiosa s.str. and A. hickelii s.str., and herbarium specimens of A. hickelii, A. vejarii and varieties of A. guatemalensis. The multivariate methods employed were principal components analysis, and UPGMA clustering. The multivariate and univariate
analyses based on 231 operational taxonomic units imply that although morphological differences exist distinct morphospecies
cannot be recognized within the A. religiosa–hickelii–guatemalensis complex. A Mantel’s test reports that taxonomic dissimilarities are significantly related to geographic distance. We suggest,
therefore, that A. religiosa, A. hickelii and A. guatemalensis are merged so that A. hickelii is referred to as A. religiosa subsp. hickelii (Flous & Gaussen) U. Strandby, K.I. Chr. & M. Sørensen, comb. et stat. nov. and A. guatemalensis as A. religiosa subsp. mexicana (Martínez) U. Strandby, K.I. Chr. & M. Sørensen, comb. nov. According to our analyses A. vejarii cannot retain its status as a separate taxon as the material studied is nested within A. religiosa subsp. mexicana.
The study of yeast cell morphology requires consistent identification of cell cycle phases based on cell bud size. A computer-based image processing algorithm is designed to automatically classify microscopic images of yeast cells in a microfluidic channel environment. The images were enhanced to reduce background noise, and a robust segmentation algorithm is developed to extract geometrical features including compactness, axis ratio, and bud size. The features are then used for classification, and the accuracy of various machine-learning classifiers is compared. The linear support vector machine, distance-based classification, and k-nearest-neighbor algorithm were the classifiers used in this experiment. The performance of the system under various illumination and focusing conditions were also tested. The results suggest it is possible to automatically classify yeast cells based on their morphological characteristics with noisy and low-contrast images.
Range-wide variation in 54 populations of Dahurian larch (Larix gmelinii) and related taxa in Northeast Asia was assessed with four mitochondrial PCR-RFLP and five chloroplast SSR markers. Eleven mitotypes and 115 chlorotypes were detected. The highest diversity was observed in the southern Russian Far East where hybrids of L. gmelinii, L. olgensis and L. kamtschatica are distributed. In contrast, only two mitotypes occurred in L. cajanderi and L. gmelinii. The Japanese larch (L. kaempferi) was found to be closely related to populations of L. kamtschatica inhabiting the Kuril Islands and South Sakhalin, populations from the northern part of Sakhalin being more closely related to continental species. In general, both mitochondrial (G(ST) = 0.786; N(ST) = 0.823) and chloroplast (G(ST) = 0.144; R(ST) = 0.432) markers showed a strong phylogeographical structure and evidence of isolation-by-distance. Yet both markers did not allow a clear delineation of species borders. In particular, and contrary to expectations, cpDNA was not significantly better than mtDNA at delineating species borders. This lack of concordance between morphological species and molecular markers could reflect extensive ancestral haplotype sharing and past and ongoing introgression. Finally the distribution of mtDNA and cpDNA variation suggests the presence of several refugia during Pleistocene glacial intervals. In particular, mtDNA and cpDNA reveal weak but visible differentiation between L. gmelinii and L. cajanderi, suggesting independent glacial histories of these species.
If a staining-permanent slide is not needed, this simple and faster microtome technique is very useful for cross-sectioning Gymnosperm needle leaves. Th e technique employs 2× polyvinyl alcohol-lactic acid-glycerol (PVLG) without the steps of fi xation, dehydration, clearing, embedding, deparaffi nisation, and hydration. Conveniently, this technique can also be applied to thick leaves and other organs of Angiosperms. Th e procedure is very simple and is suggested for use in plant anatomy research.
High variability of tissue elements is indicated in needles of Abies balsamea (L.) Mill., A. lasiocarpa (Hook.) Nutt. and A. fraseri (Pursh) Poir. during their development from juvenile to adult ages. Consequently, care must be taken in using resin canal position as a taxonomic character for identifying these species. The development stage of the tree, the location in the crown, and age of needle selected must be specified. There are highly significant differences between the positions of resin canals in needles of juveniles and adult trees, but no significant differences between those in needles from adult trees of the three species. Neither latitude nor elevation affect the positioning of resin canals in the needle tissue. It may be concluded that: (1) Change of resin canal position is not affected by the gradually changing microclimate from the top to the base of the crowns. (2) Change of needle tissues follows periods of aging of needle and tree. The differentiation of tissues is under specific genetic control, and ecological factors do not in an essential way affect the new establishment of tissue elements during the initial stage of needle development.
Abies magnifica A. Murray bis var. critchfieldii var. nov. Lanner (Critchfield red fir) is described. The new variety comprises the southernmost Sierra Nevada populations of California red fir. It differs from the typical variety in having smaller cones with protruding cone bracts. Because of the protruding bracts, populations of the new variety have been assumed to be disjuncts of the bracted A. magnifica var. shastensis Lemmon (Shasta red fir), described over a century ago from Mt. Shasta and considered present in NW California and SW Oregon. However, geographic patterns of morphological variation, artificial crossing results, and recent molecular studies indicate that Shasta red fir consists of California red fir introgressed by noble fir (A. procera Rehder), and that the new variety is not hybridized with noble fir.
Using species-specific random amplified polymorphic DNA (RAPD) markers and morphological characters, natural hybridization between the closely related black spruce Picea mariana (Mill.) B.S.P. and red spruce P. rubens Sarg. was evaluated in natural populations from north-eastern North America. Sampling included populations from both areas of allopatry and also 14 populations from part of the area of sympatry located in the province of Québec and covering several thousands of square kilometres. Classification results from RAPD species-specific markers and from a discriminant function based on morphology were compared. Molecular analysis of the allopatric populations indicated a small amount of interspecific gene leakage with no asymmetric directionality to introgression. A high occurrence of hybrid/introgressant individuals was observed within sympatric populations, suggesting weak reproductive isolation. As expected, the detection of such individuals was more efficient using molecular markers than with morphological traits. The hybrid zone appeared extensive with variable species structure and, in some stands, the main component composed of hybrid/introgressant trees. Implications for the genecology and genetic management of these species are discussed.
Hybrid zones provide biologists with the opportunity to examine genetic and ecological interactions between differentiated populations. Accurate identification of hybrid genealogies is considered a necessary prerequisite to understanding observed patterns of hybridization-related phenomena. We analysed molecular and morphological data from individuals in a hybrid zone between two species of willows (Salix sericea Marshall and S. eriocephala Michaux) and report the use of randomly amplified polymorphic DNA (RAPD), chloroplast DNA (cpDNA), and ribosomal DNA (rDNA) markers, as well as vegetative morphology and foliar chemistry data to identify individuals in terms of hybrid genealogy and to infer the direction and extent of backcrossing and introgression within the hybrid zone. A novel version of a maximum likelihood estimate approach (developed for this study) was used to calculate hybrid index scores from RAPD marker data; this method produced results similar to those obtained using traditional arithmetic methods. Distribution of rDNA, cpDNA, and chemistry data were examined within the graphical context of RAPD-based hybrid index score histograms and principal component analyses (PCA) on RAPD and morphology data. Seven of the 21 plants classified as S. eriocephala in the field were possible introgressants. Another plant presented an unequivocal example of backcrossed S. sericea chemistry and RAPD markers. Inter- and intraspecific chloroplast diversity found within the hybrid zone suggests both historic introgression (perhaps in a glacial refugium), and contemporary hybridization. Patterns of inheritance and expression within the hybrid zone suggest that morphological characters are often not expressed in a simple additive fashion, and problems associated with both morphological and molecular data are considered.
Sub-alpine Abies veitchii and A. homolepis are distributed in the central part of Honshu Island, Japan, and their habitats are segregated vertically. These species sometimes form a mixed forest in the overlapping area of the two species, that is, in the upper limit of the A. homolepis habitat and the lower limit of A. veitchii. These species have been considered to be distantly related because they were classified into different sections by most conventional classifications. No natural hybridization has been reported between the two species. The aim of this study was to demonstrate, through the use of molecular markers, whether natural hybridization takes place between these two species at two experimental sites on Mt. Fuji, where the species occur naturally. DNA markers from paternally inherited chloroplast DNA (cpDNA), maternally inherited mitochondrial DNA (mtDNA) and biparentally inherited nuclear DNA (nDNA), were used for this study. As organelle DNA markers, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) markers were developed to determine the maternal and paternal species for each individual. Two of 334 individuals possessed a cpDNA haplotype derived from A. homolepis and a mtDNA haplotype from A. veitchii. Furthermore, the nDNA of these two individuals was analysed using the random amplified polymorphic DNA (RAPD) assay to investigate their genomic composition. RAPD analysis indicated that the nuclear genomes of the two individuals were derived from both species. We conclude that A. veitchii and A. homolepis produce natural hybrids, and that their systematic relationship should be re-evaluated.