Gene flow between cultivated and wild gene pools is common in the contact zone between agricultural lands and natural habitats and can be used to study the development of adaptations and selection of ...novel varieties. This is likely the case in the northern Adriatic region, where centuries-old cultivated orchards of sweet chestnut (Castanea sativa Mill.) are planted within the natural distribution area of the species. Thus, we investigated the population structure of several orchards of sweet chestnuts. Furthermore, the genetic background of three toponymous clonal varieties was explored. Six genomic simple sequence repeat (gSSR) and nine EST-derived SSR (EST-SSR) loci were utilized in this research, and both grafted and non-grafted individuals were included in this study. Five closely related clones were identified, which represent a singular, polyclonal marron variety, found in all three cultivation areas. Furthermore, many hybrids, a result of breeding between cultivated and wild chestnuts, have been found. Analyzed semi-wild orchards defined by a diverse genetic structure, represent a hotspot for further selection and could result in creation of locally adapted, high-yielding varieties.
The quantity and quality of seedlings in the nursery has an impact on the success of re-establishment and later growth. High germination rates enable a sufficient number of seedlings, and their ...quality is assessed using a number of parameters, including seedling height and root collar diameter. These parameters are influenced in some species by seed size, but the correlation between them is species-specific. The model species in this research was sweet chestnut (Castaneasativa Mill.), and seeds from 12 populations from two distinct biogeographical regions of Croatia were collected. We examined the influence of seed size on four parameters: germination rate, seedling height, root collar diameter and sturdiness quotient. Seed size has been shown to have a positive influence on both seedling height and root collar diameter, whereas no such correlation was noted for germination rate and sturdiness quotient. Significant differences in nut size and seedling growth parameters were found between the Mediterranean and continental populations, with higher values observed in the coastal Mediterranean populations. We concluded that seed origin and seed size have a significant impact on seedling growth and are important factors to consider when choosing seed material. Further nursery operations should consider seed origin and local environmental conditions when choosing seedlings for reforestation efforts and general forest operations.
The chemical composition, morphometric and qualitative nut characteristics were studied in four traditional sweet chestnut and hybrid varieties produced on private estates in the Lovran surroundings, ...on the eastern slopes of Mount Učka, under the specific conditions of the sub-Mediterranean climate. Seven morphological characteristics were measured, and 12 nut and kernel qualitative characteristics were estimated using standardized descriptors. In addition, the samples were analyzed for proximate constituents (moisture, crude fat, crude protein, ash and total carbohydrates) and macro- and micro-nutrients (K, Mg, Ca, Na, Mn, Fe, Zn and Cu). Significant differences between traditional sweet chestnut and hybrid varieties were found in almost all of the studied morphometric and chemical nut characteristics. In general, chestnuts of hybrid varieties were characterized by larger fruits with higher moisture, crude protein, potassium, magnesium, sodium, iron and copper contents than in traditional sweet chestnut varieties. On the other hand, nuts of traditional sweet chestnut varieties were richer in total carbohydrates and crude fat. In addition, the presence of raised stripes, a small hilar scar and transversally ellipsoid nut shape were found to be typical for the traditional sweet chestnut varieties. Overall, our results suggest that the traditional varieties of the sweet chestnut can be easily differentiated from the new modern hybrid varieties by both morphological and chemical characteristics of the nut, and because of these differences, these two groups of chestnut varieties can have different practical uses.
Almond-leaved willow (Salix triandra L., Salicaceae) is a dioecious shrub, rarely a small tree that grows under various environmental conditions. We examined the population structure of 12 ...populations of almond-leaved willow using nine leaf morphological traits and specific leaf area. Populations were selected from a range of habitats, from continental to the sub-Mediterranean zone, to examine the influence of environmental conditions (climate and altitude) and geographic distance on leaf variability. Significant differences were confirmed among all populations for all traits, with significant correlations between geographic location of populations and morphological traits, and between environmental conditions and morphological traits. Large-leaved populations were found in continental and sub-Mediterranean climates, while small-leaved populations were found in higher elevations and smaller karstic rivers. In addition, populations from floodplains showed greater variability than populations from the karstic habitats, indicating a positive influence of lowland habitats and possible underlying differences in gene pool size. In conclusion, we found that environmental conditions and geographical distances in addition to genetic drift, are the main influences on the variability in almond-leaved willow, with the species showing a high level of plasticity and adaptation to local environmental conditions.
Marginal populations are usually smaller and more isolated and grow in less favourable conditions than those at the distribution centre. The variability of these populations is of high importance, as ...it can support the adaptations needed for the conditions that they grow in. In this research, the morphological variability of eight Tatar maple (
L. subsp.
) populations was analysed. Tatar maple is an insect-pollinated and wind-dispersed shrub/tree, whose northwestern distribution edge is in southeastern Europe. Morphometric methods were used to analyse the variability of the populations using leaf and fruit morphology. The research revealed significant differences between and within populations. Furthermore, differences in the distribution of the total variability were noted, which suggest that different evolutionarily factors affect different plant traits. Correlation analysis confirmed a weak dependency between the vegetative and generative traits. In addition, no evidence was found for the presence of isolation by environment (IBE). However, the Mantel test for isolation by distance (IBD) was significant for the leaf morphometric traits and non-significant for the fruit morphometric traits. Being the marginal leading-edge populations, they are younger and were less likely to have had time for adaptation to local environments, which would have resulted in the development of IBE. Overall, edge populations of Tatar maple were characterised by great morphological variability, which helps these populations in their response to the intensive selective pressures they face in their environment.
Common or English yew (Taxus baccata L., Taxaceae) is a conifer species, native to Europe, northern Africa, Asia Minor and Caucasus. It is a dioecious, wind-pollinated and animal-dispersed tree, ...known for its high-quality wood and medicinal properties, albeit poisonous. The species is rare and has been legally protected at the European and national levels. In addition, its low population density and disjunct character of distribution have reinforced the need for its protection as regeneration is mostly lacking. The aim of this study was to phenotypically characterise the north-western Balkan yew populations. Phenotypic diversity was examined for seven populations, using morphometric analysis of nine phenotypic traits of needles. Descriptive and multivariate statistical analyses were conducted to evaluate the inter- and intrapopulation variability. In addition, to test correlations between geographic, climatic and phenotypic data, Mantel test was used. We identified a geographic structure across studied populations that exhibited high levels of variability on intra- and interpopulation levels. Two groups of populations have been defined and are consistent with previously described genetic divergent lineages from separate refugia. In addition, a significant correlation between phenotypic and geographic data were revealed, i.e., isolation by distance (IBD). However, the Mantel test revealed no significant correlation between morphometric and environmental data. In conclusion, our data reveal that the historical events and persistent IBD acted in combination to produce the morphological patterns observed in common yew populations in the north-western part of the Balkan Peninsula. Finally, we suggested conservation measures to be implemented on a stand level, with habitat preservation as the main goal. In addition, ex situ conservation should be considered, both in the form of collections and urban planting, as both provide additional gene pool reserves.
Service tree, Sorbus domestica L., is a rare and neglected wild fruit tree species of southern and central Europe. Being distributed in different eco-geographical regions, with fragmented and ...low-density populations, S. domestica represents an interesting model case for investigating patterns of within- and between-population diversity at geographical and environmental scales. This study aimed to analyze the proximate composition, antioxidant activity, and morphometric fruit characteristics. We examined the diversity and population divergences of 49 S. domestica individuals originating from seven populations across continental and Mediterranean eco-geographical regions. In addition, tests of isolation by distance and environment were performed to detect the magnitude of divergence explained by geographic and environmental variables. Significant differences between the studied populations were found in almost all of the studied morphometric and chemical fruit characteristics. The studied service tree populations were characterized by high phenotypic variation despite the low number of trees per population. Model-based population structure analysis using morphometric and chemical fruit characteristics revealed three groups of service tree populations. We concluded that non-effective pollen and seed dispersal along with genetic drift and specific environmental factors resulted in a distinct phenotype with a specific chemical composition in the isolated island population. In addition, a pattern of isolation by the environment was revealed. We infer that morphological and chemical differences between the studied populations in the true service tree from different eco-geographical regions were mediated by adaptation to the specific environmental conditions.
Leaves play a central role in plant fitness, allowing efficient light capture, gas exchange and thermoregulation, ensuring optimal growing conditions for the plant. Phenotypic variability in leaf ...shape and size has been linked to environmental heterogeneity and habitat characteristics. Therefore, the study of foliar morphology in plant populations can help us to identify the environmental factors that may have influenced the process of species diversification. In this study, we used European wild pear (
(L.) Burgsd., Rosaceae) as a model species to investigate the phenotypic variability of leaves under different environmental conditions. Using leaf morphometric data from 19 natural populations from the north-western part of the Balkan Peninsula, a high level of variability among and within populations were found. Leaf traits related to leaf size were more variable compared to leaf shape traits, with both influenced by geographic and environmental factors. Consequently, patterns of isolation by environment (IBE) and distance (IBD) were identified, with IBE showing a stronger influence on leaf variability. Multivariate statistical analysis revealed that European wild pear populations from the north-western part of the Balkan Peninsula can be divided into two morphological clusters, consistent with their geographical distance and environmental conditions. Our results confirm a high level of phenotypic variability in European wild pear populations, providing additional data on this poorly studied species, emphasizing phenotypic plasticity as a major driver in the adaptation of this noble hardwood species to rapid climate change.
Phenotypic differentiation is often the result of the ecological diversity of a species with a wide natural range. It is favoured by natural selection, as well as factors such as gene flow, genetic ...drift, or founder events. This is especially true for species of the riparian habitats and for species with light seeds that are easily dispersed by both water and wind. One such species is rosemary willow (Salix eleagnos Scop.), which occurs in both humid riparian habitats and arid karstic sites in central and southern Europe. The species was used as a model species in this research to determine the potential morphotypes suitable for different habitat conditions. In addition, the extent of the influence of environmental conditions on leaf morphometrics was analysed and the structuring of populations was investigated. We analysed three populations of S. eleagnos from karstic habitats and five populations found in riparian habitats. Leaf samples were collected from ten individuals per population, and nine leaf traits were analysed. Leaf phenotypic traits showed a clear bimodal distribution across populations, with samples from dry karstic habitats having smaller leaves than those from riparian habitats. In addition, habitat conditions showed to have a strong influence on morphology, consistent with a pattern of isolation by environment (IBE). These results were also substantiated by the AMOVA analysis, with 34.53% of the overall variability assigned to the variability of individuals between the two habitats (karstic vs. riparian). Furthermore, karstic populations exhibited homogeneous and low multivariate diversity index (MDI) values, as well as lower variability between the populations when compared to the riparian populations, thus reflecting phenotypic adaptability to uniform environmental conditions. In contrast, riparian populations exhibited both high and low levels of diversity, as well as greater interpopulation variability than that of karstic populations, which may be attributed to different origins of the populations and different environmental conditions. Overall, our results suggest that plant-habitat interactions are a complex process and that these two clearly distinct groups of populations of rosemary willow may represent two ecotypes.
Fenotipska diferencijacija često je rezultat ekološke raznolikosti u vrsta sa širokom prirodnom rasprostranjenošću. Općenito gledano, morfološka varijabilnost populacija neke vrste rezultat je djelovanja osnovnih mikroevolucijskih procesa (prirodne selekcije, mutacije, genetičkog pomaka i protoka gena) te fenotipske plastičnosti. To se posebno odnosi na vrste obalnih staništa i vrste s laganim sjemenkama koje lako raznose i voda i vjetar. Jedna takva vrsta je i sivkasta vrba (Salix eleagnos Scop.), koja raste i na vlažnim obalnim staništima i na sušnim, krškim područjima u srednjoj i južnoj Europi. Upravo zbog široke ekološke valencije, ova je vrsta izabrana kao modalna vrsta za određivanje potencijalnih morfotipova prilagođenih na različite stanišne uvjete. Osim toga, analiziran je i učinak okolišnih uvjeta na morfološke karakteristike listova, kao i struktura istraživanih populacija. Istraživanje je obuhvaćalo tri populacije sivkaste vrbe iz krških staništa i pet populacija s obalnih staništa. Uzorci lišća prikupljeni su s deset jedinki u svakoj populaciji, a analizirano je devet morfoloških svojstava listova. Fenotipska svojstva lista pokazala su jasnu bimodalnu distribuciju po populacijama, pri čemu su uzorci iz suhih, krških staništa imali manje listove od onih iz obalnih i vlažnih staništa. Osim toga, pokazalo se da uvjeti staništa snažno utječu na morfologiju, što potvrđuje značajan utjecaj obrasca izolacije uslijed ekoloških udaljenosti (IBE). Takvi rezultati također su potkrijepljeni i AMOVA analizom, koja je 34,53 % ukupne varijabilnosti pripisala varijabilnosti jedinki između dvaju staništa (krško naspram obalnog). Nadalje, krške populacije pokazale su homogene i niske vrijednosti multivarijatnog indeksa raznolikosti (MDI), kao i manju varijabilnost između populacija u usporedbi s obalnim populacijama, što odražava fenotipsku prilagodljivost na jednolične uvjete okoliša. Nasuprot tome, obalne populacije pokazale su i visoku i nisku razinu raznolikosti, uz veću međupopulacijsku varijabilnost od one u krških populacija, što se može pripisati različitom podrijetlu populacija i uvjetima staništa. Naši rezultati jasno upućuju da je interakcija između biljke i staništa vrlo složen proces i da ove dvije, jasno odvojene skupine populacija sivkaste vrbe potencijalno mogu predstavljati dva različita ekotipa.
Juniperus L. is a very diverse genus of dioecious or monoecious conifers distributed throughout the Mediterranean region. In addition to the complex taxonomic characteristics of the genus, sexual ...dimorphism leads to sex-specific differences in the morphology of juniper species, which further complicates the delimitation of species. Two of these species, Juniperus oxycedrus L., which occurs in the western part of the Mediterranean, and J. deltoides R.P.Adams, which occurs in the eastern part, have only recently been delimited as separate species. To further support the delimitation of the species, we examined the phenotypic traits of the cones and needles of both species for both sexes. Three populations from the western and three from the eastern part of the Mediterranean region were sampled and a total of 2400 needles, 1200 cones and 1200 seeds were measured and analyzed. Both needles and cones of J. oxycedrus were slightly larger, longer and wider than those of J. deltoides and also less variable. Sexual dimorphism was observed in most of the needle traits measured, with the majority of traits in J. oxycedrus being larger in females than in males. Although sexual dimorphism was confirmed based on needle morphology, no consistent pattern of diversity was observed between the two species. In addition, variability among populations of J. oxycedrus was higher than that of J. deltoides . Our results confirm the previous species delimitation and open the possibility for further exploration of sex-specific differences in adaptability, as well as the potential implications for differential management and conservation of individuals of both sexes.
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