Evaluation of leaf features in forest trees: Methods,techniques, obtainable information and limits

Tree leaves are interfaces between the whole organism and the environment. Leaves display a series of attributes that are linked to specific functions (functional leaf traits—FLT) and/or show responses to biotic and abiotic stress factors (stress response traits, SRT), which can be subdivided into: (a) morphological traits; (b) chemical traits; (c) physiological traits; (d) symptoms. The analysis of FLT is a useful tool for tree species and provenance phenotyping, due to the adaptation of trees to environmental stress. Additionally, FLT can be used as response factor in long term and large spatial scales surveys of forest conditions. Despite these potential benefits of leaf traits in the assessment of ecosystem health and functioning, leaf sampling in forests is time-consuming and costly, especially in forests with a complex vertical and horizontal structure and in remote forest areas. Once a foliar sample has been collected, many different analyses can be carried out; however, analyses should be technically simple and able to be performed within one day following the leaf collection (i.e., on fresh samples), or after air-drying the leaves themselves (analysis of dried specimens). This paper reports the results of leaf sampling and foliar analyses carried out in previous research projects and revises the current state-of-the-art. The leaf traits that are easily obtainable from leaf sampling are listed, together with the operational procedures necessary for their measurement, described in a standardized protocol. Their ecological and functional relevance is discussed in relation to their potential information (as indicators of climatic stress, drought, air and soil pollution, tree light-use and competition, plant nutritional status, health and general plant stress conditions). Finally, this review provides suggestions for the elaboration and reporting of data, and proposes some guidelines to improve the effectiveness of foliar analysis in the assessment of forest ecosystem health, properties and functioning.     

In vitro induction of haploid,diploid and triploid plantlets by anther culture of Iochroma warscewiczii Regel

Pollen of Iochroma warscewiczii Regel (Solanaceae) produced embryogenic calli or embryos inside anthers cultured on Nitsch & Nitsch medium. Two distinct pathways could be recognized in this process, one involving mainly the vegetative cell, and the second starting with two equal cells in the pollen grains.In all media tested, androgenesis initiation was highest when anthers contained pollen at the first mitosis, or close to it, at inoculation. High sucrose (7%) and calcium (11.3 mM) concentrations were found to be highly desirable for the induction of androgenesis in this species. Addition of benzylaminopurine (0.5 mg l^–1) to the culture medium seems to slightly improve callus or embryo production. When all three factors were present at optimal concentrations as much as 13.9% of inoculated anthers were found to be embryogenic.Plantlet development from pollen embryos required lower sucrose (3%) and a combination of 0.1 mg l^–1 benzylaminopurine and 0.5 mg l^–1 gibberellic acid in the culture medium. Cytological analysis of 55 regenerated plantlets showed that about 49% were haploids, but diploid (ca. 49%) and triploid (ca. 2%) plants were also obtained.     

Ammonite aptychi: Functions and role in propulsion

Seven previous proposals of aptychus (sensu stricto) function are reviewed: lower mandible, protection of gonads of females, protective operculum, ballasting, flushing benthic prey, filtering microfauna and pump for jet propulsion. An eighth is introduced: aptychi functioned to actively stabilize the rocking produced by the pulsating jet during forward foraging and backward swimming. Experiments with in-air models suggest that planispiral ammonites could lower their aperture by the forward shift of a mobile cephalic complex. In the experiments, the ventral part of the peristome is lowered from the lateral resting (neutral) position by the added “ballast” of a relatively thin Laevaptychus to an angle < 25° from horizontal with adequate stability to withstand the counter-force produced by the jet of the recurved hyponome. However, of the shell forms tested, only brevidomes with thick aptychi, e.g., the Upper Jurassic Aspidoceratidae with Laevaptychus and average whorl expansion rates, were stable enough to swim forward by jet propulsion at about Nautilus speed (∼ 25 cm/s). We propose that aptychus function most commonly combined feeding (jaw, flushing, filtering) with protection (operculum), and, more rarely, with locomotion (ballast, pump, diving and stabilizing plane). Aptychi may thus have been multi-functional.     

Higher investment in flight morphology does not trade off with fecundity estimates in a poleward range‐expanding damselfly

1. Evolutionary increases in dispersal‐related traits are frequently documented during range expansions. Investment in flight‐related traits is energetically costly and a trade‐off with fecundity may be expected during range expansion. 2. However, in contrast to wing‐dimorphic species, this trade‐off is not general in wing‐monomorphic species. In the absence of a dispersal‐‐fecundity trade‐off, an increased investment in clutch size at the expansion front is expected possibly at a cost of reduced offspring size. 3. The study evaluated investment in female flight morphology and fecundity‐related traits (clutch size, hatchling size) and potential trade‐offs among these traits in replicated populations of the poleward range‐expanding damselfly Coenagrion scitulum. 4. Females at the expansion front had a higher relative thorax length, indicating an increased investment in flight; this can be explained by spatial sorting of dispersal ability or in situ natural selection at the expansion front. Edge females produced larger hatchlings, however, this pattern was totally driven by the population‐specific thermal larval regimes and could not be attributed to the range expansion per se. By contrast, clutch sizes did not differ between core and edge populations. There was no signal of a dispersal–fecundity trade‐off either for a trade‐off between clutch size and hatchling size. 5. These results indicate that evolution of a higher dispersal ability at the expansion front of C. scitulum does not trade off with investment in fecundity, hence a dispersal–fecundity trade‐off is unlikely to slow down range expansion of this species.     

The occurrence and frequency of 2n pollen in 2x, 4x,and 6x wild,tuber-bearing Solanum species from Mexico,and Central and South America

Summary The occurrence of 2n pollen-producing plants was investigated in 187 plant introductions (PIs) of 38 wild species of tuber-bearing Solanum. These 2x, 4x, and 6x species are from Mexico, and Central and South America. The determination of 2n pollen-producing plants was conducted using acetocarmine glycerol. Plants with more than 1% large-size pollen were regarded as 2n pollen-producing plants. 2n pollen-producing plants were identified in the following species: 10 out of 12 Mexican 2x species, seven of nine South American 2x species, seven of seven Mexican and Central American 4x species, five of five South American 4x species, and five of five Mexican 6x species. The frequency of 2n pollen-producing plants varied among species at the same ploidy level, but the range of frequency, generally between 2 and 10% among species, was similar over different ploidy levels. The general occurrence of 2n pollen in both 2x and polyploid species, which are evolutionarily related, is evidence that the mode of polyploidization in tuber-bearing Solanums is sexual polyploidization. Furthermore, the frequencies of 2n pollen-producing plants in autogamous disomic polyploid species were not markably different from those of their related diploid species. It is thought that the frequent occurrence of 2n gametes with autogamy tends to disturb the fertility and consequently reduce fitness of polyploids. Thus, we propose that the breeding behavior of polyploids and the occurrence of 2n gametes may be genetically balanced in order to conserve high fitness in polyploid species in tuberbearing Solanum.Paper No. 3114 from the Laboratory of Genetics. Research supported by the College of Agriculture and Life Sciences; International Potato Center; USDA, SEA, CGRO 84-CRCR-1-1389; and Frito Lay, Inc.     

Evolution and disappearance of sympatric Coregonus albula in a changing environment—A case study of the only remaining population pair in Sweden

During the past 50 years, Fennoscandian populations of spring‐spawning Baltic cisco (Coregonus albula), sympatric to common autumn‐spawners, have declined or disappeared; for example, three out of four known spring‐spawning populations in Sweden are regarded as extinct. Over the same period, the climate has changed and populations have been subject to other anthropogenic stressors. We compared historic (1960s) and recent (1990–2000s) morphological data from the still‐existent sympatric cisco populations in Lake Fegen, Sweden. Phenotypic changes were found for spring‐spawners making them more similar to the sympatric autumn‐spawners that had remained virtually unchanged. Based on results for other salmoniform fishes, a phenotypically plastic response to increased temperature during early development appears unlikely. The recent material was also analyzed with microsatellite markers; long‐term effective population size in spring‐spawners was estimated to be about 20 times lower than autumn‐spawners, with signs of long‐term gene flow in both directions and a recent genetic bottleneck in spring‐spawners. We suggest the change toward a less distinct phenotype in spring‐spawners to reflect a recent increase in gene flow from autumn‐spawners. Time since divergence was estimated to only c. 1,900 years (95% CI: 400–5,900), but still the Fegen populations represent the most morphologically and genetically distinct sympatric populations studied. Consequently, we hypothesize that less distinct population pairs can be even younger and that spring‐spawning may have repeatedly evolved and disappeared in several lakes since the end of the last glaciation, concurrent with changed environmental conditions.     

Molecular phylogeny and host-plant use (Lamiaceae) of the Thymogethes pollen beetles (Coleoptera)

The 24 members of the Euro-Asiatic genus Thymogethes are highly specialized pollen beetles associated as larvae with flowers of Lamiaceae Nepetoideae. All members of the genus were analysed in within the framework of an integrative taxonomy approach, which was aimed to reconstruct the phylogenetic relationships, as well as the possible pattern of evolution of their larval-host-plant association. Evidence from multiple molecular markers [COI; 16S; H3], combined with an estimation of divergence times using an average rate of 0.0177 substitutions/site/My among branches, placed the origin of the genus at a minimum of 9–10 Mya. This date of origin approximates the known evolution of the host plants in Euro-Mediterranean areas. Evidence from combined molecular and cladistic morphological analyses resulted in suitable agreement with the previously established morphology-based systematics of the genus, although members of the exilis species-group were split into three clades. The only disagreement between results of this new combined phylogeny and previous classification is in the exclusion of “Thymogethes” grenieri. This species is herein positioned outside the genus, based on molecular evidence. Our analysis depicts several Thymogethes species differentiating in the last few Mys, specifically those included in the T. lugubris species-group. Combined evidence from DNA, morphology and ancestral state parsimony reconstruction of larval-host-plant associations suggests that subtribe Menthinae likely represents the ancestral host plants, with a series of independent host shifts during the radiation of the clade, in association first with Menthinae and subsequently with Lavandulinae and Nepetinae. Steno-oligophagy is the most frequent (86%) condition, while strictly monophagous species are less numerous (14%).