Ecological analysis and environmental niche modelling of Dactylorhiza hatagirea (D. Don) Soo: A conservation approach for critically endangered medicinal orchid

The natural populations of Dactylorhiza hatagirea have been greatly affected due to incessant exploitation. As such, studies on its population attributes together with habitat suitability and environmental factors affecting its distribution are needed to be undertaken for its conservation in nature. Present study aimed at accessing an impact of anthropogenic pressure on population structure and locate suitable habitats for the conservation of this critically endangered orchid. Considerable changes in the phytosociological attributes were observed on account of the changing magnitude and extent of anthropogenic threat in their natural abode. The distribution pattern of species indicated that more than 90% of the populations exhibit substantially aggregated spatial distribution. Maximum Entropy (MaxEnt) distribution modelling algorithm was used to predict suitable habitat and potential area for its cultivation and reintroduction. Twenty-seven occurrence records, nineteen bioclimatic variables, altitude, and slope were used. MaxEnt map output gave the habitat suitability for this species and predicted its distribution in the North-Western Himalayas of India for approximately 616 km². Jackknifing indicated that maximum temperature of warmest month, annual mean temperature, mean temperature of the driest quarter, and mean temperature of the wettest quarter were the governing factors for its distribution and hence, presented a higher gain with respect to other variables. According to permutation importance, precipitation seasonality and mean temperature of wettest quarter shows the prominent impact on the habitat distribution. Results of AUC (area under curve) were statistically significant (0.940) and the line of predicted omission falls very close to an omission on training samples, validating a better run of the model. Response curves revealed a probable increase in the occurrence of D. hatagirea with an increase in mean temperature of the wettest quarter and maximum temperature of the warmest month contributed more than 50% to predicted habitat suitability. Direct field observations concurrent with predicted habitat suitability and google-earth images represent greater model thresholds for successful inception of the species. Together, the study proposes that the species can be conserved in or near its present-day natural habitats and is equally effective in determining the possible habitats for its cultivation and reintroduction.     

An assessment of human impacts on endangered red pandas (Ailurus fulgens) living in the Himalaya

Anthropogenic factors play an important role in shaping the distribution of wildlife species and their habitats, and understanding the influence of human activities on endangered species can be key to improving conservation efforts as well as the implementation of national strategies for sustainable development. Here, we used species distribution modeling to assess human impacts on the endangered red panda (Ailurus fulgens) in high‐altitude regions of Nepal. We found that the distance to paths (tracks used by people and animals), livestock density, human population density, and annual mean temperature were the most important factors determining the habitat suitability for red pandas in Nepal. This is the first study that attempts to use comprehensive environmental and anthropogenic variables to predict habitat suitability for the red pandas at a national level. The suitable habitat identified by this study is important and could serve as a baseline for the development of conservation strategies for the red panda in Nepal.     

Carbon sink limitation and frost tolerance control performance of the tree <Emphasis Type="Italic">Kageneckia angustifolia</Emphasis> D. Don (Rosaceae) at the treeline in central Chile

The decrease in temperature with increasing elevation may determine the altitudinal tree distribution in different ways: affecting survival through freezing temperatures, by a negative carbon balance produced by lower photosynthetic rates, or by limiting growth activity. Here we assessed the relative importance of these direct and indirect effects of altitudinal decrease in temperature in determining the treeline in central Chile (33°S) dominated by Kageneckia angustifolia. We selected two altitudes (2000 and 2200 m a.s.l.) along the treeline ecotone. At each elevation, leaf non-structural carbohydrates (NSC) and gas exchange parameters were measured on five individuals during the growing season. We also determined the cold resistance of K.␣angustifolia, by measuring temperatures that cause 50% seedling mortality (LT₅₀) and ice nucleation (IN). No differences in net photosynthesis were found between altitudes. Although no differences were detected on NSC concentration on a dry matter basis between 2000 and 2200 m, when NSC concentration was expressed on a leaf area basis, higher contents were found at the higher elevation. Thus, carbon sink limitations may occur at the K. angustifolia’s upper altitudinal limit. For seedlings derived from seeds collected at the 2200 m, LT₅₀ of cold-acclimated and non-acclimated plants were −9.5 and −7 °C, respectively. However, temperatures as low as −10 °C can frequently occur at this altitude during the end of winter. Therefore, low temperature injury of seedlings seems also be involved in the treeline formation in this species. Hence, a confluence of global (carbon sink limitation) and regional (freezing tolerance) mechanisms explains the treeline formation in the Mediterranean-type climate zone of central Chile.     

Effects of individual size,local competition and canopy closure on the stem volume growth in a monoclonal Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don) plantation

We studied how the dominant factor affecting stem volume growth changes during stand development in a monoclonal stand of Cryptomeria japonica D. Don. Stem analysis was used to compare growth history of trees in an unthinned plot (closed canopy) and a thinned plot (open canopy). In the unthinned plot, the dominant factor affecting stem volume growth was basal area (BA) before canopy closure, whereas neighborhood competition index (CI) was the dominant factor after canopy closure. In contrast, the dominant factor affecting stem volume in the thinned plot was BA throughout stand development. Spearman’s rank correlation coefficient between BA and CI continued to increase after canopy closure and size rank among individuals became increasingly fixed. Our results indicated that stem volume growth shifts from size-dependent to competition-dependent growth at canopy closure. The apparent correlation between tree size and growth rate observed in many previous studies may be the result of competition-mediated positive feedback between size and growth.     

The development of lingual glands in the domestic duck (Anas platyrhynchos f. domestica): 3D‐reconstruction,LM, and SEM study

The major salivary glands of birds develop by branching or elongation of the epithelial cords. The development of the minor salivary glands in form of the lingual glands has never been described. Among birds, only Anatidae have three types of the lingual glands: rostral, caudo‐lateral, and caudo‐medial lingual glands. The study aims to characterize the manner and rate of the lingual glands development in the domestic duck and their topographical arrangement relative to the hyoid apparatus. The study reveals that all three types of the lingual glands develop by branching. We describe five stages of the lingual glands development in the domestic ducks: prebud, initial bud, pseudoglandular, canalicular, and terminal bud stage. The pattern of the lingual glands development in birds is similar to that described for mammals, with the exception, that the terminal buds are formed at the same time as the lumen of the glands. Generally, the rostral lingual gland starts to branch earlier than the caudal lingual glands. The 3D‐reconstruction shows the location and direction of lingual gland development relative to the entoglossal cartilage and basibranchial bone. Light microscopy and scanning electron microscopy allow to characterize the histogenesis of the embryonic epithelium into glandular epithelium. At a time of hatching only secretory units of caudal lingual glands resemble the secretory units of the adult domestic duck. The rostral and caudo‐lateral lingual glands are arranged on the sides of the entoglossal cartilage and basibranchial bone and caudo‐madial lingual glands are located over the basibranchial bone. We suggest that such an arrangement of the lingual glands in the domestic duck is important during food intake and responsible for reduction of friction and formation of food bites.     

A long-term study on interactions between the Adh and αGpdh allozyme polymorphisms and the chromosomal inversion In(2L)t in a seminatural population of D. melanogaster

The Adh and αGpdh allozyme loci (both located on the second chromosome) showed considerable fluctuations in allele frequencies in a seminatural population of Drosophila melanogaster during 1972–97. Both long-term and short-term fluctuations were observed. The short-term fluctuations occurred within almost all years and comparison of allele frequencies between winters and summers showed significantly higher Adh^S (P < 0.001) and αGpdh^F (P < 0.01) allele frequencies in summers. Frequencies of these alleles were significantly positively correlated with environmental temperature, suggesting the adaptive significance of these allozyme polymorphisms. Frequency changes of the Odh locus (located on the third chromosome) showed no seasonal pattern and were not correlated with environmental temperature. Almost all short-term and long-term increases in Adh^S frequency were accompanied by a corresponding decrease in αGpdh^S frequency (r = –0.82, P < 0.001) and vice versa. Further analysis showed that gametic disequilibria between the Adh and αGpdh loci, which frequently occurred, were due to the presence of inversion In(2L)t located on the same chromosome arm and In(2L)t frequencies were positively correlated with environmental temperature. Gametic disequilibria between Adh and Odh and between Odh and αGpdh were hardly observed. Because In(2L)t is exclusively associated with the Adh^S/αGpdh^F allele combination, the observed correlated response in Adh/αGpdh allele frequencies is (at least partly) explained by hitchhiking effects with In(2L)t. This means that the adaptive value of the allozyme polymorphisms has been overestimated by ignoring In(2L)t polymorphism. Fluctuations in Adh allele frequencies are fully explained by selection on In(2L)t polymorphism, whereas we have shown that αGpdh frequency fluctuations are only partly explained by chromosomal hitchhiking, indicating the presence of selective differences among αGpdh genotypes in relation with temperature and independent of In(2L)t. Frequency fluctuations of αGpdh and In(2L)t are consistent with their latitudinal distributions, assuming that temperature is the main environmental factor varying with latitude that causes directly or indirectly these frequency distributions. However, the results of the tropical greenhouse population show no correlation of Adh (independent of In(2L)t) and Odh allele frequencies with environmental temperature, which may indicate that the latitudinal distribution in allele frequencies for these loci is not the result of selection on the F/S polymorphism in a direct way.