Biology and conservation of Coptis teeta Wall. – an endemic and endangered medicinal herb of Eastern Himalaya

1998 ◽  
Vol 25 (3) ◽  
pp. 262-272 ◽  
Author(s):  
M. K. PANDIT ◽  
C. R. BABU
Keyword(s):  
Scientific Information ◽  
Small Population ◽  
Vital Role ◽  
Eastern Himalaya ◽  
Evolutionary Divergence ◽  
External Threats ◽  
Population Sizes ◽  
Over Exploitation ◽  
Endangered Medicinal Herb ◽  
The Tropics

Medicinal plants are a valuable resource for regional economic development in the tropics, and the Eastern Himalaya in particular harbours many such species. Extensive deforestation and over-exploitation in this region have brought several species to the brink of extinction, and Coptis teeta is such an endangered species; yet scientific information for its conservation is lacking. Investigations on the distribution range, demography, ecology, cytology, reproductive biology and population genetic structure of C. teeta were carried out; it was found to be endemic to a small area, to occupy a very narrow habitat and to be highly dispersed with very small population sizes. Edaphic factors were found to have played a vital role in ecological preference, natural distribution and evolutionary divergence of the species. The species exhibits a ‘K’ strategy, high male sterility, low reproductive success and efficiency, inadequate seed dispersal, and little genetic variability. A combination of these genetic hurdles and external threats in the form of habitat disturbance and over-exploitation for commercial purposes could result in its extinction. The species was found to have highly specific microsite requirements that cannot be met in other habitats. It is argued that in situ conservation measures would be the best strategy for the continued survival of this species. For effective management of the species it is recommended that its habitat be declared a protected area with the active cooperation of local inhabitants including the sharing of benefits of conservation.

scholarly journals Global distribution and drivers of language extinction risk

2014 ◽  
Vol 281 (1793) ◽  
pp. 20141574 ◽  
Author(s):  
Tatsuya Amano ◽  
Brody Sandel ◽  
Heidi Eager ◽  
Edouard Bulteau ◽  
Jens-Christian Svenning ◽  
...  
Keyword(s):  
Economic Growth ◽  
Extinction Risk ◽  
Small Population ◽  
Global Distribution ◽  
Human Populations ◽  
Small Range ◽  
Geographical Patterns ◽  
Socioeconomic Drivers ◽  
Population Sizes ◽  
The Tropics

Many of the world's languages face serious risk of extinction. Efforts to prevent this cultural loss are severely constrained by a poor understanding of the geographical patterns and drivers of extinction risk. We quantify the global distribution of language extinction risk—represented by small range and speaker population sizes and rapid declines in the number of speakers—and identify the underlying environmental and socioeconomic drivers. We show that both small range and speaker population sizes are associated with rapid declines in speaker numbers, causing 25% of existing languages to be threatened based on criteria used for species. Language range and population sizes are small in tropical and arctic regions, particularly in areas with high rainfall, high topographic heterogeneity and/or rapidly growing human populations. By contrast, recent speaker declines have mainly occurred at high latitudes and are strongly linked to high economic growth. Threatened languages are numerous in the tropics, the Himalayas and northwestern North America. These results indicate that small-population languages remaining in economically developed regions are seriously threatened by continued speaker declines. However, risks of future language losses are especially high in the tropics and in the Himalayas, as these regions harbour many small-population languages and are undergoing rapid economic growth.

scholarly journals Evolutionary Method of Detecting Intrusions using Different Population Dynamics

2020 ◽  
Vol 9 (5) ◽  
pp. 1924-1931
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Large Population ◽  
Computation Time ◽  
Small Population ◽  
Vital Role ◽  
Local Optima ◽  
Population Sizes ◽  
Speed Up ◽  
Dynamic Population

Chaos theory plays a vital role in any evolutionary based algorithms for avoiding the local optima and to improve the convergence speed. Various researchers have used different methods to increase the detection rate and to speed up the convergence. Some researchers have used evolutionary algorithms for the same purpose and has proved that the application of those algorithms provide good results. Most of the researchers have used population sizes which remains constant throughout the evolution. It has been seen that small population size may result in premature convergence and large population size requires more computation time to find a solution. In this paper, a novel application of different population dynamics to the genetic programming (GP) algorithm has been applied to manage the population size. The main focus was to improve the accuracy of the normal GP algorithm by varying the population sizes at each generation. The experiments were conducted on the standard GP algorithm using static and dynamic population sizes. Different population dynamics has been used to check the effectiveness of the proposed algorithm. The results obtained has shown that dynamic population size gives better results compared to static population size and also solves the problem of local optima.

scholarly journals Fern diversity and distribution in the UBD campus

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Daniele Cicuzza ◽  
Muhammad Adib Hidayatullah Ahmad ◽  
Ahmad Rafi’uddin Bin Jipli ◽  
Dk Noorul Suhailah Binti Pg Sapudin ◽  
Nor Syukriah Akmal Bte Awg Hj Ismail
Keyword(s):  
Small Population ◽  
Forest Fragments ◽  
Infrastructure Development ◽  
Brunei Darussalam ◽  
Forested Areas ◽  
Population Sizes ◽  
Conservation Projects ◽  
The Tropics ◽  
Flora Diversity ◽  
Small Forest

Green areas and parks are important for maintaining local biodiversity in urbanised habitats. Recent studies have demonstrated that the biodiversity retained in these areas is also important for engaging citizen scientists in conservation projects. Most of the documentation on biodiversity is from temperate regions, whereas in the tropics this field is still in its infancy. This study documented the fern and fern allies richness and abundance within the Universiti Brunei Darussalam (UBD) campus, Brunei Darussalam. We found 39 species in total, belonging to 20 families and 28 genera. Although the total richness did not differ between forest and open plots, ordination showed that forested areas retained a different species composition. Although none of the identified species were IUCN listed, nearly half of the species were recorded once or twice, indicating small population sizes and the biological value of small forest fragments. Our study contributes to understanding the flora diversity of the UBD campus. These results can be used to minimise environmental degradation during infrastructure development on the UBD campus.

scholarly journals Effects of Habitat Fragmentation on Genetic Diversity in Cycas Balansae (Cycadaceae)

2017 ◽  
Vol 23 (3) ◽  
pp. 193
Author(s):  
Nguyen Minh Tam ◽  
Nguyen T. Phuong Trang ◽  
Vu T. Ha Giang ◽  
L. Triest Triest
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Polyacrylamide Gel Electrophoresis ◽  
Genetic Distances ◽  
Small Population ◽  
Species Survival ◽  
Geographical Distances ◽  
Population Sizes ◽  
Over Exploitation ◽  
High Level

Habitat fragmentation is a serious threat to species survival. In Vietnam, Cycas balansae has been considered as threatened species because of the reduction and fragmentation of its habitats and over-exploitation. We assessed genetic variability and the pattern of population structure among six populations sampled in four provinces: Hoa Binh, Ha Nam, Ninh Binh and Quang Ninh. Polyacrylamide gel electrophoresis was performed on leaf tissues from 152 individuals representing 6 populations of C. balansae. Six of twelve enzyme systems were used to estimate genetic diversity at population and species levels. Eleven loci were examined. The allozyme data showed high levels of genetic diversity within all populations, ranging from 0.538 in Ba Sao to 0.628 in Tan Dan (average 0.576). The maintenance of high levels of expected heterozygosity (average 0.571) and low in observed heterozygosity (average 0.347) might be related to great heterozygote deficiency and increased frequencies of rare alleles. Genetic differentiation among populations was low (Dst = 0.036 and Gst = 0.064), indicating high level of gene flow (Nm = 3.22). Isolation by geographical distance was observed, however, no significant relationship between genetic distances and geographical distances was recorded. Our studies suggest small population sizes of cycads brought about by fragmentation of its habitats, over-exploitation, and increasing number of inbred individuals within populations. 

Estimating the exposure of carnivorous plants to rapid climatic change

2018 ◽  
Author(s):  
Matthew C. Fitzpatrick ◽  
Aaron M. Ellison
Keyword(s):  
Climatic Change ◽  
Habitat Suitability ◽  
Species Distributions ◽  
Dispersal Limitation ◽  
Small Population ◽  
Carnivorous Plant ◽  
Carnivorous Plants ◽  
Habitat Specialization ◽  
Population Sizes ◽  
Suitable Habitats

Climatic change likely will exacerbate current threats to carnivorous plants. However, estimating the severity of climatic change is challenged by the unique ecology of carnivorous plants, including habitat specialization, dispersal limitation, small ranges, and small population sizes. We discuss and apply methods for modeling species distributions to overcome these challenges and quantify the vulnerability of carnivorous plants to rapid climatic change. Results suggest that climatic change will reduce habitat suitability for most carnivorous plants. Models also project increases in habitat suitability for many species, but the extent to which these increases may offset habitat losses will depend on whether individuals can disperse to and establish in newly suitable habitats outside of their current distribution. Reducing existing stressors and protecting habitats where numerous carnivorous plant species occur may ameliorate impacts of climatic change on this unique group of plants.

scholarly journals Phytotoxic Activity and Growth Inhibitory Substances from Albizia richardiana (Voigt.) King & Prain

2021 ◽  
Vol 11 (4) ◽  
pp. 1455
Author(s):  
Kawsar Hossen ◽  
Arihiro Iwasaki ◽  
Kiyotake Suenaga ◽  
Hisashi Kato-Noguchi
Keyword(s):  
Spectral Analysis ◽  
Vital Role ◽  
Deciduous Tree ◽  
Dependent Manner ◽  
Aqueous Methanol ◽  
Barnyard Grass ◽  
Phytotoxic Activity ◽  
Growth Inhibitory ◽  
Albizia Richardiana ◽  
The Tropics

Albizia richardiana, a fast-growing, large deciduous tree belonging to the Fabaceae family, grows well in hot and humid areas but mainly grows in the tropics of the Old World. The medicinal and other uses of Albizia richardiana are well documented, but the phytotoxic effects of this tree have not yet been investigated. We conducted this study to investigate the phytotoxic activity of Albizia richardiana leaves and to identify growth inhibitory substances for controlling weeds in a sustainable way. Aqueous methanol extracts of Albizia richardiana leaves greatly suppressed the growth of cress and barnyard grass seedlings in a concentration- and species-dependent manner. Two phytotoxic substances were separated using several purification steps and characterized through spectral analysis as dehydrovomifoliol and loliolide. Dehydrovomifoliol and loliolide significantly arrested the seedling growth of cress in the concentrations of 0.1 and 0.01 mM, respectively. The extract concentrations needed for 50% growth inhibition (I50 values) of cress seedlings were 3.16–3.01 mM for dehydrovomifoliol and 0.03–0.02 mM for loliolide. The results suggest that these two allelopathic substances might play a vital role in the phytotoxicity of Albizia richardiana leaves.

Terminalia catappa (Singapore almond).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
Indian Ocean ◽  
Plant Communities ◽  
Western Indian Ocean ◽  
Agroforestry Systems ◽  
The Philippines ◽  
Vital Role ◽  
South East Asia ◽  
Edible Fruit ◽  
Tree Component ◽  
The Tropics

Abstract T. catappa is a hardy, fast-growing, deciduous multipurpose tree, reaching 25 (-40) m tall and producing an edible fruit. It plays a vital role in coastline stabilization as a tree component of strandline plant communities in the western Indian Ocean, South-East Asia and the South Pacific. Under suitable conditions it is a well-formed tree and has been widely planted throughout the tropics for shade, ornament and nuts, especially along sandy seashores (Heinsleigh and Holaway, 1988; Little and Skolmen, 1989). It is much used in agroforestry systems in the Philippines.

Evolutionary conservatism will limit responses to climate change in the tropics

2021 ◽  
Vol 17 (10) ◽  
Author(s):  
Ethan B. Linck ◽  
Benjamin G. Freeman ◽  
C. Daniel Cadena ◽  
Cameron K. Ghalambor
Keyword(s):  
Thermal Tolerance ◽  
Species Turnover ◽  
Tropical Species ◽  
Evolutionary Divergence ◽  
Closely Related Species ◽  
Tropical Mountains ◽  
Low Latitudes ◽  
Parapatric Speciation ◽  
The Tropics

Rapid species turnover in tropical mountains has fascinated biologists for centuries. A popular explanation for this heightened beta diversity is that climatic stability at low latitudes promotes the evolution of narrow thermal tolerance ranges, leading to local adaptation, evolutionary divergence and parapatric speciation along elevational gradients. However, an emerging consensus from research spanning phylogenetics, biogeography and behavioural ecology is that this process rarely, if ever, occurs. Instead, closely related species typically occupy a similar elevational niche, while species with divergent elevational niches tend to be more distantly related. These results suggest populations have responded to past environmental change not by adapting and diverging in place, but instead by shifting their distributions to tightly track climate over time. We argue that tropical species are likely to respond similarly to ongoing and future climate warming, an inference supported by evidence from recent range shifts. In the absence of widespread in situ adaptation to new climate regimes by tropical taxa, conservation planning should prioritize protecting large swaths of habitat to facilitate movement.

scholarly journals Nestling Sex Ratio in the Southwestern Willow Flycatcher

The Condor ◽  
2002 ◽  
Vol 104 (4) ◽  
pp. 877-881
Author(s):  
Eben H. Paxton ◽  
Mark K. Sogge ◽  
Tracy D. McCarthey ◽  
Paul Keim
Keyword(s):  
Sex Ratio ◽  
Molecular Genetic ◽  
Small Population ◽  
Geographic Isolation ◽  
Breeding Populations ◽  
Population Sizes ◽  
Genetic Techniques ◽  
Willow Flycatcher ◽  
Empidonax Traillii ◽  
Negative Impacts

AbstractUsing molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts.Cociente de Sexos en Polluelos de Empidonax traillii extimusResumen. Utilizando técnicas moleculares determinamos el sexo de 202 polluelos de Empidonax traillii extimus pertenecientes a 95 nidos que fueron muestreados durante un período de cinco años. En general, el cociente de sexos no varió significativamente de 50:50 entre años, ya sea por orden de la nidada o por estrategia de apareamiento (monogamia vs. poligamia). Sin embargo, observamos diferencias significativas entre los cuatro sitios muestreados, en los cuales la razón de sexos estuvo sesgada hacia los machos o las hembras dependiendo del sitio. Dados los pequeños tamaños poblacionales y el aislamiento geográfico de muchas de las poblaciones reproductivas de esta subespecie en peligro, las diferencias en el cociente de sexos pueden tener un impacto negativo a nivel local.

scholarly journals Trade-offs between burrowing and biting force in fossorial scincid lizards?

2020 ◽  
Vol 130 (2) ◽  
pp. 310-319
Author(s):  
Margot Le Guilloux ◽  
Aurélien Miralles ◽  
John Measey ◽  
Bieke Vanhooydonck ◽  
James C O’Reilly ◽  
...  
Keyword(s):  
Vital Role ◽  
Cranial Morphology ◽  
Energetic Cost ◽  
Evolutionary Divergence ◽  
Trade Offs ◽  
Large Head ◽  
Functional Advantage ◽  
Phenotypic Diversification ◽  
And Performance ◽  
The Brain

Abstract Trade-offs are thought to be important in constraining evolutionary divergence as they may limit phenotypic diversification. The cranial system plays a vital role in many functions including defensive, territorial, predatory and feeding behaviours in addition to housing the brain and sensory systems. Consequently, the morphology of the cranial system is affected by a combination of selective pressures that may induce functional trade-offs. Limbless, head-first burrowers are thought to be constrained in their cranial morphology as narrow heads may provide a functional advantage for burrowing. However, having a wide and large head is likely beneficial in terms of bite performance. We used 15 skink species to test for the existence of trade-offs between maximal push and bite forces, and explored the patterns of covariation between external head and body morphology and performance. Our data show that there is no evidence of a trade-off between bite and burrowing in terms of maximal force. Species that generate high push forces also generate high bite forces. Our data also show that overall head size covaries with both performance traits. However, future studies exploring trade-offs between force and speed or the energetic cost of burrowing may reveal other trade-offs.

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