Wild Yam Research Articles

Effects of Okinawan wild yam and its component diosgenin on glucose and lipid metabolism in type 2 diabetes model KK-Ay mice

Effects of Okinawan wild yam and its component diosgenin on glucose and lipid metabolism in type 2 diabetes model KK-Ay mice

Effects of mode of reproduction on genetic polymorphism and divergence in wild yams (Dioscoreaceae: Dioscorea)

Evolutionary transitions from sexual to asexual reproduction should have significant influences on genetic divergence and polymorphism at the genome level. Plant lineages with diverse reproductive systems provide opportunities to investigate this question using comparative approaches and studies of molecular evolution. We investigated evidence for differences among the transcriptomes of 19 Dioscorea species (wild yams) with diverse reproductive systems. These included sexual species, those that propagate primarily by bulbils, and those with mixed sexual and asexual reproductive modes. We examined how transitions between these reproductive systems affected between-species divergence and within-species polymorphism. Primarily asexual species exhibited a reduced efficacy of natural selection and accumulation of deleterious mutations for both divergence and polymorphism. In contrast, species with mixed reproductive strategies involving both seed and clonal reproduction showed no evidence of an increased fixation of harmful mutations at the divergence level, while an accumulation of genetic load present in polymorphism was evident. Our study indicates that the genetic consequences of evolutionary transitions from sexual to predominantly clonal reproduction is likely to depend on both the duration and extent of asexuality occurring in populations.

Pseudomonas fortuita sp. nov., isolated from the endosphere of a wild yam

Pseudomonas fortuita sp. nov., isolated from the endosphere of a wild yam

The association between Dioscorea sansibarensis and Orrella dioscoreae as a model for hereditary leaf symbiosis.

Hereditary, or vertically-transmitted, symbioses affect a large number of animal species and some plants. The precise mechanisms underlying transmission of functions of these associations are often difficult to describe, due to the difficulty in separating the symbiotic partners. This is especially the case for plant-bacteria hereditary symbioses, which lack experimentally tractable model systems. Here, we demonstrate the potential of the leaf symbiosis between the wild yam Dioscorea sansibarensis and the bacterium Orrella dioscoreae (O. dioscoreae) as a model system for hereditary symbiosis. O. dioscoreae is easy to grow and genetically manipulate, which is unusual for hereditary symbionts. These properties allowed us to design an effective antimicrobial treatment to rid plants of bacteria and generate whole aposymbiotic plants, which can later be re-inoculated with bacterial cultures. Aposymbiotic plants did not differ morphologically from symbiotic plants and the leaf forerunner tip containing the symbiotic glands formed normally even in the absence of bacteria, but microscopic differences between symbiotic and aposymbiotic glands highlight the influence of bacteria on the development of trichomes and secretion of mucilage. This is to our knowledge the first leaf symbiosis where both host and symbiont can be grown separately and where the symbiont can be genetically altered and reintroduced to the host.

Climate-Adapted Circular Poultry Production: Salt-Treated Wild Yam Tubers as Sustainable Supplementary Feed Ingredients Via Osmosis-Based Detoxification

Wild yams have tremendous potential as nutritious food and feed sources. However, anti-nutritional factors like oxalates and phenolics limit their utilization. This study evaluated salt-assisted osmosis for detoxification and nutritional improvement of wild yam tubers and assessed their application as a feed ingredient for native chickens. Wild yam tubers were treated with 10%, 20%, and 30% salt solutions to induce osmosis-based leaching of water-soluble toxins. Proximate analyses confirmed nutrient retention post-treatment. Four isonitrogenous experimental chicken feeds were formulated with varying proportions of standard commercial diet and salt-treated wild yam meal. Ninety-six 5-week-old native chicks were randomly allocated to the diets for 8 weeks to assess growth performance, intake, meat quality, and physiological parameters. Toxin levels decreased up to 50% with a 30% salt solution while beneficial nutrients were preserved. The inclusion of treated yam meal did not adversely affect growth rate, though higher salt levels reduced feed palatability. Carcass traits remained unaffected although minor organ weight and serum biomarker changes indicated physiological stress. Salt-assisted osmosis the demonstrates potential for efficient detoxification to promote better utilization of under-explored nutritious crops like wild yam as sustainable, alternative feed sources without compromising nutritional adequacy. Further optimization to prevent anti-nutrient reaccumulation and physiological imbalance is recommended before scalability for food/feed security.

Nutritional value, anti-nutrient and amino acid profile of raw and processed wild aerial yam (Dioscorea bulbifera) meal

Nutritional value, anti-nutrient and amino acid profile of raw and processed wild aerial yam (Dioscorea bulbifera) meal

Wild edible yams from Madagascar: New insights into nutritional composition support their use for food security and conservation.

Yams (Dioscorea species) are an important food resource in Madagascar, where both cultivated winged yam (D. alata) and wild edible yams are consumed. However, there is limited knowledge on the nutrient composition of wild edible yams in Madagascar, and on how they compare with the cultivated winged yam. Therefore, in this study, nine wild edible yam species, one with two subspecies from Madagascar (D. bako, D. buckleyana, D. irodensis, D. maciba, D. orangeana, D. pteropoda, D. sambiranensis subsp. bardotiae and subsp. sambiranensis, D. seriflora, and Dioscorea species Ovy valiha), were analyzed for their nutrient composition, compared with cultivated D. alata. They include 6/6 of the most favored wild edible yam species in Madagascar. New nutrient composition data (protein, carbohydrate/starch, energy, lipid, β-carotene, and minerals) are presented for these nine wild edible yam species. The results show that they contain comparable levels of lipids and starch to D. alata, but none are better sources of protein than D. alata. The results show that D. irodensis contains a significantly higher β-carotene content when compared to all other edible yams analyzed, and that D. buckleyana, D. irodensis, and D. sambiranensis subsp. bardotiae have a higher calcium content than cultivated D. alata, while all nine wild edible yam species analyzed contain a higher iron content, compared to cultivated D. alata. The nutrient composition data presented could provide new incentives to conserve wild edible yams and inform on strategies to select Dioscorea species for sustainable cultivation and use, providing opportunities to enhance future food security in Madagascar.

Blending neglected and underutilised wild yam tubers from forest to functional food

The exploitation of neglected and underutilised wild yam species is an important livelihood strategy for tribal community along with providing food and nutritional security. In order to integrate them into developmental interventions, a region-specific assessment of their consumption, traditional processing, and optimal use by tribal groups is necessary. This study analysed the traditional use, consumption pattern and preferences of different wild yam species by tribal communities from 45 villages of Koraput (part of Eastern ghats of India). There are eight wild Dioscorea species have been used as food and medicine by the tribal people of this region. Among the wild species, D. pubera was the most preferred species with highest use vale (UV) of 1.76 followed by D. pentaphylla by the tribal communities. Further these two wild tubers were selected for making value-added products such as cookies and namkeen. From sensory evaluation, D. pubera cookies and namkeen showed better taste, crispiness, smell, colour and over all acceptability of a good score. In addition, these value-added products recorded higher protein, fiber, energy, antioxidants and nutritionally superior than conventional products. These functional foods from wild yam will helpful for mass consumption and will encourage the start-ups for enhancing economic growth of tribal people of the locality.

Physicochemical Properties of Wild Yam (Dioscorea villosa) Starch.

Native starch extracted from wild yam (Dioscorea villosa) was evaluated for its intrinsic physicochemical properties. From the results, essential metals such as K, Ca, P, and Fe were detected along with some nonessential heavy metals below the WHO permissible limits. Bulk density was 0.13-0.63 g/mL. The water absorption capacity, oil absorption capacity, swelling power, and solubility of the starch were pH-responsive. Thermal profiles showed onset temperature, To (59.21 °C), peak temperature, Tp (60.22 °C), endset temperature, Tc (63.12 °C), gelatinization enthalpy, ΔHgel (0.54 J/g), temperature range of gelatinization, R (3.91 °C), and peak height index, PHI (1.87 J/g °C). Exhibiting a crystallite size of 0.03 nm, absorption peaks of 15.3119°, 24.4120°, and 18.4170°, corresponding to interplanar d-spacings of 3.7500 Ǻ, 5.14000 Ǻ, and 4.954610 Ǻ, were obtained. Evidence of C-H at 1338.1 cm-1, C-O at 640.0 cm-1, C-H stretch at 2829.7 cm-1, and a strong and broad O-H group at 3291.2 cm-1 were obtained. The starch granules had low particle sizes, were homogeneous, and were aggregates of irregular shapes. At a lower pH (2-4), the wild yam starch studied could be a potential absorbent material in the production of disposable diapers and female napkins and as biodegradable films due to its high hydrophobicity at a high pH (8-12).

Physico-chemical compositions, nutraceutical properties, and starch-related techno-functional, thermal, and morphological characteristics of underutilized yam flour (Dioscorea spp.) from Odisha

High-yielding wild species of yam (Dioscorea spp.) play a vital role in the diet, nutritional, and economic stability of the tribal community. Lack of in-depth research provides scant information on the nutritional value and quality characteristics of tubers. In the present study, physicochemical, nutraceutical, antinutrients, structural, morphological, and thermal properties of lesser-known yam species: Dioscorea pentaphylla (five-leaf yam), Dioscorea bulbifera (bitter yam), Dioscorea hispida (intoxicating yam), and Dioscorea tomentosa (locally called ‘targai kanda’) were investigated. Total protein, fat, fiber, ash, carbohydrate, and metabolic energy of the investigated species are 5.05–8.79%, 0.33–1.01%, 3.53–14.15%, 3.30–5.31%, 62.60–78.26%, and 1241–149 kJ/100 g, respectively. Significant variations (P ≤ 0.05) were observed among the species for antioxidant, bioactive compounds, and physicochemical attributes, where Dioscorea tomentosa exhibited the highest antioxidant capacity. The starch and amylose content varied between 24.7–57.8% and 12.7–29%. X-ray diffractograms of D. pentaphylla and D. bulbifera displayed a B-type pattern, A-type starches in Dioscorea hispida, and CB–type starch for D. tomentosa. The FT-IR spectra confirmed the polysaccharide nature of the yam flours. The particle size ranged between 9.6 and 72.4 μm. The TG/DTG curves revealed that the yam flour could be subjected to cooking up to 180 °C without carbonization. The reported wild yam flours may have tremendous potential for industrial application. However, the study revealed that the presence of antinutrients might affect the mineral bioavailability, cause toxicity, and health hazards. Thus, this could be overcome by processing before safe consumption. The current study also recommended that these wild yam species are safe and can meet potential nutrition and food security through mainstream cultivation.

Investigating the Usefulness of Wild Dioscorea esculenta (Wild Yam) Flour as Substrate for Citric Acid Biosynthesis

Background and Objective: The cost of substrate represents a significant percentage of the total biosynthesis cost of citric acid. There is need to continue searching for better and cheap underutilize starchy raw material for citric acid biosynthesis. Therefore, the objective of this research was to biologically synthesis citric acid in submerged fermentation of Aspergillus niger using wild Dioscorea esculenta (wild yam) tubers.
 Methodology: Submerged fermentation was conducted and the effect of Dioscorea esculenta concentrations, combined pretreatment and membrane permeability induction on citric acid biosynthesis were carried out.
 Results: Citric acid concentration increased as the concentration of the wild yam increased with maximum citric acid production of 10.5 ± 0.9 g/ l after 96 hours of fermentation. The overnight combined pretreatment with 0.3 % NaOH before pretreatment at 121oC for 20 minutes as one time combined pretreatment yielded 15. 0 ±1.2 g/l citric acid. Calcium chloride membrane induction produced 24.5 ± 1.3 g/l citric acid concentration respectively after 96 hours of fermentation.
 Conclusion: The result showed that wild Dioscorea esculenta tubers can be used as a substrate for the biosynthesis of citric acid. The biosynthesis of citric acid from Dioscorea esculenta tubers was enhanced by increased in concentration, combined pretreatment and membrane permeability induction.

Environment factors influencing abundance and growth of wild yam in broadleaved forest, Tsirang District, Bhutan

Yams (Dioscorea) consist of approximately 600 species in the world. Yams are considered a staple food in Asia, tropical and subtropical regions. Genetic erosion and unsustainable harvesting practices are among the main problems associated with wild yam plants. This study was conducted with the objectives to enumerate wild yam species composition and environmental parameters affecting its growth and abundance. Systematic sampling of the study site was carried out based on different land aspects. Line transects were laid out in selected land aspects within the elevation range of 825 – 1935 m. Five plots in each transect with a 100 m plot interval comprising seven transects were laid out in the study area. Each plot was divided into sub-plot of 20 x 20 m, 5 x 5 m, and 1 x 1 m to enumerate trees, shrubs, and herbs respectively. Seven species of yams were found from the broadleaved forest and spearman correlation showed negative association of yam abundance with tree counts and canopy closure. The areas with higher density of trees had low count of yam abundance. Yam grows well in open canopy in lower altitudes comparing to high altitudes. Yam abundance was positively related with shrubs, herbs, soil moisture, soil organic matter, soil organic carbon, and nitrogen content. Analysis of Variance (ANOVA) showed significant difference of yam abundance in 7 different transects due to different ecological parameters influencing the abundance in different transects though transect being in a broadleaved forest.

Optimization of Water-Based Drilling Muds Using Dioscorea Villosa Starch: A Response Surface Methodology Approach

The need for environmentally friendly alternatives to water-based drilling fluids has prompted an investigation into the effects of Dioscorea villosa starch as a natural additive in the petroleum and gas industry. In this study, a design of experiments approach utilizing Response Surface Methodology (RSM) through Box-Behnken design (BBD) was employed to optimize the extraction of starch from wild yam (Dioscorea villosa) and formulate drilling muds. The regression model was used to determine the optimized parameters for starch extraction and the results showed a close agreement between the experimental and predicted values with a difference of only 1.295%. The responses considered in the design were plastic viscosity, yield point, apparent viscosity, filtrate volume, and filtercake thickness, with three factors being considered: bentonite, Dioscorea villosa starch, and temperature. The properties of the formulated water-based drilling muds enhanced with Dioscorea villosa starch were analyzed using ANOVA, and linear models were selected based on their significance. The findings suggest that the addition of Dioscorea villosa starch improves the filtration and rheological properties of the drilling muds, with optimal concentrations of 16.92g of bentonite, 3.85g of Dioscorea villosa starch, and a temperature of 81.90°F. Overall, the study demonstrates the potential of Dioscorea villosa starch as a natural additive in water-based drilling fluids, providing an eco-friendly alternative to chemical additives and offering potential environmental benefits.

Diosgenin, a Natural Steroidal Sapogenin, Alleviates the Progression of Diabetic Retinopathy in Diabetic Mice.

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and a major cause of blindness in working-age adults. Diosgenin (DG), a natural steroidal sapogenin extracted from fenugreek seeds and wild yam roots, has hypolipidemic, hypoglycemic, anticancer, and anti-inflammatory properties. Given its pharmacological effects, we speculated that DG may be a promising treatment for DR. Therefore, this study was aimed at evaluating the effectiveness of DG in preventing or slowing DR progression in a mouse model (+Leprdb/+Leprdb strain) of type 2 diabetes (T2D). DG (5.0 mg/kg body weight) or phosphate-buffered saline (PBS) was administered to 8-week-old T2D mice via oral gavage daily for 24 weeks. Paraffin-embedded eye tissues from the mice were collected and stained with hematoxylin and eosin to evaluate retinal histopathology. Apoptosis-related proteins BCL2-associated X (Bax), B-cell lymphoma 2 (Bcl-2), and cleaved caspase-3 were evaluated by western blotting of mouse retinas. Body weight was slightly reduced in the DG-treated group; however, glucose levels were not markedly different between the DG- and PBS-treated groups. Total retinal thickness, thickness of the photoreceptor and outer nuclear layers, and loss of ganglion cells significantly improved in the retina of the DG-treated T2D mice compared with those in the PBS-treated T2D mice. Cleaved caspase-3 level significantly decreased in the retina of the DG-treated T2D mice. Conclusion: DG alleviates DR pathology and exerts a protective effect on the T2D mouse retina. The inhibitory effects of DG on DR may involve mechanisms of the anti-apoptotic pathway.

Tracing the Supply Chain of Medicinal Wild Yam Species (Dioscorea spp.) in Cundinamarca, Colombia

Tracing the Supply Chain of Medicinal Wild Yam Species (Dioscoreaspp.) in Cundinamarca, Colombia. Wild yams (Dioscorea spp.) are widely distributed non-timber forest products that are traditionally used as medicine in Cundinamarca, Colombia, and represent a source of income for rural families in the region. The market for these native medicinal species has been growing due to their increasing popularity as a remedy for circulatory and blood problems; however, the supply and demand dynamics of this plant in the forest have not yet been documented. Through qualitative research methods, this study identifies the links and distribution of the wild yam supply chain in Cundinamarca and considers the implications for conservation and sustainability of the resource. Tuber collection was documented in forested areas in 14 municipalities in the Department of Cundinamarca. The tubers are destined for wholesale markets in Bogotá and are purchased by retailers from all over Cundinamarca, even those based in the municipalities from which the tubers were extracted. The collection, distribution, and consumption of Dioscorea species in Cundinamarca respond to growing demand and rely on extraction of the species directly from forest remnants within the Department; these could be at risk of overharvesting if management measures are not taken, or if participatory propagation programs that benefit harvesters and sellers are not implemented. This is the first study of the supply chain in an emerging new market for wild yams in Latin America. It highlights the dynamic, evolving nature of the medicinal plant trade from the local to the national scale, and beyond.

Immune‐stimulating properties of Wild Yam (Dioscorea villosa) root extract in triple‐negative breast cancer cells

Testing the roots of Wild yam (Dioscorea villosa extract (WYE) in vitroconsistently induced cell death at low IC50 concentrations in many types of cancers, including glioblastoma, melanoma, colon cancer, neuroblastoma, and breast cancer. However, reports also demonstrate that WYE contains detergent steroidal saponin surfactants, which act on contact to reduce oil‐water interfacial tensions causing disintegration of the bio‐lipid membranes. In the current investigation we separated cell death from saponins from its biological effects that occur at sub‐lethal doses, where lytic cell death is not an interfering variable in MDA‐MB‐231 triple‐negative breast cancer cells. Moreover, we confirmed the inverse relationship between rising saponin content with destruction to plasma and mitochondrial membranes, concurrent to toxicity in 2D and 3D cell cultures. Once appropriate sub‐lethal concentrations were established, we monitored the changes in whole transcriptomic (WT) mRNA miRNA. Also, the intergenic non‐coding RNAs concurrent to the biological cell proliferation studies, spot test of antibody‐protein arrays, and an ELISA were documented. The results indicate that at sub‐lethal concentrations of WYE, the microarray data show 346 differentially expressed genes (DEGs) of 48,226 transcripts tested; 166 upregulated and 180 downregulated. Upregulated DEGS reflected immune‐stimulating effects on TNF signaling, COX2, cytokine release, and elevated cholesterol/steroid biosynthesis. Downregulated DEGs reveal extensive damage to cell cycle processes, including loss of transcripts for cell division cycle (CDC) genes (25A,45,6,7, A2, A7, A7L,8) cyclins (CCN) (A2, B1, B2, E2, F), cyclin‐dependent kinases (CDKs), centromere proteins (CENP), kinesin family members (KIFs), and polo‐like kinases (PLKs) with exception to a corresponding up‐regulated DEG for p21 gene CDKN1A. The transcriptome data matches cytostatic effects observed in a 6‐day proliferation study. It was concluded that WYE mediates a saponin lytic effect by direct contact and this breast cancer cell model has two different biological consequences at lower concentrations and independent of cell death, including pro‐inflammatory and collapse of the cell cycle effects.

A Review of Human-Elephant Ecological Relations in the Malay Peninsula: Adaptations for Coexistence

Understanding the relationship between humans and elephants is of particular interest for reducing conflict and encouraging coexistence. This paper reviews the ecological relationship between humans and Asian elephants (Elephas maximus) in the rainforests of the Malay Peninsula, examining the extent of differentiation of spatio-temporal and trophic niches. We highlight the strategies that people and elephants use to partition an overlapping fundamental niche. When elephants are present, forest-dwelling people often build above-the-ground shelters; and when people are present, elephants avoid open areas during the day. People are able to access several foods that are out of reach of elephants or inedible; for example, people use water to leach poisons from tubers of wild yams, use blowpipes to kill arboreal game, and climb trees to access honey. We discuss how the transition to agriculture affected the human–elephant relationship by increasing the potential for competition. We conclude that the traditional foraging cultures of the Malay Peninsula are compatible with wildlife conservation.

Combined scouring-bleaching of cotton fabric from wild yam root

The conventional single-stage pre-treatment technique requires more electricity, is more expensive, polluting, harmful, and unhealthy because it uses artificial chemical compounds and auxiliaries. This research focuses on environmentally friendly and cost-effective textiles scouring-bleaching of cotton fabric with saponin and wild yam (Dioscorea villosa L.) root powder. The root of the wild yam contains alkaloids, amylose starch, and saponin. The investigations discovered important findings in cotton wet processing by developing a safe, water- and electricity-saving scouring method. Cotton fabric, along with the utilization of wild yam roots resulted in a significant cost effective method. As a result, it was used as a natural surfactant, foam stabilizer, and emulsifier in this scouring. The single stage Bot scouring was optimized with 40 g of untamed yam and a weight to volume (MLR in W/V) (weight of fabric to water) ratio of 1:10 at 80°C for 60 min on a pH of 5–7. The treatment’s effectiveness was measured using a weight reduction percentage and an absorbency test (a drop of water, capillary upward thrust, sinking time). In terms of weight reduction, water absorbency, capillary boost, as well as amazing friendliness, scouring cotton fabric with wild yam powder at optimized scouring conditions is comparable to scouring cotton fabric with 30% (at the weight of cloth) caustic soda. To verify the fabric samples’ resistance to microbiological development and strength maintenance, wild yam and Caustic soda scoured cotton fabrics were subjected to a soil burial test. The fabric sample scoured with wild yam has a much lesser standard deviations of toughness and elongation at break than the caustic soda scoured and untreated control samples. The Single stage scouring of cotton fabric with wild yam powder met the requirements for green scouring while also providing antibacterial qualities.

Cyanogenic compounds removal and characteristics of non- and pregelatinized traditional detoxified wild yam (Dioscorea hispida) tuber flour

The presence of cyanide compounds restricts the utilization of wild yam (Dioscorea hispida) tubers for food or food ingredients. Traditional detoxification, usually used in wild yam chips processing, has not been evaluated for its effectiveness in reducing cyanogenic compounds. Processing into flour will increase wild yam tubers utilization and pregelatinization usually improve flour functional properties. This study aimed to evaluate the effect of 4 traditional detoxification methods and pregelatinization on cyanogenic compounds removal and wild yam tuber flour characteristics. The different methods were in rubbing ash, soaking time, and pregelatinization methods by boiling or steaming. The duration of a particular step was also different. The results showed that traditional detoxification methods reduced total cyanides 97%, cyanogenic glycosides 98-100%, acetone cyanohydrin 89-97%, and HCN 94-95%; also affected degree of cyanogenic compounds removal. Pregelatinization also reinforced the degree of cyanogen removal. Tuber flour physicochemical properties were affected by detoxification methods and pregelatinization. Modification of starch might occur due to the presence of SiO2 and calcium in rubbing ash and affected functional properties of wild yam tuber flour. Starch granule morphology appeared not to be affected by detoxification methods. Traditional detoxification methods could be used to make a safe wild yam tuber flour.

Medicinal uses, phytochemistry and pharmacological properties of Dioscorea dregeana (Kunth) T. Durand & Schinz

Dioscorea dregeana (Kunth) T. Durand & Schinz is a twining herb commonly known as wild yam which naturally occurs in Eswatini, Mozambique and South Africa. There are several medicinal plants and natural products in South Africa that play an important role in traditional materia medica. However, there is scarce information in the public domain on some of these species, including D. dregeana. Therefore, this investigation documented the medicinal uses, phytochemistry and pharmacological properties of D. dregeana. D. dregeana is mainly used to facilitate child birth, as antenatal, sedative and ethnoveterinary medicine, and traditional medicine for respiratory infections, convulsions, epilepsy, hysteria, insanity, insomnia, soporifics, nervous spasms, cramps, psychosis, sores, wounds and cuts. A variety of phytochemical compounds such as sitosterol, stigmasterol, dodecanosyl 3-[4′-hydroxy, 3′-methoxyphenyl] propenoate, 3, 4′,5-trihydroxybibenzyl, crinamine and dioscorine were identified from the tubers of D. dregeana. The ethyl acetate, methanol, aqueous and dichloromethane extracts of D. dregeana tubers exhibited antibacterial and antifungal activities. More research is needed to assert the medicinal and ethnopharmacological uses of D. dregeana, and also to determine the phytochemical active ingredients, toxicological properties and pharmacological effects of the species.