Shannon Weaver Research Articles

Phenotypic diversity in the pigeonpea (Cajanus cajan) core collection

The pigeonpea core collection developed at ICRISAT genebank consists of 1,290 accessions from 53 countries. The core collection, which includes selected lines in extra early, early, medium and late maturity groups was evaluated for 18 qualitative and 16 quantitative characters during the 2004 rainy season, to assess the phenotypic diversity and determine the relative importance of different characters in evaluating pigeonpea germplasm accessions. The four maturity groups differed significantly for all characters under study. The medium maturity group showed significantly higher mean number of primary, secondary and tertiary branches, number of racemes, pod bearing length, pods per plant, shelling percent and plot seed yield. Late maturity group showed significantly higher mean for leaf size, plant height, pod length, seeds per pod and 100-seed weight, indicating this group as a good source of vegetable pigeonpea. Significant positive correlations were found between number of secondary branches and pods per plant in extra early group (r = 0.756), late maturity group (r = 0.776) and entire core (r = 0.728) and between number of racemes and pods per plant in all maturity groups and entire core. Principal coordinate and principal component analysis showed that seven qualitative and nine quantitative traits were important in explaining multivariate polymorphism. The Shannon–Weaver diversity index (H′) varied for different maturity groups and traits. Phenotypic diversity, averaged over all the 16 characters, increases from extra early group (0.36 ± 0.04) to late maturity group (0.42 ± 0.04) suggesting that medium and late maturity groups have greater diversity compared to extra early and early maturity groups.

Status and Trends of Benthic Populations in a Coastal Drowned River Mouth Lake of Lake Michigan

Muskegon Lake was designated an Area of Concern because of severe environmental impairments from direct discharge of industrial and municipal wastes. Since diversion of all municipal and industrial wastewater in 1973, few studies have assessed ecological changes associated with improved water quality. We examined distributions and long-term changes in the benthic macroinvertebrate community at 27 sites. Distributions were evaluated relative to distance from the river mouth, water depth, grain size, and known areas of sediment contamination. Temporal changes were assessed relative to wastewater diversion. Oligochaeta and Chironomidae dominated the community, and the oligochaete trophic condition index indicated that, in 1999, the lake was generally mesotrophic to eutrophic. Cluster analysis resulted in four distinct site groupings. A cluster of sites near the river mouth had the highest total density (9,375 m −2) and lowest diversity (Shannon Weaver Index 1.05) suggesting an enriched habitat. A site cluster in the south central region had the lowest oligochaete density (2,782 m −2), lowest oligochaete trophic condition index scores (1.00), and highest diversity (2.24), suggesting the best habitat. The chironomid community in this site cluster was dominated by predatory species, possibly resulting from high concentrations of heavy metals at some sites. Densities of all major taxonomic groups increased significantly between 1972 and 1999. Decreasing proportions of oligochaetes (0.85 to 0.68) and increasing diversity suggest improved environmental conditions over this period. Evidence suggests that changes in Muskegon Lake's benthic community were more a result of wastewater diversion than Dreissena invasion.

Amphibian abundance and diversity in Meru National Park, Kenya

AbstractThe diversity and abundance of amphibians were investigated in Meru National Park, Kenya, using transect sampling, drift‐fence and pitfall trapping and opportunistic collecting. A total of 430 individuals under seven genera (Amietophrynus, Hemisus, Hyperolius, Phrynobatrachus, Phrynomantis, Ptychadena, Xenopus) comprising eleven species were sampled in three different habitats (apart from this, two additional species are known from Meru National Park): Acacia‐wooded grassland; Combretum‐wooded grassland; Acacia–Commiphora bushland. The sex ratio for almost all species was balanced (chi‐square, χ2; P > 0.5) and was not affected by habitat type (ANOVA: F = 8.3026, P = 0.6914). Shannon–Weaver Index (2.227) and Simpson's Index (8.244) were relatively high, and most of the eleven species sampled appeared to have a relatively even distribution (Shannon's Evenness Index, E = 0.927). However, Hemisus marmoratus and Phrynomantis bifasciatus were exclusively recorded in Acacia‐wooded grassland and in low abundances. There was a positive linear relationship of body weight against snout–vent length for two randomly selected anurans (Hyperolius glandicolor, Phrynobatrachus natalensis) among all three vegetation communities.

Home gardens in western Nepal: opportunities and challenges for on-farm management of agrobiodiversity

Home gardens are defined as a system of production of diverse crop plant species, which can be adjacent to household or slightly further away and is easily accessible. Species composition and management systems of Nepalese home gardens are poorly known. The study was conducted to develop an inventory on composition of crop species and varietal diversity to characterise the home gardens of Rupandehi and Gulmi of western Nepal, and to observe the species change over the time for last 10–15 years. Semi-structured Interviews, Direct Observation and Focus Group Discussions were employed to collect primary data. Shannon–Weaver index (SWI) was used to determine the species richness. Principal Component Analysis (PCA) was employed to characterise the home gardens. Mid-hill SWI (H′ = 4.41) revealed the higher species diversity (131 species) as compared to terai (123 species). This species richness was significantly higher (p = 0.001) in the mid-hill area. The vegetable species constitute the major component followed by fruits and fodder species that also contributed to the species diversity. The size of home gardens and species richness was positively correlated (rs = 0.29, p = 0.001). Twenty crop species have been lost during the last 10–15 years and eleven species were threatened in the studied home gardens. Inaccessibility of local seed crops and deforestation were the major causes reported accounting for this trend. Self-saved seed was the major source of planting material in home gardens. There is a need to study the seed supply system for these home gardens. Therefore, a challenge is to make these home gardens self-supporting through creating a mechanism on strengthening local seed supply systems for long term sustainability of home garden in agrobiodiversity management.

Effects of continuous cucumber cropping and alternative rotations under protected cultivation on soil microbial community diversity

The diversity of soil microbial communities as affected by continuous cucumber cropping and alternative rotations under protected cultivation were evaluated using community level physiological profiles (CLPP) and random amplified polymorphic DNA (RAPD) analysis. The soils were selected from six cucumber cropping systems, which cover two cropping practices (rotation and continuous cropping) and a wide spectrum for cucumber cropping history under protected cultivation. Shannon–Weaver index and multivariate analysis were performed to characterize variations in soil microbial communities. Both CLPP and RAPD techniques demonstrated that cropping systems and plastic-greenhouse cultivation could considerably affect soil microbial functional diversity and DNA sequence diversity. The open-field soil had the highest Shannon–Weaver index (3.27 for CLPP and 1.50 for RAPD), whereas the lowest value occurred in the 7-year continuous protected cultivation soil (3.27 for CLPP and 1.50 for RAPD). The results demonstrated that continuous plastic-greenhouse cultivation and management can cause the reduction in the species diversity of the biota. Higher Shannon–Weaver index and coefficients of DNA sequence similarity were found in soils under rotation than those under continuous cropping. Cluster analysis also indicated that microbial community profiles of continuous cultivation soils were different from profiles of rotation soils. The reduction in diversity of microbial communities found in continuous cultivation soils as compared with rotation soils might be due to the differences in the quantity, quality and distribution of soil organic matter.

A new local estimator of regional species diversity, in terms of ‘shadow species’, with a case study from Sumatra

In a local biodiversity inventory the locally rare species are of particular importance. The main problem of sample-based inventories is that many species are so rare that they will not be observed. The observed frequencies of species in the sample provide an estimate of the species proportion in the population. This may be used to estimate the number of species which exist in the population, but which were not observed in the sample (shadow species). This non-parametric approach provides an unbiased estimate of the relative frequency distribution of the species in the population, which differs very significantly from the sample distribution, particularly for the rare species. The approach leads to a new and ecologically meaningful estimator of the Renyi–Hill generalized species diversity measure, which includes species abundance, the Shannon–Weaver and Simpson's diversity measures, amongst others. The use of the estimator is illustrated on data from a biodiversity inventory of trees on a 3-ha forest sample plot in Sumatra.

Community ecotoxicology: Invertebrate emergence from Fire Trol 934 contaminated vernal pool and salt marsh sediments under contrasting photoperiod and temperature regimes

Fire retardant chemicals are being used increasingly throughout the world to effectively manage wildland fires. The widespread use and high volume of retardant products being applied increase the potential for contamination of temporary wetlands that represent critical habitat for numerous species. This study aimed at assessing the emergence response of invertebrates from fire-retardant-contaminated sediments derived from two temporary wetlands, a vernal pool and a salt marsh, which differ distinctly in their invertebrate resting egg bank structure. Two application rates (1 and 3 L m −2) of the commercially available fire retardant, Fire Trol 934, were used to simulate environmentally realistic contamination scenarios for wetlands situated in Mediterranean grasslands and shrublands, respectively. Two contrasting emergence conditions (winter versus spring flooding conditions) were simulated to take into account the high inter- and intra-annual variability of pond filling in Mediterranean areas. Results showed a decrease in abundance ( p < 0.001), taxonomic richness ( p < 0.001) and biodiversity based on Shannon–Weaver diversity indices ( p < 0.001) in both wetlands and under both emergence conditions with increased retardant application rate. This was due to the loss of chydorids, daphnids, ostracods, and rotifers in the vernal pool, and rotifers, nematodes, protozoa and aquatic fungi in the salt marsh. The observed patterns were similar for many taxa and community metrics at either retardant level irrespective of hatching regime, suggesting that the timing of pond filling was generally not an important influence in community response to Fire Trol. A multivariate approach to characterize community structure suggests that wetlands that undergo periodic drying are resilient to perturbations by chemicals and that community responses to anthropogenic stressors may be well within the range of response to natural disturbances.

Structural characterization of fulvic acids, extracted from sewage sludge during composting, by thermochemolysis–gas chromatography–mass spectrometry

Thermochemolysis coupled with gas chromatography and mass spectrometry were applied to determine the chemical structure of fulvic acids (FA) extracted from a sewage sludge and straw mixture at different steps of composting. The FA starting structures were composed mainly of mono-, di- and tri-methoxy (alkyl) benzoic acids representing lignin derivatives in an advanced stage of oxidation, as well as of methylated polyphenols and a series of fatty acids saturated C15, C16, C18, unsaturated and branched C18:1. Besides, there are many unidentified structures suspected to be N-containing compounds. During the composting process, the fate of the three structural typical monomer units of lignin was followed. The p-hydroxyphenyl units showed a strong relative decrease especially at the beginning of composting. The guiaicyl units showed a steady increase in course of composting. A relative decrease of syringyl units was noted at the beginning of composting, but they then relatively increased towards the end of composting. These changes support the formation during composting of more oxidized units. All subunits composing the fulvic acid structures have been subdivided into main five groups of similar chemical structure. The lignin-like C6–C3 subunits showed a relative decrease during composting attributed to microbial oxidation, but there was a relative increase during the intermediate step of composting related probably of an enhancing of lignin solubility. The C6–C1 subunits were reduced at the beginning of composting, which mainly attributed to the oxidation of 4-methoxybenzaldehyde to hydroquinones derivatives under the composting conditions. Although, the relative increase of these subunits (C6–C1) at the end of composting originates from oxidation of C6–C3 lignin side-chains or could be partly attributed to microbial neosynthesis. The unidentified N-containing compounds increased strongly during course of composting. The rise in the level of fatty acids at the beginning of composting is attributed to an increase of branched-chain fatty acids such as C18:1 commonly used as bacterial biomarkers. Their amounts were greatly reduced at the end of composting. Both the Shannon–Weaver and similitude indices show a relative increase in structural diversity at the start of composting conditions following the appearance of hydroquinone derivatives and unidentified nitrogen compounds in the FA network. But, the produced FA structure reaches a certain level of homogeneity at the end of composting through self-polycondensation or recombination of C6–C1 subunits and hydroquinones derivatives with N-containing compounds.

Hybrid Zones Between Two European Oaks: a Plant Community Approach

Phenomena of hybridization can affect the ecology and evolution of the species involved in the process, as well as their communities. Although numerous papers focus upon the problem of taxonomy, few of these have attempted to study hybrid zones in relation to the analysis of their communities. On the Iberian Peninsula, hybridization phenomena among different oak species are frequent. It is, however, between Quercus faginea Lam. and Quercus pubescens Willd. where the most noteworthy hybridization phenomenon occurs. In this respect, we are familiar with the existence of different introgression levels but we are unaware of whether these hybrids are the transitory result of the interspecific genetic flow or whether these are maintained by means of extrinsic selection processes. Study of plant communities’ flora and environment might shed light upon this issue. Comparison between plant communities dominated by one of the parental species and those dominated by individuals of hybrid origin might enable us to establish the presence or absence of an environment that is potentially selective in favour of the hybrids. Thus the possible existence of extrinsic selection. Furthermore, this information will help us to understand plant community distribution in an area␣that is difficult to interpret. To this purpose, we used multivariate ordination techniques (DCA and CCA) based upon a total of 395 floristic releves covering the whole range of the parental species on the Iberian Peninsula and upon climatic and edaphic variables for each of these releves. We also compared the groups obtained in relation to floristic similarity (Jaccard index), richness and diversity (Shannon–Weaver index). Forests associated with Quercus pubescens are related to heavy summer precipitation, whereas Quercus faginea forests correspond to lower values of this variable and higher ones for continentality. Between both formations, there is a broad hybrid zone, with diffused borders that are related to an environmental gradient of Mediterranean influence. In this region, two types of forest communities were distinguished, which enabled us to divide the hybrid zones into two territories. Our results allowed us to locate the hybrid zone in an ecotone. The differentiation between habitats appears to indicate models of ecological selection. These models require, by definition, the presence of an environmental gradient between the parental zones. We are, however, aware of the need for future experiments in order to establish whether the hybrids are better adapted than the parental species. Only with availability of all this information can intrinsic selection be rejected.

Effects of elevated atmospheric CO 2 and N fertilization on abundance, diversity and C-isotopic signature of collembolan communities in arable soil

Rising atmospheric CO 2 concentrations are expected to have marked impacts on the carbon (C) turnover in agro-ecosystems through increased plant photosynthetic rates, leading to an enhanced biomass, and wider plant C/N ratios. Through increased carbon allocation below-ground, as well as through changed litter quality, CO 2 enrichment will indirectly affect soil faunal communities. In the present study we investigated how elevated atmospheric CO 2 and two different levels of N fertilization may affect abundance and diversity of collembolans, as important catalysts in decomposition processes, within an agro-ecosystem under winter wheat cultivation. The investigations were carried out in 2002 within a field experiment using the “Free Air CO 2 Enrichment” technique (FACE) at the Federal Agricultural Research Centre (Braunschweig, Germany). Stable C-isotopic analysis of collembolans, soil, and crops gave insight into C translocation. During our investigations δ 13C values of all components analysed were significantly more negative under FACE compared to ambient air conditions. Stable C-isotopic signatures of collembolans were similar to those of soil under ambient air, but in between those of soil and roots under elevated CO 2 conditions. Our results revealed significant effects of both treatments (CO 2 enrichment and N fertilization) on density and species diversity of collembolans. Overall, collembolans were stimulated under elevated CO 2 conditions, showing an increased abundance of more than 50% (11 240 ind m −2) as well as a higher biodiversity (Shannon Weaver index = 2.5; evenness = 0.75) compared to ambient air conditions (7520 ind m −2; Shannon Weaver index = 2.2; evenness = 0.72). With regard to N supply, a decrease of about 20–30% under CO 2 enrichment and 45–55% under ambient air conditions in collembolan abundance with no alteration in diversity was recorded under reduced N fertilization. The observed impacts were species-specific.

Soil microbial functional diversity response following nematocide and biocide amendments in a desert ecosystem

The aim of the current study was to gain a better understanding of the changes that occur in soil microbial community and in its functional diversity as a result of the use of nematocide and biocide inhibitors in natural ecosystems. Both inhibitors are known to have a great effect on the nematode community and total biota, playing an important role in soil food web and biota interactions. The experiment was set up in the Negev Desert using sixteen 1×1 m soil plots, to which two chemical inhibitors were applied: (a) a biocide, to eliminate the whole biotic community; and (b) a nematocide, to eliminate the nematode community in soil. In addition, water treatment was applied to the same soil plots, while untreated soil plots were used as control. Microbial functional diversity, together with abiotic parameters such as soil moisture and total organic carbon, was tested monthly in soil samples collected from the 0–10 and 10–20 cm soil layers. The results of the abiotic parameters showed similar patterns in the two soil layers regardless of the inhibitor treatments. An increase in soil water content followed rainfall patterns. Total organic carbon was low during the wet season and increased during the dry seasons. The Shannon–Weaver index value for microbial functional diversity was found to increase in spring after the wet season in both soil layers. In the upper soil layer, an increase was observed both in the inhibitor and water treatments. However, the increase in the water treatment lasted longer compared to the increase observed in the inhibitor-treated soil plots. In the 10–20 cm soil layer, a different pattern was observed: an increase in microbial functional diversity was observed in the inhibitor-treated soil plots, while an increase in the water-treated soil plots was seen at a later stage. Principal Component Analysis was also conducted, revealing different patterns between inhibitors and water treatments on both a temporal scale, when changes from a homogeneous to heterogeneous consumption pattern were observed, and in the nature of communities that proliferate in the soil. Differences were also observed in the microbial community between the upper 0–10 and the lower 10–20 cm soil layers, where an opposite pattern of substrate consumption was observed. This study emphasizes the important role the biotic component plays in the soil of an arid climate, studying the long-term effects of key species elimination on the microbial community in desert soil.

Senders, Receivers and Deceivers: How Liar Codes Put Noise Back on the Diagram of Transmission

Senders, Receivers and Deceivers: How Liar Codes Put Noise Back on the Diagram of Transmission

Coral Point Count with Excel extensions (CPCe): A Visual Basic program for the determination of coral and substrate coverage using random point count methodology

Photographic and video methods are frequently used to increase the efficiency of coral reef monitoring efforts. The random point count method is commonly used on still images or frame-grabbed video to estimate the community statistics of benthos. A matrix of randomly distributed points is overlaid on an image, and the species or substrate-type lying beneath each point is visually identified. Coral Point Count with Excel extensions (CPCe) is a standalone Visual Basic program which automates, facilitates, and speeds the random point count analysis process. CPCe includes automatic frame-image sequencing, single-click species/substrate labeling, auto-advancement of data point focus, zoom in/out, zoom hold, and specification of random point number, distribution type, and frame border location. Customization options include user-specified coral/substrate codes and data point shape, size, and color. CPCe can also perform image calibration and planar area and length calculation of benthic features. The ability to automatically generate analysis spreadsheets in Microsoft Excel based upon the supplied species/substrate codes is a significant feature. Data from individual frames can be combined to produce both inter- and intra-site comparisons. Spreadsheet contents include header information, statistical parameters of each species/substrate type (relative abundance, mean, standard deviation, standard error) and the calculation of the Shannon–Weaver diversity index for each species. Additional information can be found at http://www.nova.edu/ocean/cpce/.

Patterns of Morphological Variation in a Sample of Cacao (Theobroma Cacao L.) Germplasm from the International Cocoa Genebank, Trinidad

The International Cocoa Genebank, Trinidad (ICG,T) contains 2300 accessions representing a broad range of diversity and geographic origins. This study was undertaken to examine the phenotypic relationships in a diverse sample of 600 cacao accessions from the Genebank. The major objectives were to test the applicability of the accepted nomenclature, viz., the definition of classes, as well as to elucidate the relationships between wild and cultivated germplasm and among accession groups. This will facilitate efficient utilisation, management and improvement of cacao genetic resources through the identification of potentially heterotic groups. In addition, information on morphological variation may be considered along with allelic richness or gene frequencies in selecting core collections, and when formulating strategies for future collections in the wild. Considerable phenotypic variation (high coefficients of variation and Shannon Weaver Diversity Index values) in the germplasm studied was found, and the main groups of cacao were clearly separated. Wild cacao was differentiated from cultivated types by all of the quantitative descriptors except pod length. Recognised genetic groups (Trinitario and Forastero) were discriminated by several quantitative traits including sepal length, cotyledon weight, length and width, and pod index. Principal Component Analysis differentiated among 14 accession groups according to geographic origin and genetic grouping. Cotyledon weight, length and number, pedicel column colour, mature pod ridge colour, sepal length, pod basal constriction and surface texture, and ovule number accounted for most of the variation recorded. The observed improvement in the cultivated germplasm, in terms of agronomic traits such as seed weight and pod index, attests to the success of past selection activities. This apparent improvement (particularly among Refractario germplasm) appears to be accompanied by increased style length, a finding that warrants further study. The reduced diversity in sepal length, ligue width, ovule number, and cotyledon length in the cultivated compared to the wild germplasm is consistent with the narrowing of the genetic base in the former. These results have significance for cacao breeding programmes, conservation and future collecting strategies.

Diversity and abundance of wild host plants of lepidopteran stem borers in two different agroecological zones of Kenya

A survey was carried out between 2004 and 2005 in two ecologically different locations, Kakamega and Muhaka to assess diversity and abundance of wild host plants of lepidopteran stem borers as compared to maize plots during the cropping and non-cropping seasons. Kakamega in Western Kenya is characterized by a Guineo-Congolian rain forest mosaic and Muhaka at the Kenyan coast by a Zanzibar Inhambane mosaic with secondary grassy and woody vegetation. In Kakamega, wild host plants and maize covered 2 and 43% of the surveyed area. No variation in diversity and relative abundance of wild host plants was observed between both the cropping and non-cropping seasons. In Muhaka, the diversity and relative abundance of wild host plant species differed between seasons, with the Shannon Weaver Index (H) of 1.67 and 0.95 for cropping and non-cropping seasons, respectively. Similarly in this location, wild host plant cover varied between cropping (23%) and noncropping (17.9%). During both seasons, this was higher than the maize cover, with 10.7% and 0% for the cropping and non-cropping seasons, respectively. For both localities, the implication of the differences found in the abundance and diversity between the cropping and non-cropping seasons is discussed.

Enhanced Biofiltration of Hydrogen Sulfide in the Presence of Methanol and Resultant Bacterial Diversity

Biofiltration is a microbial treatment technology used for the elimination of contaminants from gaseous and liquid effluents, in which pollutants are transferred to the solid matrix of the biofilter, where microorganisms metabolize them to CO2, H2O, or intermediates. Industrial emissions commonly contain compound mixtures (e.g., CH3OH and H2S in the pulp and paper industry) that are structurally different, requiring a diverse microbial community for complete degradation, and results in removal kinetics different from those of single-compound studies. This article describes changes in the bacterial community of a compost biofilter measured using 16S rRNA genes cloned from the biofilter and the impact of the presence of methanol (CH3OH) on degradation kinetics of hydrogen sulfide (H2S). Before H2S addition, the initial bacterial community in the biofilter was characterized by high diversity (Shannon Weaver index, H = 3.65), species richness (richness index, d = 23.94), and evenness. After 20 days of acclimatization to H2S, ribotypes related to the sulfur-oxidizing bacteria Thiobacillus and Sulfobacillus dominated, resulting in lower diversity and richness (H = 1.33, d = 2.77). Introduction of CH3OH resulted in the enrichment of a variety of CH3OH and H2S degraders, thus enhancing the bacterial community (H = 3.02, d = 15.10). Comparison of the mean first-order rate constant for degradation of H2S showed that the rate constant was significantly higher (t-test, p-value = 0.002) with CH3OH introduction (0.040 0.011 s-1) than without (0.022 0.009 s-1). These results indicate that introduction of a co-metabolic substrate enhances bacterial diversity, potentially leading to increased degradation of target compounds. This approach to biostimulation warrants further investigation to identify other non-toxic, easily available stimulants that could be used to improve biofilter performance.

Geographical patterns of diversity for qualitative and quantitative traits in the pigeonpea germplasm collection

We analysed the patterns of variation for 14 qualitative and 12 quantitative traits in 11,402 pigeonpea germplasm accessions from 54 countries, which were grouped into 11 regions. Semi-spreading growth habit, green stem colour, indeterminate flowering pattern and yellow flower colour were predominant among qualitative traits. Primary seed colour had maximum variability and orange colour followed by cream were the two most frequent seed colours in the collection. Variances for all the traits were heterogeneous among regions. The germplasm accessions from Oceania were conspicuous by short growth duration, short height, fewer branches, pods with fewer seeds, smaller seed size and lower seed yields. The accessions from Africa were of longer duration, taller, with multi-seeded pods and larger seeds. The germplasm diversity indicated by Shannon–Weaver diversity index (H′) pooled over all traits, was highest for Africa (0.464±0.039) and lowest for Oceania (0.337±0.037). The cluster analysis based on three principal component scores using 12 quantitative traits revealed formation of three clusters: cluster 1 includes accessions from Oceania; cluster 2 from India and adjacent countries; and cluster 3 from Indonesia, Thailand, the Philippines, Europe, Africa, America and the Caribbean countries. Pigeonpea-rich countries such as Myanmar, Uganda, and others like Bahamas, Burundi, Comoros, Haiti and Panama are not adequately represented in the collection, and need priority attention for germplasm exploration.

Development of Core Collection in Pigeonpea [Cajanus cajan (L.) Millspaugh] using Geographic and Qualitative Morphological Descriptors

Pigeonpea is an important pulse crop grown by smallholder farmers in the semi-arid tropics. Most of the pigeonpea cultivars grown to date are selections from the landraces, with a narrow genetic base. With the expansion of the crop to newer areas, problems of local importance are to be addressed. Hence, an economically feasible and faster germplasm evaluation mechanism, such as a core collection, is required. This article describes the development of core collection from 12,153 pigeonpea accessions collected from 56 countries and maintained at ICRISAT, Patancheru, India. The germplasm accessions from 56 countries were placed under 14 clusters based primarily on geographic origin. Data on 14 qualitative morphological traits were used for cluster formation by Ward’s method. From each cluster ≈10% accessions were randomly selected to constitute a core collection comprising 1290 accessions. Mean comparisons using Newman–Keuls test, variances’ comparisons by Levene’s test, and comparison of frequency distribution by χ2-test indicated that the core collection was similar to that of the entire collection for various traits and the genetic variability available in the entire collection is preserved in the core collection. The Shannon–Weaver diversity index for different traits was also similar for both entire and core collection. All the important phenotypic associations between different traits available in the entire collection were preserved in the core collection. The core collection constituted in the present study facilitates identification of useful traits economically and expeditiously for use in pigeonpea improvement.

Phenotypic Diversity of Foliar Traits in Coconut Germplasm*

Coconut palm is a multipurpose crop cultivated in tropics. Diversity in this crop is rich in South Pacific Ocean and Indian Ocean Islands. Foliar traits have not been studied extensively to understand the diversity. Seven traits relevant to wind tolerance, dry matter production and taxonomic discrimination known in palms are used in the study. An attempt was made using Shannon–Weaver index with an objective to understand the level of diversity for these traits in a germplasm collection from diversity hotspot areas. Seven tall groups and four dwarf groups representing seven island territories were studied using 206 individuals. Diversity estimate was the highest in Nicobar tall group whereas it was low in tall genotypes of Fiji and Tonga. Thickness of leaf sheath fiber of weft and warp strands had shown high diversity estimates. Results obtained in this study were analyzed in relation to adaptation, geographical affinity, mating system and taxonomic forms (typica and nana) along with the importance of foliar traits in diversity of coconut.

Land-use diversity index: a new means of detecting diversity at landscape level

Preservation of ecological diversity is a guiding principle of landscape management and planning. Although diversity is often quantified with measurable indices, common approaches used to measure diversity, for example the Shannon–Weaver index, are not adequate for many landscape studies, because they are affected by scale and sampling efforts. A robust index for measurement of landscape diversity should be able to quantify distinctive components of a landscape mosaic. This paper provides a new diversity index for landscape studies that improves the measurement of diversity at landscape level. The key features of the method are inclusion of an implication of physical moment and quantification of diversity by placing greater weight on the structure and composition of a patch. We have named the new index the “land-use diversity index”, or LUDI, and have concluded that the LUDI is the preferred measure of diversity at landscape level.