Relationship between species richness,taxonomic distinctness,functional diversity,and local contribution toβdiversity and effects of habitat disturbance in the riparian spider community of the Ganga River,India

Background In the riverine riparian ecosystem,particularly in India,the knowledge of the effects of habitat disturbance on taxonomic distinctness,functional diversity,and local contribution toβdiversity(LCBD)of spider community is elusive.The present study examined the relationships between the index of taxonomic distinctness(Δ^(+)),index of variation in taxonomic distinctness(λ^(+)),functional evenness(FEve),functional divergence(FDiv),functional dispersion(FDis),and LCBD of spider community of the Ganga River and the effects of habitat disturbance on these indices.A total of 27 sampling sites were selected along the bank of the Ganga River.Based on the rating of the disturbance scores,the sites were classified into lowly,moderately,and highly disturbed sites.To understand the relationships between species richness,Δ^(+),λ^(+),FDis,FDiv,FEve,LCBD,and habitat disturbance score,Pearson’s correlation was calculated,followed by the linear regression model.The one-way multivariate analysis of variance was used to find differences in taxonomic distinctness and functional diversity in the different disturbed sites.Results Significant relationships were found betweenλ^(+)andΔ^(+),FDis andΔ^(+),FDis andλ^(+),FDiv and species richness,FEve and species richness,FEve andλ^(+),FEve and habitat disturbance,LCBD and FEve,and LCBD and habitat disturbance.A significant difference was present in the indices of functional diversity between the lowly,moderately,and highly disturbed sites.Agriculture,garbage dump,human settlement,and created embankment influenced the spider community’sλ^(+),FEve,and LCBD.Conclusion Unrestrained anthropogenic activities exacerbate habitat disturbance by affecting ecological processes.Thus,understanding linkages between ecosystem disturbance,taxonomic,functional,andβdiversity can be fundamental to managing and conserving natural resources.This work highlights the importance of including taxonomic and functional diversity to comprehend the impact of habitat disturbance on riverine riparian spiders beyond just the number of species.An integrated taxonomic and functional diversity approach coupled withβdiversity can be used to support environmental assessment,restoration,and conservation planning of the biological resources of the Ganges River.

Plant assemblage and diversity variation with human disturbances in coastal habitats of the western Arabian Gulf

Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal habitats.This study examined the effects of human disturbance intensity in coastal habitats of Kuwait on diversity,composition,identity and assemblage of vascular plant species.Plant survey data from 113 plots （5m×5m each） were randomly selected in 51 sites at coastal fragmented habitats at three levels of disturbance intensities （high,moderate and low） and were statistically analyzed.The results revealed that about 76% of the recorded species are considered threatened species in Kuwait,most of which are being lost in high disturbed habitats.Disturbance led to the dominance of Zygophyllum qatarense,Cornulaca aucheri and Salsola imbricata,which are species of disturbance indicators.Richness,total plant cover and species diversity were higher in moderate and low disturbed habitats than in high disturbed habitats.Beta diversity between high and low disturbed habitats was higher than either between high and moderate,or between moderate and low disturbed habitats.Cluster analyses showed statistically significant differences in composition of plant assemblages,which indicate high beta diversity between the habitat types.Intensive urbanization and industrialization are among the most serious threats that contribute to declines in biological diversity and rapid fragmentation of coastal habitats in Kuwait.Establishing protective enclosures in the disturbed habitats,planting endangered and vulnerable species,and establishing a natural reserve at Nuwaiseeb are recommended conservation actions to avoid loss of the fragmented coastal habitats and to facilitate restoration of native plants.

Changes of woody species diversity, horizontal and vertical distribution of stems across interior to outside within a primate rich habitat of Northeast India

The interior forest of protected area（PA）recover quickly in terms of greater diversity and structural complexity than peripheral and outsides, which may be due to high plant-frugivore interactions in the interior forest than the disturbed outsides. To describe the structural and functional differences in tree communities from interior to outside forests with in small PA, we quantitatively analyzed the vegetation of Trishna Wildlife Sanctuary, a rich primate habitat of Northeast India. Vegetation was sampled at C10 cm girth at breast height by 10 m 9 500 m sized20 line transects（10 ha） laid in the interior（N = 7）,peripheral（N = 7） and outside（N = 6） zones of this sanctuary. All transects were ordinated by Principal Component Analysis based on correlation between diversity and existing disturbance indices. We found significant differences（P ／ 0.05） in taxonomic richness and diversity indices between the habitat. Van diagram confirmed greater unique species richness in the interior zone（64） than peripheral（28） and outside（6） zones. Overall density（ha-1） did not differed across the zones, but basal area（m2ha-1） was significantly（P ／ 0.01） high in peripheral zone. Vertical distribution of stem density was linearly declined across zones（r2adj[ 0.70; P ／ 0.01） with increase in the canopy height. Horizontal distribution of adult stems showed significant inverse quadratic relationship（r2adj[ 0.80; P ／ 0.001）, which suggests very low density of canopy forming voluminous trees in the interior zone.Immediate protection, restoration and management of interior regions are required to preserve local plant genetic diversity and also to maintain suitable habitat for threatened wildlife.

Biodiverse rotifer assemblage (Rotifera： Eurotatoria) of floodplain lakes of the Brahmaputra basin of lower Assam, northeast India： composition and ecosystem diversity

The study aims to ascertain the hypothesis on the rich rotifer biodiversity of the floodplain lakes （beels） of the Brahmaputra river basin and to use these metazoans to assess trophic status or to characterize habitat variations of wetlands. The plankton samples collected from four beels of lower Assam revealed 160 Rotifera species belonging to 35 genera and 19 families. The richness is of biodiversity value as -38.0% and -57.0% of the rotifer species known till date from India and northeast India （NEI）, respectively. One species each is new to the Oriental region and NEI, and three species are new to Assam; 23 species merit global biogeography interest and several exhibit distribution values in the Indian sub-region. The diverse Lecanidae 〉 Brachionidae 〉 Lepadellidae 〉 Trichocercidae and speciose littoral-periphytic Lecane〉 Lepadella〉Trichocerca, and richness of Brachionus spp. following removal of aquatic macrophytes are noteworthy. Overall rotifer composition showed homogeneity amongst beels while lower monthly richness and community similarities affirmed heterogeneity within individual beels. We propose L/B quotient based on Lecane： Brachionus species ratios to characterize habitat variations of the sampled wetlands. Slfide^ek＇s B/T quotient based on Brachionus： Trichocerca species ratios affirmed general ＇meso-trophic＇ status of different beels. Our results provided little insight on the influence of individual abiotic factors but the canonical correspondence analyses asserted higher cumulative influence of ten abiotic parameters on Rotifera richness in each beel.

Hummingbird-plant interactions in Chile:An ecological review of the available evidence

Hummingbird species have closely evolved with the plants they feed on,which is confirmed by their often tight ecological relationships in natural settings.Hummingbird-plant interactions are of interest for research areas such as ecology,evolution,and even agriculture,as they usually inform on the conservation status of interacting species assemblages,and its disappearance may precede the population extinction of the species involved in the interaction.In Chile,there are nine hummingbird species,which interact with a large and diverse number of angiosperm species in forest,desert,and mountain range environments.The motivation to perform this review is to systematize the available information regarding the flowering plants visited by hummingbird species in Chile,to present some basic plant-hummingbird pollination network metrics,and on this basis to identify the components of the plant-hummingbird relationships in need of further research.A plant-hummingbird metanetwork revealed a low connectance value,low niche overlap,and strong modularity among species.However,the fact that most species present a strong allopatric distribution across Chile,suggests that network structure results mostly from the history of colonization rather than from ecological organization.Nowadays,the main threats to Chilean hummingbirds are anthropogenic disturbance and climate change,which disrupt hummingbird-plant interactions,leading to unpredictable ecological consequences at the community level.Long periods of drought may reduce the resource base for hummingbirds,with dramatic consequences for the maintenance of bird and plant populations.

Sexual and Breeding Systems in a Xerophytic Shrubland

Reproductive systems are fundamental attributes for understanding life cycle and regeneration processes and provide information about seed production and genetic diversity. Analyses of reproductive strategies within communities and their associations with functional groups can indicate how physical and biological characteristics may influence the reproductive ecology of such communities. The main goal was to determine if the reproductive systems and their associated functional groups have particular characteristics related to extreme conditions and disturbance within xerophytic shrubland. Floral morphology analysis and four experimental tests were conducted to determine the reproductive systems of species and their associations with the life form, succulence, carbon metabolism, dispersal syndrome, pollination, and disturbance. Of the 144 plant species studied, 72.9% were hermaphrodite, 22.9% were monoecious, and 4.2% were dioecious. Dioecy was associated with woodiness, frugivory and undisturbed areas, while monoecy was more common in herbs. Adichogamy, protandry and herkogamy were more frequent than dichogamy, protogyny and no herkogamy, respectively. Xenogamous species tend to be woody and grow in undisturbed areas, while partially xenogamous species were mainly herbs occurring in disturbed areas. The majority of species were partially self-incompatible. High levels of outbreeding strategies tended to occur mainly in woody K-strategy species from undisturbed areas, mixed breeding strategies occurred in disturbed areas and overall community, and inbreeding strategies were associated with mostly herbaceous r-strategy primarily in disturbed areas.

Human occupation explains species invasion better than biotic stability:evaluating Artocarpus heterophyllus Lam.(Moraceae;jackfruit)invasion in the Neotropics

Aims Biological invasions are recognized to put native species in risk of extinction.In this study,I tested whether the invasion of Artocarpus heterophyllus Lam.(Moraceae;jackfruit)in the Neotropics was explained by its biotic stability,an intrinsic force,or by human occupation,an extrinsic force.Methods I used an ensemble framework combining 12 ecological niche models(ENMs)and 4 atmosphere-ocean general circulation models.ENMs were constructed for the pre-industrial time period in the Indo-Malaya biogeographic region,the native habitat of A.heterophyllus,and were then projected to past(last glacial maximum,21000 years ago and mid-Holocene,6000 years ago)and future(end of century,2080)peri-ods.The ENMs were used to establish the biotic stability of A.hetero-phyllus in areas where it was predicted to be present concomitantly within these four time periods.This biotic stability was projected onto the Neotropics,and then I used a null model and logistic regression to test what the main driver of A.heterophyllus invasion.Important Findings In general,the presence of A.heterophyllus in the Neotropics was not explained by biotic stability,tested by the null model.However,human occupation explained much of its presence in the invaded habitat,once all standardized coefficients related to this driver was significant positive in the logistic regression.Based on these results,humans sustained the presence of A.het-erophyllus in the Neotropics,probably because of the additive influences of propagule pressure and habitat disturbance.Thus,the recommendation is that the cultivation of A.heterophyllus in the Neotropics must be regulated and supervised,primarily near reserve areas.

Biotic resistance limits the invasiveness of the western flower thrips, Frankliniella occidentalis （Thysanoptera： Thripidae）, in Florida

The spread of the western flower thrips, Frankliniella occidentalis （Pergande）, has resulted in the world-wide destabilization of established integrated pest management programs for many crops. It is hypothesized that frequent exposure to insecticides in intensive agriculture selected for resistant populations, which allowed invasive populations in the eastern USA to overcome biotic resistance from the native community of species. Research conducted in Florida to understand the role of biotic factors in limiting the abundance of the western flower thrips is reviewed. Orius spp. （Hemiptera： Anthocoridae） are effective predators that suppress populations of thrips on crop and non-crop hosts in southern and northern Florida. Orius are more effective predators of the western flower thrips than the native flower thrips, E tritici （Fitch） and E bispinosa （Morgan）. The native species are competitors of the western flower thrips. Excessive fertilization and the use of broad-spectrum insecticides in crop fields further enhances populations of the western flower thrips. Interactions with native species clearly limit the abundance of western flower thrips in Florida, but populations are abundant in fertilized crop fields where application of insecticides excludes predators and competitor species.