نتایج جستجو برای: richness

تعداد نتایج: 20745  

2006
Catherine H. Graham Robert J. Hijmans

Aim Maps of species richness are the basis for applied research and conservation planning as well as for theoretical research investigating patterns of richness and the processes shaping these patterns. The method used to create a richness map could influence the results of such studies, but differences between these methods have been insufficiently evaluated. We investigate how different metho...

2007
Boris R. Krasnov Georgy I. Shenbrot Irina S. Khokhlova Robert Poulin

Aim We searched for signs of the ‘bottom-up’ diversity effect in the association between fleas (Siphonaptera) and their small mammalian hosts (Rodentia, Insectivora and Lagomorpha). We asked (1) whether a strong dependence of flea species richness on host species richness is characteristic for both Palaeoarctic and Nearctic realms; (2) if yes, whether the ratio of host species per flea species ...

2012
SOPHIA QIAN NIU MICHAEL P. FRANCZYK JASON H. KNOUFT

1. Local assemblage structure, from a deterministic perspective, is presumably dictated by the regional species pool as well as regulated by local factors. We examined the relationships of the regional species pool and local hydrological characteristics to local species richness of North American freshwater fishes using data sets collected during the National Water Quality Assessment program co...

2016
Krithi K. Karanth Vishnupriya Sankararaman Shashank Dalvi Arjun Srivathsa Ravishankar Parameshwaran Sushma Sharma Paul Robbins Ashwini Chhatre

Wildlife Conservation Society, New York, NY, USA, Centre for Wildlife Studies, Bangalore, India, 3 Environmental Science and Policy, Nicholas School of the Environment, Duke University, Durham, NC, USA, 4 India Program, Wildlife Conservation Society, Bangalore, India, Department of Wildlife Ecology and Conservation, School of Natural Resources and Environment, University of Florida, Gainesville...

2004
MANUEL A. GRAÇA PAULO PINTO RUI CORTES NUNO COIMBRA SIMONE OLIVEIRA MANUELA MORAIS MARIA JOÃO CARVALHO

We analysed the spatial patterns in macroinvertebrate taxon richness and abundance at two scales: sampling unit and basin. We sampled 12 stream sites in three zones of Portugal, differing in climate geomorphology and water chemistry. At a sampling unit scale, substratum organic matter content, depth and the dominant size of substratum particles were correlated with numbers of taxa and individua...

2014
Steve Wathen James H. Thorne Andrew Holguin Mark W. Schwartz

Evidence for significant losses of species richness or biodiversity, even within protected natural areas, is mounting. Managers are increasingly being asked to monitor biodiversity, yet estimating biodiversity is often prohibitively expensive. As a cost-effective option, we estimated the spatial and temporal distribution of species richness for four taxonomic groups (birds, mammals, herpetofaun...

Journal: :The Journal of animal ecology 2011
Dale G Nimmo Simon G James Luke T Kelly Simon J Watson Andrew F Bennett

1. Patterns of species richness often correlate strongly with measures of energy. The more individuals hypothesis (MIH) proposes that this relationship is facilitated by greater resources supporting larger populations, which are less likely to become extinct. Hence, the MIH predicts that community abundance and species richness will be positively related. 2. Recently, Buckley & Jetz (2010, Jour...

ژورنال: :مجله گیاهشناسی ایران 2013
مهدی زارع احمدرضا خسروی محمد رضا جوهرچی

پراکنش جغرافیایی جنس کوزینیا در ایران با استفاده از 3095 گزارش ثبت شده در منابع و یا بر اساس نمونه های هرباریومی واکاوی گردید. 241 گونه این جنس در تمام کشور گسترده اند، هرچند که حدود یک سوم از گزارش ها از استان های خراسان رضوی، تهران و فارس می باشد. این جنس 135 گونه نادر و 197 گونه انحصاری دارد. بیشترین مقدار برای شاخص حداکثر فاصله میان دو فرد از یک گونه (maxd) 1863 کیلومتر می باشد. استان های خ...

Journal: :international journal of aquatic biology 0
bhushan kumar sharma department of zoology, north-eastern hill university, shillong-793022, meghalaya, india. telsing paongam haokip department of zoology, north-eastern hill university, shillong-793022, meghalaya, india. sumita sharma department of zoology, north-eastern hill university, shillong-793022, meghalaya, india.

a total of 162 species (s) of rotifera belonging to 40 genera and 20 families examined from loktak lake, an important floodplain lake of northeast india (nei), is one of the richest assemblages of the taxon known from the indian sub-region. it merits biodiversity value as ~40.0% and ~62.0% of species recorded from india and nei, respectively. one species is new to india, 23 species are new to m...

Journal: :international journal of aquatic biology 0
bhushan kumar sharma department of zoology, north-eastern hill university, shillong-793022, meghalaya, india. sumita sharma department of zoology, north-eastern hill university, shillong-793022, meghalaya, india.

the plankton and semi-plankton samples examined from mizoram state of northeast india (nei) revealed speciose and diverse rotifera assemblage including a total richness (s) of 162 species belonging to 19 families and 35 genera. the reports of six species new to india, four species new to nei and 76 new records to mizoram merit biodiversity interest. the occurrence of one australasian, one orien...

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