Assessment Of Rarity Research Articles

Assessment of rarity and ecological preferences of the non-marine ostracods (Crustacea) in Çanakkale Province (Türkiye)

Rarity as a multidimensional concept has not been discussed for the ostracods along with the effects of physicochemical factors and sedimentation rates of waters on their distribution. We randomly sampled 91 aquatic sites including eight habitat types in the Çanakkale Province to study ostracod species rarity, commonness, and ecological preferences, and to test the relationships between the rarity index (average of geographic range, habitat specificity, and population size indices) and environmental factors. A total of 44 ostracod taxa (25 living) were reported from 75 sites. Among the species, Candonocypris caledonica was recorded for the first time in Türkiye. Sixty percent of 25 living species exhibited cosmopolitan characteristics, making significant contributions to the diversity of ostracods. The well-known cosmopolitan species, Heterocypris salina (rr = 0.268), Cypridopsis vidua (rr = 0.289), Limnocythere inopinata (rr = 0.330), Ilyocypris bradyi (rr = 0.370), and Psychrodromus olivaceus (rr = 0.390), were identified as common species based on the rarity index (rr) values. Of the environmental variables, only sediment grain sizes (×2000, ×500, and ×63 μm) were found to be effective on the distribution of ostracod species. The Shannon index exhibited a positively significant association with ×2000, while the population size index displayed a linear relationship with ×63 μm grain size, indicating a small population size and rarity. Associations among index values, sediment grain size, and water quality variables showed that comprehensive studies on ostracods, analyzing both water and sediment, can provide a clearer and more precise information for evaluating the rarity and ecological preferences of species.

Floristic diversity and rarity assessment along altitudinal gradient in diverse forest types of Pithoragarh, Kumaun Himalaya, Uttarakhand, India

Present study was carried out in four different forest types (Sal, Pine, Oak and Deodar) of Kumaun Himalaya along altitudinal gradient 650 to 2200 m asl. A total 337 species of vascular belonging to 280 genera and 98 families were recorded from the present study. Of these, 303 species were Angiosperms (252 Dicotyledons and 51 Monocotyledons), 3 Gymnosperms and 31 Pteridophytes and their distribution in different life forms, i.e., trees (53 spp.), shrubs (74 spp.), herbs (196 spp.) and climber (14 spp.). Among angiosperms Asteraceae (37 spp.) was dominant family followed by Poaceae (24 spp.), Fabaceae (24 spp.) and Lamiaceae (21 spp.). In Gymnosperms only two family (Pinaceae and Cupreceae) was recorded. A total of 31 species of Pteridophytes were recorded from present study. 49 species recorded in IUCN criteria (2022–23) one species were Vulnerable one near threatened and 47 were under least concern.

Comparative analysis of biological and ecological differentiation of Anemone palmata L. (Ranunculaceae) in the western Mediterranean (France and Spain): an assessment of rarity and population persistence

The western Mediterranean geophyte Anemone palmata L. is one of the most endangered angiosperm taxa in France. The biological and ecological characteristics of French populations are contrasted with those of populations from near the centre of the species distribution in east Spain. A Correspondence Analysis discriminates the French and Spanish populations according to substrate and the composition of the plant communities where they grow. The karyological study reveals that east Spanish plants are autotetraploid, whilst the French are all diploid. In addition, morphological differences were registered, Spanish plants generally being more vigorous. French populations consist mostly of senile plants, without or with very low rates of sexual reproduction, whereas the populations from Spain include all age groups with an important percentage of juvenile plants. The main factors which could affect the French populations are habitat destruction and modification of plant communities due to land-abandonment. Conservation measures should be supported by immediate protection of the French localities and habitats to prevent the total decline of this rare species. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 140, 95–114.