Elevational distribution and species diversity of freshwater Ostracoda (Crustacea) in Çankırı region (Turkey)

We investigated how the richness and ecological characteristics of non-marine ostracod species varied across nine 100-m elevation bands (from 549 to 1457 m) in the Çankırı region. We collected a total of 37 taxa (25 living and 12 sub-recent) from 114 of 130 aquatic sites sampled during September of 2011; 34 of the taxa were new records for the region. Eight widely distributed ‘cosmopolitan’ species (Candona neglecta, Cypridopsis vidua, Heterocypris incongruens, Ilyocypris bradyi, Limnocythere inopinata, Potamocypris villosa, Prionocypris zenkeri, and Psychrodromus olivaceus) were found more frequently than other species. The first two axes of canonical correspondence analyses (CCA) explained 73.2% of the correlation between 11 species and 5 environmental variables. Of which, electrical conductivity (F = 3.99, p = 0.028) and altitude (F = 2.69, p = 0.004) were the most explanatory (p < 0.05) variables for species. Optimum altitude and water temperature values of the cosmopolitan species were relatively higher than the other species. Significant regression models (p < 0.01, r2 = 0.81) indicate that the frequency of occurrence was affected by changes in numbers of samplings sites from 549 to 1457 m. When highest numbers of species (15 spp.) were found at the range of 1231–1332 m, numbers of asexual species (10 spp.) were twice of the sexual species (5 spp.) with no statistical difference between numbers of swimming (7 spp.) and non-swimming (8 spp.) species. Results were discussed based on the ecological conditions that individual species prefer.本研究以昌克勒（Çankırı）地区为研究区域，针对9个间隔为100米的海拔梯度带（549米至1457米），探究了非海洋介形类（non-marine ostracod）物种的丰富度及生态特征沿海拔的变化规律。2011年9月，研究团队对该区域130个水生样点开展采样，最终从114个样点中采集到37个分类单元（含25个现生类群与12个亚近代类群），其中34个分类单元为该区域的新记录物种。8种广布性物种（*Candona neglecta*、*Cypridopsis vidua*、*Heterocypris incongruens*、*Ilyocypris bradyi*、*Limnocythere inopinata*、*Potamocypris villosa*、*Prionocypris zenkeri*及*Psychrodromus olivaceus*）的检出频率显著高于其他类群。典范对应分析（canonical correspondence analyses, CCA）的前两个轴解释了11个物种与5个环境变量间相关性的73.2%；其中电导率（F=3.99，p=0.028）与海拔（F=2.69，p=0.004）是对物种分布解释度最高的环境变量（p<0.05）。广布性物种的最适海拔与最适水温均相对高于其他物种。本研究构建的回归模型具有统计学显著性（p<0.01，r²=0.81），结果表明物种出现频率随549米至1457米海拔梯度内样点数量的变化而发生改变。在1231米至1332米的海拔区间内，物种丰富度达到峰值（15个物种）；其中无性繁殖物种共10个，为有性繁殖物种（5个）的2倍，而游泳型物种（7个）与非游泳型物种（8个）的数量未表现出统计学差异。本研究结合各物种偏好的生态条件对研究结果展开了讨论。