Search Results (6)

This study explores the biogeographic processes shaping the distribution of benthic foraminifera along a salinity gradient in the Contaco Estuary, southeastern Pacific, Chile. The primary aim was to evaluate the applicability of key ecological paradigms—Rapoport’s rule, the mid-domain effect, ecotones, and source–sink dynamics—to unicellular eukaryotes in estuarine environments. A 1550 m longitudinal transect, sampled at 50 m intervals, revealed a pronounced salinity-driven pattern in species richness and diversity, with calcareous taxa dominating euhaline zones and agglutinated taxa thriving in brackish and freshwater areas. Source–sink dynamics were not supported, as beta diversity analyses identified turnover as the dominant driver, highlighting species replacement along the salinity gradient. Evidence of a longitudinal Rapoport effect was observed, with broader distribution ranges in low-salinity environments, reflecting adaptations to suboptimal conditions. Contrary to predictions, the mid-domain effect was not supported, as foraminiferal richness showed a monotonic decline. These findings extend macroecological principles to microbial communities, emphasizing deterministic processes in shaping estuarine diversity. This research provides a robust framework for understanding biodiversity patterns in dynamic ecosystems, offering valuable insights for conservation and ecological monitoring. Full article

Elevational gradients provide an excellent opportunity to assess biodiversity patterns and community structure. Previous studies mainly focus on higher elevations or are limited to small areas in mountainous regions. Little information can be found on amphibian biodiversity in middle- and low-elevational areas, hence our study was devoted to filling up the current gaps in these research areas. To understand the variability of biodiversity of amphibian species in the Fujian Junzifeng National Nature Reserve in eastern China, our study included taxonomic and phylogenetic components to describe the various patterns of regional and elevational distribution. The results showed that (1) most of the taxonomic and phylogenetic diversity metrics were correlated; with regard to the surveyed area, Faith’s phylogenetic diversity index (PD) and net relatedness index (NRI) were positively correlated with the Shannon–Wiener index (H’), Margalef index (DMG), and species richness (S), while negatively with the Pielou index; whereas for elevation, only the Pielou index was positively correlated with the nearest taxon index (NTI), but negatively with other indices; (2) taxonomic and phylogenetic diversities did not differ among the three survey locations but differed significantly along the elevational gradient; Simpson index, H’, S, and DMG had a hump-shaped relationship with elevations, and PD decreased gradually with the increase in elevation, whereas NRI and NTI sharply increased at the elevation above 900 m; (3) the species range size and the corresponding midpoint of amphibians were affected by a strong phylogenetic signal, which supports the elevational Rapoport’s rule upon removal of Pachytriton brevipes and Boulenophrys sanmingensis from the study. Full article

Rapoport’s rule proposes that a species’ range size increases with the increase in a gradient (such as latitude, altitude or water depth). However, altitudinal distributions and Rapoport’s rule have rarely been tested for Asian Lepidoptera. Pyraustinae and Spilomelinae (Lepidoptera: Crambidae) are extremely diverse in temperate Asia, including on Mount Taibai, which is considered a hotspot area for studying the vertical distribution patterns of insect species. Based on the investigation of altitudinal distribution data with identification by using both DNA barcoding and the morphological classification of Pyraustinae and Spilomelinae, this paper determines the altitudinal gradient pattern for these two subfamilies on the north slope of Mount Taibai, and provides a test of the universality of Rapoport’s rule in Lepidoptera by using four methods, including Stevens’ method, Pagel’s method, Rohde’s method, and the cross-species method. Our results show that the alpha diversity of Pyraustinae and Spilomelinae both decrease with rising altitude. By contrast, the species’ ranges increase with rising altitude. Three of the four methods used to test Rapoport’s rule yielded positive results, while Rohde’s results show a unimodal distribution model and do not support Rapoport’s rule. Our findings fill the research gap on the elevational diversity of Lepidoptera in temperate Asia. Full article

Understanding patterns of species richness along an altitudinal gradient is one of the central focuses of ecological research and can offer us insights into the mechanisms of species diversity. However, few studies have focused on a large scale. Based on the distribution data of 3538 species collected from the local flora of the entire Qinling Mountains, the patterns of seed plant richness along the altitude were analyzed; three hypotheses proposed to explain the pattern were tested, and five methods verifying the applicability of Rapoport’s rule were examined. The results of the research were as follows: species richness of seed plants along an altitudinal gradient in the Qinling Mountains displayed a single peak, occurring at 1000–1500 m (R² = 0.67, p < 0.001), and similar patterns were also observed at the genus and family level; The proportion and density of endemic species were increased monotonously with altitude; the altitudinal patterns of species richness in the Qinling Mountains were not fully explained by a single hypothesis such as species area relationship (SAR), mid-domain effect (MDE) and ecological metabolism theory (MTE), while the interpretation amount of SAR and MDE was 80.4%, indicating that area and mid-domain effect significantly affect the patterns of plant species richness in the Qinling Mountains; only the Pagel upper-bound method supported Rapoport’s rule. However, all species were grouped according to their altitude distribution; most of results of the species-by-species method, Rohde midpoint method, and Stevens method conformed to Rapoport’s rule. The test of Rapoport’s rule is obviously affected by the test method, so more advanced and universal methods are expected to be developed in future. Full article

The pattern of earthworm diversity along altitudinal gradients has rarely been investigated. The aim of the current study was to examine the patterns of earthworm diversity on the western slopes of Kopaonik Mountain. Earthworms were sampled in four-month periods (from April to July) in both 2018 and 2019. In total, 30 plots at altitudinal transects between 420 and 1950 m a.s.l. were sampled within two years’ fieldwork. Overall, 27 earthworm species belonging to 11 genera were found at the study sites. A combination of Pearson’s correlation, linear regression and cluster analysis (UPGMA) was used to determine the effects of altitude on earthworm diversity. Essentially, we found monotonically declining relationships between total abundance/species richness and altitudinal gradients (from 14 to 6 species and from 118 to 39 individuals). Cluster analysis revealed two patterns of earthworm community composition: one that characterizes a low altitude (up to 1000 m) and one that was observed at the middle and high altitudes (from 1000 m). Nevertheless, a high number of taxa with broad ecological tolerances was observed, which means an increase in the altitudinal range with increasing altitudes, thus supporting Rapoport’s altitudinal rule. Overall, this study provides new insights into the understanding of the effect of altitude on earthworm diversity. Full article

The distribution of plant species diversity has long been a major focus on biogeography. Yet, the universality of the popular Rapoport’s rule remains controversial for endemic plants, as previous studies have focused more on broad-ranged species. Here, we collected data for 4418 endemic woody seed plant species across China, including trees, shrubs, and lianas, to explore the latitudinal patterns of species range size and richness, and test the relevant biogeographic law. The species range size distribution was examined for conformity with Rapoport’s rule using four methods (i.e., Steven’s, Pagel’s, the mid-point, and the across-species method). Spatial patterns of species richness along latitudinal gradient were also investigated by parabolic regression. Results showed that species range size increased with latitude for all species as well as by trees, shrubs and lianas, especially assessed by Pagel’s method. Species richness was highest at low latitude, where species range size was smallest, and decreased with increasing latitude. The species range size and richness of shrubs were maximum, followed by trees then lianas. These findings prove that Rapoport’s rule is strongly supported by latitudinal patterns of species distribution in Chinese endemic woody seed plants. Full article