Pattern of ant diversity in Korea: An empirical test of Rapoport's altitudinal rule

Two diversity patterns (hump-shaped and monotonic decrease) frequently occur along altitude or latitude gradients. We examined whether patterns of ant species richness along altitudes in South Korea can be described by these patterns and whether ranges of ant species follow Rapoport's altitudinal rule. Ants on 12 high mountains (> 1100 m) throughout South Korea (from 33° N to 38° N) were surveyed using pitfall traps at intervals of 200–300 m altitude. The temperatures at the sampling sites were determined from digital climate maps. Ant species richness decreased monotonically along the altitudinal gradient and increased along the temperature gradient. However, species richness of cold-adapted species (highland species) showed a hump-shaped pattern along altitude and temperature gradients. The altitude and temperature ranges of ant species followed Rapoport's rule. Sampling site temperature ranges were significantly correlated with coldness. Therefore, Rapoport's rule can be explained by high cold-tolerance of species inhabiting high altitudes or latitudes.     

Neotropical savanna ants show a reversed latitudinal gradient of species richness,with climatic drivers reflecting the forest origin of the fauna

Aim

To evaluate the extent to which ant species richness in Neotropical savannas varies with macrogeographic variables, and to identify the potential climatic drivers of such variation.

Location

The Cerrado savanna biome of central Brazil, in a region spanning ca. 20° of latitude and 18°of longitude.

Methods

Standardized sampling of the arboreal and ground‐dwelling faunas was performed in 29 well‐preserved savanna sites using pitfall traps. Species were classified according to their habitat affinities: open‐savanna specialists, forest‐associated species or habitat generalists. We used generalized linear models to evaluate the importance of geographic (latitude, longitude and elevation) and climatic (mean temperature and three metrics of rainfall) variables as predictors of species richness.

Results

The total number of species recorded at each site varied more than twofold (from 59 to 144), and latitude was the best geographic correlate of overall species richness. However, contrary to the expected pattern, more species were found at higher than lower latitudes. This reversed latitudinal pattern of diversity occurred for both the arboreal and ground‐dwelling faunas, and for the habitat generalists and forest specialists. The savanna specialists showed a mid‐latitudinal peak in diversity. Overall, there was a significant positive association between rainfall and species richness, but the strength of this relationship varied with ant habitat affinity.

Main conclusions

The Cerrado ant fauna shows a reverse latitudinal gradient in species diversity, and this can be explained by increasing rainfall during the warmest months of the year (and therefore in plant productivity) with increasing latitude. The sensitivity of Cerrado ant diversity to declining rainfall contrasts with the high resilience to aridity of the Australian savanna ant fauna, and this reflects the contrasting evolutionary histories of these faunas. Our findings highlight the importance of historical processes as drivers of intercontinental contrasts in macroecological patterns.     

Latitudinal patterns of mammalian species richness in the New World: the effects of sampling method and faunal group

Abstract. Although the latitudinal gradient of species richness for mammals in North America is well documented, few investigators have quantified the relationship in South America. We examined the pattern in North and South America, at two spatial scales (2.5° and 5°) for each of two sampling methods (quadrats and latitudinal bands). A scale effect was evident for quadrats but not for bands. Significant linear relationships between species richness and latitude were found for three faunal groups: all mammals, nonvolant species, and bats. Effects of area confound the latitudinal relationship. By statistically removing such effects, we found that the latitudinal gradient is not an artifact of the species-area relationship, and that the latitudinal gradients for North and South America were statistically indistinguishable. Our data suggest that both faunal subgroups, nonvolant species and bats, contributed substantially to the overall mammalian pattern. Further, multiple regression analyses showed that only latitude is a necessary variable to explain bat richness; for nonvolant species, in addition to latitude, area and longitude may be important.     

Centers of endemism and diversity patterns for typhlocybine leafhoppers （Hemiptera： Cicadellidae： Typhlocybinae） in China

This study identifies ＇centers of endemism＇ for typhlocybine leafhoppers in China, revealing diversity patterns and congruence of patterns between total species rich- ness and endemism. Distribution patterns of 774 Typhlocybinae （607 described and 167 undescribed species） were mapped on a 1.5° × 1.5° latitude/longitude grid. Total species richness, endemic species richness and weighted endemism richness were calculated for each grid cell. Grid cells within the top 5% highest values of weighted endemism richness were considered as ＇centers of endemism＇. Diversity patterns by latitude and altitude were obtained through calculating the gradient richness. A congruence of diversity patterns between total species richness and endemism was confirmed using correlation analysis. To investigate the bioclimatic factors （19 variables） contributing to the congruence be- tween total species richness and endemism, we compared the factor＇s difference between non-endemic and endemic species using the Kruskal-Wallis test. Eleven centers of en- demism, roughly delineated by mountain ranges, were identified in central and southern China, including the south Yunnan, Hengduan Mountains, Qinling Mountains, Hainan Is- land, Taiwan Island and six mountain areas located in western Sichuan, northwest Fujian, southeast Guizhou, southeast Hunan, central and western Guangdong, and north Zhejiang. Total species richness and endemic species richness decreased with increased latitude and had a consistent unimodal response to altitude. The proportions of endemism decreased with increased latitude and increased with rising altitude. Diversity patterns between total species richness and endemism were highly consistent, and ＇Precipitation of Coldest Pe- riod＇ and ＇Temperature of Coldest Period＇ may contribute to the congruence of pattern. Migration ability may play a role in the relationship of endemism and species richness; climate, environment factors and important geologic isolation events can also play crucial effect     

Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: afirst overview

Abstract Aims Ants (Hymenoptera: Formicidae) of the Baja California peninsula are poorly known, with information based largely on scattered museum and literature records. We provide the first comprehensive account of ant species occurring on the peninsula, we examine distribution patterns, and we assess the ‘peninsular effect’ which predicts that species richness declines from the base to the tip of a peninsula. Location Peninsula of Baja California, Mexico. Methods Data collection involved examining, identifying and recording label data from c. 2350 series of ants. These records provide a provisional, if incomplete, species list. We applied the incidence‐based estimator, Chao‐2, to our data base of specimen records to estimate the total number of ant species on the peninsula. We assessed endemism by comparing our peninsular species list to those from adjacent states. The peninsular effect was tested by comparing genus and species level richness between the two states of Baja California, and across five latitudinal blocks. Results We document 170 native ant species in thirty‐three genera, plus six non‐native species, in Baja California. It seems likely that additional species remain to be discovered: the Chao‐2 estimator of species richness, at 206.0 species, is about 20% higher than our observed species richness. About 30% of the species and 20% of the genera are restricted within Baja California to the relatively mesic California Floristic Province of north‐western Baja California. Nearly all of these species also occur in California. Forty‐seven species (27.6%) are peninsula endemics. Using our entire data set, the peninsular effect appears to be strong, with about twice as many species in the northern state of Baja California than are recorded from the southern state of Baja California Sur; the ratio of genera is 33 to 24. However, this effect becomes weak at the species level and absent at the genus level when minimizing habitat effects by omitting species restricted to the California Floristic Province. At a finer scale, across latitudinal blocks of about 1.9°, the number of species declines towards central portions of the peninsula and then increases in the Cape Region. Nine ant species display strongly disjunct distributions, and these occur in two general patterns: peninsula disjuncts and peninsula–mainland disjuncts. Main conclusions The Baja California peninsula supports a diverse and distinctive ant fauna, with the proportion of endemic species similar to that displayed by plants. Patterns of species and genus richness across the five latitudinal blocks provide poor support for the peninsular effect. Moreover, habitat diversity, especially that related to topographic relief, appears to be the most important factor affecting the gradient of ant species richness in Baja California. Additional collections are needed to develop a more complete species list and to determine the boundaries and status of many species. Nevertheless, the present data base provides a useful starting point for understanding the evolution of ant assemblages in Baja California and for comparison with peninsular patterns in other taxa.     

Patterns of an elevational gradient affecting moths across the South Korean mountains: effects of geometric constraints,plants, and climate

We investigated elevational richness patterns of three moth groups (Erebidae, Geometridae, and Noctuidae) along four elevational gradients located on one northern and three southern mountains in South Korea, as well as the effects of plants and climatic factors on the diversity patterns of moths. Moths were collected with an ultraviolet light trap at 32 sites from May through October, 2013. Plant species richness and mean temperatures for January and June were acquired. Observed and estimated moth species richness was calculated and the diversity patterns with null models were compared. Species richness along four elevational gradients peaked at mid-elevations, whereas deviations occurred at elevations below mid-peak in the southern mountains and elevations higher than mid-peak on the northern mountain. Species richness curves of three moth groups also peaked at mid-elevations throughout South Korea. However, the species richness curves for Erebidae were positively skewed, indicating that a preference for lowlands, whereas curves of the Geometridae were negatively skewed, indicating a preference for highlands. The mid-peak diversity pattern between plants and moths on the Korean mountains showed an elevational breadth that overlapped between 800 and 900 m. Multiple regression analysis revealed that plant species richness and January mean temperature significantly influenced moth species richness and abundance. The rapid increase in mean annual temperature in the Korean peninsula and the unimodal elevational gradients of moths across the country suggest that an uphill shift in peak optimum elevation and changes in the highest peak of the curve will occur in the future.     

The influence of habitat heterogeneity and latitude on gamma diversity of the Nearctic Simuliidae,a ubiquitous group of stream‐dwelling insects

Among the most prominent, large‐scale patterns of species richness are the increases in richness with decreasing latitude and with increasing habitat heterogeneity. Using the stream‐dwelling larval and pupal stages of North American black flies (Diptera: Simuliidae), we address 3 broad questions about species richness: (i) Does a significant latitude–richness relationship exist? (ii) How does habitat heterogeneity influence gamma diversity? (iii) What is the sign (positive or negative) of the latitude–richness and the heterogeneity–richness relationships? We found no evidence that habitat heterogeneity influences gamma diversity. The estimated peak species richness for black flies in North America was at 50–53°N, which also corresponds with peak generic richness. All plesiomorphic, extant lineages of the Simuliidae in the Western Hemisphere are found in cool mountainous environments of North America, suggesting that peak richness at 50–53°N might be a signature of this phylogenetic pattern and a reflection of underlying historical processes.     

Effects of forest degradation on butterfly communities in the Gwangneung Forest

This study was carried out to clarify the response of butterfly communities on forest degradation in the Gwangneung Forest, Korea. We monitored butterfly communities with varying degrees of human activities by conducting a line transect twice a month in 2011. A total of 70 species and 4676 individuals of butterflies were observed in four sites: natural forest (NR), two plantation forests, and the Korean National Arboretum (AR). The result on niche breadth, habitat breadth and habitat type of butterfly was not consistent with our predictions. Species richness of habitat type was only significantly different between NF and AR. Species diversity was significantly different among sites. Butterfly diversity associated with landscape patterns based on aerial photographs supported a mosaic concept. A forest management plan to conserve butterfly diversity in forests is necessary to maintain various habitats and to ensure that grasslands are protected.     

Red herring or low illumination? The peninsula effect revisited

Aim The peninsula effect is the prediction that the number of species declines from a peninsula's base to its tip. We evaluated evidence for and against the peninsula effect, and conducted a field study designed to test alternative hypotheses for that effect. Location The Florida peninsula, USA. Methods First, we critically reviewed the accumulated literature on peninsula effects; second, we sampled microcrustaceans in palustrine wetlands on the ridges of peninsular Florida. Site selection in our field study accounted for historical effects and partially controlled for habitat effects. Statistical analyses further accounted for habitat effects, leaving peninsular geometry as the remaining causative mechanism for residual variation in species richness regression analyses. Results Our literature review found mixed evidence (49% of cases) for a peninsula effect. However, most study designs did not control for alternative hypotheses, most comparisons of alternative hypotheses were qualitative, and most studies focused on vertebrate animals. Our field study found that freshwater microcrustaceans inhabiting isolated wetlands on Florida’s peninsular ridges do not exhibit a peninsula effect. Essentially, no variation in microcrustacean species richness could be attributed to peninsular geometry, but 82.5% of variation in species richness was attributed to habitat and sampling effort. Main conclusions Although our research results support the ‘red herring’ label for the peninsula effect, our literature review leads us to argue that more illumination (in the form of study design and quantitative analysis) is needed if mechanisms causing the peninsula effect hypothesis are to be resolved. Future studies of peninsula effects need to control for alternative causative hypotheses (geometry, habitat or history) in study design, and compare quantitatively the effects of hypothesized mechanisms on peninsular diversity patterns. Additionally, studies of taxa other than vertebrate animals need to be conducted for generality. Our study may serve as an example of such an approach.     

Latitudinal gradient in species richness of the New World Triatominae (Reduviidae)

Aim To quantify the latitudinal gradient in species richness in the New World Triatominae and to explore the species‐energy and area hypotheses as possible causes. Location The gradient was studied for North and South America, between 43° N and 32° S. Methods A database was constructed containing the geographical distribution of the 118 New World Triatominae species based on data extracted from several published sources. Species richness was recorded as the number of species present within 5° latitudinal bands. We used univariate and multivariate models to analyse the relationship between area within each latitudinal belt, land surface temperature, and potential evapotranspiration as explanatory variables, and species richness. All variables were georeferenced and data were extracted using a GIS. Results Species richness of Triatominae increases significantly from the poles towards the Equator, peaking over the 5°?10 ° S latitudinal band. It increases according to a linear model, both north and south of the Equator, although a quadratic model fits better to southern hemisphere data. Richness correlates with habitable geographical area, when it is analysed through a nonlinear multiple regression factoring out latitude, only in the southern hemisphere. Regarding the species‐energy hypothesis, a multiple regression analysis controlling the effect of latitude shows a significant relationship between temperature and species richness. This effect is more pronounced in the southern hemisphere. Species richness shows a strong longitudinal trend south of the Equator (increasing to the east), but not north of the Equator. This differential pattern is reflected in significant interactions between longitude and both latitude and temperature in models of the species richness of the New World Triatominae. Main conclusions To our knowledge, this is the first time that a latitudinal gradient in species richness has been shown and analysed for obligate haematophagous organisms, and it shows that the species–energy hypothesis can account for this phenomenon. This relationship is stronger in the southern hemisphere.