Faunistic patterns of leaf beetles (Coleoptera, Chrysomelidae) within elevational and temporal gradients in Sierra de San Carlos, Mexico

Abstract

The study of biodiversity of Chrysomelidae in Mexico and its variation within ecological gradients has increased recently, although important areas in the country remain to be explored. We conducted a faunistic inventory and analyzed the elevational and temporal variation of leaf beetle communities in the Sierra de San Carlos, in the state of Tamaulipas, in northeastern Mexico. This is an area with high to extreme priority for conservation, and due to its insular geographical position and to the vegetational communities present, it must be considered as a sky island. We selected seven sample sites distributed in different elevations within three localities, and comprising different vegetational communities. At each site, we randomly delimited 12 sample plots of 400 m2 where sampling was conducted by entomological sweep netting and collecting directly by hand. Sampling was conducted monthly at each plot, for a total of 1,008 samples between February 2013 and January 2014. By the end of the study, we had obtained a total of 3,081 specimens belonging to six subfamilies, 65 genera, and 113 species, with Trichaltica scabricula (Crotch, 1873) being recorded for first time in Mexico. Species richness was less than the values observed at other studies conducted in the same region, which is attributed to differences in the number of plant species and to the insular location of Sierra de San Carlos; however, the higher diversity values suggest a higher quality of natural resources and vegetational communities. No consistent pattern of leaf beetle communities was correlated with elevation, although higher values of species richness and diversity were obtained at the highest elevation site. The seasonal gradient showed that the rainy season is most favorable for leaf beetle communities. We found that species composition was different between sites and months, and also that there exists a significant association between the abundance obtained at each site and particular months. These results highlight the importance of different microhabitats for species distribution, and suggest that each species of Chrysomelidae has a differential response to environmental factors that vary within the elevational gradient and according to seasons. Also, we confirm and emphasize the important status of Sierra de San Carlos as a key natural area for biological conservation.

Successional and seasonal changes of leaf beetles and their indicator value in a fragmented low thorn forest of northeastern Mexico (Coleoptera, Chrysomelidae)

“…In general terms, the values represent 34 % of the observed chrysomelid richness in Tamaulipas (Niño-Maldonado et al 2014), as well as 3.19 % of the country-wide values (Niño-Maldonado and Sánchez-Reyes 2017). In addition, the abundance values were higher than for other studies carried out in the region, including those conducted in larger geographical areas also during an annual period (Niño-Maldonado et al 2005, Sánchez-Reyes et al 2014, 2016). One of the factors that can give rise to such results is the complexity of the plant structure in the study area, which consists of tropical vegetation elements in conjunction with species from semi-arid or subtropical areas, such as Tamaulipan thorn scrub or submontane scrub (Treviño-Carreón and Valiente-Banuet 2005, García-Morales et al 2014).…”

“…However, the environmental heterogeneity in the LTF, resulting from disturbance and secondary succession, is perhaps the most important factor leading to the observed patterns. Previous studies had been carried out mainly in natural protected areas, where ecosystems have a high degree of conservation and low occurrence of fragmentation (Niño-Maldonado et al 2005, Sánchez-Reyes et al 2014, 2016). Contrastingly, LTF in northeastern Mexico, particularly in the eastern boundaries of the NPA Altas Cumbres, constitutes a highly heterogeneous habitat, which has been subject to strong fragmentation and presently is composed of patches with different succession times (Sánchez-Reyes et al 2017).…”

“…Overall, the seasonal effect on leaf beetle communities has been previously assessed in natural gradients (Bouzan et al 2015, Sánchez-Reyes et al 2014, 2016). However, the interaction between seasonality and secondary succession, as investigated here, has been poorly quantified (Janzen 1976, Linzmeier and Ribeiro-Costa 2009).…”

“…Accordingly, we consider that indicator species in this study, such as Centralaphthonadiversa , Cyclotrypemafurcata and Heterispavinula , are potentially suitable as indicators of succession time and for environmental monitoring in other areas with similar vegetation; in addition, species like Acrocyumdorsalis could be useful to detect conserved areas of LTF (Figure 7). These species are easily identifiable (even in the field), are abundant (so their proportion in different degrees of disturbance can be statistically quantified), and are widely distributed in the region (Niño-Maldonado et al 2014, Sánchez-Reyes et al 2016). Therefore, they fulfill the expected characteristics for a good indicator taxon (Carignan and Villard 2002, Ribera and Foster 1997).…”

“…In each of the four categories, a sample size of eight plots of 10 × 10 m was established; sample size was delimited through the analysis of preliminary data with the Clench model (Jiménez-Valverde and Hortal 2003). Sampling plots were located randomly using a previously established procedure (Sánchez-Reyes et al 2016) using geographic information systems and specialized software (ArcView GIS, IDRISI Selva 17.0). With this method, it was possible to assess the geographical location of each plot before field sampling, in order to minimize the edge effect, as well as the closeness between plots, which guarantees the feasibility of sampling and the independence of the samples.…”