Micrathena alpha, Caporiacco, 1947

Tovar-Márquez, José, Torres, Richard A. & Alvarez-Garcia, Deivys M., 2021, Diversity of orb-weaving spiders (Arachnida: Araneae) from tropical dry forest in Northern Colombia, with eleven new records for the country, Journal of Natural History 55 (19 - 20), pp. 1237-1250 : 1242-1244

Alpha and beta diversity

According to the diversity profile, the primary forest (La Esmeralda) has a higher diversity than the secondary forest (Santa Inés) for all orders of q (richness, common and dominant species), and the differences were statistically significant as reflected by the two nonoverlapping 95% confidence intervals ( Figure 3 ; Table 3). The observed and estimated diversity was similar in each forest ( Table 3). Given the high sample coverage in both forests (> 95%), it is possible to directly compare the magnitude of the differences in species richness (47/63 × 100 = 75%), in the number of common species (28.60/ 38.88 × 100 = 74%) and dominants (19.39/26.34 × 100 = 74%) ( Table 3). These percentages remain constant across orders q due to the ‘doubling property’ of Hill numbers (See Hill 1973; Jost 2006). Based on the above data, the secondary forest (Santa Inés) has approximately 74% of the diversity of the primary forest (La Esmeralda). In addition, the distribution of relative abundances was uneven in both forests ( Figure 3 ; Table 3).

Of the 76 species recorded, 34 were shared between the two forests. In La Esmeralda (primary) forest, 29 (46%) species were exclusives, whereas in the Santa Inés forest (secondary), there were 13 exclusives (28%). According to the Chao-Jaccard index, the compositional similarity among the forests was 43%. The similarity profile showed that the value of C qN = 0 was higher than C qN = 2, indicating that the dominant species in each forest are less similar between forests and that rare species contribute the most to similarity between the two forests ( Figure 4 ).

Figures

Figure 3. Diversity profile for q between 0 and 2 of the forests studied.The shaded areas correspond to 95% confidence intervals.

Figure 4. Similarity profile CqN for q = 0, q = 1 and q = 2 among forests. The bars correspond to 95% confidence intervals.