Folia Entorno/. Mex. 42(2): 177-190 (2003) COMMUNITY STRUCTURE OF NATIVE BEES IN FOURVEGETATION TYPES IN THE DRY TROPICS OF YUCA TAN, MEXICO 1 1 2 LUISA F. NOVELO-RINCÓN , HUGO DELFÍN-GONZÁLEZ , RICARDO A Y ALA ANO HEZZARD H. CONTRERAS-ACOSTA1 'Universidad Autónoma de Yucatán, Facultad de Medicina Veterinaria y Zootecnia, Departamento de Zoología. A. P. 4-116 Col. Itzimná, 97100 Mérida, Yucatán, México 2 Estación de Biología Charnela, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 21, San Patricio, Jalisco, 48980, Mexico Novelo-Rincón, L.F., H. Delfin-González, R. Ayala and H.H. Contreras-Acosta. 2003. Community structure ofnative bees in four vegetation types in the dry tropics ofYucatan, Mexico. Folia Enlomo!. Mex., 42(2): 177-190. ABSTRACT. The structure of native bee communities was studied in four vegetation types in the state of Yucatan, Mexico. Community structure was established using índices (dominant, common and rare species), four lifeways and unique species. A total of 5, 701 specimens were collected, falling in five families, 55 genera and 140 species. Community structure was equal, and independent ofvegetation type. On average, rare species represented 51.2% of community structure, common species 31.2% and dominant species 17.6%, while parasocials represented 50.8%, solitaries 30.1%, eusocials 9.1% and parasitic 7.5%. Results suggest that parasocial species are the most important in terms of dominance and richness and that the sampled vegetation associations are rich in social bees. This coincides with descriptions demonstrating that eusocial Apidae and Halictidae are most common and abundant. The bee communities do not differ in the size and composition of dominant, common, and rare species assemblages, or in strata composition. The bee communities differ in richness and evenness values. Differences do exist in specific composition and the number of unique species. KEY WORDS. Apoidea, biodiversity, community structure, Yucatan, Mexico. Novelo-Rincón, L. F., H. Delfin-González, R. Ayala y H. H. Contreras-Acosta. 2003. Estructura de las comunidades de abejas nativas de cuatro tipos de vegetación en el estado de Yucatán, Méxio. Folia Enlomo!. Mex., 42(2): 177-190. RESUMEN. Se estudió la estructura de las comunidade~ de abejas nativas de cuatro tipos de vegetación en el estado de Yucatán, México. La estructura de las comunidades se estableció mediante índices (dominantes, comunes y raras), cuatro formas de vida y especies únicas. Se colectaron 5,701 ejemplares de cinco familias, 55 géneros y 140 especies. La estructura de la comunidad fue igual e independiente del tipo de vegetación; en promedio las especies raras representaron el 51.2% de la estructura de la comunidad, las comunes el 31.2% y las dominantes el 17.6%; las parasociales el 50.8%, las solitarias el 30.1 %, las eusociales el9.1% y las parásitas el 7.5%. Los resultados sugieren que en términos de dominancia y riqueza, las especies parasociales son las más importantes y que las asociaciones vegetales muestreadas son sitios ricos en abejas sociales. Nuestros resultados concuerdan con las descripciones que señalan a los Apidae eusociales y Halictidae como más comunes y abundantes. Las comu­ nidades no difieren en tamaño y composición de los ensambles de especies dominantes, comunes y raras, ni en la composición de los estratos, sólo difieren en los valores de riqueza y equidad. Las diferencias están en la composición específica y en el número de especies únicas. PALABRAS CLAVE. Apoidea, biodiversidad, estructura de la comunidad, Yucatán, México. Bees are one ofthe taxonomically best studied 1884 species (Aya1a et al., 1993; 1996), which in insect groups (Michener, 2000). In Mexico, they tum represent a1most 10% of the known wor1d­ are represented by six fami1ies, 144 genera and wide richness. The importan ce of Apoidea lies in Novelo-Rincón et al. :Community structure of native bees of Yucatan, Mexico the fact that they are pollinators that ensure se­ referring to "large", "long-tongue" and "short­ xual reproduction of many flowering plants in na­ tongue" bee groups are difficult to interpret. Reports of bee fauna in Mexico. Th~ forest, SDV: Sandy dune vegetation tural communities, as well as fruit production for Study of community structure is currently one 4 forest, POF: Pine-oak forest, TF: T human consumption. Des pite being well studied, of the research areas of greatest activity within vegetation, 7 STF: Semi-evergreen tro¡ there are still a number aspects relating to bees ecology. Communities are understood as a group Seasonal flooded forest, S about which there is little information ( e.g. beha­ of populations that interact among themselves vior, natural history, biogeographical relation­ (Price, 1997). Structure can be described via spe­ S tate Vegetati ships, ecology, etc.). Future studies will provide cies diversity, interactions and trophic group ana­ Jalisco TDF, the tools to develop management and conserva­ lysis (Milis, 1994; Schowalter, 2000). Diversity Jalisco PF,OI tion strategies for threatened habitats or for ex­ has two components: species number, frequently ploitation ofsome ofthe resources these provide defined as richness; and evenness, which refers to Jalisco TDF, (Ayala et al., 1996). the way in which abundances are distributed Guanajuato TF,' among species (Ludwig and Reynolds, 1988); the Bee fauna in the Americas is richest in desert DF A' and less rich in tropical and temperate zones (Mi­ majority ofthe communities show few dominant X chener, 1979; Ayala, 1988). In temperate clima­ species and relative high numbers of common Puebla tes richness is greater than in tropical climates species (Krebs, 1989). A community is conside­ Quintana Roo STF, TSF, TDF, S and the first communities are characterized by a red complex the greater its species richness and Yucatán Un low Apoidea frequency, apparently because ofa the fewer its dominant species. A community is Yucatán Un lack of nesting sites (Heithaus, 1979; Roubik, more even when its species have similar abun­ 1989; Pascarella et al., 2000). Community rich­ dances, or more dominant when one or more spe­ ness and abundan ce in the tropics generally expe­ cies have abundances greater than other species MATERIALS AND METH( rience strong influence from highly social bees (Begon et al., 1990). The study included two locati that are active year round and polyphagous and Based on the above, a plausible hypothesis for Yucatán, the Ría Lagartos Spec generalist (in their pollen preferences ), but whose explaining native bee community structure, in serve and Tekom (Fig. 1) (Fli contribution to species richness is relatively low. any kind of vegetation, is that the balance bet­ 1994). The overall tendency seen in descriptions oftro­ ween the assemblages ofeusocial, parasocial and The Ría Lagartos Special B pical bee assemblages is the abundance and do­ solitary bees shows constant values and defines (21 o 24' 07" and 21 o 3 7' 22" N minance of Apidae and Halictidae ( which contain community structure in terms of richness and 87° 32' 00" and 88° 14' 37" \\ many social species), and lower abundances of abundance. Given that eusocial bees are polypha­ located on the north coast of 1 Megachilidae, Colletidae and Andrenidae (Rou­ gous and generalist (Thorp et al., 1994 ), and pre­ mate is type BSl(h') w"I, witl bik, 1989; Wilms, 1996). In higher latitudes Me­ sent year round, they may be dominant in tropical year round (García, 1981), and gachilidae and Apidae are dominant (Pascarella landscapes and landscapes influenced by seaso­ varying between 500 and 1000 et al., 2000). Comparison is difficult, however, as nal cycles (Bullock et al., 1995). In faunistic stu­ contains eight vegetation type. available bee community descriptions are based dies of bees carried out in Mexico (Table 1), which the predominant types, on different, not necessarily comparable, criteria. community descriptions are restricted to richness study, are: "Sandy Dune Ve¡ Sorne descriptions indicate that rare species do­ values and identification ofthe most common ta­ "Tropical Deciduous Forest" ( mínate in northem forests, deciduous tropical fo­ xa. No studies ha ve been done of heterogeneity Forest" (TF). In the SDV the p rests and savannas (Heithaus, 1979; MacKay and measurements. In the present study, native bee minated by creeping plants anc Knerer, 1979); solitary bees domínate in Medite­ communities in the four dominant vegetation meters in height, while the ser rranean communities (Neffand Simpson, 1993); types in the state ofYucatan, southeast Mexico, populations of Pseudophoem and that solitary bees are more abundant and di­ are described and compared. TDF consists oftrees with an a· verse in open forest (Moldenke, 1976). Studies ging from 6-15 meters. The Tl 178 ~ of Yucatan, Mexico Folia Entorno/. Mex. 42(2) (2003) 1 ge", "long-tongue" and "short­ Table 1 ups are difficult to interpret. Reports of bee fauna in Mexico. The vegetational types are refered as the authors described it. 1 TDF: Tropical deciduous unity structure is currently one forest, SDV: Sandy dune vegetation, 2 PF: Pine forest, OF: Oak forest, POF: Pine-oak forest, 3 TDF: Tropical deciduous forest, POF: Pine-oak forest, 4 TF: Thorn forest, TDF: Tropical deciduous forest, 5 ATS: Arid tropical scrub, 6 XV: Xeric areas of greatest activity within 7 vegetation, STF: Semi-evergreen tropical forest, TSF: Tropical subdeciduous forest, TDF:. Tropical deciduous forest, SFF: ities are understood as a group Seasonal flooded forest, S: Savanna, MF: Mangrove forest, P: Peten, SDV: Sandy dune vegetatiol). hat interact among themselves cture can be described via spe- S tate Vegetational type Families Genera Species Reference eractions and trophic group ana- Jalisco TDF, SDV 1 6 87 228 Ayala, 1988 4; Schowalter, 2000). Diversity 2 nts: species number, frequently Jalisco PF, OF, POF 5 69 171 Estrada, 1992 ss; and evenness, which refers to Jalisco TDF, POF3 5 58 172 Fierros-López, 1998 eh abundances are distributed Guanajuato TF, TDF' 6 61 177 Godínez, 1991 udwig and Reynolds, 1988); the DF ATS5 5 34 97 Hinojosa, 1996 mmunities show few dominant ive high numbers of common Puebla XV6 7 69 259 Vergara and Ayala, 2002 989).