Sociobiology 61(1): 9-20 (March, 2014) DOI: 10.13102/sociobiology.v61i1.9-20 Sociobiology An international journal on social insects Research article - ANTS Composition and Diversity of Ant Species into Leaf Litter of Two Fragments of a Semi- Deciduous Seasonal Forest in the Atlantic Forest Biome in Barra do Choça, Bahia, Brazil Freitas, JMS1,2,3, Delabie, JHC1,2 & Lacau, S1,2,3 1 - Universidade Estadual de Santa Cruz, Ilhéus-BA, Brazil. 2 - Laboratório de Mirmecologia, CEPLAC/CEPEC/SECEN, Ilhéus-BA, Brazil. 3 - Universidade Estadual do Sudoeste da Bahia, Itapetinga-BA, Brazil. Article History Abstract Edited by: We present here the results of a study of leaf litter ant diversity in remnant areas of Gilberto M M Santos, UEFS, Brazil semi-deciduous seasonal forests in the Atlantic Forest biome. Standardized collections Received 05 November 2013 Initial acceptance 13 December 2013 were made in 2011, using pitfall traps and Winkler sacks in two fragments of native forest Final acceptance 14 January 2014 in the municipality of Barra do Choça in the micro-region of the Planalto da Conquista, in southwestern of the state of Bahia, Brazil. A total of 107 species from 37 ant genera and Keywords 9 subfamilies was collected. The observed richness was high, and the diversity indices Formicidae, Planalto da Conquista, (Shannon-Wiener) of the two fragments suggest that in spite of being strongly impacted Atlantic Forest, Tropical forest by anthropogenic actions, they maintained high faunal diversity levels, similar to those Corresponding author observed in other original Atlantic Forest sites in state of Bahia. Analyses of the spe- Juliana Martins da Silva Freitas cies accumulation curves (Jackknife 2), however, indicated that survey effort was not Univ. Estadual do Sudoeste da Bahia sufficient to capture all of the species present. The high observed numbers of unique Laboratório de Biossistemática Animal species, the shape of the species accumulation curves, and high values of estimated Itapetinga-BA, Brazil richness suggest that the survey areas were quite heterogeneous. These results provide E-mail:[email protected] new information concerning regional biodiversity that will be useful for continuing studies on fragmentation processes in the region. Introduction (Schowalter & Sabin, 1991). Ant community structures re- spond directly and quickly to both quantitative and qualita- Ants (Hymenoptera: Formicidae) form one of the most tive environmental changes, and have therefore been the focus diverse and ecologically important insect groups in terms of of stu-dies investigating the effects of environmental distur- their diverse and essential functions in terrestrial ecosystems bances on ecological communities (Veiga-Ferreira et al., 2005; (Wilson & Hölldobler, 1990; Alonso & Agosti, 2000). Their Delabie et al., 2006, 2007). predominance can be attributed in part to their eusocial nature, Ants maintain numerous biotic associations with other which favors their dispersal and successful occupation of new organisms in their environments (Wilson & Hölldobler, 1990; habitats (Wilson & Hölldobler, 2005). Since the Cretaceous Rico-Gray & Oliveira, 2007), rapidly respond to habitat alter- period, these animals have demonstrated successful radiation ations such as fragmentation (Peck et al., 1998; Veiga-Ferreira throughout almost all terrestrial habitats, with numerical and et al., 2005; Delabie et al., 2006) and are relatively easily col- biomass predominance in most of them (Fernández & Ospina, lected and identified (Peck et al., 1998), making them ideal 2003; Wilson & Hölldobler, 2005). models for studying and monitoring global biodiversity and Ant diversity in forest ecosystems is particularly high useful as bioindicators of disturbances caused by ecosystem in the leaf litter (Alonso & Agosti, 2000; Silva & Brandão, size reductions 2010), although community composition is influenced by nu- The Atlantic Forest biome has been a focal area for merous factors, including the nature of the surrounding plant environmental conservation efforts (Dean, 2002). Studies formations, soil composition and the local microclimate of Atlantic Forest biodiversity have almost exclusively fo- Open access journal: http://periodicos.uefs.br/ojs/index.php/sociobiology ISSN: 0361-6525 10 Freitas, JMS, Delabie, JHC & Lacau, S. - Leaf-litter Ant Communities in Bahia Atlantic Forest, Brazil cused on ombrophilous forests on the coastal plains of Brazil (Ivanauskas & Rodrigues, 2000; Costa & Mantovani, 1993; Martins, 1993). However, a number of diverse ecosystems are found in this biome (Brasil, 2000), including semi-deciduous and deciduous seasonal forests in the region of southwestern of the state of Bahia, and some have been poorly studied (es- pecially those situated more inland) (Brasil, 2000). The semi- deciduous seasonal forest exhibits high biodiversity due to the confluence between Atlantic Forest, Caatinga (dryland vegeta- tion), and Cerrado (Neotropical savanna) biomes (Soares- Filho, 2000; Daniel & Arruda, 2005; Dean, 2002). They are highly threatened and have experienced critical levels of fragmentation due to agricultural expansion, pasture forma- Fig 1 - Satellite picture of the two forest remnant where the experi- tion, and urban occupation, among other factors (Campanili ment was conducted. Barra do Choça, Bahia, Brazil (Source: Google & Prochnow, 2006). Earth, 2011). One of the most highly neglected regions in terms of studies of ant fauna diversity is the Atlantic Forest in the Collection methodology southwestern region of the state of Bahia, principally the Planalto da Conquista. These vegetation formations are con- Ant collections were made in January and April/2011 sidered “Inland Atlantic Forests of Bahia” (classified as semi- using 47 Winkler sacks and 47 pitfall traps (Bestelmeyer et deciduous seasonal forests) The present study was designed al., 2000) in each fragment (one Winkler sack was destroyed to examine the ant fauna of this region and characterize the in fragment 1, Table 1) distributed at intervals of 30 m within composition and diversity of ant species in the leaf litter of an area of approximately 10 hectares – but always at least 100 two remnant forest fragments situated in the municipality of m from the external edges of the fragment. A pitfall trap was Barra do Choça, in the Planalto da Conquista, state of Bahia installed at each collection point and left for two days. These State, Brazil. traps consisted of cups of 7 cm diameter by 10 cm height con- taining only water and detergent. When the pitfall trap was re- Materials and Methods moved, an additional sample of 1 m² of leaf litter was removed from the same site, passed through a sieve, and then processed Collection sites in a Winkler extractor for 48 hours (Bestelmeyer et al., 2000). This standardized methodology was adapted from the Ants of The surveys were performed in two areas of Semi- the Leaf Litter Protocol of Agosti & Alonso (2001). Deciduous Seasonal Forest: “Remnant 1” (14°50’00”S 40°33’13”W; 86 hectares) and “Remnant 2” (14°48’29”S Biological material 40°35’23”W; 62 hectares) (Fig. 1). Both fragments were lo- cated in the municipality of Barra do Choça, in the state of The biological material collected in the field was pre- Bahia, Brazil, within the transition zone between dense om- served in ethanol and then taken to the Laboratório de Mirme- brophilous forests and seasonal deciduous forest areas (IBGE, cologia (CEPLAC/CEPEC/SECEN) and Laboratório de 1993; 1997) in formations locally known as “mata de cipó” Biossistemática Animal (UESB/DEBI) where ant specimens (Soares-Filho, 2000) ; between 20 and 50% of the trees there were sorted out from the samples, mounted and identified to are large deciduous species (IBGE, 1993; 1997; Soares-Filho, species level. The nomenclature follows Bolton et al. (2011) 2000). and Wilson (2003). Representative materials of all of the spe- These once extensive native forest formations are cur- cies are deposited in the Myrmecology Laboratory Collection rently represented only by remnant fragments that have expe- (CPDC) under the reference number #5729. rienced intense processes of environmental degradation from agro-pastoral activities and the selective extraction of com- Data analyses mercially valuable trees (Soares-Filho, 2000; Projeto Mata Atlântica Interiorana da Bahia, 2002; Oliveira-Filho et al., 1994). Data was recorded using Excel version 10 software The fragments studied here are embedded within monoculture (Microsoft, 2007) which was used to calculate the relative and pasture matrices, and their interiors demonstrate clear frequencies of the species and their species richness for each evidence of selective cutting and cattle trails. The regional different area and for each type of trap. EstimateS software climate is classified as high-elevation tropical (IBGE, 1993; version 8.2 (Colwell, 1997) was used to generate species 1997), with a mean annual temperature of 19.8 ºC, and a mean accumulation curves for each area and each type of trap in annual rainfall rate of 734 mm. terms of the sampling effort employed (Santos, 2003). The Sociobiology 61(1): 9-20 (March, 2014) 11 estimated species richness was subsequently calculated for In both types of trap, fragment 1 demonstrated greater each area using the Jackknife 2 index – an index based on the taxonomic richness than fragment 2 in terms of the species, numbers of species that occur only once in a sample (single- genus, and subfamily levels. This result is somewhat