Anurans in a forest remnant in the transition zone between cerrado and atlantic rain forest domains in southeastern Brazil

This study presents the species richness, temporal distribution and reproductive activity of anurans from the uaimií State Forest (Floresta Estadual do uaimií – FLOE uaimií), situated in the Quadrilátero Ferrífero region, municipality of Ouro Preto, Minas Gerais state, Brazil. Field activities were performed monthly from September 2009 to August 2010. We recorded 36 anurans species, distributed in 10 families. The greatest richness of the sampled sites corresponds to a permanent rivulet in a secondary forest. The majority of anuran species presented seasonal vocalization activity pattern, mainly in the rainy season. The anuran species composition of FLOE uaimií is similar to others studied areas from the Quadrilátero Ferrífero region.


INTRODUCTION
Communities can be seen as units determined by biotic interactions (Pianka 1973).In anurans communities, several strategies are used allowing many species to coexist within the same environment (Cardoso and Haddad 1992).Among these strategies, there are differences in the use of breeding (Rossa-Feres andJim 1994, Conte andRossa-Feres 2007) and calling sites (Cardoso et al. 1989), preferences for activities in different seasons (Cardoso and Haddad 1992, Eterovick and Sazima 2000, Conte and Rossa-Feres 2006), or for activities at different times of the day (Cardoso and Haddad 1992).These differences can be interpreted as mechanisms of pre-zygotic reproductive isolation (Wells 1977).
Brazil presents a great diversity of geographical reliefs, among them are the mountain ranges of Espinhaço and Mantiqueira, in eastern Brazil.The Espinhaço Mountain Range (hereafter called EMR) corresponds to a transition between two domains, the Cerrado and the Atlantic Forest, and is the largest rocky meadow formation in Brazil, considered by some authors as another domain (Gontijo 2009).The EMR covers an area of approximately three million hectares and its geographical range beginning in the south in the municipality of Ouro Preto, Minas Gerais state, extending northwards to the municipality of Jacobina, in Bahia state (Gontijo 2009).The north portion of the Mantiqueira Mountain Range (hereafter called MMR) connects with the plateaus and hills of the EMR through an elevated region, RENATA M. PIRANI, LUCIANA B. NASCIMENTO and RENATO N. FEIO which joins Serra do Ibitipoca (situated in MMR) to the meridional portion of the Espinhaço, making it difficult to establish the precise limits between them (Cruz and Feio 2007).
The Quadrilátero Ferrífero region, at Minas Gerais state, is included in south portion of in EMR (Gontijo 2009) and comprises the mountain ranges of Caraça, Curral, Piedade, Itacolomi, Itabirito, Ouro Branco, and Moeda (viana and Filgueiras 2009).The region is known for the iron ore richness and, consequently, for intense mining activities that modify the natural landscape (Silvano and Segalla 2005).Besides, the Quadilátero Ferrífero region is considered a priority area for amphibian conservation in Minas Gerais state.The main current threat to amphibian populations at this region is the natural habitat destruction by deforestation, due to urban, agricultural and mining activities (Silvano and Segalla 2005).Faced with these threats, one of the recommendations to protect this region is scientific research (drummond et al. 2005).
According to the context given above, the present study shows data on the species richness and temporal distribution of an anuran community in Uaimií State Forest (Floresta Estadual do uaimií -FLOE uaimií), a conservation unit in the municipality of Ouro Preto, at Quadrilátero Ferrifero region, at Minas Gerais state, with comments on the biogeography of southeastern region of Brazil.Additionally, it describes the annual reproductive activity patterns, based mainly on vocalization activity.

STUDY AREA
The FLOE uaimií (20°29'66"S, 43°57'47"W, Figure 1) comprises an area of approximately 4,400 ha.located in the municipality of Ouro Preto, Minas Gerais state, at Quadrilátero Ferrífero region, in the southern portion of the Espinhaço mountain range (Alvarenga et al. 1997, IEF 2008).The conservation unit has typical vegetation of the transition between the Cerrado and Atlantic Forest morphoclimatic domains, with the occurrence of rocky meadows (campos rupestres) at the highest elevations, with altitudes ranging from 900 to 1,400 metres.It is the main source water source of the Rio das Velhas, the largest tributary of the São Francisco River Basin (IEF 2008).
The climate class of the study region is Cwa (sensu Köppen 1918) comprising a rainy season that occurs from October to March, with a monthly average of more than 110 mm, accounting for approximately 81.5% of the total annual average at 1,373 mm.The dry season is from April through September, during which the average rainfall is 42 mm per month (Sá Junior et al. 2011).

FIELD ACTIVITIES
Expeditions to study the anurans temporal distribution were performed monthly, lasting five days from September 2009 to August 2010.The temporal distribution study was conducted at four sites: two permanent rivulets (named Riacho do Alojamento -R1 -and the Cachoeira de São Bartolomeu -R2), one permanent pond (Brejo da Estrada -P1) and one temporary pond (Brejo do Campo Rupestre -P2).The areas were chosen based on their potential to host anuran species and also for easy access (Table I).Direct visualisations of individuals and/or zoophony were used for recording the species.Reproductive activity evidence was recorded considering the following parameters: a) couples in amplexus; b) mature females identified by visualization of oocytes through abdominal transparency; c) clutches; d) tadpoles and e) froglets.
The vocalization patterns of anuran species at FLOE uaimií were defined as: (1) continuous: for species that vocalize, or for more than nine RENATA M. PIRANI, LUCIANA B. NASCIMENTO and RENATO N. FEIO months of the study; (2) rainy season: for species with calling activity associated with the rainy months; (3) dry season: vocalization associated with the dry months; (4) opportunistic: for species that vocalized only after rains; and (5) not defined: species for which it was not possible to define a pattern (adapted from Bertoluci 1998, Bertoluci and Rodrigues 2002, Canelas and Bertoluci 2007, São Pedro and Feio 2010).
For the species inventory, data collected at other sampling sites in FLOE uaimií and from other campaigns in the area were used.The data for accumulated rainfall in the region were provided by área de Controle Ambiental from the company Novelis do Brasil LTDA, located in the municipality of Ouro Preto, Minas Gerais state, around 13 km from FLOE uaimií.The air temperature at each site was measured at the beginning and the end of each night during observation activities.Its average was used as the month's temperature.

DATA ANALYSIS
The taxonomic nomenclature used in the present study is according to Pyron and Wiens (2011).
The Sorensen index (Krebs 1999) was used to verify the similarity in anurans species composition at FLOE uaimií to the following mountain regions  (Krebs, 1999) was performed to determine the existence of locations with similar species composition.The clusters were defined at a level with at least 40% similarity.For this analysis we considered only taxa with confirmed specific identity.
The family Hylidae was the most representative, with a total of 19 species (51%), and two that were unidentified, Bokermannohyla sp.(gr.circumdata) and Scinax sp.(aff.perereca).The last one corresponds to a species that is in the description process (L.B.Nascimento unpublished et al., data).
The Figure 3

Hylidae
Aplastodiscus arildae (Cruz & Peixoto, 1987"1985") x x Aplastodiscus cavicola (Cruz & Peixoto, 1985"1984") x (gr.circumdata) was placed in the not defined vocalization pattern, mature females were observed in October and January, a male was observed vocalizing in February and soon after (May and June), tadpoles and froglets were observed.In spite of the species Haddadus binotatus being assigned to the not defined pattern, a male was observed vocalizing in March.
The species composition of FLOE uaimií was most similar to other conservation units in the municipality of Ouro Preto (PE Itacolomi and EE Tripuí) which were also similar to Serra do Ouro Branco.The group formed by them has showed greater similarity with the RPPN Serra do Caraça.All these locations are in the Quadrilátero Ferrífero region, forming a separate group in the similarity dendrogram (Figure 4A).Two other mountainous regions in the MMR, the PESB and PARNA Caparaó, are similar regarding the anurans composition and they form a group with the Quadrilátero Ferrífero studied areas.The PE Ibitipoca, also in the MMR, formed an isolated branch, indicating that its species composition is different from that found in the other locations.The PARNA Cipó, in the EMR, was the location with the lowest similarity to the study area (Figures 4A and 4B).

DISCUSSION
The 36 species recorded in FLOE uaimií correspond to 50% of the anurofauna known in the Quadrilátero Ferrífero region, situated in EMR, Minas Gerais state (Leite et al. 2008).The species richness of this conservation unit is only surpassed by Serra do Ouro Branco, with 47 species (São Pedro and Feio 2011), and RPPN Serra do Caraça, with 43 species (Canelas and Bertoluci 2007).The recording of the species Hylodes babax represents the first record for the Quadrilátero Ferrífero region (Pirani et al. 2010).
The great richness of amphibian species associated with the EMR is due not only to its large area and high longitudinal and altitudinal amplitude, but certainly to the existence of a complex and intricate relationship between this historical and ecological formation and its adjacent biomes, the Cerrado and the Atlantic Forest (Leite et al. 2008).The EMR has a large environmental heterogeneity, presenting a mosaic of habitats from open areas to forests, providing a high resources variety, which has also been shown in other studies (Pedralli et al. 2001, Canelas and Bertoluci 2007, São Pedro and Feio 2010, São Pedro and Feio 2011).According to Rapini et al. (2008) and Versieux et al. (2008), the same pattern of great richness is observed for the flora of the rocky meadows of the EMR which also presents a high endemism rate.
Among the study sites, the Brejo da Estrada (P1) was the richest environment, housing 14 species.Cardoso et al. (1989) and Conte and Rossa-Feres (2006) highlighted spatial heterogeneity as a determinant of the environment richness.The amount of microhabitats with substrates for male calling activity available in each environment can be a determining factor for differentiating the richest site.Although we have not quantified, the P1 seems to be the sampled environment that presented the largest number of microhabitats.
The Cachoeira de São Bartolomeu rivulet (R2) presented lower richness, with only eight species, which may be related to the high flow of people in the area compared to the others study sites, due to the presence of a waterfall and an oratory dedicated to Saint Bartholomew.The Riacho do Alojamento (R1) and Brejo do Campo Rupestre (P2) presented the lowest richness, with seven species.Other studies show that temporary environments attract  more species due to the reduced amount or absence of tadpoles predators (Alford 1999, Bertoluci andRodrigues 2002).This is not observed at P2 in FLOE uaimií.The majority of the FLOE uaimií anurans followed a seasonal pattern of calling activity in which the species vocalized during the warmer and wetter months of the year.This same pattern was noted in studies conducted in other Brazil regions (Heyer et al. 1990, Rossa-Feres and Jim 1994, Pombal Jr 1997, Bertoluci 1998, Bernarde and Anjos 1999, Bernarde et al. 1999, Vasconcelos and Rossa-Feres 2005, Canelas and Bertoluci 2007, São Pedro and Feio 2010).In tropical regions, the rain seems to be the main factor regulating the anurans reproductive activities (Aichinger 1987, Heyer 1973), not only because of the vulnerability of these animals to desiccation, but also because it is the rain that determines the viability and duration of their reproductive sites (Gottsberger and Gruber 2004).
Some species like Aplastodiscus arildae and Hypsiboas polytaenius had a continuous vocalization period.The same pattern was observed for the A. arildae in Parque das Mangabeiras, in the municipality of Belo Horizonte (Carvalho et al. 2006) and at RPPN Serra do Caraça (Canelas and Bertoluci 2007) and for H. polytaenius at this last locality and at Serra do Ouro Branco (Canelas andBertoluci 2007, São Pedro andFeio 2010, respectively).
It was not possible to define the vocalization pattern for some species, such as D. minutus, H. albopunctatus, and H. faber, because they were registered only once during the study period at FLOE uaimií.however, the three species are very abundant in other studied areas within the Quadrilátero Ferrífero region and were registered almost all the year, presented a higher density of calling males during the rainy season (Grandinetti and Jacobi 2005, Canelas and Bertoluci 2007, São Pedro and Feio 2010).
Other anuran species can present explosive reproductive patterns (sensu Wells 1977), so they call for only a short period.Field activities did not coincide with the nights when they vocalized (Toledo et al. 2003).This may be the case for the species Elachistocleis cesarii, which demonstrated explosive reproductive patterns in Fazenda Intervales, state of São Paulo (Bertoluci 1998) and RPPN Serra do Caraça (Canelas and Bertoluci 2007).
Three species of the genus Leptodactylus, from the L. fuscus species group (sensu Heyer 1978), occurring in P2, had overlapping vocalization periods in the rainy season, as observed in other studies (Canelas andBertoluci 2007, São Pedro andFeio 2010).Apparently, they demonstrated a different spatial distribution of calling sites on the body water edge.Leptodactylus fuscus was found on the soil, L. furnarius within the grasses, and L. cunicularius among the rocks.However, the indication of a spatial partitioning could be speculative in this case.
The studied communities at localities that are included at the Quadrilátero Ferrífero region (FLOE uaimií, PE Itacolomi/EE Tripuí, Serra do Ouro Branco, and RPPN Serra do Caraça) form a cluster in the similarity dendrogram.According to Leite et al. (2008), and within what is currently known, it is possible to recognise three major relief units along the EMR, based on the endemic anurans species distribution, and one of which is at the Quadrilátero Ferrífero.The present study confirms this proposal, because the most similar anuran communities are from this unit.The dissimilarity verified in this study among the PARNA Cipó and others studied areas from the EMR could be also explained by the proposal of Leite et al. (2008).The second proposed unit begins at Serra do Cipó and continues to mountains in the north of the Minas Gerais state.One endemic species of the EMR could exemplify this fact, Bokermannohyla martinsi, whose distribution is related only to the Quadrilátero Ferrífero unit (Leite et al. 2008).RENATA M. PIRANI, LUCIANA B. NASCIMENTO and RENATO N. FEIO Although, it is important to point out that most studies conducted at PARNA Cipó are related to the rocky meadows complex and on the western slopes of the mountain range bordering the São Francisco river basin (Madeira et al. 2008).According to Madeira et al. (2008), the Atlantic Forest portion located in Serra do Cipó is poorly sampled for various species groups, including amphibians.
The Cerrado and Atlantic Forest biomes influence on the EMR is an important factor for understanding the current observed distribution of these amphibian species (Leite et al. 2008).The EMR not only separates the coastal hydrographic basins from the inland basins, but also the Cerrado (in the west) and Atlantic Forest biomes (in the east/southeast) and it acts as a barrier for many species typical of these different phytogeographic formations (Leite et al. 2008).Thus, the western EMR acts as the occurrence limit of species or even genera (e.g.Phasmahyla, Thoropa, Crossodactylus, Hylodes and Cycloramphus) that have the centre of their occurrence areas in the Atlantic Forest.The same can be observed for species typical from Cerrado biome (e.g.Ameerega flavopicta and Physalaemus centralis), whose geographic distribution does not extend further than the western slope of the EMR (Leite et al. 2008).
Species with restricted distributions, related physiologically, occupying the same environmental physiognomy in different mountain ranges (Espinhaço and Mantiqueira), suggest biogeographic homologies and raise speculations about the influence of the geomorphologic evolution in the anurans speciation patterns (Nascimento et al. 2005, Cruz andFeio 2007).Species with distribution in both the EMR and MMR (e.g.The PE Ibitipoca is composed of quartzite, forming a prominent elevated lowland hill (Cruz et al. 2009).Its vegetation is composed mainly of montane meadows at higher altitudes (from 1,050 to 1,784 m), patches of rocky meadows, and forest formations (Cruz et al. 2009).Even though the continuous altimetry provides some form of connection between the EMR and MMR, differences in the geological formations and relationships to the biogeographic domains provide PE Ibitipoca with some environmental peculiarities, making it less similar to FLOE Uaimií (Cruz et al. 2009).
Although the most part of the amphibians species registered in this study have showed wide geographical distribution, the FLOE uaimií anuran community include species from both mountain complex, the EMR and MMR.Endemic distribution of anurans species emphasizes the needing of strategies to conserve the FLOE Uaimií and also the EMR.Foram registradas 36 espécies de anuros, distribuídas entre 10 famílias.Maior riqueza de espécies foi verificada em uma área de riacho permanente em mata secundária.

Figure 3 -
Figure 3 -Monthly rainfall (bars), average monthly temperature (line) and annual pattern of reproductive activity of 24 anuran species sampled in FLOE uaimií (Ouro Preto, MG), from September 2009 to August 2010.

TABLE I Sample sites for the study of temporal distribution characterization of the anuran communities in the FLOE Uaimií (Ouro Preto, MG) from September 2009 to August 2010.
Rhinella pombali, R. rubescens, Haddadus binotatus, Bokermannohyla sp.(gr.ANURANS IN A FOREST REMNANT IN SOUTHEASTERN BRAZIL RENATA M. PIRANI, LUCIANA B. NASCIMENTO and RENATO N. FEIO circumdata), Dendropsophus minutus, Hypsiboas albopunctatus, and H. faber.The species Phasmahyla jandaia and Elachistocleis cesarii could not be placed in any of the defined patterns since they were not observed vocalizing.The species Phasmahyla jandaia was recorded only in February and a young of E. cesarii was recorded only in October.Although Bokermannohyla sp.