INTRODUCTION
The Amazon is home to thousands of species of terrestrial vertebrates, which interact among them and with the environment in a unique way. These interactions define the ecological niches of these species and how they are distributed in time and space (Hirzel and Le Lay, 2008). Deforestation, climate change, and other anthropogenic pressures have caused drastic changes in the structure of native habitats in the Amazon in the last 40 years (PRODES, 2021), which have consequences on the interactions of species with their environment (Coelho et al., 2014; Mendes-Oliveira et al., 2017; Sales et al., 2019). Deforestation and climate change already act as associated factors for the transformation of natural habitats into degraded areas of the Amazon, where the drought-deforestation feedback will leave the climate in these areas warmer and drier (Staal et al., 2020).
After nine years of reduction in deforestation, the Brazilian Amazon has experienced an increase in degradation. During the last two years (2019-2021), about 21,000 km2 of the Brazilian Amazon Forest were deforested (PRODES-Terrabrasilis/INPE, 2021). About 60% of this deforestation was concentrated in the States of Pará and Mato Grosso, which border the Cerrado Biome, also is called the Brazilian savannah. Significant forest losses and climatic variations are projected for this region in the coming years, increasing the transition zone area between forests and savannah (Lyra et al., 2016). These changes can negatively affect specialist forest species, and in turn favor the use of the degraded landscape by species able to use savannah habitats (Sales et al., 2020). Nevertheless, degraded landscapes can lead species into ecological traps, where modified environments may lead to false clues to favorable habitats, making it impossible to accurately assess the suitability value for species in these habitats (Hale and Swearer, 2016).
Ecological traps occur when species settle in lower quality habitats, even if this reduces their productivity or survival (Hale and Swearer, 2016). This situation has been happening mainly due to the rapid environmental changes caused by anthropogenic actions, which generate new conditions in the habitats, different from the original ones, but which may be somehow related to the evolutionary history of the species (Robertson et al., 2013). In this way, species capture signals, which are not indicative of habitat quality, and mistakenly establish themselves in unfavorable locations for their survival in the medium and long term (Robertson and Huto, 2006). In this paper, we raise the possibility that this process occurs with some species in the Amazon region, driven by the intense dynamics of land use and rapid environmental changes caused by degradation, deforestation, and climate change. In this way, understanding the factors that determine the occupation of high-quality sites by species can help to mitigate the harmful effects of choosing poorly adapted habitats (Robertson and Hutto, 2006; Gilroy and William, 2007).
Most neotropical vertebrates live in natural environments already altered at some level, directly or indirectly, by human activities. The response of the fauna to significant changes in their native habitats can vary according to their ecological demands and niche differences (Sih et al., 2011; Hagen et al., 2012). Also, a species’ fitness is closely related to its evolutionary history, shaped by environmental factors that influenced the ecological preferences and demands of the species over an evolutionary time (Harper et al., 1961). Although the main question is how recent significant changes in natural environments are altering patterns shaped during evolution and whether species’ responses can mislead them into ecological traps and thereby reduce their fitness. In this sense, it is necessary to have a baseline knowledge about species’ original distribution, habitat preferences, and what determines their occurrences.
Members of the Canidae family have undergone morphological and behavioral changes due to environmental changes and degradation of their native habitats (Yom-Tov et al., 2007; Figueirido et al., 2015; De Moura Bubadué et al., 2016). Canids appeared around 40_Ma in North America (Wang et al., 2007). They diversified throughout the Pleistocene and occupied different niches and geographical locations (Berta, 1987; Tchaicka et al., 2016). The emergence of a wide variety of morphologies and diets over a relatively short evolutionary period (Perini et al., 2010; Nyakatura and Bininda-Emonds, 2012; Figueirido et al., 2015), make canids a very interesting group for studies of ecological plasticity. For instance, small variations in masticatory or locomotor systems have caused large differences in their adaptive capacity (Figueirido et al., 2015; Penrose, 2019). Currently, 10 species of canids occur in South America, with high morphological and ecological diversity among them (Perini et al., 2010).
Three species of canids are represented in the Amazon: Atelocynus microtis (Sclater, 1883) (short-eared dog), Speothos venaticus(Lund, 1842), (bush dog), and Cerdocyon thous(Linnaeus,1766) (crab-eating fox) (Appendix, Figure 1). These are small to medium-sized (from 4 to 11 Kg) canids with a broad and partly sympatric distribution in the Amazon region. The occurrence and distribution of canids have been associated with environmental characteristics and interspecific competition (De Oliveira and Pereira, 2014; De Moura Bubadué et al., 2016; Rocha et al., 2020). Rocha et al. (2020) showed a strong connection of A. microtis to forest habitats, and how it has been negatively affected by deforestation in the Amazon.
Competition between canid species that occur in sympatry is commonly reported in the literature (Cypher, 1993; Johnson et al., 1996; Di Bitetti et al., 2009). Under environmentally favorable conditions, sympatry species can coexist by partitioning spatial or temporal niches (Bueno and Mota-Junior, 2004; Di Bitetti et al., 2009). Usually, the dominant species with greater body mass consume the larger prey species, while the sub-dominant species consume foods with lower nutritional value (Penrose, 2019). There are several reports of sympatry betweenA. microtis and S. venaticus (Michalski, 2010; Santos and Mendes-Oliveira, 2012), and between C. thous and S. venaticus (Da Silva et al., 2013; Vieira and Oliveira, 2020); however, to our knowledge only one occurrence of sympatry has been reported between A. microtis and C. thous (Carvalho et al., 2014).
In this paper, we investigate the dynamics of occurrence and distribution of A. microtis, C. thous, and S. venaticus related to anthropogenic threats imposed on their habitats in the Amazon Forest. We investigate the possible environmental thresholds for the occurrence of the three species and how their distribution might be influenced by climate change and deforestation, and whether these factors can lead these species to fall into ecological traps in the Amazon Rainforest. We also model the future occurrence and distribution of those species, considering a pessimistic climate change scenario. Our hypothesis is that all species are influenced by different environmental variables, and changes in these variables can lead species to ecological traps. We also believe that these environmental variables explain different patterns of occurrences and niche distributions now and in the future.