<p>The geographic distribution of consumers and their resources shapes the spatial signature of trophic interactions in heterogeneous landscapes. Bees are central place foragers that consume a wide variety of plant species around their nests, thus, bee communities in urban landscapes are an opportune system for understanding intra- and interspecific spatial variation in resource use. Here, we investigated how the spatial distribution of nests of four species of Neotropical stingless bees (<i>Tetragonisca angustula</i>, <i>Plebeia droryana</i>, <i>Nannotrigona testaceicornis</i>, <i>Scaptotrigona postica</i>) and their taxonomic identity combine to shape resource use variation in an urban landscape. We predicted that, within species, geographically closer nests consume more similar trophic resources. Also, because niche partitioning favors local coexistence of similar species, we expected to observe interspecific trophic partitioning between the studied species. We used stable isotopes of carbon (δ¹³C) to measure trophic differences between nests, which allowed us to quantify both intra and interspecific patterns of trophic divergence. Although we found a relatively narrow range of isotopic values within and across species, there is significant isotopic partitioning between species. Interestingly, for only two (<i>T. angustula</i> and <i>S. postica</i>) of the four studied species, we found that nests with greater spatial distance have larger isotopic distances than nests closer to each other. This result suggests that these two species are partitioning their niche with conspecific nests in response to resource changes across the landscape. Thus, our results reveal a lack of a general spatial structure of isotopic niches across species, offering new insights into the ecology and conservation strategies for Neotropical stingless bee species in urban landscapes.</p>

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Spatial structure partially explains niche variation in urban Neotropical stingless bees

  • Raquel Bendocchi Alves,
  • Vladimir Eliodoro Costa,
  • Raul Costa-Pereira

摘要

The geographic distribution of consumers and their resources shapes the spatial signature of trophic interactions in heterogeneous landscapes. Bees are central place foragers that consume a wide variety of plant species around their nests, thus, bee communities in urban landscapes are an opportune system for understanding intra- and interspecific spatial variation in resource use. Here, we investigated how the spatial distribution of nests of four species of Neotropical stingless bees (Tetragonisca angustula, Plebeia droryana, Nannotrigona testaceicornis, Scaptotrigona postica) and their taxonomic identity combine to shape resource use variation in an urban landscape. We predicted that, within species, geographically closer nests consume more similar trophic resources. Also, because niche partitioning favors local coexistence of similar species, we expected to observe interspecific trophic partitioning between the studied species. We used stable isotopes of carbon (δ¹³C) to measure trophic differences between nests, which allowed us to quantify both intra and interspecific patterns of trophic divergence. Although we found a relatively narrow range of isotopic values within and across species, there is significant isotopic partitioning between species. Interestingly, for only two (T. angustula and S. postica) of the four studied species, we found that nests with greater spatial distance have larger isotopic distances than nests closer to each other. This result suggests that these two species are partitioning their niche with conspecific nests in response to resource changes across the landscape. Thus, our results reveal a lack of a general spatial structure of isotopic niches across species, offering new insights into the ecology and conservation strategies for Neotropical stingless bee species in urban landscapes.