Vol.:(0123456789) 1 3 Insectes Sociaux https://doi.org/10.1007/s00040-020-00763-8 RESEARCH ARTICLE Ants nesting in dry fallen petioles of Cecropia obtusifolia Bertol. (Urticaceae): vertical stratifcation and nest site limitation S. Novais 1,2,3  · V. Hernández‑Ortiz 4  · K. Rodríguez‑Hernández 5  · M. Quesada 2,3  · J. Valenzuela 6  · G. W. Fernandes 1  · A. Aguirre‑Jaimes 4 Received: 22 October 2019 / Revised: 12 February 2020 / Accepted: 20 April 2020 © International Union for the Study of Social Insects (IUSSI) 2020 Abstract Cecropia (Urticaceae) trees continuously shed their old large leaves, which fall directly on the forest foor (ground stratum) or accumulate on the aboveground vegetation under Cecropia canopies (vegetation stratum). Since twig-nesting ants are expected to be more nest site limited in the higher forest strata than at ground level, we predict that richness, abundance, and colonization frequency of ant nests in Cecropia petioles are greater in the vegetation stratum when compared with ground stratum. During June 2019, ffteen trees of C. obtusifolia were sampled in a tropical rainforest, in Veracruz, Mexico. For each tree, we collected ten dry fallen petioles per stratum, for 300 petioles in total. We recorded 44 ant nests from 21 ant species. Forty-two nests were found in individual petioles, although in one case a single petiole housed two diferent ant species. Thirty-four (23%) petioles were colonized in the vegetation stratum and only nine (6%) in the ground stratum. At tree scale, ant nest richness and abundance were signifcantly greater in the vegetation stratum. Furthermore, frequency of petiole colonization per tree was greater in the vegetation stratum (14 trees; 93.3%) when compared with the ground stratum (5 trees; 33.3%). A stratifed pattern of ant occupation in natural nesting sites was observed, supporting that twig-nesting ants are more nest site limited in the upper forest strata than at ground level. Because nesting sites are a limiting resource for arboreal twig-nesting ants, we suggest that Cecropia trees are key components of tropical forests that maintain arboreal ant diversity by promoting nesting sites through dry fallen petioles. Keywords Ecosystem engineering · Twig-nesting ants · Facilitation · Microhabitat · Forest strata · Limiting factors Introduction In tropical forests, ants are species-rich, dominant, and colo- nize all habitats, from the soil to the canopy (Hölldobler and Wilson 1990; Klimes 2017). Along this vertical gradient, ant colonies inhabit several types of micro-habitats, such as soil, leaf litter, hollow cavities in living or dead plant structures (Soares and Schoereder 2001; Arruda et al. 2016; Klimes 2017; Mottl et al. 2019). Myrmecophytic plants already present specialized hollow structures known as domatia, which are found in stems (e.g., Cecropia, Cordia, Leonar- doxa, Macaranga), thorns (Acacia), petioles (Piper), and Insectes Sociaux Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00040-020-00763-8) contains supplementary material, which is available to authorized users. * A. Aguirre-Jaimes armando.aguirre@inecol.mx 1 Laboratório de Ecologia Evolutiva e Biodiversidade, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais, 30270-971 Belo Horizonte, MG, Brazil 2 Laboratorio Nacional de Análisis y Síntesis Ecológica, Escuela Nacional de Estudios Superiores Unidad Morelia, Universidad Nacional Autónoma de México, 58190 Morelia, MICH, México 3 Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, 58190 Morelia, MICH, México 4 Instituto de Ecología A.C., Red de Interacciones Multitrófcas, Red de Interacciones Multitrófcas, Carretera Antigua a Coatepec 351, El Haya, 91070 Xalapa, VER, México 5 Posgrado del Instituto de Ecología A.C., Carretera Antigua a Coatepec 351, El Haya, 91070 Xalapa, VER, México 6 Instituto de Ecología A.C., Red de Ecología Funcional, Carretera Antigua a Coatepec 351, El Haya, 91070 Xalapa, VER, México