Interactions between mammals and fruit of an endemic tree (Amphitecna montana, Bignoniaceae) with megafauna traits

ABSTRACT

Several features in the fruit of some neotropical trees likely evolved in response to the interaction with the mammalian megafauna extinct in the late Pleistocene. However, few studies have assessed the interactions between these plants and mammals in the absence of megafauna. We conducted a camera-trapping study in the Reserve of El Triunfo, Chiapas, Southern Mexico, to record the fauna consuming the fruit of the endemic tree Amphitecna montana which has megafauna traits. We surveyed the abundance and the spatial distribution of trees, saplings, and seedlings in 10 transects totalizing 0.1 ha, analyzed the chemical composition of their fruit, and assessed the impact of seed manipulation on germination success and seedling establishment. We recorded 12 species of medium-large mammals but the most frequent consumers of fruit were squirrels. The relationship among trees, saplings, and seedlings did not indicate the existence of a regeneration limitation. All the plant stages showed a clustered spatial pattern, which is in agreement with squirrels being the main seed dispersers. Free seeds were the more successful to germinate and establish as seedlings. Despite the current lack of megafauna in our study area, the A. montana population does not show signs of declining.

Resumen

Varias de las características que observamos en los frutos de algunas especies de árboles neotropicales probablemente evolucionaron en respuesta a la interacción con la megafauna que se extinguió en el Pleistoceno. Sin embargo, hay pocos estudios de campo que evalúen las interacciones entre estas plantas y mamíferos en sitios donde la megafauna está ausente. Estudiamos las interacciones entre mamíferos trerrestres y frutos de Amphitecna montana en la Reserva de El Triunfo, Chiapas en el sureste de México. Instalamos cámaras trampa para registrar a la fauna que consume los frutos. Evaluamos la abundancia y la distribución especial de árboles, juveniles y adultos en diez transectos, totalizando 0.1 ha y analizamos la composición química de los frutos. Evaluamos experimentalmente el impacto de la manipulacion de semillas en la germinación y establecimiento de las plántulas. Registramos 12 especies de mamíferos pero las ardillas fueron las que más frecuentemente consumieron los frutos. La relación entre árboles, juveniles y plántulas no indicó la existencia de una limitación en la regeneración. Todas las etapas de la planta mostraron un patrón especial agrupado que coincide con que las ardillas sean las principales dispersoras de semillas. Las semillas libres tuvieron más éxito para germinar y establecerse como plántulas. A pesar de la ausencia de megafauna la población de A. montana no muestra signos de decaimiento.

KEYWORDS:

• Anachronisms
• Cuniculus paca
• plant–mammal interactions
• Sciurus deppei
• seed germination

Acknowledgments

We thank the staff of the Biosphere Reserve El Triunfo for their support in all the logistics involved and to Oscar Godínez-Gómez and Sergio Morales-Juan for their help during fieldwork. Ruben Martínez and Emmanuel Martinez heped with plant identification. Angela A. Camargo-Sanabria, Romeo Saldaña-Vázquez, Clementina González-Zaragoza, and Yurixhi Maldonado-López provided very valuable advice and comments that greatly improved an earlier version of this paper. We appreciate comments made by an anonymous reviewer and Kim McConkey which were of great help to improve our manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01650521.2023.2207420

Additional information

Funding

This work was supported by the Coordinación de la Investigación Científica from the Universidad Michoacana de San Nicolás de Hidalgo (Project: ‘Ecology and conservation of plant-mammal interactions in a globally threatened ecosystem’).