Effects of season, sex and age on the diet of Homonota fasciata (Squamata, Phyllodactylidae) from Monte region of Argentina

Abstract

ABSTRACT. This study aimed to investigate the diet of the gecko Homonota fasciata (Duméril & Bibron, 1836) in a population from Monte of San Juan Province, Argentina, and to analyze possible temporal, sexual, and ontogenetic variations in feeding behavior. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. We also assessed trophic diversity and trophic equity. Homonota fasciata had a generalist and diverse diet based on arthropods, including insects and arachnids. Individuals adopted a passive 'sit and wait' foraging strategy. There were seasonal-, sex-, and age-related variations in the trophic spectra. The results of this study provide a valuable contribution to our understanding of the biology of this species, with implications for the establishment of management guidelines both for the species and its habitat.KEYWORDS. Foraging ecology, gecko, trophic niche, trophic overlap. RESUMEN. Efectos de la estacionalidad, el sexo y el grupo etario sobre la dieta de Homonota fasciata (Squamata, Phyllodactylidae) en una región del Monte de Argentina. El objetivo de este trabajo fue conocer y describir la dieta de Homonota fasciata (Duméril & Bibron, 1836) en una población del Monte de la provincia de San Juan Argentina, analizando posibles variaciones temporales, sexuales y ontogenéticas en la alimentación. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa, y se calculó el Índice de Importancia Relativa (IRI). Se evaluaron diversidad y equidad trófi ca, además de variaciones estacionales, sexuales y etarias del espectro trófi co. La dieta de H. fasciata es generalista, diversa, basada en artrópodos, incluyendo insectos y arácnidos. La estrategia de forrajeo exhibida fue pasiva ("sit and wait"). Se encontraron variaciones estacionales, sexuales y ontogénicas en la alimentación. Este estudio permite una valiosa contribución al conocimiento de la biología de esta especie, útil a la hora de fi jar pautas de manejo para la misma, como así también para los ambientes que habita.PALABRAS-CLAVE. Ecología trófi ca, gecko, nicho trófi co, solapamiento trófi co.

Effect of agricultural activity on diet in an assemblage of lizards from Monte, Argentina

“…The study was carried out in an area known as Médanos Grandes, located in the southwestern part of the San Juan province, Argentina. The system is characterized by sand dunes and belongs to the phytogeography region of Monte of Sierras and Bolsones, covering an area of 2000 km 2 (Nieva‐Cocilio et al., 2016). It presents xerophytic and psammophytic vegetation, with representatives typical of the Monte such as Larrea divaricata , Prosopis flexuosa and Bulnesia retama , some Cetacea, including Opuntia sulphurea and Tephrocactus aerocanthus and annual herbaceous species like Portulaca spp and Panicum racemosum .…”

“…Although we adhered to the methodology proposed by Pincheira‐Donoso (2008), which states that euthanizing individuals is not necessary in diet studies, collected specimens were used for other morphological and reproduction studies, therefore, they were killed by freezing (Lillywhite et al., 2017; Shine et al., 2015), fixed in 10% formalin and preserved in 70% alcohol (Belver & Ávila, 2001; Nieva‐Cocilio et al., 2016). We registered snout–vent length, body mass, mouth width to the corners, head length from the rostral scales to the tympanic membrane and head height through the medial line of the tympanum to the nearest 0.1 mm using a Vernier calliper (Moreno‐Azócar & Acosta, 2011).…”

“…Each individual was labelled, dissected and the complete digestive tract was excised and then preserved in 70% alcohol (Belver & Ávila, 2001). We used a binocular stereoscopic lens, model Zeiss CM‐2000A, to identify stomach contents (SC) and prey categories by order (Nieva‐Cocilio et al., 2016). Individual arthropod prey items were identified at the order level using the Bland and Jaques (2010) classification; the reproductive structures of plants and seeds were classified using elements from the herbarium belonging to the Botanical Collection of the Instituto y Museo de Ciencias Naturales at Universidad Nacional de San Juan, and from specimens collected at both sampling sites.…”

“…Several authors have demonstrated that most species of the genus Liolaemus have diets with a Formicidae consumption of over 70% (Acosta et al, 1996;Aun & Martori, 1998;Halloy et al, 2006;Kozykariski et al, 2011;Quatrini et al, 2001;Semhan et al, 2013;others), including the species belonging to this genus observed at the study site, L. darwinii (Avila & Acosta, 1993;de Viana et al, 1994), L. wiegamnnii (Aun et al, 1999), L. riojanus (Ripoll Busso, unpublished data) and L. cuyanus, although the latter is classified as an omnivore (Moreno-Azócar & Acosta, 2011). For species of the Phylodactillidae family, preference for Hymenoptera as fundamental prey category has been recorded in H. underwoodi (Blanco Fager, unpublished data), H. horrida (before H. fasciata) (Martori et al, 2002;Nieva-Cocilio et al, 2016) and other species of the genus (Blanco et al, 2009;Kun et al, 2010). In the case of the Teiidae family, the T. oculatus (Acosta et al, 1991;Cappellari et al, 2007), T. suquiensis (Avila et al, 1992), Ameiva ameiva (Vitt & Pianka, 2004;Zaluar & Rocha, 2000) and Cnemidophorus ocellifer (Sales et al, 2012) species have Orthoptera, Isoptera, Coleoptera and Arachnida as their preferred diet, differing from what was found for T. teyou and A. longicauda, where principal orders were Hymenoptera and Arachnida.…”

“…Therefore, it is necessary to increase knowledge of species in less productive environments, such as deserts. Feeding habits of various reptile species have been studied extensively (de Viana et al., 1994; Halloy et al., 2006; Hawlena & Pérez, 2009; Moreno‐Azócar & Acosta, 2011; Nieva‐Cocilio et al., 2016; Perry & Garland, 2002; Rivas et al., 2019), however, few studies compare diet between an environment disturbed by agricultural activity in a desert area and native habitat, and even fewer make these comparisons at the assemblage level.…”