Diet of the lizard Liolaemus occipitalis in the coastal sand dunes of southern Brazil (Squamata-Liolaemidae)

Abstract

Knowledge of a species' diet provides important information on adaptation and the relationship between the organism and its environment. The genus Liolaemus occurs in the southern region of South America and is an excellent model to investigate the adaptive processes of vertebrate ecology in ecosystems of this region of the world. Liolaemus occipitalis is an endangered species that inhabits the coastal sand dunes of southern Brazil. This species is the most abundant vertebrate in this environment, and it presents unique adaptation characteristics to the restinga environment. The present study analyzed this lizard's diet to verify similarities or differences between this species and other species of the same genus. Specimens were collected monthly from January 1996 to December 1997. The number of items, frequency of occurrence and volume of each prey taxon were determined. Arthropods were identified to the order level, and plant material was identified as flower, fruit, seed and leaves. Variations in the diet of males and females, adults and juveniles and seasons were also analyzed. The data indicate that Liolaemus occipitalis is a generalist, "sit-and-wait" or ambush predator as well as omnivorous, feeding on both arthropods and plant material. Significant ontogenetic differences were verified. Juveniles are more carnivorous, and the intake of plant material increases with size and age. Seasonal differences in diet composition were also observed. In the spring, arthropod and plant materials were more diversified and, therefore, consumed more often.Keywords: Liolaemus, southern Brazil, restinga, foraging, seasonal variation. Dieta do lagarto Liolaemus occipitalis nas dunas costerias do sul do Brasil(Squamata-Liolaemidae) ResumoO conhecimento sobre a dieta de uma espécie traz informações importantes sobre a adaptação e relações entre o organismo e seu ambiente. O gênero Liolaemus, que ocorre na região austral da América do Sul, tem-se mostrado como excelente modelo em ecologia de vetebrados para entender os processos adaptativos nos ecossistemas desta região do mundo. Liolaemus occipitalis é uma espécie ameaçada de extinção que habita as dunas costeiras do extremo sul do Brasil. É o vertebrado mais abundante neste ambiente e apresenta características peculiares de adaptação aos ambientes de restingas. No presente estudo analisou-se a dieta deste lagarto com o intuito de verificar se há diferenças com as espécies do gênero ou segue o mesmo padrão. Foram realizadas coletas mensais entre janeiro/96 e dezembro/97. Determinou-se o número de itens, a frequência de ocorrência e o volume de cada táxon de presa, identificados até o nível de ordem, no caso dos artrópodes, e como flor, fruto, semente e folhas o material vegetal. Foram analisadas as variações da dieta entre machos e fêmeas, entre adultos e jovens, e também entre as estações. Os dados indicam que Liolaemus occipitalis possui uma dieta onívora consumindo tanto artrópodes como material vegetal. Caracteriza-se por ser um predador generalista, forrageando ...

Are lizards sensitive to anomalous seasonal temperatures? Long-term thermobiological variability in a subtropical species

“…In spite of thermal constraints, sustained winter activity likely responds to various interplaying factors: species distribution transiting between mid and low latitudes, avoiding the cold thresholds which prompt winter dormancy in several temperate lizards [63]; small individual size, resulting in high rates of heat gain/loss and consequently in fast warming-up capacity [64,65]; and habitat features, namely the clear, sandy substrate which acts as a primary heat source in sunny, winter days due to its rapid absorption of solar irradiation, and the dune system that provides windless spots. Winter performance in year-round active species holds a crucial biological role associated to foraging and basking time, which optimises reproductive success through strengthened gonad growth and yield, and embryonic development [31,66,67]. High activity in summer and spring and in midday hours provides evidence for a preference for warm conditions, as expected for an ectotherm, although individuals were often exposed to temperatures of over 40 °C that approach their critical thermal maximum (CT max ) and jeopardize physiological stability [4,38].…”

“…arambarensis occurs in the breeding season that follows birth, thus survival of young individuals is crucial for reproduction [47]. Although activity may only be weakly connected to demographic trends, the higher levels of 2015 could be translated in population expansion, derived from a strong recruitment of juveniles during an ecologically-favourable breeding period in spring-summer, and high survival rate and strengthened gonad growth and gamete development in winter [31,66,67]. Demographic analyses would enlighten this hypothesis.…”

“…wiegmannii [72]. Winter activity restrictions may imperil population persistence because foraging and basking time is reduced, leading to failed energy intakes that underpin reproductive physiology [31,66,67]. Species range can be also reduced due to activity restrictions, with a drastic effect on microendemisms [15,29,30].…”

Trophic analysis and parasitological aspects of Liolaemus parvus (Iguania: Liolaemidae) in the Central Andes of Argentina

“…Consuming Formicidae is common in different lizards of the genera Liolaemus (De Viana et al, 1994;Aun and Martori, 1998;Aun et al, 1999;Azocar and Acosta, 2011;Kozykariski, 2011), Homonota (Nieva et al, 2015), and Phrynosoma (Pianka, 1982). According to background studies, L. ruibali (Villavicencio et al, 2005) and L. occipitalis (Verrastro and Ely, 2015) display a sit-and-wait behavior. Species like L. wiegmannii (Aun et al, 1999) and L. saxatilis (Martori et al, 2002) exhibit a mixed strategy (between active mode and sit-and-wait).…”