Uso do hábitat, períodos diários de atividade e ecologia térmica de Ameiva ameiva (Squamata: Teiidae) em uma área de caatinga do nordeste do Brasil.

Abstract

Habitat use, daily activity periods, and thermal ecology of Ameiva ameiva (Squamata: Teiidae) in a caatinga area of northeastern Brazil. We studied the use of spatial, temporal, and thermal resources by the Neotropical lizard Ameiva ameiva during rainy and dry seasons in a caatinga (xerophilous open forests) environment in northeastern Brazil. Lizards used the vegetation habitats and microhabitats in the ground, but never were seen in the rocky habitat. Adults usually used the arboreal-shrubby habitat, whereas juveniles were sighted more often in the shrubby-herbaceous habitat. Ontogenetic differences in spatial use seem to be linked to different thermal needs between age groups owing to differences in body size. Body temperatures were significantly higher in juveniles than in adults. Most teiid species have elevated body temperatures, usually above 37 o C, and are active during the hottest times of day, as was observed for A. ameiva in this study. Seasonality influenced habitat use and daily activity periods of adults, but not body temperatures. We verified annual fluctuations in adult abundance, with a decline of active lizards in the dry season; this phenomenon may be related to aestivation and/or increased mortality rate during the driest months.Keywords: abundance, body size, ontogeny, seasonality, thermoregulation.Resumo Uso do hábitat, períodos diários de atividade e ecologia térmica de Ameiva ameiva (Squamata: Teiidae) em uma área de caatinga do nordeste do Brasil. Estudamos o uso dos recursos espaciais, temporais e térmicos pelo lagarto neotropical Ameiva ameiva durante as estações seca e chuvosa em um ambiente de caatinga do nordeste do Brasil. Os lagartos utilizaram os hábitats e micro-hábitats de vegetação baixa, mas nunca foram observados no hábitat rochoso. Os adultos 166Phyllomedusa -10(2), December 2011 utilizaram usualmente o hábitat arbóreo-arbustivo, enquanto os juvenis foram observados mais frequentemente no hábitat arbustivo-herbáceo. Diferenças ontogenéticas no uso do espaço parecem estar relacionadas a diferentes necessidades térmicas entre as classes de idade devido a diferenças de tamanho corporal. As temperaturas corporais dos juvenis foram significativamente maiores que as dos adultos. A maioria das espécies de Teiidae possui temperaturas corporais elevadas, usualmente acima de 37 o C, e atividade concentrada nas horas mais quentes do dia, como observado em A. ameiva neste estudo. A sazonalidade influenciou o uso do hábitat e os períodos diários de atividade dos adultos, mas não influenciou as temperaturas corporais. Verificamos flutuações anuais na abundância de indivíduos adultos, com um declínio de lagartos ativos na estação seca; esse fenômeno pode estar relacionado à estivação e/ou ao aumento da taxa de mortalidade durante os meses mais secos.

Influence of Life History Traits on Trophic Niche Segregation between Two Similar SympatricTupinambisLizards

“…In group C3, the niche becomes broader, with dominance of native fruits and seeds for Tupinambis rufescens, whereas for T. merianae diversification of prey items is limited and Arthropoda is dominant (probably due to the limitation in prey availability in anthropogenic environments). Body size probably affects not only diet volume but also diet composition (Magnusson and da Silva, 1993); consequently, as we observed in T. rufescens, despite incorporating larger prey into their diet, the largest size classes continue to consume small prey consistently, leaving minimum prey size constant and increasing niche breadth (Sales, 2011). In T. merianae consumption of large prey such as Mammalia is not only feasible but also advantageous in terms of energy gain, although some large lizards may also consume small and abundant prey available in the habitat, such as Arthopoda, due to the low energy costs associated with their capture and ingestion (e.g., Siqueira et al, 2013).…”

“…However, Morisita's Index showed trophic niche overlap between sexes of both species. Similarly, other studies focused on sexually dimorphic lizards did not find sexual differences in the types of selected prey (e.g., Zaluar and Rocha, 2000;Kolodiuk et al, 2010;Sales et al, 2011Sales et al, , 2012. Therefore, morphological differences could be also shaped by other selective pressures such as sexual selection forces (Naretto et al, 2014).…”

“…Diet can vary in one sex but not in the other sex. Sex can influence prey type and size due to differences in morphology and/or behavior between males and females (Vitt, 2000;Sales et al, 2011). In species with sexually dimorphic body size, the occurrence of dietary differences between sexes is expected because the larger sex has the potential to consume larger or more diverse prey (Sales et al, 2012).…”

Estado de conservación, sexo y tamaño corporal de reptiles en Santiago Nonualco, El Salvador

“…El registro de mayor cantidad de individuos adultos en casi todas las especies puede ser indicativo de que los subadultos son excluidos del área de distribución de los adultos, al interior de cada especie esto representa una forma de evitar la competencia por el recurso alimentario y microhábitats (Kerr et al, 2005;Sales et al, 2011). Por su parte, Vidal et al (2002), sugiere que cuando el recurso térmico es limitado, los individuos adultos muestran un comportamiento agresivo y los subadultos tienden a usar sustratos subóptimos, mostrando así una segregación espacial entre clases de edad.…”

“…Al haber encontrado que en A. macrophallus y A. wellbornae los machos son más grandes que las hembras, estaría en concordancia con un patrón frecuente en los saurios y ampliamente estudiado en Dactyloidae, Phrynosomatidae y Teiidae (Losos, 2009;Sales et al, 2011;Ramírez-Bautista et al, 2016). El tamaño corporal a favor de los machos se relaciona con una conducta territorial, de cubrir sitios más amplios y ejercer control sobre las hembras que residen dentro de esa área (Losos, 2009).…”