Piatti L, Souza F L
Programa de Pós-Graduação em Ecologia e Conservação, Universidade Federal de Mato Grosso do Sul – UFMS, CEP 79070-900, Campo Grande, MS, Brazil.
Braz J Biol. 2011 Aug;71(3):653-61. doi: 10.1590/s1519-69842011000400009.
Artificial ponds or irrigated systems scattered throughout farmlands can offer important habitats for anurans and can be interesting sites for research on species resources use in a changing landscape. This study describes the diet and resource partitioning among anurans inhabiting irrigated rice fields in the Pantanal region. Twenty categories of prey were found in the stomachs of Leptodactylus chaquensis, L. elenae, L. podicipinus and Rhinella bergi, the most frequent being Coleoptera, Hymenoptera, larvae of Hexapoda, Hemiptera, Diptera and Orthoptera. The great differences found in the diet of these species in rice fields compared to other locations, according to available records in the literature, was the increased importance of Hemipitera and Orthoptera and the decrease in importance of Hymenoptera in the diet of leptodactylids. These differences might be attributed to changes in the availability of resources in response to habitat modification. Although diet composition was very similar among species, niche overlap was larger than expected by chance, suggesting that the competition for food resources is not, or has not been, a significant force in determining the structure of this frog community. Two non-exclusive hypotheses could be considered as a justification for this result: 1) the high niche overlap could result from resource availability, which is sufficient to satisfy all species without any strong competition; 2) or the high values of niche overlap could be a selective force driving species to compete, but there has not been enough time to express a significant divergence in the species diet because the study area is characterised as a dynamic habitat influenced by frequent and cyclical changes.
遍布农田的人工池塘或灌溉系统可为无尾目动物提供重要栖息地，并且可能成为研究不断变化的景观中物种资源利用情况的有趣场所。本研究描述了潘塔纳尔地区灌溉稻田中无尾目动物的食性和资源分配情况。在查科细趾蟾、埃氏细趾蟾、蹼趾细趾蟾和贝氏蟾蜍的胃中发现了20类猎物，其中最常见的是鞘翅目、膜翅目、六足纲幼虫、半翅目、双翅目和直翅目。根据文献中的现有记录，与其他地点相比，这些物种在稻田中的食性存在很大差异，即半翅目和直翅目在细趾蟾科动物的食物中重要性增加，而膜翅目重要性降低。这些差异可能归因于栖息地改变导致的资源可利用性变化。尽管物种间的食物组成非常相似，但生态位重叠比随机预期的要大，这表明食物资源竞争并非或尚未成为决定该蛙类群落结构的重要因素。对于这一结果，可以考虑两个并非相互排斥的假设：1）高生态位重叠可能是由于资源可利用性导致的，即资源足以满足所有物种，不存在激烈竞争；2）或者高生态位重叠值可能是一种驱动物种竞争的选择力量，但由于研究区域具有频繁和周期性变化的动态栖息地特征，尚无足够时间使物种食性出现显著分化。
