Belchior Ceres, Sendoya Sebastián F, Del-Claro Kleber
Programa de Pós-Graduação em Ecologia e Conservação de Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia MG, Brazil.
Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, C.P. 6109, Campinas SP, Brazil.
PLoS One. 2016 Jul 20;11(7):e0158283. doi: 10.1371/journal.pone.0158283. eCollection 2016.
Plants bearing extrafloral nectaries (EFNs) are common in the Brazilian cerrado savanna, where climatic conditions having marked seasonality influence arboreal ant fauna organization. These ant-plant interactions have rarely been studied at community level. Here, we tested whether: 1) EFN-bearing plants are more visited by ants than EFN-lacking plants; 2) ant visitation is higher in the rainy season than in dry season; 3) plants producing young leaves are more visited than those lacking young leaves in the rainy season; 4) during the dry season, plants with old leaves and flowers are more visited than plants with young leaves and bare of leaves or flowers; 5) the composition of visiting ant fauna differs between plants with and without EFNs. Field work was done in a cerrado reserve near Uberlândia, MG State, Brazil, along ten transects (total area 3,000 m2), in the rainy (October-January) and dry seasons (April-July) of 2010-2011. Plants (72 species; 762 individuals) were checked three times per season for ant presence. Results showed that 21 species (29%) and 266 individuals (35%) possessed EFNs. These plants attracted 38 ant species (36 in rainy, 26 in dry season). In the rainy season, plants with EFNs had higher ant abundance/richness than plants without EFNs, but in the dry season, EFN presence did not influence ant visitation. Plant phenology affected ant richness and abundance in different ways: plants with young leaves possessed higher ant richness in the rainy season, but in the dry season ant abundance was higher on plants possessing old leaves or flowers. The species composition of plant-associated ant communities, however, did not differ between plants with and without EFNs in either season. These findings suggest that the effect of EFN presence on a community of plant-visiting ants is context dependent, being conditioned to seasonal variation.
带有花外蜜腺（EFNs）的植物在巴西塞拉多稀树草原很常见，那里气候条件具有明显季节性，影响着树栖蚂蚁群落的组织。这些蚂蚁与植物的相互作用在群落层面很少被研究。在此，我们测试了以下几点：1）有花外蜜腺的植物是否比没有花外蜜腺的植物更受蚂蚁光顾；2）雨季蚂蚁的光顾率是否高于旱季；3）在雨季，长出嫩叶的植物是否比没有嫩叶的植物更受蚂蚁光顾；4）在旱季，有老叶和花的植物是否比有嫩叶且无叶或无花的植物更受蚂蚁光顾；5）有花外蜜腺和没有花外蜜腺的植物上光顾的蚂蚁群落组成是否不同。实地研究在巴西米纳斯吉拉斯州乌贝兰迪亚附近的一个塞拉多保护区进行，沿着十条样带（总面积3000平方米），在2010 - 2011年的雨季（10月至1月）和旱季（4月至7月）进行。每个季节对植物（72种；762株个体）检查三次蚂蚁的存在情况。结果表明，21种（29%）和266株个体（35%）具有花外蜜腺。这些植物吸引了38种蚂蚁（雨季36种，旱季26种）。在雨季，有花外蜜腺的植物比没有花外蜜腺的植物蚂蚁丰度/丰富度更高，但在旱季，花外蜜腺的存在并不影响蚂蚁的光顾。植物物候以不同方式影响蚂蚁丰富度和丰度：有嫩叶的植物在雨季蚂蚁丰富度更高，但在旱季，有老叶或花的植物上蚂蚁丰度更高。然而，在两个季节中，有花外蜜腺和没有花外蜜腺的植物上与植物相关的蚂蚁群落物种组成没有差异。这些发现表明，花外蜜腺的存在对访问植物的蚂蚁群落的影响取决于环境，受季节变化制约。
