Convergence in the variation of local and regional galling species richness

Abstract

RESUMO -Foram investigados os determinantes locais e regionais da riqueza de insetos indutores de galhas sobre o arbusto dióico Baccharis concinna Barroso (Asteraceae) na porção sudeste da Cadeia do Espinhaço, MG. O número total de espécies de insetos indutores de galhas e a riqueza de Cecidomyiidae (Diptera) foram influenciados pelo sexo da planta. Plantas masculinas apresentaram maior riqueza de insetos indutores de galhas do que plantas femininas, corroborando a hipótese da herbivoria mediada pelo sexo na comunidade. O número total de espécies de insetos galhadores e a riqueza de Cecidomyiídeos mostraram um pico em altitudes intermediárias. A riqueza de todas as espécies de insetos galhadores e de cecidomiideos foi fortemente influenciada pelo habitat. Plantas no habitat xérico apresentaram mais espécies de insetos galhadores do que plantas no habitat mésico, corroborando a hipótese do estresse higrotérmico/nutricional. Os resultados indicam que os fatores locais podem ser importantes estruturadores da comundade de insetos galhadores em B. concinna. PALAVRAS-CHAVE:Baccharis concinna, comunidade ecológica, diversidade, gradiente altitudinal, .....herbívoro ABSTRACT -We investigate the local and regional determinants of galling insect richness on the dioecious shrub Baccharis concinna Barroso (Asteraceae) in the southeastern portion of the Espinhaço Mountains in Brazil. The total number of galling species and the richness of galling Cecidomyiidae (Diptera) were influenced by plant gender. Male plants supported a higher richness of galling insects than female plants, supporting the hypothesis of sex-biased herbivory at the community level. The total number of galling species and the richness of galling cecidomyiids showed a peak at intermediate altitudes. The richness of all galling species and galling cecidomyiids were strongly influenced by habitat. Plants in xeric habitats supported more galling species than plants in mesic habitats, corroborating the hypothesis of hygrothermal/nutritional stress. Our results indicate that local factors may be the most important factors structuring the galling insect community on B. concinna.

Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome

“…Admittedly, the 96 proportion of herbivore taxa among invertebrates is lower in Arctic regions than at lower latitudes (Danks 1986), 97 and invertebrate herbivores generally occur at relatively low abundances in tundra (Haukioja 1981). However, 98 outbreaks of invertebrate herbivores have been well documented in the forest-tundra ecotone (Jepsen et al 2008; 99 Kaukonen et al 2013) internally feeding herbivores as they provide safer shelter against pathogens and reduce levels of desiccation 154 (Carneiro et al 2005). We propose that the same distinction between external and internal feeders will drive 155 differences in the patterns of invertebrate herbivory in tundra.…”

Are gall midge species (Diptera, Cecidomyiidae) host-plant specialists?

“…The galling insect control of gall morphological is suggested by the fact that many galls with very different galler-specific morphologies may grow on the same plant host at the same time (Stone & Schönrogge 2003). In the rupestrian fields for example, 13 gall morphotypes were found on Baccharis concinna Barroso 1976 (Asteraceae) and a single individual plant supported 11 species simultaneously (Carneiro et al 2005). Many other studies reported the same observation (e.g., Waring & Price 1989;Stone et al 2002).…”

Leaf miner and plant galler species richness on Acacia: relative importance of plant traits and climate

“…Climatic conditions have long been linked to distribution patterns of a diverse array of taxa, and this is apparent from the species richness trends observed with latitude and altitude (Carneiro et al 2005;Price 1988, 1991;Mittelbach et al 2007;Price 1991). However, this trend is not consistent across all taxa, especially when equivalent habitats are assessed using comparable methods across the latitudinal range of a single host plant for species richness, herbivory and abundance-biomass relationships (Andrew and Hughes 2004, 2005b.…”

“…However, this trend is not consistent across all taxa, especially when equivalent habitats are assessed using comparable methods across the latitudinal range of a single host plant for species richness, herbivory and abundance-biomass relationships (Andrew and Hughes 2004, 2005b. Galling species represent an anomaly to the global trend, with studies documenting a peak in diversity at intermediate latitudes in environments of increasing temperature and aridity (Blanche and Ludwig 2001;Carneiro et al 2005;Fuentes-Contreras et al 1999;Goncalves-Alvim and Fernandes 2001). Increasing gall species richness in habitats that become hotter and drier has led to the hypothesis that the gall-forming habit is an adaptation to harsh or stressful environments (Baust et al 1979;Carneiro et al 2005;Crespi et al 1997;Fernandes et al 2004;Fernandes and Price 1988, 1991Lara et al 2002;Marques et al 2000;Waring 1986).…”