Diversity and structure of dung beetle assemblages under two contrasted habitats in Tunisia: oases vs. humid pastures Imen Labidi, 1 Saïd Nouira 1 and Faïek Errouissi 2 * 1 Faculté des Sciences de Tunis, Tunis El Manar University, Campus Universitaire – Farhat Hachad, Tunis 1060, Tunisia. 2 Institut Supérieur des Sciences Biologiques Appliquées de Tunis, Tunis El Manar University, 9 Avenue Zohaïr ESSEFI 1006 Tunis, Tunisia. Abstract Dung beetles were used as an indicator group to identify whether oases play an important role as a refuge for biodiversity under harsh environmental conditions in Mediterranean ecosystems. Here, we provide a comparative framework for analysing seasonal changes in species composition, abundance and diversity in two local dung beetle assemblages trapped at two contrasted habitats. Using pitfall traps, we collected 3585 dung beetle specimens representing two subfamilies, 15 genera and 28 species (11 Aphodiinae and 17 Scarabaeinae). We trapped 24 and 10 species in humid pasture and oases habitats, respectively. Aphodiinae was more abundant in humid habitats, while Scarabaeinae dominated in oases. Abundance of the six common species was higher in oases than in humid pastures. Multivariate analyses showed that there were two different faunas functioning differently. The humid pastures assemblage showed net temporal segregation with high alpha and beta (temporal turnover) diversities, which may be the result of a well-established community adapted to local climatic conditions. Furthermore, the contrast generated by the oases in the desert environment has allowed for widely distributed and some non-desert-adapted species to be more abundant. The harsh conditions of the desert environment have led to the development of an impoverished fauna with lower temporal heterogeneity (low temporal beta diversity). Evenness, core species and groups were lower under oases conditions than compared with humid habitats. This study demonstrates that humid pastures in Tunisia have richer dung beetle assemblages than oases, but with comparison to surrounded area, oases may represent a refuge for some species and an important conservation area for dung beetles living in harsh conditions in desert environments. Key words assemblage diversity, dung beetles, humid habitats, oases, spatial and temporal analyses. INTRODUCTION In grazed ecosystems, the recycling of organic materials of animal origin is a complex linkage of slow processes in which microorganisms and the edaphic fauna intervene at the soil surface as well as in the upper layers of the soil, where climatic conditions influence the activity of dung-breeding insects, especially Scarabaeidae (Lumaret & Kadiri 1995). Studies on local dung beetle assemblages in the Western Mediterranean Basin have been greatly developed, both on the northern side (Lumaret 1978; Martin-Piera 1982; Errouissi 2003; Niogret 2007; Agoglitta et al. 2012), and more recently in the southern side, particularly in Morocco and in Tunisia (Janati-Idrissi 2000; Haloti et al. 2006; Errouissi et al. 2009, 2011; Labidi et al. 2012). Dung beetles belong two distinct taxonomic groups: Geotrupidae and Scarabaeidae (with two subfamilies: Scarabaeinae and Aphodiinae) (Ahrens et al. 2014). Aphodiinae and Geotrupidae are dominant in the northern parts of the temperate regions, while Scarabaeinae are dominant in Mediterranean regions and the tropics (Lobo et al. 2002). In southern part of Tunisia, landscape is characterised by scattered oases, which are isolated semi-natural agrosystems surrounded by an inhospitable desert matrix. The oases vegetation is dominated by date palm trees protecting two understoreys consisting of fruit trees and herbaceous plants. (Kassah 1996). Three types of oases can be observed in southern Tunisia: littoral (Gabés), continental (Tozeur) and mountain (Tamaghza) oases. These agrosystems play major economic role for indigenous people (Sghaier 1995; Kassah 1996). It has been noticed that the animal diversity, ‘mainly for birds’ may be dependent on the oases habitat in southern Tunisia (Heim de Balsac & Mayaud 1962; Selmi 2000). As refuges, these ecosystems are receiving increasing attention in study dealing with the conservation of biodiversity (Selmi & Boulinier 2003). Moreover, it has been shown that the traditional practice in these agrosystems is largely being responsible for local level of biodiversity. Labidi (2007) and Labidi et al. (2012) showed that dung beetles were richer and more diverse in humid part of Tunisia than in the south, but despite their importance in pas- tures and semi-natural agrosystems, no study has examined the ecology of dung beetles associated with animal dung in oases. In this paper, we compared dung beetle assemblages from oases and humid habitats in Tunisia. We investigated the relationship between the habitat type and the dung beetle compo- sition and structure of assemblages, and we tested two hypothe- ses: (i) dung beetles diversity was drastically reduced in oases *faiek.rouissi@issbat.rnu.tn © 2016 Australian Entomological Society doi: 10.1111/aen.12210 Austral Entomology (2016) ••, ••–••