Temporal Patterns of Ant Diversity across a Mountain with Climatically Contrasting Aspects in the Tropics of Africa

Abstract

Factors that drive species richness over space and time are still poorly understood and are often context specific. Identifying these drivers for ant diversity has become particularly relevant within the context of contemporary global change events. We report on a long-term bi-annual (wet and dry seasons), standardized sampling of epigeal ants over a five year period on the mesic and arid aspects of an inselberg (Soutpansberg Mountain Range) in the tropics of Africa. We detail seasonal, annual and long-term trends of species density, test the relative contribution of geometric constraints, energy, available area, climate, local environmental variables, time, and space in explaining ant species density patterns through Generalized Linear Mixed Models (GLMM) where replicates were included as random factors to account for temporal pseudo-replication. Seasonal patterns were very variable and we found evidence of decreased seasonal variation in species density with increased elevation. The extent and significance of a decrease in species density with increased elevation varied with season. Annual patterns point to an increase in ant diversity over time. Ant density patterns were positively correlated with mean monthly temperature but geometric constraints dominated model performance while soil characteristics were minor correlates. These drivers and correlates accounted for all the spatio-temporal variability in the database. Ant diversity was therefore mainly determined by geometric constraints and temperature while soil characteristics (clay and carbon content) accounted for smaller but significant amounts of variation. This study documents the role of season, elevation and their interaction in affecting ant species densities while highlighting the importance of neutral processes and temperature in driving these patterns.

The influence of distance to perennial surface water on ant communities in Mopane woodlands, northern Botswana

“…However, we found that the effects of distance to water in general were higher during the wet than the dry season. Seasonal variation in rainfall has been shown to influence invertebrate activity patterns, competitive interactions, and the availability of resources (Wolda, 1988), including in ants (Munyai & Foord, 2015). Our results suggest that rainfall increased rather than decreased the effect of distance to water on ant communities.…”

“…Seasonal variation in rainfall has been shown to influence invertebrate activity patterns, competitive interactions, and the availability of resources (Wolda, 1988), including in ants (Munyai & Foord, 2015). Seasonal variation in rainfall has been shown to influence invertebrate activity patterns, competitive interactions, and the availability of resources (Wolda, 1988), including in ants (Munyai & Foord, 2015).…”

The effect of elevation and time on mountain spider diversity: a view of two aspects in the Cederberg mountains of South Africa

“…The interaction between season and elevation leads to a qualitative change in seasonal richness patterns. Contrastingly, ants along elevational gradients (Bishop et al ., ; Munyai & Foord, ) had similar richness patterns in both wet and dry seasons. The Cederberg mountains experience snowfall during the winter.…”

Epigaeic ant diversity and distribution in the Sandstone Sourveld in KwaZulu‐Natal, South Africa

“…These results are in agreement with the findings of Keroumi, Naamani, Soummane, and Dahbi () who reported greater abundance and higher species richness of ants in the wet than dry season in an Argan forest of Morocco. Munyai and Foord () reported that ground‐dwelling ants are intolerant of cold conditions and are more active and abundant in the wet than dry season. Activities of ground‐dwelling ants are affected by food resource availability, temperature, moisture and solar radiation, whose influence declines in the dry season and increases in the wet season (Abhinandini & Venkatesha, ).…”

“…Each vegetation type was sampled in three replicates. Each replicate had ten pitfall traps laid in a 2 × 5 grid with 10 m spacing between adjacent pitfall traps as described by Munyai and Foord (). Replicates were randomly located in each vegetation type and were separated by at least 300 m. Replicates in the disturbed grassland straddled patches of alien plants and secondary grassland as previously described for this vegetation type.…”