Spatio-temporal patterns of colony distribution in monodomous and polydomous species of North African desert ants, genus Cataglyphis

Abstract

Summary. Two monogynous species of North African desert ants belonging to the formicine genus Cataglyphis exhibit extremely different habitat preferences, population densities, and population structures. C. fortis is the only Cataglyphis species within the salt-pan flats of the Algerian and Tunisian chotts and sebkhas, whereas C. bicolor, alongside C. albicans and C. ruber, inhabits the nutritionally richer low-shrub semi-deserts surrounding the salt pans. We present a comparative study of the spatio-temporal patterns of colony distribution of the two monogynous species over periods of at least 5 (maximally 15) years. In C. fortis low population densities (0.5 kg body mass per km 2 ) and, correspondingly, large inter-nest distances (40.6 m mean nearest neighbour nest distance) are correlated with absolute intra-annual and high inter-annual nest-site stability (more than 75 % inter-annual survival rate) and a monodomous colony structure. In C. bicolor the population density is one hundred times higher (42 kg body mass per km 2 , 9.1 m mean nearest neighbour nest distance), nest-site stability is extremely low in both intra-annual and inter-annual terms (67 % intra-annual survival rate for 13-day periods; less than 5 % inter-annual survival rate), and polydomy prevails. These marked differences in population structure are discussed with respect to adapted traits such as foraging range, running speed, and relative lengths of the legs.

Vector-based and landmark-guided navigation in desert ants inhabiting landmark-free and landmark-rich environments

“…To address these questions, we had to select colonies of both species that were located in the same type of habitat, in our case in bare desert environments devoid of any reliable landmark cues. This was easy for C. fortis, because such featureless terrains define the typical habitat of this species (Dillier and Wehner, 2004), but it was difficult for M. bagoti, a species normally inhabiting densely cluttered desert habitats, which are rich in grass tussocks and loosely scattered trees (Muser et al, 2005;Cheng et al, 2009), i.e. rich in visual cues that have previously been shown to be used as navigational aids (Kohler and Wehner, 2005;Narendra 2007b;Narendra et al, 2007b;Sommer et al, 2008;Graham and Cheng, 2009a;Graham and Cheng, 2009b;Wystrach et al, 2011).…”

“…The question of course remains whether these differences are species specific or environment dependent. In trying to tackle this question, we selected colonies that in both species were located on bare, flat desert ground devoid of any vegetation, stones or pebble, and had been at these locations for at least 3years [for C. fortis (Dillier and Wehner, 2004), for M. bagoti (C.B., K.C. and R.W., personal observations)].…”

Uncertainty about nest position influences systematic search strategies in desert ants

“…All ants belonged to the same colony, which had not changed its nest location over at least 5 years (Dillier and Wehner, 2004). (Forel 1902, Wehner 1983 were trained to feeders south of their nest (Fig.·1A).…”

Ontogeny of learning walks and the acquisition of landmark information in desert ants,Cataglyphis fortis

“…In contrast to their congeneric relatives, C. fortis ants occupy a featureless habitat devoid of shrubs or other prominent visual landmarks (Dillier and Wehner, 2004). Even though they are confronted with only a few obvious visual landmarks in their natural environment, and therefore rely predominantly on vector navigation (for a review, see Cheng et al, 2014), many studies have shown their ability to learn and use artificial landmarks successfully (for a review, see Wehner, 2008).…”