ORIGINAL PAPER A morphological and life history comparison between desert populations of a sit-and-pursue antlion, in reference to a co-occurring pit-building antlion Inon Scharf & Ido Filin & Aziz Subach & Ofer Ovadia Received: 7 April 2009 / Revised: 24 May 2009 / Accepted: 28 May 2009 / Published online: 27 June 2009 # Springer-Verlag 2009 Abstract Although most antlion species do not construct pits, the vast majority of studies on antlions focused on pit- building species. We report here on a transplant experiment aiming to test for morphological and life history differences between two desert populations of a sit-and-pursue antlion species, Lopezus fedtschenkoi (Neuroptera: Myrmeleonti- dae), originating from habitats, which mainly differ in plant cover and productivity. We raised the antlion larvae in environmental chambers simulating either hyper-arid or Mediterranean climate. We found significant differences in the morphology and life history of L. fedtschenkoi larvae between the two populations. For example, the larvae originating from the more productive habitat pupated faster and had a higher growth rate. In agreement with the temperature–size rule, antlions reached higher final mass in the colder Mediterranean climate and exhibited a higher growth rate, but there was no difference in their develop- mental time. Observed differences in morphology between populations as well as those triggered by climate growing conditions could be explained by differences in size allometry. We also provide a quantitative description of the allometric growth axis, based on 12 morphological traits. Comparing the responses of L. fedtschenkoi with those observed in a co-occurring pit-building antlion indicated that there were neither shape differences that are independent of size nor was there a difference in the plasticity level between the two species. Keywords Foraging mode . Myrmeleontidae . Reaction norm . Temperature . Transplant experiment Introduction Species with a broad geographical range may be subjected to a wide spectrum of different environmental conditions. When the strength and/or direction of selection within such a species range are not uniform, adaptations to local conditions can emerge (Blanckenhorn 1997; Reznick and Travis 2001). Local adaptations, however, are not the single solution for coping with environmental variability. When environmental conditions vary over time in a predictable manner, phenotypic plasticity (i.e., the environmentally sensitive production of more than one phenotype by the similar genotypes) should be preferred (Nylin and Gotthard 1998; David et al. 2004). Clearly, what is usually found in natural systems is a mixture of local adaptations selecting for a local optima of different traits, combined with a population-specific range of phenotypes developed in response to different environmental conditions (e.g., Reznick and Travis 2001; Volis et al. 2002). Occasionally, the strength of phenotypic plasticity also differs across populations. Some populations are extremely plastic, I. Scharf (*) : I. Filin : A. Subach : O. Ovadia Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105, Israel e-mail: schari@bgu.ac.il I. Filin e-mail: ido.filin@helsinki.fi A. Subach e-mail: aziz@bgu.ac.il O. Ovadia e-mail: oferovad@bgu.ac.il I. Filin Department of Mathematics and Statistics, University of Helsinki, PO Box PL 68, 00014 Helsinki, Finland Naturwissenschaften (2009) 96:1147–1156 DOI 10.1007/s00114-009-0576-z