Cahokia-Moundville Interaction

A 1997 chapter by the author concluded that evidence of direct interaction between Cahokia and the large Mississippian center at Moundville, Alabama, was negligible. This chapter updates that assessment, especially in light of much recent research on the earliest period at Moundville. Exotic artifacts include infrequent Mill Creek chert bifaces and hoe chips, a Missouri flint clay effigy pipe, and sheet copper objects with possible Cahokia connections. Mound architecture includes a “greathouse” arguably built in a Cahokian style. Even so, evidence of direct contact between the two centers remains minimal, and there is no evidence of Cahokian involvement in Moundville’s emergence.

Termite mound architecture regulates nest temperature and correlates with species identities of symbiotic fungi

BackgroundLarge and complex mounds built by termites of the genusMacrotermescharacterize many dry African landscapes, including the savannas, bushlands, and dry forests of the Tsavo Ecosystem in southern Kenya. The termites live in obligate symbiosis with filamentous fungi of the genusTermitomyces. The insects collect dead plant material from their environment and deposit it into their nests where indigestible cell wall compounds are effectively decomposed by the fungus. Above-ground mounds are built to enhance nest ventilation and to maintain nest interior microclimates favorable for fungal growth.ObjectivesIn Tsavo Ecosystem twoMacrotermesspecies associate with three differentTermitomycessymbionts, always with a monoculture of one fungal species within each termite nest. As mound architecture differs considerably both between and within termite species we explored potential relationships between nest thermoregulatory strategies and species identity of fungal symbionts.MethodsExternal dimensions were measured from 164Macrotermesmounds and the cultivatedTermitomycesspecies were identified by sequencing internal transcribed spacer (ITS) region of ribosomal DNA. We also recorded the annual temperature regimes of several termite mounds to determine relations between mound architecture and nest temperatures during different seasons.ResultsMound architecture had a major effect on nest temperatures. Relatively cool temperatures were always recorded from large mounds with open ventilation systems, while the internal temperatures of mounds with closed ventilation systems and small mounds with open ventilation systems were consistently higher. The distribution of the three fungal symbionts in different mounds was not random, with one fungal species confined to “hot nests.”ConclusionsOur results indicate that differentTermitomycesspecies have different temperature requirements, and that one of the cultivated species is relatively intolerant of low temperatures. The dominantMacrotermesspecies in our study area can clearly modify its mound architecture to meet the thermal requirements of several different symbionts. However, a treacherous balance seems to exist between symbiont identity and mound architecture, as the maintenance of the thermophilic fungal species obviously requires reduced mound architecture that, in turn, leads to inadequate gas exchange. Hence, our study concludes that while the limited ventilation capacity of small mounds sets strict limits to insect colony growth, in this case, improving nest ventilation would invariable lead to excessively low nest temperatures, with negative consequences to the symbiotic fungus.

Evidence for the use of magnetic cues in mound construction by the termite Amitermes meridionalis (Isoptera : Termitinae)

The termite Amitermes meridionalis builds meridionally elongated mounds. We removed the tops of such mounds and then allowed the termites to repair their mounds in the natural geomagnetic field and in artificial magnetic fields with different magnetic declinations. Cross-sections of repaired mounds were taken and the arrangement of the small, elongated cells that form the basis of mound architecture was assessed. The results suggest that the termites align mound cells along the existing axis of the mound and the cardinal axes of the horizontal component of the applied magnetic field.