Positive Interactions between Desert Granivores: Localized Facilitation of Harvester Ants by Kangaroo Rats

Facilitation, when one species enhances the environment or performance of another species, can be highly localized in space. While facilitation in plant communities has been intensely studied, the role of facilitation in shaping animal communities is less well understood. In the Chihuahuan Desert, both kangaroo rats and harvester ants depend on the abundant seeds of annual plants. Kangaroo rats, however, are hypothesized to facilitate harvester ants through soil disturbance and selective seed predation rather than competing with them. I used a spatially explicit approach to examine whether a positive or negative interaction exists between banner-tailed kangaroo rat (Dipodomys spectabilis) mounds and rough harvester ant (Pogonomyrmex rugosus) colonies. The presence of a scale-dependent interaction between mounds and colonies was tested by comparing fitted spatial point process models with and without interspecific effects. Also, the effect of proximity to a mound on colony mortality and spatial patterns of surviving colonies was examined. The spatial pattern of kangaroo rat mounds and harvester ant colonies was consistent with a positive interspecific interaction at small scales (<10 m). Mortality risk of vulnerable, recently founded harvester ant colonies was lower when located close to a kangaroo rat mound and proximity to a mound partly predicted the spatial pattern of surviving colonies. My findings support localized facilitation of harvester ants by kangaroo rats, likely mediated through ecosystem engineering and foraging effects on plant cover and composition. The scale-dependent effect of kangaroo rats on abiotic and biotic factors appears to result in greater founding and survivorship of young colonies near mounds. These results suggest that soil disturbance and foraging by rodents can have subtle impacts on the distribution and demography of other species

Life history, distribution and abundance of the giant earthworm Rhinodrilus alatus RIGHI 1971: conservation and management implications

Rhinodrilus alatus is an endemic giant earthworm of the Brazilian Cerrado hotspot used as live bait for about 80 years. The goal of this study was to gather ecological data about this species, which will support the establishment of management strategies. The life history, distribution and abundance of R. alatus were investigated in Cerrado, pastures and Eucalyptus plantation areas following the harvesting activities of the local extractors of this species. We found that this earthworm is abundant in all of the sampled areas, showing its resilience to land-use conversion. The Capture Per Unit Effort was 4.4 &#177; 5 individuals per 100 metres of transect and 5.6 &#177; 3 individuals per hour. The earthworm's annual cycle is markedly seasonal, with an aestivation period throughout the driest and coldest season of the year. Significant differences in the length and diameter of the body and in the diameter and depth of the aestivation chambers were found between the juveniles and adults. The distribution range of the species was expanded from two to 17 counties. The life history, abundance, distribution and resilience of R. alatus to certain perturbations are key elements to be considered in conservation and management strategies for this species

The emerging roles of YAP and TAZ in cancer

Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are the major downstream effectors of the Hippo pathway, which regulates tissue homeostasis, organ size, regeneration and tumorigenesis. In this Progress article, we summarize the current understanding of the biological functions of YAP and TAZ, and how the regulation of these two proteins can be disrupted in cancer. We also highlight recent findings on their expanding role in cancer progression and describe the potential of these targets for therapeutic intervention