Mutualism disruption by an invasive ant reduces carbon fixation for a foundational East African ant-plant.

Invasive ants shape assemblages and interactions of native species, but their effect on fundamental ecological processes is poorly understood. In East Africa, Pheidole megacephala ants have invaded monodominant stands of the ant-tree Acacia drepanolobium, extirpating native ant defenders and rendering trees vulnerable to canopy damage by vertebrate herbivores. We used experiments and observations to quantify direct and interactive effects of invasive ants and large herbivores on A. drepanolobium photosynthesis over a 2-year period. Trees that had been invaded for ≥ 5 years exhibited 69% lower whole-tree photosynthesis during key growing seasons, resulting from interaction between invasive ants and vertebrate herbivores that caused leaf- and canopy-level photosynthesis declines. We also surveyed trees shortly before and after invasion, finding that recent invasion induced only minor changes in leaf physiology. Our results from individual trees likely scale up, highlighting the potential of invasive species to alter ecosystem-level carbon fixation and other biogeochemical cycles.

Metastatic penile cancer in a young Caucasian male: impact of delayed diagnosis.

Penile cancer is an uncommon malignancy in the developed world, with only 1200 estimated cases per year in the United States. This is usually a cancer of older men and often the diagnosis is delayed because of lack of suspicion on the part of the patient or primary care provider. We report a case of penile cancer in a young Caucasian male in whom a delay in diagnosis had a deleterious impact on outcome. We describe and illustrate how, to palliate his symptoms, the patient required a hemipelvectomy plus a total pelvic exenteration. We present this case to alert physicians of the possibility of penile cancer in young Caucasian males as well as to demonstrate the significant morbidity and mortality that can ensue from a delay in diagnosis.