Comparing invasive species to metastatic cancers inspires new insights for modelers.

Evidence that power laws govern invasive species came from crop pathogen studies and computer simulations reported in such journals as Nature , Science , and Genetics . Marco and fellow authors Marcelo Montemurro, Ph.D., and Sergio Cannas, Ph.D., have studied biological invasions for years and suspected that the same laws govern tumor growth. They confi rmed their suspicions by comparing an Argentine forest including invasive species to noninvasive human glioma cells cultured either in live mice or in Matrigel, a patented gelatinous protein mixture secreted by mouse tumors. “Noninvasive cells from the center of the glioma” — which were used as an experimental control — “were genetically engineered to become invasive by expressing angiopoietin 2, a regulator that promotes tissue infiltration,” Marco explained. Likewise, aerial black-and-white photographs taken in 1970, 1987, and 1996 revealed the gradual spread of English elm ( Ulmus minor ), an ornamental European tree that invaded Argentina in the mid-20th century. From 1987 to 1997, 74 elm tree patches became 189 patches scattered across 17 acres. While Marco “would not say that trees native to the forest were a control,” she did identify two noninvasive species — Lithraea ternifolia and Fagara coco — as tantamount to “tissue surrounding a spreading tumor.”