Final answer:
The 'Ecologist Union' concept likely refers to the collaboration and eventual merger of various smaller environmental groups into larger, influential organizations such as the WWF and IUCN. These groups represent a significant advancement in global environmentalism and conservation.
Step-by-step explanation:
The question relates to the evolution of environmental organizations and their rebranding to adapt to broader environmental conservation aims. While there is no direct reference to the 'Ecologist Union' in the provided references, a significant moment for modern environmentalism was indeed the establishment of various environmental groups and coalitions in response to an expanded understanding of environmental issues during the 20th century. This movement included collaborations and amalgamations of several smaller groups into larger, more influential organizations that could better pool their resources and efforts, similar to the Save Our Environment Action Center described in the text.
Some of the best-known examples of such organizations include the World Wide Fund for Nature (WWF) and the International Union for Conservation of Nature (IUCN). These entities absorbed smaller groups and united efforts on a global scale to address a wide array of environmental concerns, such as biodiversity conservation and sustainable development.