What happens when a joint swells up?

Ais a group of individuals of the same that exist together in the same place at the same time

Zoo geographic regions are characterized by the presence of specific groups of animals these regions are determined by the taxonomic or phylogenetic relationships of animals. the map shows the zoogeographic regions proposed by the naturalist alfred russel wallace in 1876. the similarities of organisms in which two areas numbered above provide the best evidence for common ancestry between the organisms in both locations ?

Why were the results whit just water so much different than the trials with the detergent ?