Identifying juveniles changes our interpretation of similarities
among communities
The Mantel test revealed that there are substantial differences in the
species compositions of communities when considering only adult
specimens or individuals of all life stages, and the ANOSIM showed that
taking immature specimens into account reduced the differences in
species composition between communities at different latitudes. The NMDS
plots also revealed differences in community similarities between the
two approaches. While in the NMDS with only adults most communities were
more similar to other communities within the same park than to
communities from different parks, this pattern was much less pronounced
in the NMDS that includes juveniles. In addition, the marked distinction
between communities at higher latitudes and communities at lower
latitudes found with adults only was not recovered when considering all
the individuals. This lower structure in the NMDS based on specimens of
all life stages suggests that phenological differences among communities
may lead to see community compositions as more different than what they
really are. In the time of the sampling, a species might be present as
adult in a certain community and still as juvenile in another community,
so by taking into account exclusively adult stages we might be
inadvertently accentuating the differences among community compositions.
Given that seasonality and marked phenologies with different life stages
present at different times of the year are very common across many
animal groups (Scott & Epstein, 1987; Jakob, Poizat, Veith, Seitz, &
Crivelli, 2003; Lazaridou-Dimitriadou & Sgardelis, 1997), we suspect
that the phenomenon that we describe here might also apply to
inventories performed with other organisms. Studies on other animal taxa
comparing alpha diversity estimates of a community using only
individuals of a certain life stage or all individuals might help reveal
if this trend is constant across different taxa.