Figure legends
Figure 1: Hypothetical effects of potential land use on fish local (alpha) diversity across elevation gradients. The solid curve represents a decay of diversity with altitude. The lower dashed curve represents potential diversity after natural lands are converted to agriculture and other human uses, where greatest diversity loss (arrows) occurs at lower altitude.
Figure 2: a) Geographical location of the sample sites. b) Examples of the aquatic ecosystems within the altitudinal levels, which are the ones recognized by van der Hammen and dos Santos (1995).
Figure 3. Comparisons of premontane and basimontane fish communities. a) Rarefaction curves approach asymptotes, indicating representative sampling. Premontane sites were inhabited by more species, as supported by evidence in b) for total abundance, richness, and effective diversity. c) Taxonomic composition differed between premontane and basimontane sites, where Siluriformes were more prominent in basimontane sites than in premontane sites. Characiformes were dominant in both site types, but in different proportions. d) NMDS of fish communities from the sampled sites. Dots represent pooled temporal data (2013-2022) for sites. Polygons represent fish communities based on altitudinal levels recognized by van der Hammen and dos Santos (1995).
Figure 4. Regression lines for species richness (a), total abundance (b), and effective diversity (c) ~ altitude, where regression lines represent GLMM predicted values and error bars. Note log axes; regressions represent power law functions.
Data accessibility: Supporting data are available at https://doi.org/10.5281/zenodo.10424407
Competing Interests Statement: All authors declare that there are no competing interests.