Ecoregional Characteristics Drive the Distribution Patterns of Neotropical Stream Diatoms

Abstract

We assessed the relative influence of ecoregional features in explaining diatom distribution in the Orinoco river basin. Ecoregions in the Colombian Orinoco can be seen as imprints of the evolutionary history of the basin, for their current biodiversity and physiographic features are the result of the geological and climatic shifts that have occurred since the Tertiary. Thus, they represent an ideal testing ground for studying the interplay between ecological and evolutionary processes shaping diversity patterns of microorganisms, such as diatoms, in the present day. To study this interplay, we compared diatom community composition variance within and among seven ecoregions and assessed the explanatory power of environmental, spatial and historical drivers. This was done by a combination of correlation analyses, multivariate methods and constrained ordinations. We also deconstructed the whole community data set into ecological guilds (low‐ and high‐profile, and motile) to explore their individual response to the contemporary and historical drivers. Taken together, these analyses indicated that contemporary constraints to species occurrence and dispersal, as well as the legacies of historical events, can provide an explanation for the contemporary distribution of diatoms in the Colombian Orinoco. Specifically, we provided evidence showing that both historical legacies and contemporary environmental conditions (temperature, pH, and phosphorus concentration) are interacting to determine diatoms’ distribution. Our results suggest the need to consider ecoregional gradients for unraveling the mechanisms shaping tropical diversity as well as for designing conservation plans.

Limnological Characteristics and Diatom Dominants in Lakes of Northeastern Poland

“…Moreover, as research concerning our study area showed, high pH and a relatively high mineralization or oligotrophy were more common in this area [63,64]. Recent research reports diatoms behavior as consistent with SPH [65]; however, more evidence will be more conclusive. Samples with a high Dominance Index were inhabited by either generalists or specialists (group 1 and 2), which is consistent with observations reported by Soininen and Heino [66]; however, samples in group 3, which were more diverse, were dominated firstly by generalists and then specialists (contradictory to Soininen and Heino [66], but this was consistent with other analyses on lakes, as in e.g, [67,68]).…”

Historical legacies and contemporary processes shape beta diversity in Neotropical montane streams

“…In total, we sampled 26 (for diatoms), and 32 (for insects) stream segments during the dry season of 2017 (January–February) (González‐Trujillo, et al, 2020; González‐Trujillo, et al, 2020). Briefly, sampling sites consisted of a segment including three consecutive riffles, representative of the stream's range of substrata types, flow velocities, channel widths and depths, and canopy cover.…”

“…Finally, substratum mobility was measured as the percentage of high mobility substrata (gravel and sand) at every stream segment. Further information on environmental variables is provided by González‐Trujillo, et al (2020), González‐Trujillo, et al (2020).…”

“…In total, we sampled 26 (for diatoms), and 32 (for insects) stream segments during the dry season of 2017 (January-February) (González-Trujillo, et al, 2020;González-Trujillo, et al, 2020). using specialized monographs (Bellinger & Sigee, 2015;Krammer & Lange-Bertalot, 1986, 1991Metzeltin & Lange-Bertalot, 2007).…”

“…Historical processes have left an imprint on the contemporary taxonomical structure of Orinocan stream (meta)communities (González‐Trujillo et al., 2020; González‐Trujillo et al., 2020). Specifically, events occurring during the Tertiary and Quaternary contributed to shaping different regional pools of species, which partially matches the distribution of ecoregions.…”