Aim Locally abundant species are usually widespread, and this pattern has been related to properties of the niches and traits of species. However, such explanations fail to account for the potential of traits to determine species niches and often overlook statistical artefacts. Here, we examine how trait distinctiveness determines the abilities of species to exploit either common habitats (niche position) or a range of habitats (niche breadth) and how niche position and breadth, in turn, affect abundance and occupancy. We also examine how statistical artefacts moderate these relationships. Location Sixteen sites in the Neotropics. Time period 1993–2014. Major taxa studied Aquatic invertebrates from tank bromeliads. Methods We measured the environmental niche position and breadth of each species and calculated its trait distinctiveness as the average trait difference from all other species at each site. Then, we used a combination of structural equation models and a meta-analytical approach to test trait–niche relationships and a null model to control for statistical artefacts. Results The trait distinctiveness of each species was unrelated to its niche properties, abundance and occupancy. In contrast, niche position was the main predictor of abundance and occupancy; species that used the most common environmental conditions found across bromeliads were locally abundant and widespread. Contributions of niche breadth to such patterns were attributable to statistical artefacts, indicating that effects of niche breadth might have been overestimated in previous studies. Main conclusions Our study reveals the generality of niche position in explaining one of the most common ecological patterns. The robustness of this result is underscored by the geographical extent of our study and our control of statistical artefacts. We call for a similar examination across other systems, which is an essential task to understand the drivers of commonness across the tree of life.
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RBINS Staff Publications 2021
Freshwater ostracods are commonly found in temporary ponds and lakes, surviving drought periods by producing resting eggs. We investigated the hatching phenology of ostracod resting eggs from the sediments of temporary floodplain lakes, considering both the taxonomic distance between species and their functional traits, such as carapace size (length and height) and shape, valve ornamentation, and reproductive mode. In addition, we tested the hypotheses: (1) that the hatching time is more similar between congeneric ostracod species than between noncongeneric species; (2) that differences in hatching time between congeneric species are often related to differences in functional traits; (3) that both species composition and functional traits composition of hatchlings change over the incubation time, but with a reduction in the variability over time. The experiment was conducted for 98 days in the laboratory, and the microcosms were monitored weekly. The first hatching of an ostracod was recorded during the second week of incubation after hydration of the sediments. A total of 12 ostracod species hatched, belonging to the families Cyprididae and Candonidae. The above three hypotheses were corroborated. The time between inundation and first hatching was mostly similar for congeneric species in the genus Chlamydotheca, but was different between some species of Strandesia, which might be owing to differences in functional traits. The species composition and functional trait composition of the hatched ostracods were significantly different over the 14 weeks of incubation due to the different hatching phenology of different species. Furthermore, our results show that both taxonomic distance and functional traits can influence the hatching time of ostracod resting eggs from temporary floodplain lakes. Thus, future studies addressing the hatching phenology of ostracod resting eggs (and resting stages from other invertebrates) should also emphasize the use of functional traits.
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RBINS Staff Publications 2021
