Biodiversity can be measured at multiple organizational scales. While traditional studies have focused at taxonomic diversity, recent studies have emphasized the ecological importance of diversity within populations. However, it is unclear how these different scales of diversity interact to determine the consequence of species loss.

Here we asked how predator diversity and presence of ontogenetic diversity within predator populations influences community structure. Ontogenetic diversity arises from shifts in the traits and ecology of individuals during ontogeny and it is one of the biggest sources of intraspecific diversity. However, whether it dampens or strengthens the negative consequences of with species loss is poorly understood.

To study this interaction of species diversity and ontogenetic diversity, we experimentally manipulated predator species diversity and diversity of developmental stages within focal predator species and analyzed their joint effect on predator and prey survival, biomass, and prey community structure in experimental pond systems.

While individual effects of ontogenetic diversity were often species-specific, losing predator species from the community often had a much smaller or no effect on prey survival, biomass, or community structure when all predator populations had high ontogenetic diversity. Thus, ontogenetic diversity within populations buffered against some of the consequences of biodiversity loss at higher organizational levels. Because the experiment controlled mean per capita size and biomass across structured vs. unstructured populations, this pattern was not driven by differences in biomass of predators. Instead, results suggest that effects were driven by changes in the functional roles and indirect interactions across and within species. This indicates that even if all environmental conditions are similar, differences in the intrinsic structure of populations can modify the consequences of biodiversity loss.

Together, these results revealed the importance of ontogenetic diversity within species for strengthening the resilience of natural communities to consequences of biodiversity loss and emphasize the need to integrate biodiversity patterns across organizational scales. 

Goals:

The main goal of this study is to examine how ontogenetic  diversity within species  interacts with species diversity and whether diversity within species can buffer against loss of species diversity. The experiment has 9 treatments manipulating size diversity (M = medium stage vs SML = very wide stage range) of 3 focal predator species. Species are either alone (single species)(A,B,C) or all three combined (ABC) in an additive design. The density of each focal predator is constant acrosss species, size &  diversity treatment. Biomass is similar across size treatments, and comparable across species (within natural limits of their morphology).

General setup and data:

The data are from a mesocosm experiment that was carried in from July 12th to August 11th 2016, at the South Campus Research Facility of Rice University, Houston, TX. 

A complete description of the methods are given in the corresonding manuscript. Briefly, experiments were carried out in 300L PVC cylindrical mesocosm with 60% shade cloth filled with declorinated water. We set up 60 mesocosm in an open field outdors in complete randomized block design. We then added several tadpole species, and concentrated zooplankton from local ponds. Finally, we factorially manipulated the size structure and presence absence of three focal invertebrate predators to examine effects on tadpole, invertebrate, and zooplankton community.   

Data includes:

Experimental design

Final focal predator abundance and mass following final take down.

Final Invertebrate dry mass and species counts following final take down.

Metamorph mass & emergence date collected daily

Final total tadpole dry mass for two amphibian species at final take down.

Zooplankton abundance by species based on subsamples obtained with depth integrated tube samplers.  

Periphyton density based on Chlorophyll a concentration extracted from glass slides

Phytoplankton density based on InVivo measurements. 

Dissolve oxygem concentration and mg/L sampled three times consecutely at sunrise 7:10-8:30am (s1), sunset 7:40-8:20pm (s2) and sunrise , 7:10-7:40am (s3) on August 8-August 9th. 

The data set includes an addotated RMarkdown file (FinalAnalysisSizevsSpecies.Rmd)  that documents all parts of the analysis and figures that were used in the main manusript, and corresponding data files. 

Data set Tadsize, Metao are individual based and thus have multiple values per replicates. Data set Zoops, InvDryMass, TadsDryMass have one value per replicate. 

Each data file X has corresponding readme_X file describing all data labels.