Depraz, A. | bioRxiv Science

bioRxiv2024

Do morphologically distinct groups correspond to reproductively isolated species? A case study in Myrmica ants from Switzerland

The most widely used definition of a species is that it is reproductively isolated from other populations. Yet, most species are described on the basis of morphological criteria, and reproductive isolation is seldom tested. Using the ant genus Myrmica Latreille (Hymenoptera, Formicidae) as a model, we ask whether species described as distinct based on (often subtle) morphological differences indeed form reproductively isolated lineages. We collected and morphologically identified 918 Myrmica ants from a 3212 km2 area in Switzerland. We then combined DNA barcoding (based on COI) and RAD sequencing to identify genetically isolated lineages. Out of the 14 morphological species identified, 13 formed genetically differentiated lineages, while the last one was not supported by our genetic data. Overall, the morphological identification was congruent with genetic lineage delineation for 94.9% of individuals. Our dataset also allowed us to screen for cryptic lineages in the five most frequent species, including in M. scabrinodis where cryptic lineages were previously suggested, but we found no evidence for cryptic species. Overall, our results indicate that morphology parallels genetic isolation in the studied species. However, an integrative approach combining morphological identification with nuclear marker genotyping is necessary for confident species identification of all individuals. Finally, our results provide a library of validated COI barcodes for future Myrmica specimen identification.

evolutionary biology↗

bioRxiv2024

LEVERAGING CITIZEN SCIENCE TO ASSESS RICHNESS, DIVERSITY, AND ABUNDANCE IN ANT COMMUNITIES

AO_SCPLOWBSTRACTC_SCPLOWCitizen science is a key resource in overcoming the logistical challenges of monitoring biodiversity. While datasets collected by groups of volunteers typically have biases, recent methodological and technological advances provide approaches for accounting for such biases, particularly in the context of modelling species distributions and diversity. Specifically, data integration techniques allow for the combination of scientifically collected datasets with haphazardly sampled presence-only datasets created by most citizen science initiatives. Here, we use a hierarchical Bayesian framework to integrate a set of ant presences collected by citizen scientists in the Vaud canton (Switzerland) with ant colony density data collected concurrently in the same region following a scientific sampling design. The community-level Poisson point process model included species-specific responses to the local (1.2 m2) and regional (1 km2) environment, with the presence-only samples incorporated at the regional scale to predict local and regional ant communities. At the regional scale, species richness followed a hump-shaped pattern and peaked near 1000 m while abundance increased with elevation. Low elevation and montane ant communities were composed of distinct species assemblages. At the local scale, the link between elevation and richness, diversity, and abundance was weak. At low elevations, local plots varied both in total abundance and species composition, while at higher elevations, the species composition was less variable. The citizen science dataset showed a general tendency toward under-representation of certain species, and heavy spatial sampling bias. Nonetheless, the inclusion of the citizen science data improved predictions of local communities, and also reduced susceptibility to over-fitting. Additionally, the citizen science dataset included many rare species not detected in the structured abundance dataset. The model described here illustrates a framework for capitalizing on the efforts of citizen scientists to better understand the patterns and distribution of biodiversity.

ecology↗