Unraveling global species richness patterns of the Lysmatidae family: a multi-scale and multi-hypothesis ecological approach

While diversity gradients are well-explored in macroecology, factors shaping species richness at broad scales remain debated. We investigated the species richness of the decapod family Lysmatidae across 4 spatial scales: realm, province, ecoregion, and local (2° × 2° grid cells). We tested 4 ecological hypotheses: physiological stress (PSH), resource availability (RAH), habitat heterogeneity (HHH), and anthropogenic impact (AIH). Occurrence data (52 Lysmatidae species) and environmental variables (salinity, temperature, primary productivity, bathymetry, coral richness, anthropogenic impact index) were obtained from online databases and literature. Fifteen regression models, incorporating spatial filters, were tested to assess the hypotheses. The highest Lysmatidae species richness occurred in the Tropical Atlantic and Central Indo-Pacific realms. Richness varied with scale, with the highest values in the transition between the tropical and subtropical zones. Bathymetry was associated with Lysmatidae richness across all scales, especially at local and ecoregional scales, while coral richness was related to province and realm scales. HHH explained Lysmatidae richness patterns at the realm scale. Variables related to PSH and AIH were associated with richness at the ecoregion and province scales. Our study emphasized the importance of scale in biodiversity research, influencing richness patterns in Lysmatidae, and pointed to bathymetry, coral richness, and temperature range as the main drivers of richness. As this study showed a relationship between Lysmatidae richness, coral richness, and temperature at 3 spatial scales, this family may be susceptible to the effects of climate change, such as tropicalization of subtropical zones and defaunation of tropical ecosystems, including coral reefs.