Environmental determinants of the current and future distribution of seven Ottelia Pers. species in African freshwater bodies

Abstract

Understanding the influence of environmental covariates on plants’ distribution is critical, especially for aquatic plant species. Climate change is likely to alter the distribution of aquatic species. However, knowledge of this change on the burden of aquatic macroorganisms is often fraught with difficulty. Ottelia Pers., a model genus for studying the evolution of the aquatic family Hydrocharitaceae, is mainly distributed in slow-flowing creeks, rivers or lakes throughout the world’s pantropical areas. Due to recent rapid climate changes, the natural Ottelia populations have declined significantly. In the present study, we use maximum entropy (MaxEnt) to explore the environmental drivers of seven Ottelia species distribution in African freshwater bodies. The models use known background points to determine how environmental covariates vary spatially and produce continental maps of these species’ distribution. We also estimate the possible influences of the optimistic and extreme pessimistic Intergovernmental Panel on Climate Change (IPCC) pathway scenarios and identify high suitability areas under these scenarios. Model performances were statistically significant than random expectations with Area Under Curve (AUC) values above 0.831, indicating the good performance of the models. We observe that our studied Ottelia species had distinct spatial patterns influenced by climate variations (e.g. Bio9- mean temperature of driest quarter, Bio12- annual precipitation, and Bio14- Precipitation of the driest month). While there is a lack of accord in defining the limiting factors for the distribution of the seven species, it is clear that water-temperature conditions have promising effects when kept within optimal ranges. Niche overlap analyses showed that most Ottelia species have similar but not equivalent climatic niches. In addition, considering the expected warming in the future, the persistence and survival of the Ottelia species in Africa could be compromised. The present findings provide a theoretical basis for the distribution of various Ottelia species in Africa.