Mapping the habitat suitability of Ottelia species in Africa

Boniface K Ngarega; John M Nzei; Josphat K Saina; Marwa Waseem A Halmy; Jin-Ming Chen; Zhi-Zhong Li

doi:10.1016/j.pld.2021.12.006

Mapping the habitat suitability of Ottelia species in Africa

Plant Divers. 2022 Jan 21;44(5):468-480. doi: 10.1016/j.pld.2021.12.006. eCollection 2022 Sep.

Authors

Boniface K Ngarega^{1

2

3

4}, John M Nzei^{1

2

3}, Josphat K Saina^{1

2

3

4}, Marwa Waseem A Halmy⁵, Jin-Ming Chen^{1

2}, Zhi-Zhong Li^{1

2}

Affiliations

¹ Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China.
² Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China.
³ University of Chinese Academy of Sciences, Beijing, 100049, China.
⁴ Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, 666303, China.
⁵ Department of Environmental Sciences, Faculty of Science, Alexandria University, Alexandria, 21511, Egypt.

Abstract

Understanding the influence of environmental covariates on plant 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, a model genus for studying the evolution of the aquatic family Hydrocharitaceae, is mainly distributed in slow-flowing creeks, rivers, or lakes throughout pantropical regions in the world. Due to recent rapid climate changes, natural Ottelia populations have declined significantly. By modeling the effects of climate change on the distribution of Ottelia species and assessing the degree of niche similarity, we sought to identify high suitability regions and help formulate conservation strategies. The models use known background points to determine how environmental covariates vary spatially and produce continental maps of the distribution of the Ottelia species in Africa. Additionally, we estimated the possible influences of the optimistic and extreme pessimistic representative concentration pathways scenarios RCP 4.5 and RCP 8.5 for the 2050s. Our results show that the distinct distribution patterns of studied Ottelia species were influenced by topography (elevation) and climate (e.g., mean temperature of driest quarter, annual precipitation, and precipitation of the driest month). While there is a lack of accord in defining the limiting factors for the distribution of Ottelia species, it is clear that water-temperature conditions have promising effects when kept within optimal ranges. We also note that climate change will impact Ottelia by accelerating fragmentation and habitat loss. The assessment of niche overlap revealed that Ottelia cylindrica and O . verdickii had slightly more similar niches than the other Ottelia species. The present findings identify the need to enhance conservation efforts to safeguard natural Ottelia populations and provide a theoretical basis for the distribution of various Ottelia species in Africa.

Keywords: African freshwater bodies; Climate change; Ecological niche modeling; Habitat suitability; Niche overlap.