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Temperature and rainfall influence the distribution, diversity and habitat suitability of Solanum species of the Leptostemonum clade in Uganda
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  • Carol Kawuma,
  • Brita Stedje,
  • Esther Katuura,
  • Perpetua Ipulet,
  • John Mulumba,
  • Esezah Kakudidi,
  • Felly Mugizi,
  • Anifat Olayemi,
  • Mary Namaganda
Carol Kawuma
Makerere University
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Brita Stedje
Natural History Museum
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Esther Katuura
Makerere University
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Perpetua Ipulet
Makerere University
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John Mulumba
National Agricultural Research Organisation
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Esezah Kakudidi
Makerere University
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Felly Mugizi
Africa Innovations Institute
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Anifat Olayemi
University of the Witwatersrand Johannesburg
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Mary Namaganda
Makerere University

Corresponding Author:namagandatm@gmail.com

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Abstract

Solanum species of the Leptostemonum clade were mapped, and predictions made on the distribution and possible habitats using a set of environmental variables. The variables were temperature, rainfall, slope, soil and land use/cover. During field surveys, location presence data (geocoded with Germin S90 GPS) was collected. Additional data were obtained from herbarium specimens kept at Makerere University Herbarium and others obtained from the Global Biodiversity Information Facility. Distribution maps were generated in ArcMap software. Using MaxEnt software (version 3.3.3), spatial distribution models were generated. Model evaluation was based on the generated Area Under Curve (AUC) of both the testing and training gain data. The Jackknife test was used to assess the importance of each environmental variable in predicting species occurrence. Eighteen species were analyzed out of the 20 known to occur in the country. Solanum chrysotrichum was recorded as a new species to Uganda, thus, a new total of 21 species known for the country. Presence of S. forskalii in Uganda was confirmed. Most of the species occur in disturbed habitats in the land use/cover areas defined as croplands, tree cover and grasslands. The highest species richness was recorded in south western Uganda with a total of 11 species. Karamoja had unique diversity with species restricted to the region and these included S. forskalii, S. lanzae, S. coagulans and S. hastifolium. The environmental parameters selected for the study when used in combination had a good fit in predicting the occurrence of species as revealed by the high AUC values. Temperature and rainfall were the most useful variables in predicting occurrence of Solanum species. Karamoja region and south western Uganda are hotspots for conservation of the spiny Solanum. Periodic field surveys should be carried out to assess the effect of climate change and anthropogenic disturbance on the occurrence of the species.