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Mashau, Aluoneswi Caroline [1], Hempson, Gareth P. [1], Lehmann, Caroline E.R. [2], Vorontsova, Maria S. [3], Visser, Vernon [4], Archibald, Sally [1].

Plant height and lifespan predict range size in southern African grasses.

Grasses (Poaceae) are ecosystem drivers across much of the African continent. The aim of this study is to determine how the range size of southern species relates to evolutionary history (phylogeny), plant height, lifespan and invasion potential. The range sizes of 757 grass species native to southern Africa were estimated for the sub-Saharan African region from geo-referenced herbarium records using the alpha hull function. Phylogenetic generalised least squares models and linear mixed effects models were fitted to test whether grass range size was related to plant height and lifespan. Tribe-level relationships between range size and plant height were assessed with linear models. For species introduced to other continents, generalised linear mixed effects models were fitted to test whether invasiveness was related to native range size, plant height and lifespan. Differences in native range size among species in four invasion-related categories were assessed with linear mixed effects models. Grass range sizes are larger for taller species and for species with shorter lifespans. The relationship between plant height and range size varies widely among tribes, with some range-restricted tribes having lower slopes. Grasses with larger native range sizes and shorter lifespans are more likely to become invasive after being introduced to other continents. The grasses that have been introduced to other continents have larger native range sizes than those that have not, and native range size increases along the introduced-naturalised-invasive continuum. The increased dispersal opportunities of annual-biannual grasses appear to have a greater effect on enabling the expansion of range size than do the long generation times of perennial grasses. Grass height has and continues to be an important driver of grass biogeography, with implications for understanding the rapid spread of certain grass tribes over the Miocene. Factors that promote large native range sizes are also likely to increase the probability of a species becoming invasive.

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1 - University of the Witwatersrand, Centre for African Ecology, School of Animal, Plant and Environmental Sciences, Private Bag X3, Wits, Johannesburg, GP, 2050, South Africa
2 - Royal Botanic Garden Edinburgh, Tropical Diversity,, Edinburgh EH3 5LR, UK
3 - Royal Botanic Gardens Kew, Comparative Plant and Fungal Biology, Surrey TW9 3AE, Richmond, UK
4 - University of Cape Town, Department of Statistical Sciences, Rondebosch, Western Cape Province, 7701, South Africa

alpha hull
species distribution
extent of occurrence (EOO)
range size.

Presentation Type: Oral Paper
Location: Virtual/Virtual
Date: Tuesday, July 20th, 2021
Time: 10:00 AM(EDT)
Number: BIOGII001
Abstract ID:567
Candidate for Awards:None

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