Climate and leaf shape relationships in four Helichrysum species from the Eastern Mountain Region of South Africa

Abstract

Morphological variation in plants can be affected by climate, which influences how species are identified as well as hypotheses of species divergence. We tested whether climatic niches were correlated with the observed morphological (leaf) variation of four geographically overlapping and reproductively similar Helichrysum species (Hilliard's Group 4 in the southern African flora). We found that two species, H. gymnocomum and H. odoratissimum, showed clear evidence for climatic niche conservatism and that across all species leaf shape was not significantly correlated with climatic niche. Interestingly, there did appear to be a pattern, albeit statistically non-significant, that linked cold, dry climates to leaf shape, particularly for the variable and widespread H. odoratissimum. For example, smaller, narrower leaf shapes were generally found in cooler, drier regions, while large, broad leaves (particularly those of H. odoratissimum) are found in warmer, more humid regions. In addition, the data also showed that two species, H. odoratissimum and H. gymnocomum, comprised a single variable group. The climate-leaf shape patterns could potentially reflect the morphological variation between these two species. Collectively, these findings suggest further work is necessary to determine the role of climate and leaf shape variation in species divergence in the Eastern Mountain Region.

Assessing the remarkable morphological diversity and transcriptomic basis of leaf shape inIpomoea batatas(sweetpotato)

“…Leaf shape variation is regulated by genetics, the environment, and the interaction of 72 genes and environment (GxE). Although the genetic and trancriptomic basis underlying leaf 73 shape diversity has been uncovered in only a small number of species (i.e., tomato, Arabidopsis, 74 cotton, and a few others; Kim Stinchcombe, 2013; Glennon & Cron, 2015). For example, submerged leaves of aquatic plants 79…”

Relationships between leaf shape and climate in Rhododendron mucronulatum

“…Larger leaves are usually associated with higher temperatures and greater amounts of precipitation (Traiser et al , Marcysiak ). For example, in Helichrysum odoratissimum small leaves are characteristic of colder districts, while large leaves are characteristic of warm and wetter districts (Glennon and Cron ). As shown here, a similar pattern in leaf size can also be seen at the local level in R. mucronulatum .…”

“…Precipitation is the most important factor during the growing season, and it is positively correlated with leaf length (Royer and Wilf 2006, Peppe et al 2011, Marcysiak 2013. For example, in Helichrysum odoratissimum, small and narrow leaves of are typical for plants growing in colder areas, while larger and wider leaves are typical in warmer and wetter areas (Glennon and Cron 2015). Thus, variations in environmental conditions are reflected in the variety of shapes and dimensions of leaves, which are determined by the phenotypic plasticity of a species as well as by selection operating on genetic variation within populations (Niinemets et al 1999, Koike et al 2001, Hanba et al 2002, Royer et al 2009, Snell-Rood et al 2010, Nicotra et al 2011).…”

The remarkable morphological diversity of leaf shape in sweet potato (Ipomoea batatas): the influence of genetics, environment, and G×E

“…Although the genetic and transcriptomic basis underlying leaf shape diversity has been uncovered in only a small number of species (i.e. tomato, Arabidopsis, cotton and a few others; Kim et al , ; Kimura et al , ; Ichihashi et al , ; Vlad et al , ; Andres et al , ; Chitwood & Sinha, ), there are many examples showing the influence of different environments on leaf shape (McDonald et al , ; Zwieniecki et al , ; Hopkins et al , ; Royer et al , ; Nicotra et al , ; Royer, ; Campitelli & Stinchcombe, ; Glennon & Cron, ). For example, submerged leaves of aquatic plants are often highly dissected as compared to their aerial counterparts (Arber, ) and leaves growing in colder environments tend to be more complex than similar ones growing in warmer environments (Huff et al , ; Royer et al , ).…”