BACKGROUND AND AIMS: Heteroblasty is a non-reversible morphological change associated with life stage change and has been linked to predictable environmental variation. It is present in several clades from mediterranean-type climates, such as African Restionaceae (restios). These have heteroblastic shoots: juvenile shoots are thin, branched and sterile (sterile shoots); adult shoots are thicker and less branched, and bear inflorescences (reproductive shoots). Ten per cent of the restios retain juvenile-like, sterile shoots as adults (neoteny). We hypothesize (1) that the two shoot types differ in ecophysiological attributes, and (2) that these shoot types (and the neoteny) are associated with different environments. METHODS: We measured shoot mass per surface area (SMA), maximum photosynthetic capacity per biomass (Amass) and chlorenchyma to ground tissue ratio (CGR) of both shoot types in 14 restio species. We also calculated environmental niche overlap between neotenous and non-neotenous species using an improved multidimensional overlap function based on occurrence data, and linked shoot types with environments using a phylogenetic generalized linear model. KEY RESULTS: Sterile shoots showed higher Amass, lower SMA and higher CGR than reproductive shoots. Neotenous and non-neotenous species overlapped ecologically less than expected by chance: neotenous species favoured more mesic, non-seasonal conditions. CONCLUSIONS: We associate sterile shoot morphology with acquisitive ecophysiological strategies and reproductive shoots with conservative strategies. The heteroblastic switch optimizes carbon efficiency in the juvenile phase (by sterile shoots) in the mesic post-fire conditions. The adult shoots present a compromise between a more conservative strategy favourable under harsher conditions and reproductive success. Heteroblasty in seasonally arid, oligotrophic ecosystems with predictable, fire-driven shifts in water and nutrient availability might play a role in the success of restios and other species-rich lineages in mediterranean-type ecosystems. It may represent a previously unrecognized adaptation in mediterranean clades sharing similar conditions, contributing to their ecological and taxonomic dominance.
BACKGROUND AND AIMS: Heteroblasty is a non-reversible morphological change associated with life stage change and has been linked to predictable environmental variation. It is present in several clades from mediterranean-type climates, such as African Restionaceae (restios). These have heteroblastic shoots: juvenile shoots are thin, branched and sterile (sterile shoots); adult shoots are thicker and less branched, and bear inflorescences (reproductive shoots). Ten per cent of the restios retain juvenile-like, sterile shoots as adults (neoteny). We hypothesize (1) that the two shoot types differ in ecophysiological attributes, and (2) that these shoot types (and the neoteny) are associated with different environments. METHODS: We measured shoot mass per surface area (SMA), maximum photosynthetic capacity per biomass (Amass) and chlorenchyma to ground tissue ratio (CGR) of both shoot types in 14 restio species. We also calculated environmental niche overlap between neotenous and non-neotenous species using an improved multidimensional overlap function based on occurrence data, and linked shoot types with environments using a phylogenetic generalized linear model. KEY RESULTS: Sterile shoots showed higher Amass, lower SMA and higher CGR than reproductive shoots. Neotenous and non-neotenous species overlapped ecologically less than expected by chance: neotenous species favoured more mesic, non-seasonal conditions. CONCLUSIONS: We associate sterile shoot morphology with acquisitive ecophysiological strategies and reproductive shoots with conservative strategies. The heteroblastic switch optimizes carbon efficiency in the juvenile phase (by sterile shoots) in the mesic post-fire conditions. The adult shoots present a compromise between a more conservative strategy favourable under harsher conditions and reproductive success. Heteroblasty in seasonally arid, oligotrophic ecosystems with predictable, fire-driven shifts in water and nutrient availability might play a role in the success of restios and other species-rich lineages in mediterranean-type ecosystems. It may represent a previously unrecognized adaptation in mediterranean clades sharing similar conditions, contributing to their ecological and taxonomic dominance.
Authors: Ian J Wright; Peter B Reich; Mark Westoby; David D Ackerly; Zdravko Baruch; Frans Bongers; Jeannine Cavender-Bares; Terry Chapin; Johannes H C Cornelissen; Matthias Diemer; Jaume Flexas; Eric Garnier; Philip K Groom; Javier Gulias; Kouki Hikosaka; Byron B Lamont; Tali Lee; William Lee; Christopher Lusk; Jeremy J Midgley; Marie-Laure Navas; Ulo Niinemets; Jacek Oleksyn; Noriyuki Osada; Hendrik Poorter; Pieter Poot; Lynda Prior; Vladimir I Pyankov; Catherine Roumet; Sean C Thomas; Mark G Tjoelker; Erik J Veneklaas; Rafael Villar Journal: Nature Date: 2004-04-22 Impact factor: 49.962
Authors: Dirk Nikolaus Karger; Olaf Conrad; Jürgen Böhner; Tobias Kawohl; Holger Kreft; Rodrigo Wilber Soria-Auza; Niklaus E Zimmermann; H Peter Linder; Michael Kessler Journal: Sci Data Date: 2017-09-05 Impact factor: 6.444
Authors: Cynthia Webster; Laura Figueroa-Corona; Iván David Méndez-González; Lluvia Álvarez-Soto; David B Neale; Juan Pablo Jaramillo-Correa; Jill L Wegrzyn; Alejandra Vázquez-Lobo Journal: Ecol Evol Date: 2022-02-16 Impact factor: 2.912