Think tank: water relations of Bromeliaceae in their evolutionary context

Abstract

Water relations represent a pivotal nexus in plant biology due to the multiplicity of functions affected by water status. Hydraulic properties of plant parts are therefore likely to be relevant to evolutionary trends in many taxa. Bromeliaceae encompass a wealth of morphological, physiological and ecological variations and the geographical and bioclimatic range of the family is also extensive. The diversification of bromeliad lineages is known to be correlated with the origins of a suite of key innovations, many of which relate directly or indirectly to water relations. However, little information is known regarding the role of change in morphoanatomical and hydraulic traits in the evolutionary origins of the classical ecophysiological functional types in Bromeliaceae or how this role relates to the diversification of specific lineages. In this paper, I present a synthesis of the current knowledge on bromeliad water relations and a qualitative model of the evolution of relevant traits in the context of the functional types. I use this model to introduce a manifesto for a new research programme on the integrative biology and evolution of bromeliad water-use strategies. The need for a wide-ranging survey of morphoanatomical and hydraulic traits across Bromeliaceae is stressed, as this would provide extensive insight into structurefunction relationships of relevance to the evolutionary history of bromeliads and, more generally, to the evolutionary physiology of flowering plants.

Hydraulics link leaf shape and environmental niche in terrestrial bromeliads

“…). The bromeliads utilize a range of water‐use strategies, with different species occupying a spectrum running from full dependence on roots for water uptake to reliance on foliar trichomes only (Pittendrigh , Benzing , Males ). Many aspects of plant morphology vary in tandem with this spectrum, including root:shoot ratios, rosette architecture, and leaf succulence (Benzing , Males ).…”

“…), it has rarely been included as a factor in quantitative investigations of bromeliad ecophysiology. Given the centrality of water relations to bromeliad ecophysiological strategies (Males ), possible connections between leaf shape and leaf hydraulics could be of particular significance. There is mixed evidence regarding the interactions between leaf shape and hydraulic function in other plant groups (Sack et al .…”

Advances in and perspectives on evolution in Bromeliaceae

“…As pointed out by Males (2016), the origins and losses of single and combined innovations could have triggered cascades of trait changes at the morphoanatomical and physiological levels during the evolution of bromeliads. In this review, the author links morphology and life form to their ecophysiological function and evolutionary history.…”

“…In this review, the author links morphology and life form to their ecophysiological function and evolutionary history. Males (2016) suggests that this model should be further tested through the examination of the relationships between innovations and environmental factors and the degree of coordination in the evolution of morphoanatomical and physiological traits. With this in mind, the author also presents a qualitative model of the evolution of ecological, physiological and morphoanatomical traits related to bromeliad water relations in the context of the five ecological bromeliad types, first described by Pittendrigh (1948) and latter modified by Benzing (2000).…”

Functional types in the Bromeliaceae: relationships with drought‐resistance traits and bioclimatic distributions

“…The Bromeliaceae is a large and extremely diverse family which includes several important examples of recent adaptive radiations, and is an emerging model system in plant evolutionary physiology and ecology (Givnish et al . ; Males ; Palma‐Silva et al . ).…”