A trait-based approach to the conservation of threatened plant species J UAN C. ÁLVAREZ-YÉPIZ,ALBERTO B ÚRQUEZ A NGELINA M ARTÍNEZ-YRÍZAR and M ARTIN D OVCIAK Abstract Traditionally the vulnerability of threatened environment, genetics and population dynamics (Gilpin & species to extinction has been assessed by studying their Soulé, ), hereafter referred to as the traditional ap- environment, genetics and population dynamics. A proach. In this context, the study of environment includes more comprehensive understanding of the factors pro- investigating the quality and quantity of available and po- moting or limiting the long-term persistence of threa- tential habitat, and thus all aspects of species’ relationships tened species could be achieved by conducting an with abiotic and biotic factors. Genetic studies focus on the analysis of their functional responses to changing envir- genetic diversity of species and populations (including onments, their ecological interactions, and their role in adaptation to change) and population bottlenecks from ecosystem functioning. These less traditional research small effective population sizes. Research on population dy- areas can be unified in a trait-based approach, a recent namics investigates species’ demography and persistence in methodological advance in ecology that is being used to a given environment manifested via population structure, link individual-level functions to species, community fecundity and, ultimately, fitness. The traditional approach and ecosystem processes to provide mechanistic explana- has proved successful in studies of threatened and non- tions of observed patterns, particularly in changing environ- threatened plant and animal species (e.g. Oostermeijer ments. We illustrate how trait-based information can be et al., ; Conard, ; Kalkvik, ). However, other translated into well-defined conservation strategies, using components of a more comprehensive assessment of the the example of Dioon sonorense, an Endangered cycad en- viability of populations (some of these originally proposed demic to north-western Mexico. Scientific information by Gilpin & Soulé, ), such as species’ functional re- yielded by trait-based research, coupled with existing knowl- sponses to a changing environment, their ecological interac- edge derived from well-established traditional approaches, tions, and their role in ecosystem functioning, have not been could facilitate the development of more integrative conser- formally incorporated into conservation research, particu- vation strategies to promote the long-term persistence of in- larly regarding threatened taxa (Schemske et al., ). dividual threatened species. A comprehensive database of These additional research areas can be unified in a trait- functional traits of threatened species would be of value in as- based approach, a recent methodological advance in ecology sisting the implementation of the trait-based approach. that is being used to link individual-level functions (mea- sured with functional traits) to species, community and eco- Keywords Biodiversity loss, conservation strategies, cycad, system processes, to provide mechanistic explanations for Dioon sonorense, Endangered species, Mexico, plant the observed patterns, particularly in changing environ- conservation, rarity ments (McGill et al., ; Violle et al., ; Garnier & Navas, ; Shipley et al., ). ‘ Introduction From the perspective of trait-based ecology, a trait is any morphological, physiological or phenological feature meas- he vulnerability of species to extinction has traditional- urable at the individual level, from the cell to the whole- Tly been assessed within three major areas of study: organism level, without reference to the environment or any other level of organization’ (Violle et al., ). These traits are called functional traits when they influence fitness through their effects on growth, reproduction and survival, † JUAN C. ÁLVAREZ-YÉPIZ* (Corresponding author), ALBERTO BÚRQUEZ and which are the three components of individual performance ANGELINA MARTÍNEZ-YRÍZAR Instituto de Ecología, Universidad Nacional Autónoma de México, Colosio y Sahuaripa, Col. Los Arcos, Hermosillo, (Violle et al., ). Species traits are usually assessed as Sonora 83250, Mexico. E-mail [email protected] mean values of individual traits per population, and such MARTIN DOVCIAK State University of New York College of Environmental Science values can vary with the environment. Thus, information and Forestry, Syracuse, New York, USA on the local environment of populations is needed to inter- *Also at: State University of New York College of Environmental Science and pret the ecological and evolutionary meaning of measured Forestry, Syracuse, New York, USA †Also at: Instituto Tecnológico de Sonora, Obregón, Sonora, Mexico traits and to make useful predictions under changing envir- Received August . Revision requested January . onmental conditions (McGill et al., ; Violle et al., ; Accepted June . First published online February . Garnier & Navas, ; Shipley et al., ). Oryx, 2019, 53(3), 429–435 © 2019 Fauna & Flora International doi:10.1017/S003060531800087X Downloaded from https://www.cambridge.org/core. IP address: 170.106.40.40, on 02 Oct 2021 at 10:30:42, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S003060531800087X 430 J. C. Álvarez-Yépiz et al. Trait-based ecology is a relatively new discipline that is increasingly used in studies of community assembly (e.g. Ackerly & Cornwell, ), biotic interactions (e.g. Wardle et al., ) and ecosystem functioning (e.g. Díaz & Cabido, ), and in predicting species’ responses to climate warm- ing (e.g. Diamond et al., ). Chown () presented a trait-based framework for use in conservation, specifically in conservation physiology, to forecast the risk of climate and habitat changes to species and higher ecological levels (communities, ecosystems). A major challenge of the trait- based approach to conservation is the identification and measurement of functional traits relevant to individual threatened species, particularly those traits related to re- sponses to changing environments, species’ ecological inter- actions, and ecosystem functioning. Here we propose and FIG. 1 How the trait-based approach complements the illustrate how a functional trait-based approach can be traditional approach to the conservation of threatened species. used to increase our understanding of the vulnerability of The traditional approach focuses on species population threatened species to extinction. We introduce the steps dynamics, habitat suitability and genetic structure, and has and structure for implementing a trait-based approach in provided essential information for guiding conservation the conservation of threatened species, and illustrate this ap- strategies for threatened species. The trait-based approach has proach in a case study of Dioon sonorense, an Endangered been formally included in conservation research to a lesser cycad endemic to north-western Mexico, including a discus- extent, even though it can provide information on physiological sion of the potential applicability of the trait-based approach responses to environmental variability and ecological interactions of species, and their roles in ecosystem functioning in guiding the conservation of this species. (which may indirectly influence species persistence). Combining these approaches may lead to more integrative conservation strategies to promote the long-term persistence of target species A trait-based approach to the conservation of exposed to anthropogenic and natural threats. There is a threatened plant species dynamic feedback (double arrow) between conservation strategies and species persistence, as they can affect each other. By definition, threatened species are already at risk of ex- tinction as a result of species-specific extrinsic and intrinsic factors. A more complete understanding of species’ vulner- to affect population fitness and species persistence, and thus ability to extinction requires knowledge not only of their en- facilitate science-based species conservation (Table ). vironment, genetics and demography but also of functional Although the collected information should be species- traits related to their responses to changing environments, specific, a multi-species framework by phylogenetic group their interactions and their role in ecosystem functioning may also be possible when related species display parallel (Gilpin & Soulé, ; Oostermeijer et al., ; Chown, responses to similar threats. ). This information can be translated into more in- Our case study illustrates how the trait-based approach tegrative management strategies to increase the viability of can provide information to understand () the individual threatened species (Fig. ). We focus on illustrating the con- physiological responses to environmental stress imposed by ceptual importance of studying functional traits to inform water, light and nutrient limitations that may be caused by the conservation of threatened species rather than on the the changing environment (e.g. Álvarez-Yépiz et al., a; methodological peculiarities of measurement and analysis Williams et al., ; Díaz-Álvarez et al., ; Urban, ), of functional traits, which can be found elsewhere (e.g. () the importance of maintaining species’ ecological inter- Díaz et al., ; Bernhardt‐Römermann et al., ; Kraft actions (e.g. plant–plant, plant–pollinator/seed disperser, &