Biogeography of species richness gradients: linking adaptive traits, demography and diversification

Abstract

Here we review how adaptive traits contribute to the emergence and maintenance of species richness gradients through their influence on demographic and diversification processes. We start by reviewing how demographic dynamics change along species richness gradients. Empirical studies show that geographical clines in population parameters and measures of demographic variability are frequent along latitudinal and altitudinal gradients. Demographic variability often increases at the extremes of regional species richness gradients and contributes to shape these gradients. Available studies suggest that adaptive traits significantly influence demographic dynamics, and set the limits of species distributions. Traits related to thermal tolerance, resource use, phenology and dispersal seem to play a significant role. For many traits affecting demography and/or diversification processes, complex mechanistic approaches linking genotype, phenotype and fitness are becoming progressively available. In several taxa, species can be distributed along adaptive trait continuums, i.e. a main axis accounting for the bulk of inter-specific variation in some correlated adaptive traits. It is shown that adaptive trait continuums can provide useful mechanistic frameworks to explain demographic dynamics and diversification in species richness gradients. Finally, we review the existence of sequences of adaptive traits in phylogenies, the interactions of adaptive traits and community context, the clinal variation of traits across geographical gradients, and the role of adaptive traits in determining the history of dispersal and diversification of clades. Overall, we show that the study of demographic and evolutionary mechanisms that shape species richness gradients clearly requires the explicit consideration of adaptive traits. To conclude, future research lines and trends in the field are briefly outlined.

Interactions between ecological, evolutionary and environmental processes unveil complex dynamics of insular plant diversity

“…Trait richness followed the humped trend of species richness, consistent with the reported positive relationship between trait and species richness (Figure c,j; Carnicer, Brotons, Stefanescu, & Penuelas, ; Petchey & Gaston, ). The initial high species packing followed by a sharp decrease (Figure k) possibly reflected strong environmental filtering (e.g.…”

Phenotypic biomarkers of climatic impacts on declining insect populations: A key role for decadal drought, thermal buffering and amplification effects and host plant dynamics

“…Declines in butterfly populations across diverse species over the last three decades have been described in the Mediterranean basin (Stefanescu, Herrando, & Páramo, 2004;Stefanescu, Carnicer, & Peñuelas, 2011;Stefanescu, Torre, Jubany, & Páramo, 2011;Wilson et al, 2005;Wilson, Gutiérrez, Gutiérrez, & Monserrat, 2007;Carnicer, Brotons, Stefanescu, & Peñuelas, 2012;Carnicer, Stefanescu, et al, 2013;Zografou et al, 2014;Melero, Stefanescu, & Pino, 2016). Negative effects of land use changes and global warming have been proposed as the main drivers of the observed declining trends (Stefanescu et al, 2004;Wilson et al, 2005Wilson et al, , 2007Stefanescu, Carnicer, et al, 2011;Stefanescu, Torre, et al, 2011).…”

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale

“…In addition, non-structural carbohydrates (NSCs) play a variety of functions in tree physiology, providing a temporal buffer to reconcile differences in carbon supply and demand, maintaining hydraulic transport and facilitating osmotic regulation, allowing leaf emergence and bud burst and actively participating in the prevention of frost and drought embolism and repair (Sala et al, 2012). The demographic performance of trees, however, is generally co-limited by other factors that frequently interact in complex ways with the processes of carbon uptake and allocation, such as direct climatic effects on photosynthesis, growth and nutrient uptake (Körner, 1998, 2003; Rennenberg et al, 2006), species-specific traits (Wright et al, 2004; Chave et al, 2009; Carnicer et al, 2012) or the impacts of secondary consumers and diseases (Bale et al, 2002). …”