Greater tree species richness in eastern North America compared to Europe is coupled to denser, more clustered functional trait space filling, not to trait space expansion

TY - JOUR

T1 - Greater tree species richness in eastern North America compared to Europe is coupled to denser, more clustered functional trait space filling, not to trait space expansion

AU - Ordonez, Alejandro

AU - Svenning, Jens-Christian

PY - 2018/11

Y1 - 2018/11

N2 - Aim: Determine if differences in species richness between currently climatically similar regions correlate to dissimilarities in functional diversity. Location: Europe and eastern North America. Time period: Neogene and Quaternary. Major taxa studied: Temperate trees of Europe and eastern North America. Methods: Using classic functional traits defining distinct ecological strategies, we described the trait spaces of European and eastern North American tree floras. The trait space of each region was described based on the occupied area, species accumulation pattern, and the trait-space size, dispersion and clustering. We then evaluated if the species richness differences between these two climatically similar regions correlate to dissimilarities in both occupied areas and species accumulation patterns; as well as differences in the trait-space size, dispersion and clustering. Results: Differences in species richness between climatically similar regions do not necessarily result in functional dissimilarities. Regardless of eastern North American species having a larger trait-space, occupied areas and species accumulation patterns converged. Although in both regions species clumped towards the trait-space centroid, we observed statistically significant differences between Europe and eastern North America in the dispersion and clustering but not in size of the trait space. Moreover, traits from species in genera still present in eastern North America but lost from Europe during the Neogene and Quaternary were fully contained within the currently occupied European trait space. Main conclusions: Positional convergence between European and eastern North American trait spaces suggests that this species richness anomaly does fully translate to the functional space. Our results suggest that species accumulation within a region occurs within a climatically restricted trait space, and not via trait-space expansion. Moreover, the consistent aggregation of species towards the trait-space centre aligns with the idea of a directional section towards a generalized morphology, which might provide the best way to interact with a broad array of environmental conditions.

AB - Aim: Determine if differences in species richness between currently climatically similar regions correlate to dissimilarities in functional diversity. Location: Europe and eastern North America. Time period: Neogene and Quaternary. Major taxa studied: Temperate trees of Europe and eastern North America. Methods: Using classic functional traits defining distinct ecological strategies, we described the trait spaces of European and eastern North American tree floras. The trait space of each region was described based on the occupied area, species accumulation pattern, and the trait-space size, dispersion and clustering. We then evaluated if the species richness differences between these two climatically similar regions correlate to dissimilarities in both occupied areas and species accumulation patterns; as well as differences in the trait-space size, dispersion and clustering. Results: Differences in species richness between climatically similar regions do not necessarily result in functional dissimilarities. Regardless of eastern North American species having a larger trait-space, occupied areas and species accumulation patterns converged. Although in both regions species clumped towards the trait-space centroid, we observed statistically significant differences between Europe and eastern North America in the dispersion and clustering but not in size of the trait space. Moreover, traits from species in genera still present in eastern North America but lost from Europe during the Neogene and Quaternary were fully contained within the currently occupied European trait space. Main conclusions: Positional convergence between European and eastern North American trait spaces suggests that this species richness anomaly does fully translate to the functional space. Our results suggest that species accumulation within a region occurs within a climatically restricted trait space, and not via trait-space expansion. Moreover, the consistent aggregation of species towards the trait-space centre aligns with the idea of a directional section towards a generalized morphology, which might provide the best way to interact with a broad array of environmental conditions.

KW - diversity anomaly

KW - Europe

KW - functional dispersion

KW - functional diversity

KW - functional evenness

KW - functional richness

KW - functional traits

KW - North America

KW - species richness

KW - ECONOMICS SPECTRUM

KW - PLANT TRAITS

KW - DIVERSITY

KW - BIODIVERSITY

KW - FRAMEWORK

KW - CLIMATE

KW - LIFE

KW - DIVERSIFICATION

KW - BIOGEOGRAPHY

KW - EXTINCTIONS

UR - http://www.scopus.com/inward/record.url?scp=85053506586&partnerID=8YFLogxK

U2 - 10.1111/geb.12785

DO - 10.1111/geb.12785

M3 - Journal article

SN - 1466-822X

VL - 27

SP - 1288

EP - 1299

JO - Global Ecology and Biogeography

JF - Global Ecology and Biogeography

IS - 11

ER -