title: Phylogenetic constraints in key functional traits behind species' climate niches: patterns of desiccation and cold resistance across 95 Drosophila species.
abstract: Species distributions are often constrained by climatic tolerances that are ultimately determined by evolutionary history and/or adaptive capacity, but these factors have rarely been partitioned. Here, we experimentally determined two key climatic niche traits (desiccation and cold resistance) for 92-95 Drosophila species and assessed their importance for geographic distributions, while controlling for acclimation, phylogeny, and spatial autocorrelation. Employing an array of phylogenetic analyses, we documented moderate-to-strong phylogenetic signal in both desiccation and cold resistance. Desiccation and cold resistance were clearly linked to species distributions because significant associations between traits and climatic variables persisted even after controlling for phylogeny. We used different methods to untangle whether phylogenetic signal reflected phylogenetically related species adapted to similar environments or alternatively phylogenetic inertia. For desiccation resistance, weak phylogenetic inertia was detected; ancestral trait reconstruction, however, revealed a deep divergence that could be traced back to the genus level. Despite drosophilids' high evolutionary potential related to short generation times and high population sizes, cold resistance was found to have a moderate-to-high level of phylogenetic inertia, suggesting that evolutionary responses are likely to be slow. Together these findings suggest species distributions are governed by evolutionarily conservative climate responses, with limited scope for rapid adaptive responses to future climate change.
authors.affiliation: Department of Bioscience, Aarhus University, Ny Munkegade 116, DK-8000 Aarhus C, Denmark. vanessa.kellermann@monash.edu
authors.forename: Vanessa
authors.initials: V
authors.lastname: Kellermann
authors.forename: Volker
authors.initials: V
authors.lastname: Loeschcke
authors.forename: Ary A
authors.initials: AA
authors.lastname: Hoffmann
authors.forename: Torsten Nygaard
authors.initials: TN
authors.lastname: Kristensen
authors.forename: Camilla
authors.initials: C
authors.lastname: Fløjgaard
authors.forename: Jean R
authors.initials: JR
authors.lastname: David
authors.forename: Jens-Christian
authors.initials: JC
authors.lastname: Svenning
authors.forename: Johannes
authors.initials: J
authors.lastname: Overgaard
mesh_terms: D000064:Acclimatization; D063147:Animal Distribution; D000818:Animals; D005075:Biological Evolution; D058639:Cold-Shock Response; D003681:Dehydration; D018428:Drosophilidae / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005260:Female; D008297:Male; D010802:Phylogeny; D013045:Species Specificity