title: What causes latitudinal gradients in species diversity? Evolutionary processes and ecological constraints on swallowtail biodiversity.
abstract: The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. Determining the evolutionary causes of this pattern remains a challenging task. To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering evolutionary processes indirectly. Instead, we use a phylogenetically integrated approach to investigate the ecological and evolutionary processes responsible for the global LDG observed in swallowtail butterflies (Papilionidae). We find evidence for the 'diversification rate hypothesis' with different diversification rates between two similarly aged tropical and temperate clades. We conclude that the LDG is caused by (1) climatically driven changes in both clades based on evidence of responses to cooling and warming events, and (2) distinct biogeographical histories constrained by tropical niche conservatism and niche evolution. This multidisciplinary approach provides new findings that allow better understanding of the factors that shape LDGs.
authors.affiliation: INRA, UMR Centre de Biologie pour la Gestion des Populations, CBGP (INRA/IRD/CIRAD/Montpellier SupAgro), Campus International de Baillarguet, 34988 Montferrier-sur-Lez, France. fabien.condamine@gmail.com
authors.forename: Fabien L
authors.initials: FL
authors.lastname: Condamine
authors.forename: Felix A H
authors.initials: FA
authors.lastname: Sperling
authors.forename: Niklas
authors.initials: N
authors.lastname: Wahlberg
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Rasplus
authors.forename: Gael J
authors.initials: GJ
authors.lastname: Kergoat
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D002080:Butterflies / Q000502:physiology*; D002980:Climate; D004463:Ecology; D010802:Phylogeny; D058974:Phylogeography; D010944:Plants; D014329:Tropical Climate