The influence of biogeographic history on the functional and phylogenetic diversity of passerine birds in savannas and forests of the Brazilian Amazon

Abstract

Passeriformes is the largest and most diverse avian order in the world and comprises the Passeri and Tyranni suborders. These suborders constitute a monophyletic group, but differ in their ecology and history of occupation of South America. We investigated the influence of biogeographic history on functional and phylogenetic diversities of Passeri and Tyranni in forest and savanna habitats in the Brazilian Amazon. We compiled species composition data for 34 Passeriformes assemblages, 12 in savannas and 22 in forests. We calculated the functional (Rao's quadratic entropy, FD _Q ) and phylogenetic diversities (mean pairwise distance, MPD, and mean nearest taxon distance, MNTD), and the functional beta diversity to investigate the potential role of biogeographic history in shaping ecological traits and species lineages of both suborders. The functional diversity of Passeri was higher than for Tyranni in both habitats. The MPD for Tyranni was higher than for Passeri in forests; however, there was no difference between the suborders in savannas. In savannas, Passeri presented higher MNTD than Tyranni, while in forest areas, Tyranni assemblages showed higher MNTD than Passeri. We found a high functional turnover (~75%) between Passeri and Tyranni in both habitats. The high functional diversity of Passeri in both habitats is due to the high diversity of ecological traits exhibited by species of this group, which enables the exploitation of a wide variety of resources and foraging strategies. The higher Tyranni MPD and MNTD in forests is likely due to Tyranni being older settlers in this habitat, resulting in the emergence and persistence of more lineages. The higher Passeri MNTD in savannas can be explained by the existence of a larger number of different Passeri lineages adapted to this severe habitat. The high functional turnover between the suborders in both habitats suggests an ecological strategy to avoid niche overlap.

Keywords: bird assemblages; community phylogenetics; ecological traits; functional beta diversity; functional biogeography; open vegetation; phylogenetic relationship.

Figure 1

Location of 34 Passeriformes assemblages compiled from studies carried out in 22 forest sites (yellow dots) and 12 savanna sites (black dots), all within the Brazilian Amazon

Figure 2

Proportional species richness (a and b) and functional diversity (FD_Q) values (c and d) for the assemblages of Passeri and Tyranni in forests and savannas of the Brazilian Amazon. Pairs with different letters differed statistically (p < .05) when compared through a paired t‐test or Mann–Whitney U‐test

Figure 3

Mean pairwise distance (MPD) (a and b) and mean nearest taxon distance (MNTD) (c and d) recorded for the Passeri and Tyranni assemblages in forests and savannas of the Brazilian Amazon. Pairs indicated with distinct letters differed statistically (p < .05) when compared through a paired t‐test or Mann–Whitney U‐test

Figure 4

Boxplots representing median, 25% and 75% quartiles and maximum and minimum values of functional turnover between Passeri and Tyranni assemblages in forests and savannas of the Brazilian Amazon

Figure 5

Principal components analysis (PCA) highlighting the distribution of the ecological traits (a and c) and the assemblages (b and d) of Passeri and Tyranni in forests and savannas of the Brazilian Amazon. Foraging stratum: ground, Underst = understory, MidHigh = mid to high levels, canopy. Diet: Invert = invertebrates, Fruit, Seed, PlantO = diverse plant material; and body mass