Trophic Niche Breadth of Falconidae Species Predicts Biomic Specialisation but Not Range Size

Abstract

Trophic niche breadth plays a key role in biogeographic distribution patterns. Theory posits that generalist strategies are favoured in a more heterogeneous set of environments across a spatio-temporal gradient of resources predictability, conferring individuals and species a greater capacity for colonising new habitats and thus expanding their distribution area. Using the family Falconidae (Aves, Falconiformes) as a model study, we tested the prediction that those species with a wider diet spectrum will have larger geographic range sizes and inhabit more biomes. We assessed the relationships between trophic breadth (diet richness and diversity) at different taxonomic resolutions of the prey (class and order), range size and biomic specialisation index (BSI; number of biomes inhabited) for the different species. Despite different diet breadth indexes and taxonomic resolutions defined differently the trophic niche of the clade and species, our findings revealed that trophic breadth was not a good predictor for range size but was for total environmental heterogeneity, with more diet-generalist species occupying a higher number of biomes. Diet breadth at the order taxonomic level showed a higher capacity of predicting BSI than at class level, and can be an important ecological trait explaining biogeographic patterns of the species.

Phylogenetic biome conservatism as a key concept for an integrative understanding of evolutionary history: Galliformes and Falconiformes as study cases

“…Specific environmental conditions might promote the development of physiological traits to cope with adverse conditions in different climatic regimes, although they might also require highly specialized functional features (Ghalambor et al, 2006;Bonetti & Wiens, 2014). Conversely, high versatility in relationship to resources and climatic conditions could, theoretically, enable a prominent capacity to colonize and occupy diverse habitat types (Jocque et al, 2010;Salisbury et al, 2012;Pigot & Tobias, 2013, 2015Lv et al, 2016;Fargallo et al, 2022). In many cases, palaeoclimatic changes might have promoted environmental flexibility by expanding climatic tolerance (Guerrero et al, 2013;Jara-Arancio et al, 2014;Ringelberg et al, 2020), a process that depends on the genetic variation of species populations (Somero, 2010;Pauls et al, 2013;Razgour et al, 2013).…”

Avian Atlas: Unveiling the Diversity Divide in Desert Realms between Tropics

“…5c and 5d). This reduces competition for migratory species and supports higher overall richness due to increased environmental heterogeneity (Fargallo et al, 2022) in TCan.…”

“…In our previous work, we have demonstrated the use of crowd-sourced bird diversity data in delineating the major ecoregions within a desert (Mukherjee et al, 2023). Such biogeographic distribution patterns in birds are known to be correlated to the trophic niche breadth (Fargallo et al, 2022). However, our further investigation on geographic distinctness of desert through mapping avian biodiversity with observational data, revealed that trophic niches not only play a crucial role in determining regional diversity but also the influx of migratory species (Mukherjee et al, 2024).…”