Micro‐spatial separation and associated morphological adaptations in the original case of avian character displacement. (21st July 2017)

• Record Type: Journal Article
• Authors: Yousefi, Masoud; Kaboli, Mohammad; Eagderi, Soheil; Mohammadi, Alireza; Rezaei, Ali; Nourani, Elham
• Is Part Of: Ibis. Volume 159:Number 4(2017:Oct.)
• Page Start: 883
• Page End: 891
• Publication Date: 2017-07-21
• Subjects: body size -- morphological divergence -- niche segregation -- spatial niche; Birds -- Periodicals; 598
• DOI: 10.1111/ibi.12505
• Languages: English
• ISSNs: 0019-1019

Abstract

Abstract : Divergent evolution between Western Rock Nuthatch Sitta neumayer and Eastern Rock Nuthatch Sitta tephronota is widely recognized as the original case study of character displacement. However, in their contact zone in the Zagros Mountains, Iran, the morphological differences important for niche segregation between the two species remain unknown. We investigated microhabitat use and morphological adaptations of the two species, predicting that morphological adaptations to different habitats in these two nuthatches have led to spatial segregation. Seventy‐seven birds were captured and measured in the contact zone and allopatric zone in Iran. Twenty‐two primary variables related to flight apparatus, functional foot apparatus and feeding apparatus were measured and 11 ratios of primary variables were calculated as secondary variables due to their importance in habitat use. We also measured environmental variables related to geological features, mineral substrates and vegetation cover at a random sample of 100 of the locations where a nuthatch was observed. Results of morphometric and habitat analyses indicated that, in addition to trophic niche segregation, the two nuthatch species also differ in their microhabitat use and show differences in morphological features accordingly. In many case studies of character displacement, much more interest has been focused on the morphological differences in feeding apparatus than on those relating to habitat use. We suggest that future studies of character displacement should pay more attention to spatial niche segregation between sympatric species rather than trophic niche segregation.