%0 Journal Article %J Ecosphere %D 2018 %T Testing the predictive capabilities of ecological niche models: a case study examining Red‐bellied Woodpeckers %A FitzGerald, Alyssa M. %A Starkloff, Naima C. %A J. J. Kirchman %K Carolinian avifauna %K climate change %K ecological niche modeling %K land cover change %K Maxent %K Melanerpes carolinus %K niche conservatism %K niche expansion %K predictive modeling %K range expansion %K Red‐bellied Woodpecker %X
As humans continue to alter natural habitats indirectly and directly, species’ geographic ranges may change as they track shifting climate regimes or changing landscapes. Ecological niche models (ENMs) are frequently used to show modern ranges and forecast future range changes. These models, however, assume that a species will exhibit niche conservatism, though this is rarely tested. Here, we examine a woodpecker species with a well‐documented recent range expansion to assess the effectiveness of predictive models by comparing the pre‐ and post‐expansion climate/habitat niche using ENMs and multivariate principal components analysis. Occurrence data for the Red‐bellied Woodpecker (Melanerpes carolinus) were obtained from the pre‐expansion (1910–1939; n = 299) and post‐expansion (1980–2009; n = 868) time periods. Ecological niche models were constructed using GIS layers describing climate data and crop cover for the pre‐ and post‐expansion time periods. We then used the pre‐expansion ENM to forecast the distribution of Red‐bellied Woodpeckers into the post‐expansion time period, and vice versa, and calculated the niche overlap of the projected distributions and the actual distributions in those time periods to determine whether pre‐ and post‐expansion niches were similar. Predictive ENMs did not closely match the actual distributions in the pre‐ and post‐expansion time periods, respectively, and the pre‐expansion and post‐expansion niches were significantly different from each other (Schoener's D = 0.745, P < 0.001). Multivariate analyses revealed that the present‐day niche encompasses the past niche and that Red‐bellied Woodpeckers today have broader temperature and precipitation tolerances and are found in both more‐ and less‐forested areas than they were in the pre‐expansion era. Our analyses reveal that Red‐bellied Woodpeckers are not exhibiting climate or habitat niche conservatism, explaining why predictive ENMs for this species could not effectively track their range shift. This study emphasizes that predictive models may not be effective for species undergoing niche changes.
%B Ecosphere %V 9 %P e02496 %8 Dec-12-2018 %G eng %U https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.2496 %N 12 %! Ecosphere %R 10.1002/ecs2.2496 %0 Journal Article %J Ecology and Evolution %D 2017 %T Division within the North American boreal forest: Ecological niche divergence between the Bicknell's Thrush (Catharus bicknelli) and Gray-cheeked Thrush (C. minimus) %A FitzGerald, Alyssa M. %K boreal forest %K Catharus thrushes %K ecological niche divergence %K ecological speciation %K niche modeling %K sister species %XSister species that diverged in allopatry in similar environments are expected to exhibit niche conservatism. Using ecological niche modeling and a multivariate analysis of climate and habitat data, I test the hypothesis that the Bicknell's Thrush (Catharus bicknelli) and Gray-cheeked Thrush (C. mimimus), sister species that breed in the North American boreal forest, show niche conservatism. Three tree species that are important components of breeding territories of both thrush species were combined with climatic variables to create niche models consisting of abiotic and biotic components. Abiotic-only, abiotic+biotic, and biotic-only models were evaluated using the area under the curve (AUC) criterion. Abiotic+biotic models had higher AUC scores and did not over-project thrush distributions compared to abiotic-only or biotic-only models. From the abiotic+biotic models, I tested for niche conservatism or divergence by accounting for the differences in the availability of niche components by calculating (1) niche overlap from ecological niche models and (2) mean niche differences of environmental values at occurrence points. Niche background similarity tests revealed significant niche divergence in 10 of 12 comparisons, and multivariate tests revealed niche divergence along 2 of 3 niche axes. The Bicknell's Thrush breeds in warmer and wetter regions with a high abundance of balsam fir (Abies balsamea), whereas Gray-cheeked Thrush often co-occurs with black spruce (Picea mariana). Niche divergence, rather than conservatism, was the predominant pattern for these species, suggesting that ecological divergence has played a role in the speciation of the Bicknell's Thrush and Gray-cheeked Thrush. Furthermore, because niche models were improved by the incorporation of biotic variables, this study validates the inclusion of relevant biotic factors in ecological niche modeling to increase model accuracy.
%B Ecology and Evolution %V 7 %P 5285–5295 %8 06/2017 %G eng %U http://onlinelibrary.wiley.com/doi/10.1002/ece3.3080/full %N 14 %R 10.1002/ece3.3080 %0 Journal Article %J Avian Conservation and Ecology %D 2017 %T Taxonomy and distribution of the imperilled Newfoundland Gray-cheeked Thrush, Catharus minimus minimus %A FitzGerald, Alyssa M. %A Whitaker, Darroch M. %A Ralston, Joel %A J. J. Kirchman %A Warkentin, Ian G. %K distribution %K endemism %K genetics %K Gray-cheeked Thrush %K habitat %K hybrid %K Labrador %K Newfoundland %K red squirrel %K subspecies %K taxonomy %XGray-cheeked Thrushes breeding on Newfoundland are purported to be a distinct subspecies (Catharus minimus minimus) and have declined precipitously since the 1980s. To assess the validity of Gray-cheeked Thrush subspecies we collected blood samples and morphological measurements from 51 individuals captured at 15 sites in Newfoundland and Labrador (2013–2015). Analysis of mitochondrial (ND2) and nuclear intron (ADAM-TS 6, FIB7) sequences from these and additional samples from Nova Scotia, Newfoundland, Labrador, Quebec, Alaska, and Siberia showed low genetic variation at both nuclear loci, and shallow mitochondrial divergence between subspecies; there were no shared haplotypes between thrushes from Newfoundland / Nova Scotia (n = 41) and those from western Labrador and further west (n = 24). Thrushes from Newfoundland also had shorter wing chords, tails, and culmens and less black in the mandible compared to those from western Labrador and Quebec. Samples from the southeast coast of Labrador (n = 13) included ND2 haplotypes both from Newfoundland and western Labrador plus one putative hybrid that was phenotypically a Gray-cheeked Thrush but that had a Bicknell’s Thrush (C. bicknelli) ND2 haplotype and was heterozygous at a segregating site in FIB7. We detected thrushes during point counts at 7 of 24 sites on Newfoundland, but failed to detect them at 10 historically occupied sites on Newfoundland or in the reported distribution gap between subspecies in Labrador. Sites where thrushes have apparently disappeared had less shrub habitat within 1250 m and more large broadleaf trees within territory-scale areas compared to sites where they persist. Additionally, red squirrels (Tamiasciurus hudsonicus) are an introduced species on Newfoundland and thrush occurrence was > 3x higher at sites where red squirrels were not detected. Our results support previous designations of C. m. minimus from Newfoundland and southeastern Labrador as a subspecies distinct from C. m. aliciae found further west.
%B Avian Conservation and Ecology %V 12 %P 10 %G eng %U http://www.ace-eco.org/vol12/iss1/art10/ %N 1 %! ACE %R 10.5751/ACE-00976-120110