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Aim Human-caused habitat alteration and disturbance have promoted widespread loss of species’ reproductive barriers, leading to hybridization and attendant changes in the distribution, abundance and interactions of most species. In theory, hybrids should have intermediate niche occupancy features compared to parental groups, thereby potentially leading to fundamental changes in the role of organisms in an ecosystem. Yet, there is a gap in our empirical understanding of how hybrids differ in their niche characteristics compared to parental types; this uncertainty is especially true for large carnivores that range over large spatial extents and have high behavioural plasticity in their niche characteristics or in the environments that they inhabit. We sought to test whether eastern wolf (Canis lycaon) – eastern coyote (C. latrans sp.) hybrids exhibited intermediate environmental niche characteristics compared to their progenitors. Location Eastern North America. Methods We integrated genetic profiling of georeferenced canid (eastern wolf, eastern coyote, hybrid) samples into species distribution models, to investigate relationships between canid genetic groups and their environment. We used relevant environmental variables to investigate niche overlap and niche breath of hybrids and their parental groups. Results Species distribution models revealed clear patterns of niche differentiation, with hybrids tending to occur in areas having intermediate environmental niche attributes and niche breadth, compared to parental groups. Niche overlap between hybrids and either parental group was greater than between the two parental groups, further highlighting the intermediate environmental niche that is occupied by hybrids. Main conclusions We show that even among wide-ranging and highly plastic large carnivores, hybrids tend to exhibit intermediate niche characteristics compared to parental groups. Our support for the intermediate phenotype hypothesis highlights its ecological relevance even when faced with coarse observational data, complex genetic structure, large spatial scale and high phenotypic plasticity.

Aim The degree to which niches of species change over time or space has important implications for ecology and evolutionary biology. However, conditions that give rise to niche shifts remain poorly understood. In particular, the relative influence of release from predation or competition (change in realized niche) vs. genetically based alterations (change in fundamental niche) has received little attention. We studied niche shifts in expanding coyote (Canis latrans) populations. During expansion from their historic range, coyotes experienced marked changes in competitive regimes and also genetic changes (i.e. hybridization), and these alterations occurred unevenly across the expanding front. The goal of this study was to determine the presence and degree of niche shifts in expanding coyote populations and the potential influence of hybridization on these patterns. Location North America. Methods We developed species distribution models and compared climatic niche overlap between historic and expanding coyote populations with different levels of genetic introgression with wolves. We also developed harvest models to examine differences in how coyote and coyote hybrids responded to human disturbance and land use. Results Niche differentiation is most pronounced for expanding coyote populations that have experienced substantial hybridization with wolves. An examination of response curves suggests that coyotes in the north-east may have shifted to a more wolflike niche. Main conclusions Hybridization or other processes that promote genetic changes in populations may be associated with niche shifts. These findings help explain why hybridization often leads to increased invasiveness, and further support the notion that genetic differentiation below the level of species can lead to niche divergence. Our results also highlight the caution needed when predicting distributional changes due to invasion or climate change, particularly among populations exposed to genetic change.