Side by Side Comparison – Interspecific vs Intraspecific Competition in Tabular Form KDEs were built using the “ks” R package (Duong, 2014). We thank all collaborators who participated in field data collection, and most particularly M.P. The species' multidimensional habitat niches were defined using a nonparametric kernel density estimator procedure (KDE; Mouillot et al., 2005). Otherwise, ecologically similar species that share a limiting resource engage in competition and the species with superior abilities eventually exclude the inferior competitor (Gause, 1934; Human & Gordon, 1996). Because interspecific competition between these bustard species is not resolved by a complete spatial segregation (both species are often found simultaneously occupying the same habitats), these species may constitute a good system to gain novel insights into ecological niche theory with relevant implications for the conservation of competing populations. R.T., M.M, and J.T conceived and designed the study and the statistical analysis. We explored whether the degree of niche overlap between the species was a density‐dependent function of interspecific competition. Study sites are often arbitrarily delimitated, and areas falling outside the local distribution of the species may be included within the study site boundaries. In order to test the hypothesis of niche release, we used niche breadth and niche position (two coordinates corresponding with each dimension of the two‐dimensional habitat niche) as the response variables, and the presence/absence of great bustard as the explanatory variable. The main reason for intraspecific competition is overpopulation. The number of observations per site and year ranged between 10 and 174 and 0 and 142 for the little and the great bustard, respectively. Graph (a) KDEs were calculated from set coordinates in order to obtain comparable values for the analysis (cross points of dotted lines). Although results do not allow us to clarify whether great bustards also affect the habitat niche of little bustard females, this possibility should be borne in mind. The PCA was built using the random and bustard points of all study sites and years (see Traba et al., 2015 for a similar approach). If you break the two terms down, "intraspecific" just means within a species, while "interspecific" means between them. The little bustard habitat niche also depends on the particular landscape composition. Members of the same species have rather similar … All KDEs were weighted by the number of individuals in the observation. Graph (b) niche overlap was calculated as the volume under the area where two KDEs intersect. Available here, 1. Empirical studies using computational tools which allow to easily obtain multidimensional niches should give more realistic insights on evolutionary and ecological processes shaping communities (Blonder et al., 2014). We also found a weak evidence of increased niche breadth in regions with great bustard presence for PC1‐PC3 habitat niche (Table 3; values per study site can be found in Appendix S1, Table S3). The first three PCA habitat axes retained 80% of the variance. This is due to the competition among the seedlings for space, water, nutrients, and sunlight. Our approach might better reflect the process of individual habitat choice than single‐variable niche spaces. Competition, whether direct or indirect, can. When a species is released from a putative competitor, its niche breadth expands because interspecific competition no longer restricts the exploitation of resources previously monopolized by the competitor (Bolnick et al., 2010; Schoener, 1989). Here, we aimed to determine the potential effects of interspecific competition between the little bustard (Tetrax tetrax) and the great bustard (Otis tarda) using a multidimensional niche approach with habitat distribution data. Interspecific competition occurs between two or more species. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce. Biological interspecific competition is a natural process of struggle between different individuals for space and resources (food, water, light). Of the 67% of species pairs in which both intra‐ and interspecific effects were negative (competitive), intraspecific competition was, on average, four to five‐fold stronger than interspecific competition. Intraspecific competition is a type of competition where two or more of the same species of animals are competeing for something, that is usually a shared resource. We expect these shifts to be density‐dependent because interspecific competition and its effects intensify with great bustard density. Surveys were conducted by car along routes using the net of roads and tracks available in each study site. The little bustard is an exploded lek species in which males establish loosely aggregated territories (Jiguet, Arroyo, & Bretagnolle, 2000), preferentially in semi‐permanent agrarian habitats like short‐ and long‐term fallows as well as legume crops (Delgado, Traba, García de la Morena, & Morales, 2010; Morales, García, & Arroyo, 2005; Wolff, Paul, Martin, & Bretagnolle, 2001). Name Annabel Roth Intraspecific and Interspecific competition I. Each field was assigned to one of the following seven habitat types: (1) cereal; (2) ploughed field; (3) leguminous crop; (4) 1‐year fallow (hereafter young fallow); (5) fallow older than 2 years and short shrubland (hereafter natural vegetation); (6) dry woody culture, including olive groves, vineyards, and almond tree orchards; and (7) others, which encompasses minority substrates avoided by the species like urban areas, or forests. As a consequence, one would expect no habitat niche overlap due to habitat niche divergence. and you may need to create a new Wiley Online Library account. This should induce a decrease in little bustard's habitat niche breadth and a niche displacement toward increased use of fallows and natural vegetation. 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