Species distribution models are often used to predict the potential distributions of invasive species outside their native ranges and rely on the assumption of realized niche conservatism. Analyses observed that freshwater invasive species often show high degrees of niche expansion, suggesting limited reliability of species distribution models. However, observed niche shifts can arise because of both actual niche shifts, determined by biological factors, and apparent shifts, due to methodological issues. We compared metrics of niche dynamics calculated using different sets of variables to identify factors that could influence the rate of niche shifts. We collected presence-only data for 40 freshwater invasive animal species, then measured niche shift dynamics using 14 different combinations of environmental variables. Shifts were assessed measuring niche overlap, expansion and unfilling, and testing for niche conservatism. We then built generalized linear mixed models relating niche shifts to methodological choices and biological features. Our results showed that methodological choices strongly affected all the considered niche dynamics metrics, while the effects of biological features were less prominent. Moreover, different niche dynamic measures sometimes provided contradictory assessments of niche conservatism. Niche analyses are powerful tools to predict areas at risk of invasion, but inappropriate methodological choices can lead to apparent niche shifts, questioning niche model reliability and biological interpretation. The high rate of niche expansion observed in freshwater invasive species highlights the importance of delineating objective criteria to determine the set of variables to be used in niche dynamic assessments.

中文翻译：

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所有的变化都不是变化：方法选择影响淡水入侵物种的生态位变化检测

物种分布模型通常用于预测入侵物种在其原生范围之外的潜在分布，并依赖于已实现的生态位保守性假设。分析观察到，淡水入侵物种通常表现出高度的生态位扩张，表明物种分布模型的可靠性有限。然而，观察到的生态位变化可能是由于实际的生态位变化（由生物学因素决定）和明显的变化（由于方法问题）引起的。我们比较了使用不同变量集计算的利基动态指标，以确定可能影响利基转变率的因素。我们收集了 40 种淡水入侵动物物种的仅存在数据，然后使用 14 种不同的环境变量组合测量生态位转变动态。评估转变测量利基重叠、扩张和未填充，并测试利基保守主义。然后，我们建立了广义线性混合模型，将利基转变与方法选择和生物学特征联系起来。我们的结果表明，方法学选择强烈影响所有考虑的利基动态指标，而生物学特征的影响则不那么突出。此外，不同的生态位动态措施有时会提供对生态位保守主义的矛盾评估。生态位分析是预测入侵风险区域的强大工具，但方法选择不当会导致明显的生态位变化，质疑生态位模型的可靠性和生物学解释。