 With respect to development, it has been argued, first, that organization plays a different role in mechanistic developmental explanations (Mc Manus 2012). In contrast to the above framework, which usually presupposes that levels of organization are simply there, and thus it does not have to clarify how levels of organization actually originate, the origin of levels and other forms of organization (e.g., spatial axes) are specifically addressed in mechanistic developmental explanations. Second, philosophers have argued that the relations between levels traced by developmental mechanisms are not exhausted by the synchronic, constitutive relations between parts and wholes, as some new mechanists suggest (Craver &amp; Bechtel 2007). In contrast, developmental explanations trace changing diachronic relationships between causal capacities of a system at different levels of organization at different time intervals (Ylikoski 2013; Baedke &amp; Mc Manus 2018; Baedke 2020; see also Love &amp; Hüttemann 2011). Third, it has been argued that explanations in evo-devo using developmental mechanisms face a challenge due to the heterogeneity of these mechanisms (Love 2018). When trying to integrate two types of explanations of developmental mechanisms – explanations of highly conserved molecular genetic mechanisms, like gene regulatory networks, and explanations of cellular-physical mechanisms, like cell migration – sometimes a tradeoff emerges. Rather than allowing a more complete explanation, integrating the two mechanisms may lead to a less general explanation, since non-phylogenetically conserved cellular-physical mechanisms yield less generality in explanations. This tradeoff can introduce an explanatory bias to projects that seek to integrate development and evolution. It could lead researchers to favors the generality of explanations, which cite highly conserved molecular genetic mechanisms and no cellular-physical mechanisms, over integrated explanations citing both kinds of mechanisms.