Artificial group selection has long been proposed as a useful method for crop breeding, yet the possibility that group selection occurs naturally in agroecosystems has not been explored. Due to natural and/or artificial selection, the fitness of an individual can depend on both the individual’s traits, the traits of neighboring individuals, and on group’s emergent traits (as density). This process is defined as multilevel selection type I. Using contextual analysis, I detected significant multilevel selection type I at the individual and group levels on weed-infested maize (Zea mays L.) genotypes with different spatial patterns and densities. In general, uniformity promoted multilevel selection type I, but this response varied within maize varieties and years. The results herein presented show that crop productivity and weed suppression increased at high density-uniformity conditions, but this also depends on variety. Multilevel selection type II is defined as the differential reproduction of entire groups, a process that in agronomic settings is implemented by humans. A reduced phenotypic variation in the angle of insertion of the oldest living leaf at harvest was identified as a group attribute to be selected for artificial multilevel selection type II. This trait experienced stabilizing selection at the individual level, which significantly increased crop productivity.

长期以来，一直有人提出将人工群体选择作为作物育种的一种有用方法，但尚未探索在生态系统中自然发生群体选择的可能性。由于自然和/或人为选择，一个人的适应能力可能既取决于该人的特质，相邻人的特质，又取决于群体的紧急特质（如密度）。这个过程被定义为I级多层次选择。通过上下文分析，我在杂草侵染的玉米（玉米）的个体和群体层次上检测到了显着的I级多层次选择类型。L.）具有不同空间模式和密度的基因型。一般而言，均匀性促进了I型多层次选择，但这种反应在玉米品种和年份之间有所不同。本文给出的结果表明，在高密度均匀性条件下，农作物的生产力和杂草抑制能力有所提高，但这还取决于品种。多级选择类型II定义为整个群体的差异繁殖，这是在农艺环境中由人类实施的过程。在收获时，最老的活叶插入角的表型变化减少被确定为要为人工多级选择类型II选择的组属性。该性状在个体水​​平上经历了稳定的选择，从而显着提高了作物的生产力。