Noreikiene Kristina, Herczeg Gábor, Gonda Abigél, Balázs Gergely, Husby Arild, Merilä Juha
Ecological Genetics Research Unit, University of Helsinki, Helsinki 00014, Finland.
Ecological Genetics Research Unit, University of Helsinki, Helsinki 00014, Finland Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest 1117, Hungary.
Proc Biol Sci. 2015 Jul 7;282(1810). doi: 10.1098/rspb.2015.1008.
The mosaic model of brain evolution postulates that different brain regions are relatively free to evolve independently from each other. Such independent evolution is possible only if genetic correlations among the different brain regions are less than unity. We estimated heritabilities, evolvabilities and genetic correlations of relative size of the brain, and its different regions in the three-spined stickleback (Gasterosteus aculeatus). We found that heritabilities were low (average h(2) = 0.24), suggesting a large plastic component to brain architecture. However, evolvabilities of different brain parts were moderate, suggesting the presence of additive genetic variance to sustain a response to selection in the long term. Genetic correlations among different brain regions were low (average rG = 0.40) and significantly less than unity. These results, along with those from analyses of phenotypic and genetic integration, indicate a high degree of independence between different brain regions, suggesting that responses to selection are unlikely to be severely constrained by genetic and phenotypic correlations. Hence, the results give strong support for the mosaic model of brain evolution. However, the genetic correlation between brain and body size was high (rG = 0.89), suggesting a constraint for independent evolution of brain and body size in sticklebacks.
大脑进化的镶嵌模型假定，不同的脑区相对可以独立进化。只有当不同脑区之间的遗传相关性小于1时，这种独立进化才有可能。我们估计了三刺鱼（Gasterosteus aculeatus）大脑及其不同区域相对大小的遗传力、进化能力和遗传相关性。我们发现遗传力较低（平均h(2)=0.24），这表明大脑结构存在很大的可塑性成分。然而，不同脑区的进化能力适中，这表明存在加性遗传方差，以便长期维持对选择的响应。不同脑区之间的遗传相关性较低（平均rG = 0.40），且显著小于1。这些结果，连同表型和遗传整合分析的结果，表明不同脑区之间具有高度的独立性，这表明对选择的响应不太可能受到遗传和表型相关性的严重限制。因此，这些结果为大脑进化的镶嵌模型提供了有力支持。然而，大脑与身体大小之间的遗传相关性很高（rG = 0.89），这表明三刺鱼的大脑和身体大小独立进化存在限制。
