Boussard Annika, Garate-Olaizola Maddi, Fong Stephanie, Kolm Niclas
Department of Zoology, Stockholm University, Stockholm, Sweden.
Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
Brain Behav Evol. 2024;99(4):212-221. doi: 10.1159/000540491. Epub 2024 Jul 23.
Variation in eye size is sometimes closely associated with brain morphology. Visual information, detected by the retina, is transferred to the optic tectum to coordinate eye and body movements towards stimuli and thereafter distributed into other brain regions for further processing. The telencephalon is an important visual processing region in many vertebrate species and a highly developed region in visually dependent species. Yet, the existence of a coevolutionary relationship between telencephalon size and eye size remains relatively unknown.
Here, we use male and female guppies artificially selected for small- and large-relative-telencephalon-size to test if artificial selection on telencephalon size results in changes in eye size. In addition, we performed an optomotor test as a proxy for visual acuity.
We found no evidence that eye size changes with artificial selection on telencephalon size. Eye size was similar in both absolute and relative terms between the two selection regimes but was larger in females. This is most likely because of the larger body size in females, but it could also reflect their greater need for visual capacity due to sex-specific differences in foraging and mating behaviour. Although the optomotor response was stronger in guppies with a larger telencephalon, we found no evidence for differences in visual acuity between the selection regimes.
Our study suggests that eye size and visual perception in guppies do not change rapidly with strong artificial selection on telencephalon size.
眼睛大小的变化有时与大脑形态密切相关。视网膜检测到的视觉信息被传递到视顶盖，以协调眼睛和身体朝向刺激物的运动，然后分布到其他脑区进行进一步处理。端脑是许多脊椎动物物种中重要的视觉处理区域，在视觉依赖物种中是一个高度发达的区域。然而，端脑大小与眼睛大小之间的协同进化关系仍然相对未知。
在这里，我们使用人工选择的端脑相对大小较小和较大的雄性和雌性孔雀鱼，来测试对端脑大小的人工选择是否会导致眼睛大小的变化。此外，我们进行了视动测试作为视力的替代指标。
我们没有发现证据表明眼睛大小会随着对端脑大小的人工选择而变化。在两种选择方式下，眼睛的绝对大小和相对大小都相似，但雌性的眼睛更大。这很可能是因为雌性的体型更大，但也可能反映出由于觅食和交配行为的性别差异，它们对视觉能力有更大的需求。尽管端脑较大的孔雀鱼的视动反应更强，但我们没有发现两种选择方式之间视力存在差异的证据。
我们的研究表明，对孔雀鱼端脑大小进行强烈的人工选择时，其眼睛大小和视觉感知不会迅速改变。
