Evol Ecol Res 16: 649-661 (2015)     Full PDF if your library subscribes.

When should faster-moving animals have better visual ability?
A computational study of Leuckart’s law

Shinsuke Satoi and Yoh Iwasa

Department of Biology, Kyushu University, Fukuoka, Japan

Correspondence: Y. Iwasa, Department of Biology, Kyushu University, Fukuoka 812-8581, Japan.
e-mail: yohiwasa@kyudai.jp

ABSTRACT

Background: Leuckart’s law postulates that, among vertebrates, swifter animals should have larger eyes with better visual ability. It was supported for mammals but rejected for birds.

Question: We ask what are the conditions in which faster-moving animals evolve to have better visual ability?

Methods: Computer simulation studies of an animal moving on a plane containing many food items as well as obstacles. The animal moved at a constant speed but changed its directional angle when it recognized food items or obstacles. We examined the number of food items the animal consumed and the number of obstacles it collided with.

Results: We assume that visible distance is in proportion to eye size, and that it is accompanied by a small cost. We obtained the optimal visual distance, which depended on movement speed, and densities of foods and obstacles in the field.

Conclusions: The positive correlation between movement speed and optimal visual distance was stronger with more obstacles and fewer food items. In contrast, the correlation was weak (Leuckart’s law does not hold) when food was abundant, obstacles were rare, and collision damage minimal.

Keywords: animal behaviour, eye size, Leuckart’s law, locomotion, visual acuity.

DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.

 

        © 2015 Yoh Iwasa. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.