From darkness to daylight: cathemeral activity in primates

Abstract

Summary – Within the primate order, Haplorrhini and Strepsirrhini are adapted to diurnal or nocturnal lifestyle. However, Malagasy lemurs exhibit a wide range of activity patterns, from almost completely nocturnal to almost completely diurnal, while others are active over the 24-hours. Cathemerality, the term minted by Tattersall (1987) to define the latter activity style, has been recorded in Eulemur and Hapalemur, as well as in some populations of the New World monkey Aotus. As most animals specialize in a particular phase of the 24hour cycle, the cathemeral strategy is expected to be the consequence of powerful pressures. We will review hypotheses and findings on ultimate reasons of primate cathemeral activity, present proximate factors shaping the activity cycle and discuss the possible roles of feeding competition, food shortage and dietary quality, thermoregulation, and predation in making this activity advantageous. Overall, we will see how unstable environments and various community characteristics would tend to select for a flexible activity phase. Most attempts to explain cathemerality have relied on adaptive explanations, which assume that this activity is stable and deep-rooted. In contrast, some researchers have suggested that cathemerality represents a non-adaptive transitional state between nocturnality and diurnality. Chronobiology studies indicate that cathemeral species should be considered as dark active primates, thus favouring a recent origin. On the other hand, anatomical analyses demonstrate that the eye of cathemeral primates is a good compromise between the functional demands of vision under both nocturnal and diurnal conditions, thus suggesting an ancient origin. On the basis of recent phylogenetic trees we will discuss different scenarios for the evolution of cathemerality and diurnality in lemurs. Furthermore, we will evaluate the hypothesis that early primate ancestors may have needed to see well both in the daytime and at night, before becoming specialized in one direction. Finally, we will consider some interdisciplinary implications of the study of a day-night activity in primates.

Cite this work

No public copy is stored for this record, so only the metadata is cited.

Stored only when both papers are in the corpus — 51 citations exist upstream.

Papers that cite the same references — the relational fallback while embeddings are still backfilling.