Vivid biofluorescence discovered in the nocturnal Springhare (Pedetidae)

Abstract

Biofluorescence has been detected in several nocturnal-crepuscular organisms from invertebrates to birds and mammals. Biofluorescence in mammals has been detected across the phylogeny, including the monotreme duck-billed platypus (Ornithorhyncus anatinus), marsupial opossums (Didelphidae), and New World placental flying squirrels (Gluacomys spp.). Here, we document vivid biofluorescence of springhare (Pedetidae) in both museum specimens and captive individuals—the first documented biofluorescence of an Old World placental mammal. We explore the variation in biofluorescence across our sample and characterize its physical and chemical properties. The striking visual patterning and intensity of color shift was unique relative to biofluorescence found in other mammals. We establish that biofluorescence in springhare likely originates within the cuticle of the hair fiber and emanates, at least partially, from several fluorescent porphyrins and potentially one unassigned molecule absent from our standard porphyrin mixture. This discovery further supports the hypothesis that biofluorescence may be ecologically important for nocturnal-crepuscular mammals and suggests that it may be more broadly distributed throughout Mammalia than previously thought.

Light and Autofluorescence, Multitasking Features in Living Organisms

“…Some ancient reports are recalled by Pine et al [229], on the changes in color and fluorescence of the fur of wild animals after killing, when introducing its work on the various colors and fluorescence of hair of museal specimens of didelphid marsupials [229]. After that a renewed attention to the phenomenon has indicated that, in general, it seems to apply greatly to some animals with active life under poor light conditions in the crepuscular and nocturnal phases of the day, transversally representing marsupial and placental mammals in Eastern, European, American and African countries [230]. The main fluorophores described in this section are summarized in Table 9.…”

“…In the nocturnal Pedetes surdaster and P. capensis, two springhare species belonging to the Pedetidae rodent family, an orange-red fluorescence has been detected from their fur under UV irradiation. The reddish fluorescence was proved to rise from the cuticle of the hairs, and was ascribed to porphyrins on the basis of fluorescence spectra recorded directly from the ventral and dorsal sides of the animals, besides the HPLC biochemical analysis of fur extract [230] (Figure 31).…”

Fur glowing under UV: a widespread consequence of porphyrin accumulation in mammals

“…As this reddish UV-PL is predominantly found in crepuscular and nocturnal species, this phenomenon has been interpreted as potentially related to visual functions for intraspeci c communication or antipredator behavior in light-deprived environments 4,8,9,24 . However, in showing that the reddish UV-PL of mammals' pelage is induced by the accumulation of photodegradable protoporphyrins, it appears more likely that this phenomenon might simply be overrepresented in crepuscular and nocturnal specimens mainly because in their case the porphyrinic compounds are less degraded than in diurnal species.…”

“…The reddish UV-PL observed on the plumage of some birds was identi ed as caused by coproporphyrin III and protoporphyrin IX [20][21][22][23][24][25] , which are common molecules playing a crucial role in various biological processes and notably in heme biosynthesis 26 . A recent analysis on springhare pelage 9 identi ed a mixture of other porphyrins, usually found in urine or feces of mammals 27 , along with an unidenti ed molecule. However, the question remains whether these compounds are also responsible for the reddish UV-PL observed in other mammals.…”

“…So far, two cases of sexual selection using PL have been experimentally demonstrated in budgerigars 14 and in jumping spiders 29 . In mammals, based on the fact that UV-PL was predominantly observed in crepuscular or nocturnal animals, it was recently hypothesized that this may serve ecological functions in light-deprived or snow-covered environments such as intraspeci c communication or antipredator behavior 4,8,9 . These hypotheses have not been tested experimentally.…”