Correlated Evolution of White Spots on Ears and Closed Habitat Preferences in Felids

Abstract

The pigmentation patterns of many carnivorous mammals comprise contrasting white patches of hair in different parts of the body whose evolution remains largely misunderstood. Some felids (Felidae) exhibit conspicuous white spots on the posterior part of the ears, while the ear color of others is uniform. On the basis that ear movement in felids has a role in intraspecific communication and that color contrast enhances detection, here it is hypothesized that white spots on ears may be particularly adaptive under conditions of poor visibility and thus be associated with the occupancy of closed habitats. This prediction was tested using phylogenetic logistic regression models with all species of extant felids. Results show a clear association between the occurrence of white spots on ears and preference for closed habitats, and this is independent of body size and whether species that occupy both closed and open habitats are considered as closed-or openhabitat specialists. Phylogenetic signal analyses indicate that the occurrence of white spots on ears is a highly conserved trait while habitat preferences are evolutionarily labile, suggesting that the presence of white spots may have partly contributed to the adaptation of felids to closed habitats. These findings indicate that some subtle pigment traits have fulfilled a significant role in determining the success of habitat occupancy by felids and possibly other mammals, which in turn has driven the evolutionary maintenance of such traits.

Melanism evolution in the cat family is influenced by intraspecific communication under low visibility

“…Therefore, melanism was documented in 15 of the 40 Felidae species (Fig 2A; S1 and S2 Files), including the domestic cat. We considered the species with white marks on the backs of ears based in Galván [24] and included African wild cat and Southern tigrina in our analysis (Fig 2A; S1 and S2 Files). We considered the record of white marks on the backs of ears in the Pampas cat, based on available images on the internet (S2 File).…”

“…Ecological data were obtained from Table S2 in Allen et al [6] and Figure 2 in Galván [24], except when indicated (S2 File). Reliable information on circadian activity was not found for the rusty-spotted cat and therefore this species was not considered in the analyses that required this information (Fig 2A; S1 and S2 Files).…”

“…Both response and predictors were coded as binary variables to meet the requirements of our analytical approach. Specifically, the ecological variable ‘circadian activity’ was coded as arrhythmic/nocturnal, and ‘environmental preference’ as open/closed ([6, 24], and studies cited in S2 File), as follows. A species was considered nocturnal (coded as 1) when more than 90% of the circadian activity was categorized as crepuscular and/or nocturnal; otherwise, the species were considered arrhythmic and coded as 0 (S1 and S2 Files).…”

“…Environmental preference associated to open environments was coded as 0; the remaining environments were considered closed and coded as 1 (S1 File). Species found on both closed and open environments were coded as 1 [24]. Closed habitats comprised forests, rain forests, riparian or brush and scrub habitats, while open habitats comprised grasslands, deserts, and arctic habitats [15, 29].…”

“…Four hypotheses of association of body markings with communication in felids were assessed: (1) white markings are associated with communication in felids living in closed environments [15, 24]; (2) melanistic phenotypes limit communication under low visibility at night due to the absence of white markings; (3) melanistic individuals depend on individuals with white marks to communicate; (4) communication by white markings (mediated by other individuals) facilitates the persistence of melanistic animals in closed environments. As a consequence of our hypotheses, we expect that the analysis of evolutionary models will support the coordinated evolution of traits (white markings on the ears, arrhythmic activity during diurnal and nocturnal periods, and occurrence in closed environments) in species with melanism, contributing to the knowledge of functional traits (i.e.…”