Shadows in the forest: Uncovering unusual colouration records in mammals from the Ecuadorian Tropical Andes

Variations in colouration patterns have been reported in numerous wildlife species, particularly birds. However, the increased use of camera traps for wildlife monitoring has enabled the detection of elusive species and phenotypic variations that might otherwise go undetected. Here, we compiled records of unusual colouration patterns in terrestrial mammals, documented through camera-trap studies over a 12-year period in the Llanganates-Sangay Connectivity Corridor, in the Tropical Andes of Ecuador. We identified colour variations in seven species of terrestrial mammals, including disorders, such as melanism, white spotting/ piebaldism, xanthocromism and progressive greying. Notably, we reported a high prevalence of melanism in wild populations of the clouded oncilla, along with observations on the species' activity patterns. Approximately half of the recorded clouded oncillas were melanistic. We detected significant differences in activty patterns between melanistic and non-melanistc clouded oncilla, with melanistic morphs showing a peak of activity between 3 a.m. and before dawn. The proportion of melanistic individuals suggests that melanism is widespread throughout the corridor. However, its impact on the species' fitness remains unclear.

First records of albinism and leucism in Ctenodactylus gundi (Rodentia: Ctenodactylidae)

Albinism and leucism are genetic disorders that cause atypical coloration. Herein, we present observation cases of hypomelanism not previously recorded in the literature for a Ctenodactylidae species. We report two observations of an albino and a leucistic specimens from two separate locations distant of 230 km in the central and southern Tunisia. The first observation was in Metlaoui (34°21′14.9″N 8°22′16.7″E) and the second in Ghomrassen (33°04′46.5″N 10°21′23.7″E). Certain factors can increase the chances of these atypical colorations in the natural population, but these phenotypes remain rare in rodents, especially in African species.

First photographic record of albinism in Baiomys taylori (Rodentia: Cricetidae)

Cases of albinism have been reported in less than 2% of living rodent species. Here, we report the first description of complete albinism in Baiomys taylori along with photographic evidence. This adult female was captured on three occasions as part of a long-term small mammal study on rangelands of extreme southern Texas. The individual was developing teats upon the third capture, an early sign of pregnancy. Despite selective pressures against albino phenotypes, this animal was able to survive to adulthood and potentially pass its albino alleles to offspring.

Distribution update, male genitalia, natural history, and conservation of the stump-tailed porcupine Coendou rufescens in South America

The stump-tailed porcupine, Coendou rufescens, is a widely distributed but scarcely documented species inhabiting the Andean region of Colombia, Ecuador, Peru, and an isolated population in Bolivia. Despite the wide distribution different aspects on its biology and ecology are still unknown. We present an update to the distribution of C. rufescens, and recent observations on the anatomy, natural history, and conservation in Colombia. For this, we described the male genitalia and present data on reproductive periods, plants used and consumed, and threats. The distribution of C. rufescens comprises 12 ecoregions in an area of 376,225 km2 for the northern group (Colombia, Ecuador, and Peru) and 393 km2 for the southern group (Bolivia). The highest elevational record is in Ecuador (4387 m), being the porcupine inhabiting at highest elevations. The anatomy of the glans is similar to that observed in Coendou quichua and constitutes the second species of Coendou with available information on glans morphology. C. rufescens consumes fruits and leaves of potato cider (Sechium edule: Cucurbitaceae) and woody shrub (Bejaria: Ericacea), and usually perches even in exotic species such as pines. Finally, common treats for the species in Colombia are related to hunting pressures, predation by domestic dogs, and roadkills.

Albinism in Brazilian common opossums (Didelphis aurita)

Albinism has been sporadically recorded in Virginia opossums (Didelphis virginiana) in the United States and Mexico, but records of pigmentation disorders in other Didelphis spp. are rare. The Brazilian common opossum (Didelphis aurita) is a cat-sized nocturnal omnivorous marsupial that inhabits Atlantic and Araucaria forests in South America. A litter of five young Brazilian common opossums was rescued at Espírito Santo state, southeast Brazil, of which two were albinos (one male, one female) and the remaining had normal pigmentation (three males). The two albinos had a complete lack of integumentary and retinal pigmentation, representing the first recorded cases of albinism in this species (and the first record in a Didelphis sp. other than the Virginia opossum).

Primer registro de leucismo en el género Coendou Lacépède, 1799 (Rodentia: Erethizontidae)

Se reporta por primera vez un caso de leucismo en la especie Coendou prehensilis. El individuo fue hallado de forma fortuita en una zona de bosque perturbado en la región de Los Andes en Venezuela.

First record of albinism in spiny rats of genus Proechimys (Rodentia: Echimyidae) from Western Amazon

Albinism is a rare condition in natural populations. One of the factors that would lead to higher allele frequency for the albino phenotype is bottleneck events, causing small population sizes and loss of genetic diversity. Here, we report the first record of albinism in one specimen of Proechimys gardneri from Porto Velho, Rondônia, Brazil. This is also the first record of albinism for the genus and for the family Echimyidae. We identified the specimen through morphology and confirmed the identification by 801 base pairs (bp) of mitochondrial marker cytochrome b (Cyt b). We also discuss the selection against albino phenotype in natural populations.

The first report of albinism in a Sundaland endemic rodent

Albinism, a congenital disorder that results in a lack of melanin deposition, is common in domesticated animals but rare in nature. Among the ∼2500 species of rodents worldwide, only 67 have published reports of albinism. Here we report the capture of an albino murid (Muridae: Rodentia) from Mt. Singgalang in West Sumatra, Indonesia. The specimen is an adolescent but sexually mature male Maxomys hylomyoides, a montane Sumatran endemic. To our knowledge, this specimen represents the first reported albino rodent from Indonesia and Sundaland, and only the second from Southeast Asia.

First record of albinism in the paca Cuniculus paca (Rodentia, Cuniculidae) in southeast Mexico

Even though there have been reports of anomalies in the colouration of several species of neotropical mammals, these events are considered to be rare within natural populations. Here we report the first case of albinism in the paca (Cuniculus paca). During the months of June and July 2017, we obtained several images of an adult albino male using camera traps in the region of Sierra Norte in Oaxaca, in the southeast of Mexico, in a medium subdeciduous forest.

Albinism in Didelphis virginiana (Kerr, 1792): the first reported case in Mexico

Atypical colorations occur in different groups of vertebrates. The loss of melanin in the skin, hair and eyes is the result of an autosomal recessive genetic entity. It causes individuals to present with a white coloration of the skin and hair, as well as red eyes, known as albino. This manuscript documents the first record in Mexico of complete albinism in a marsupial, Didelphis virginiana, captured in the Yucatan peninsula.

Albinism in Dasyurus species – a collation of historical and modern records

A new record of an albino marsupial, the northern quoll (Dasyurus hallucatus), is described and placed in the context of 10 records since 1874 from all four Australian quoll species. Of the 10 previous records, one was D. hallucatus, seven are likely to be D. viverrinus, one D. maculatus and one unknown. The recent record comprises the live capture of a healthy adult female northern quoll from the Pilbara region of Western Australia. Despite the rarity and likely deleterious nature of the albino condition, this animal appeared to be in good health, carrying eight pouch young, and was released at location of capture following tissue sampling for DNA analysis.

First record of albinism for the doglike bat, Peropteryx kappleri Peters, 1867 (Chiroptera, Emballonuridae)

Albinism is a type of deficient in melanin production could be the result of genetic anomalies that are manifest as the absence of coloration of part or the entire body of an organism. This type of chromatic disorder can affect several vertebrate species, but is rarely found in nature. Among bats, more than 450 cases of total or partial loss of body pigmentation have been reported. Herein we provide the first report of albinism for the bat species Peropteryxkappleri (Chiroptera: Emballonuridae) with two such specimens being observed from iron formation caves in a conservation unit “Floresta Nacional de Carajás”, Amazon forest, northern of Brazil.

Effect of isolation on coat colour polymorphism of Polynesian rats in Island Southeast Asia and the Pacific

Populations of vertebrate species introduced onto islands regularly develop similar phenotypic changes, e.g., larger or smaller body size, shortened limbs, duller coats, as well as behavioural changes such as increased tameness and reduced flight-initiation distance. These changes overlap in part with those associated with the 'domestication syndrome', especially tameness and changes in coat patterns, and might indicate a similar neural crest involvement in the concurrent development of multiple phenotypic traits. Here I examine long-term data on free-living populations of wild Polynesian rats from seven mainland countries and 117 islands (n = 3,034), covering the species' native and introduced range. Mainland populations showed no aberrant coat patterns, with the exception of one albino, whereas aberrant coat patterns were found in 12 island populations. Observed coat colour polymorphisms consisted of leucistic (including singular white patches), melanistic (darkly pigmented) and piebald (mixed) coat patterns. After isolation for at least seven centuries, wild Polynesian rat populations on islands seem to exhibit a trend towards a higher incidence of aberrant coat patterns. These phenotypic changes are here explained as a neutral, non-adaptive process, likely part of the 'domestication syndrome' (via the commensal pathway of domestication), in combination with genetic drift, little or no gene flow between the islands and/or the mainland and a relaxed selection (as a result of the weakening or removal of competitor/predator pressure) under commensality.