Dark Pelage Research Articles

Ancient hybridization patterns between bighorn and thinhorn sheep.

Whole-genome sequencing has advanced the study of species evolution, including the detection of genealogical discordant events such as ancient hybridization and incomplete lineage sorting (ILS). The evolutionary history of bighorn (Ovis canadensis) and thinhorn (Ovis dalli) sheep present an ideal system to investigate evolutionary discordance due to their recent and rapid radiation and putative secondary contact between bighorn and thinhorn sheep subspecies, specifically the dark pelage Stone sheep (O.dalli stonei) and predominately white Dall sheep (O.dalli dalli), during the last ice age. Here, we used multiple genomes of bighorn and thinhorn sheep, together with snow (O.nivicola) and the domestic sheep (O.aries) as outgroups, to assess their phylogenomic history, potential introgression patterns and their adaptive consequences. Among the Pachyceriforms (snow, bighorn and thinhorn sheep) a consistent monophyletic species tree was retrieved; however, many genealogical discordance patterns were observed. Alternative phylogenies frequently placed Stone and bighorn as sister clades. This relationship occurred more often and was less divergent than that between Dall and bighorn. We also observed many blocks containing introgression signal between Stone and bighorn genomes in which coat colour genes were present. Introgression signals observed between Dall and bighorn were more random and less frequent, and therefore probably due to ILS or intermediary secondary contact. These results strongly suggest that Stone sheep originated from a complex series of events, characterized by multiple, ancient periods of secondary contact with bighorn sheep.

Myotis chiloensis(Chiroptera: Vespertilionidae)

Myotis chiloensis (Waterhouse, 1838), the Chilean myotis, is found only in Argentina and Chile, where it is the most common bat species in the southern part of Chile. It is a small insectivorous bat and differs from other members of the genus because of its darker pelage. It uses human buildings and caves to establish colonies, and forages in dense forests of Nothofagus to capture insects, thereby providing ecosystem services to agriculture and forestry. M. chiloensis is considered of “Least Concern” by the International Union for Conservation of Nature and Natural Resources.

Mustela africana(Carnivora: Mustelidae)

Abstract: Mustela africana Desmarest, 1818, is a mustelid commonly called the tropical or Amazon weasel and is South America's largest weasel. It has dark pelage with little variation in color on the dorsum; the venter is pale colored with a dark medial longitudinal stripe, matching the color of the dorsum. The species is endemic to the Amazon Basin. Known from about 30 records over 2 centuries from different localities of Brazil, Ecuador, and Peru, it may be one of the rarest carnivores in South America. Globally, it is considered “Least Concern” by the International Union for Conservation of Nature and Natural Resources.

A new species of swamp rat of the genus Scapteromys waterhouse, 1837 (Rodentia: Sigmodontinae) endemic to Araucaria angustifolia forest in Southern Brazil.

A new species of swamp rat of the genus Scapteromys from the Meridional Plateau of Southern Brazil is described. Morphological, molecular, and karyological analysis support the recognition of the new species, distinct from S. aquaticus and S. tumidus. Scapteromys sp. nov. is significantly smaller than the congeneric taxa considering most of the external and craniometric measurements and the pelage is conspicuously grayer and darker. It can be distinguished from S. tumidus by the laterally extended thenar pad of the manus and the parallel edges of the hamular process of the pterygoid, and from S. aquaticus by a grayer and darker pelage and smaller values of most external and craniometric measurements. Karyological analysis indicated a difference in chromosome numbers across the distributional range: 2n=34 and 2n=36. A total of 11 haplotypes were found along the range of the new species within the biogeographic province of Araucaria angustifolia Forest. Strongly supported substructure was found within the new taxon, resulting in two reciprocally monophyletic clades.

Peromyscus furvus (Rodentia: Cricetidae)

Abstract Peromyscus furvus Allen and Chapman, 1897 is a cricetid rodent commonly called the blackish deermouse because of its characteristically dark pelage coloration. It is 1 of 56 species in the genus Peromyscus and is of large size compared with the majority of its congeners. Its distribution is restricted to moderate- to high-elevation cloud forests along the eastern slopes of the Sierra Madre Oriental in Mexico. The International Union for Conservation of Nature and Natural Resources' status was recently reassessed and set to “Data Deficient,” although P. furvus has lost the majority of its natural habitat to deforestation. Sequence data indicate that P. furvus may be a composite taxon, with the southern population forming an independent evolutionary lineage.

The enigmatic Arunachal macaque: its biogeography, biology and taxonomy in Northeastern India

The purpose of this study was to determine the taxonomic status of an unidentified enigmatic macaque seen by scientists since the late 1990s in Arunachal Pradesh, India. We surveyed 49 troops of enigmatic macaques in four districts of Arunachal Pradesh. The population studied is from the macaque sinica-group as defined by the reproductive organs. The main species-separating trait in the sinica-group is tail length to head and body length ratio that decreases with latitude and elevation. We gathered data on morphology, pelage descriptions, tail to head and body ratios and tail to hind foot ratios from photos and live animals (43 individuals from 36 areas) within the range of and between the two subspecies of the Assamese macaque (Macaca assamensis). We compared the data to six western Assamese macaques and studies of Assamese macaques and related species. We found great variability in tail length, pelage color, facial skin color, and facial and hair patterns. The tail/head-body and tail/foot ratios, although varied, supported the hypothesis that these enigmatic forms were part of a population of Assamese macaques found in the gap between the two subspecies ranges and were not a new species as described earlier. Instead, we found evidence that darker pelage, larger body size, and shorter tails occur at higher elevations and latitudes similar to the general trend in the sinica-group's adaptations to colder climates. Thus, the population may be important for its variation, throwing light on the speciation process and how the northern species of Tibetan macaques evolved from an ancestor similar to the Assamese macaques as adaptations to a colder climate.

Temperature's influence on the activity budget, terrestriality, and sun exposure of chimpanzees in the Budongo Forest, Uganda

Chimpanzee (Pan troglodytes schweinfurthii) activity budget, terrestriality, and sun exposure were found to be influenced by the immediate environmental temperature. Thirty adult chimpanzees in the Budongo Forest, Uganda, were observed for 247 h. Temperatures in the shade and sun, sky cover, sun exposure, activity, and terrestriality were recorded at 5-min intervals at <15 m from the center of the party. Terrestriality frequency was 26.5% for females and 41.5% for males. Terrestriality and resting both show a significant positive correlation with temperature in the sun. Controlling for seven potential confounding factors, temperature in the sun remained the strongest predictor of terrestriality. The difference between temperatures in the sun and shade had a significant effect on chimpanzee sun exposure frequency. Time spent continuously in the sun was negatively correlated with temperature, beginning to decrease around 30 degrees C, and markedly decreasing around 40 degrees C. A concurrent experiment determined that dark pelage (lacking physiological coping mechanisms) exposed to the same solar regime can easily reach 60 degrees C within minutes. This study indicates that both temperature in the sun and sun exposure play a role in influencing chimpanzee activity behavior, and specifically suggests that chimpanzees thermoregulate behaviorally both by moving to the ground and by decreasing their activity level. These results, in the context of deforestation and increasing global temperatures, have physiological and conservation implications for wild chimpanzees.

Ecological and behavioral correlates of coloration in artiodactyls: systematic analyses of conventional hypotheses

To test the generality of adaptive explanations for coat coloration in even-toed ungulates, we examined the literature for hypotheses that have been proposed for color patterns exhibited by this taxon, and we derived a series of predictions from each hypothesis. Next, we collected information on the color, behavioral, and ecological characteristics of 200 species of even-toed ungulates and coded this in binary format. We then applied chi-square or Fisher's Exact probability tests that pitted presence of a color trait against presence of an ecological or behavioral variable for cervids, bovids, and all artiodactyls. Finally, we reanalyzed the data by using concentrated-changes tests and a composite molecular and taxonomic phylogeny. Hinging our findings on whether associations persisted after controlling for shared ancestry, we found strong support for hypotheses suggesting even-toed ungulates turn lighter in winter to aid in concealment or perhaps thermoregulation, striped coats in adults and spotted pelage in young act as camouflage, side bands and dark faces assist in communication, and dark pelage coloration is most common in species living in the tropics (Gloger's rule). Whereas white faces, dark legs, white legs, dark tails, and white tails did not appear to assist in communication alone, legs and tails that were either dark or white (i.e., conspicuous) did seem to be linked with communication. There was moderate support for hypotheses that countershading aids concealment, that white faces are a thermoregulatory device, and that white rumps are used in intraspecific communication. There was weak support for spots in adults and stripes in young providing camouflage and for dark leg markings being a form of disruptive coloration. We found little or no evidence that overall coat color serves as background matching, that side bands are disruptive coloration devices, or that white rumps help in thermoregulation. Concealment appears the principal force driving the evolution of coloration in ungulates with communication, and then thermoregulation, playing less of a role.

REVIEW OF BULLIMUS (MURIDAE: MURINAE) AND DESCRIPTION OF A NEW SPECIES FROM CAMIGUIN ISLAND, PHILIPPINES

Bullimus is 1 of 15 genera of murid rodents endemic to the oceanic portion of the Philippines (i.e., excluding Palawan and other islands on the Sunda Shelf). Two species have been recognized previously: B. bagobus, widespread on Mindanao and on islands that were connected to it during Pleistocene periods of lower sea level and B. luzonicus, occurring only on Luzon. Recent surveys have revealed a 3rd species endemic to the small island of Camiguin, located just north of Mindanao and isolated from that large island by deep water. Multivariate analyses support the recognition of these 3 species. The new species of Bullimus from Camiguin is distinguishable from congeners by its smaller size, soft and uniformly dark pelage, inflated braincase, shorter palate and incisive foramina, more divergent molar toothrows, and other cranial and dental features. The patterns of variation and island distribution in Bullimus are consistent with our understanding of regional geography; the 3 species occur on separate islands or island groups that remained isolated during periods of lower sea level. The discovery of a species endemic to Camiguin reflects the fact that this small island is close enough to Mindanao to have received some nonvolant mammals by overwater dispersal, but its isolation has been sufficient to promote speciation.

Morphologic Variation among Rock Pocket Mice (Chaetodipus intermedius) from New Mexico Lava Fields

-Intraspecific variation in external and cranial measurements of rock pocket mice (Chaetodipus intermedius) was evaluated using 312 adult specimens (145 males and 167 females). Males were larger than females for 8 of 16 characters examined, and significant geographic variation occurred in 15 characters for one or both sexes. Generally, largest means of male and female characters were from specimens representing the Carrizozo malpais; the smallest mice were from the Afton lava flows. Specimens from the Pedro Armendariz lava field and the nearby Fra Cristobal Range were the closest geographically and the most similar morphologically. Rock pocket mice (Chaetodipus intermedius) occur in northwestern Mexico and throughout much of Arizona and New Mexico (Hall, 1981). Of the 10 currently recognized subspecies of C. intermedius (Hall, 1981), three are confined to isolated black-lava outcrops, C. i. nigrimontis occurs on Black Mountain, Pima Co., Arizona; C. i. ater occupies the Carrizozo malpais, Lincoln and Otero Cos., New Mexico; and C. i. rupestris is found on the Afton lava flows, Dona Ana Co., New Mexico. In addition, an isolated population of C. intermedius inhabits the Pedro Armendariz lava field in Sierra and Socorro Cos., New Mexico (Weckerly, 1983). These geographic isolates differ markedly in coloration from populations of rock pocket mice in surrounding areas (Dice, 1929; Benson, 1932; Blossom, 1933; Weckerly, 1983). How much these populations differ morphologically from each other or from nearby populations has not been established. The restricted distribution and presumably intense natural selection for dark pelage coloration may also be associated with some selection for morphologic variation among the forms inhabiting lava fields. Best and James (1984) noted that some lava-dwelling rattlesnakes (Crotalus), in addition to being darker, were much smaller than other populations in New Mexico. Perhaps body size, as well as coloration, are affected by selection pressures on lava fields. However, Rogers and Schmidly (1981) found essentially no morphologic differentiation among similar populations of Neotoma albigula. To determine if populations of C. intermedius differed between lava fields and an adjacent rocky outcrop, we studied morphologic variation in specimens collected from three lava fields and one mountain range in south-central New Mexico. Our purposes were to investigate the degree of sexual dimorphism, amount and pattern of interlocality variation within each character, and phenetic relationships among populations. MATERIALS AND METHODS.-We analyzed 4 external and 12 cranial measurements (Fig. 1) for 312 adult Chaetodipus intermedius. Total length, tail length, hind foot length, and ear length were recorded to the nearest mm from the specimen tag. Nasal width and interparietal width were taken with an ocular micrometer in a stereo microscope at lOx, and the remaining cranial and mandible measurements were made to the nearest 0.1 mm using dial calipers. Specimens were NOVEMBER 27, 1985 THE SOUTHWESTERN NATURALIST 30(4):491-501 This content downloaded from 157.55.39.144 on Mon, 25 Jul 2016 04:07:31 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist

Age Estimation of Living Sea Otters

First premolars extracted from 46 immobilized sea otters (Enhydra lutris) in Prince William Sound, Alaska, were used to ascertain age by counting cementum annuli in stained, longitudinal sections. Weight, body measurements, teeth condition, and pelage coloration were strongly associated with age as estimated from cementum annuli. A relationship between morphological characteristics and cementum age was particularly evident in males. In instances where teeth cannot be extracted, morphological characteristics provide a means for estimating age. Previous investigators used such characteristics as weight and pelage coloration to assess age, but were unable to verify their estimates. J. WILDL. MANAGE. 48(2):456-463 Techniques for estimating age of sea otters have been based largely upon tooth wear and replacement, characteristics of the skull, and size or weight of the baculum, enabling researchers to categorize dead individuals as pups, immatures, subadults, adults, and aged adults (Fisher 1941, Lensink 1962, Kenyon 1969, Morejohn et al. 1975). Barabash-Nikiforov (1935) used body size and weight to establish narrower age groupings (intervals <2 years) but had no means of verification. More exact methods of age estimation developed since the discovery that annual growth rings form in the teeth and bones of many mammals (Scheffer 1950, Laws 1952, Klevezal' and Kleinenberg 1967), including sea otters (Klevezal' and Marakov 1966 in Klevezal' and Kleinenberg 1967; K. B. Schneider, unpubl. rep., Alaska Dep. Fish and Game, Fed. Aid Proj. W-17-4 and W-17-5, 1973; Green 1978). However, none of these researchers used teeth from live otters. Weight and pelage coloration have been used to classify age of live otters (Loughlin 1980). Loss of pigmentation in the guard hairs on the head and neck with progressive whitening of the shoulders and chest with increased age have long been recognized (Steller 1751, Barabash-Nikiforov et al. 1947, Jones 1951, Kenyon 1969, Estes 1980). This condition occurs in both sexes, but has been observed more frequently in males; it does not occur in all individuals as otters with dark pelage and worn teeth have been observed (Barabash-Nikiforov et al. 1947, Kenyon 1969). Age categories ba ed on pelage color or weight have not been correlated with chronological age. In my study, cementum annuli of teeth extracted from living sea otters provided a standard for age estimation by which other age classification techniques, based on body size and pelage color, were compared. Dapson (1980:542) recommended against this type of analysis, where one age estimation technique is compared to ages derived by another technique (instead of to known ages), arguing that there is little practical utility for such information. Indeed, the limitations of this procedure should be considered. However, if it can be shown that cementum annuli provide a reasonably accurate indication of chronological age, then accurate predictors of the number of cementum annuli also may be accurate predictors of age. These predictors of age should be better than age classification techniques currently available for sea otters and may 'Present address: Forest Wildlife Populations and Research Group, Minnesota Department of Natural Resources, 1201 East Highway 2, Grand Rapids, MN 55744. 456 J. Wildl. Manage. 48(2):1984 This content downloaded from 157.55.39.243 on Thu, 06 Oct 2016 05:00:20 UTC All use subject to http://about.jstor.org/terms SEA OTTER AGE ESTIMATION * Garshelis 457 contribute substantially to field studies of the species. I thank J. A. Garshelis, D. B. Siniff, T. D. Williams, and J. O. Ruehle for assistance with data collection. This study was supported by a grant from the U.S. Dep. of Energy, contract DE-AC0276EV01332. The U.S. Fish and Wildl. Serv., in particular A. M. Johnson, provided necessary field equipment. The Univ. of Minnesota Computer Cent. furnished computer time for data analysis.

First report of an ectoparasite, Cryptonyssus desultorius (Acari: Mesostigmata: Macronyssidae), associated with the spotted bat.

The Spotted Bat, Euderma maculatum (Vespertilionidae), has been known since 1890, but it has been collected infrequently despite considerable interest in the species. Interest may have been generated by the batʼs striking appearance, with unique white markings on a generally dark pelage and very large ears, as well as by its elusiveness and the paucity of biological knowledge about it.

Differentiation of the Canada lynx, Felis (Lynx) canadensis subsolana, in Newfoundland

Cranial measurements, standard measurements, weights, and pelage color of the lynx from Newfoundland (Felis canadensis subsolana) and the North American mainland (F. c. canadensis) were compared to assess the difference between the two forms. Of the nine bivariate cranial relationships investigated, five (zygomatic width, mastoid width, interorbital width, postorbital width, and width between the postorbital processes) were found to be significantly greater relative to condylobasal length in F. c. subsolana. Overlap in variation between the two forms is considerable, however, Standard measurements and weights do not differ significantly. In addition, F. c. subsolana has a somewhat darker pelage than the mainland form. The isolation of the insular form may be of relatively recent date, as it has diverged only slightly from mainland populations and its recognition as a separate subspecies is questionable.

Taxonomic Status of the Brush Mouse, Peromyscus boylii cansensis Long, 1961

In the colurse of a study of mammals from southeastern Kansas and northeastern Oklahoma, the authors have collected specimens of the brush mouse, Peromyscus boylii cvnsensix Long, from its typn locality and also from a place about 16 miles southwest of the type locality. The results of studies of these specimens, and of the holotype and paratypes of the subspecies, are presented and discussed herein. Long (1961:101) named Peromyscux boylii cvnCensiS from specimens obtained in Chautauqua and Cowley counties of Kansas. He thought it was geographically isolated from Peromyxcgs boylti attwateri, which is linown from farther to the east in Kansas, as well as from southwestern Missouri and northwestern Arkansas, southwestward through Oklahoma to Texas (see Hall and Kelson, 1959:634). According to Long (1961: 101-102), canxensis differs from attwateri as follows: less protuberant eyes; shorter tail (91 verxus 103 per cent of length of head and blody); darker pelage; and longer skull and nasals.

Six Mutations Affecting Coat Color in Ranch-Bred Mink

Various workers have reported six mutant genes (p, b, S, F, ip and cH) affecting coat color in the ranch-bred mink. In this paper, symbols have been proposed for six additional genes, and the main effects of these in altering the coat color of the dark (wild type) mink to the royal silver (sRs or sRsR), colmira (Cmcm), ebony (Ebeb), aleutian (alal), green-eyed pastel (bgbg) and goofus (oo) color phases have been discussed. Several color phases resulting from combinations of some of these mutant genes have been described. S and sR are alleles; Eb and b are linked, being approximately 26 cross over units apart. The twelve mutant genes can be divided roughly into two groups on the basis of their major effects in changing the wild type (dark) coat color to the different color phases. F, S, sR, Cm and Eb when singly substituted for their non-mutant alleles alter the natural dark pelage of the mink by producing a pattern. These patterns for the most part result from white spotting (royal silver, black cross), a differential between the pigmentation of the underfur and the guard hair (ebony), or a combination of both (blufrost, colmira). On the other hand, the genes p, ip, al, b, bg, and cH, which produce the recessive color phases platinum, imperial platinum, aleutian, brown-eyed pastel, green-eyed pastel and albino respectively when substituted for their non-mutant alleles, alter the natural dark color by affecting the pigmentation over the entire pelage. The gene for the goofus color phase is the only exception to this rule so far, in that it is recessive to its non-mutant allele, but alters the wild type color by producing a pattern as do the dominant mutant genes.