Don E. Wilson

Mammal species of the world : a taxonomic and geographic reference

Wilson and Reeders Mammal Species of the World is the classic reference book on the taxonomic classification and distribution of the more than 5400 species of mammals that exist today. The third edition includes detailed information on nomenclature and, for the first time, common names. Each concise entry covers type locality, distribution, synonyms, and major reference sources. The systematic arrangement of information indicates evolutionary relationships at both the ordinal and the family level. This indispensable reference work belongs in public and academic libraries throughout the world and on the shelf of every biologist who works with mammals.

Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus

Abstract The substantial body of research on Holarctic ground squirrels amassed over the past century documents considerable variability in morphological, cytogenetic, ecological, and behavioral attributes in the genus Spermophilus F. Cuvier, 1825. Recent molecular phylogenetic studies suggest that the traditionally recognized genera Marmota Blumenbach, 1779 (marmots), Cynomys Rafinesque, 1817 (prairie dogs), and Ammospermophilus Merriam, 1892 (antelope ground squirrels) render Spermophilus paraphyletic, potentially suggesting that multiple generic-level lineages should be credited within Spermophilus. Herein, we recognize 8 genera formerly subsumed in Spermophilus, each of which is morphologically diagnosable, craniometrically distinctive, and recovered as a monophyletic clade in phylogenetic analyses utilizing the mitochondrial gene cytochrome b. Generic-level names are available for each of these ground squirrel assemblages, most of which are exclusively or predominantly North American in distribution (Notocitellus A. H. Howell, 1938; Otospermophilus Brandt, 1844; Callospermophilus Merriam, 1897; Ictidomys J. A. Allen, 1877; Poliocitellus A. H. Howell, 1938; Xerospermophilus Merriam, 1892; and Urocitellus Obolenskij, 1927). Only Spermophilus sensu stricto is restricted to Eurasia. Generic subdivision of Spermophilus more aptly illuminates the taxonomic relationships, ecomorphological disparity, and biogeographic history of Holarctic ground squirrels.

Morphologic Properties of Bat Wings

A method was devised for estimating aspect ratio, wing ratio, wing area, wing loading, and wing length from study skins of bats. These measures were taken of 136 species representing 15 families. Wing area and loading are positively, and wing length negatively, correlated with size. Aspect and tip ratios are independent of size and of each other. Distinctive combinations of some of these variables characterize groups of bats that presumably have similar flight modes. Speed is positively correlated with aspect ratio and tip index, but regresses significantly only on the former. Long tips coupled with low aspect ratio may characterize hoverers. Long wings and short tips may characterize bats that are capable of remaining airborne at slow speeds. Most bats with low aspect ratios are forest dwellers, whereas species with high aspect ratios are migrants and foragers in open areas.

Relative Brain Size and Demographic Strategies in Didelphid Marsupials

Mean cranial volumes were established for 17 species of didelphid marsupials. The variability in mean cranial capacity for any given weight class was examined. Arboreal preference is associated with a relatively large brain except in the case of Philander opossum. Among didelphid opossums those with relatively large cranial capacities are characterized by a relatively longer life span and lower litter sizes. When compared to prosimians, didelphids generally exhibit shorter life spans, smaller relative cranial capacities, and larger litters. It is concluded that some didelphid marsupials (e.g., Caluromys) have undergone selection toward a demographic strategy which is in part convergent with the extant nocturnal prosimians.

Observations on the neotropical disk-winged bat, Thyroptera tricolor spix.

Study of 42 marked Thyroptera tricolor in Puntarenas Province, Costa Rica, revealed that the animals live in groups of six to seven individuals. The members of each group always roost together in a rolled leaf of a plant, usually of the genus Heliconia. Each roost is occupied for one day. Each group seems to occupy an exclusive roosting area that averages 3000 square meters. The disk-winged bat, Thyroptera tricolor Spix, is one of two species in the Neotropical family Thyropteridae. It occurs from southern Mexico through much of tropical South America. A second species, T. discifera, occurs in parts of Central and South America. These small, delicately built bats (average weight about 4 grams) have forwardly directed funnel-shaped ears and very small eyes like funnel-eared bats (family Natalidae) and smoky bats (family Furipteridae). Thyroptera differs from bats of these other two Neotropical families, however, in having well-developed suction disks located at the wrist and on the ventral surface of the hind foot. These disks, the anatomy and functioning of which have been studied in detail by Wimsatt and Villa (1970), allow the animal to attach itself to smooth surfaces, such as leaves or glass. So far disk-winged bats are known to roost only inside the rolled new leaves of members of the banana family (Musaceae) or related plants. Within the leaves the bats arrange themselves in a vertical row in a head-up posture, attaching themselves to the leaves by means of the suction disks. Our studies of these bats in lowland Costa Rica revealed that the number of suitable roosts in a given area on any given day is very limited. Thus it is possible to locate all the potential roosts and find the resident bats with a considerable degree of predictability. After capture the animals may be marked for future recognition, and relocated at will. Here we present the results of two weeks of study of these intriguing little bats in Puntarenas Province, Costa Rica. Our findings suggest that the bats are organized into roosting colonies, that the members of each colony remain together, rejoining even if separated, and that each colony occupies an exclusive roosting area.

Ecological Significance of Chiropteran Morphology

That form is related to function in animal life is a concept that goes back at least to Aristotle. Relating structure to function has been a central occupation of anatomists, and the subject of functional morphology has a dedicated following. Yet the suggestion that an organism’s ecological role can be predicted from its morphology often elicits opposition. Because behavior is so flexible, individual animals may do many things that a study of their anatomy would not predict. Ducks with bills highly specialized for filtering small particles from water and mud may, nevertheless consume small vertebrates, centipedes, lettuce, corn, and dog food with great skill. The objection to making ecological predictions from morphology seems to be that although we can assert that a bat eats fruit because its teeth are constructed in a certain way, because of the observed variability in dietary proclivities of individual fruit bats we cannot make more refined predictions about the size and kind of fruit consumed, the extent to which animals are eaten, the nature of seasonal changes in diet, and so on. Our contention is that because the selective regimen imposed on a species through evolutionary time includes these minor variations, they are probably reflected in a bat’s phenotype. By comparing the morphology of members of a feeding guild of bats, it should be possible to predict ways in which the several species differ in food habits, foraging styles, shelter seeking, and other ecological traits.

A SYNOPSIS OF DISTRIBUTION PATTERNS AND THE CONSERVATION OF MAMMAL SPECIES

The 26 orders of living mammals occur in a variety of habitats; 97.5% of the species occupy terrestrial while only 2.5% inhabit marine environments. The most recent complete compilation lists 136 families, 1,135 genera, and 4,629 living and recently extinct species. The Ethiopian region possesses the most diverse fauna (52 families, 17 endemic) and 23% of all described species. This region has the highest generic and species endemism; almost 80% of the genera and >90% of the species are endemic. Fauna of the Oriental region also is rich (50 families, three endemic), including >20% of the worlds species. The Palearctic region possesses 42 families (none endemic) and 18% of the worlds species. The Australian region includes 10% of the worlds species in 28 families (12 endemic); >60% of the genera and almost 90% of the species are endemic. The richest diversity of mammals in the New World occurs in the Neotropical region with 50 families (19 endemic) and 24% of the worlds species (>80% endemic). The Nearctic region (37 families, two endemic) is home to 14% of all described species. Three terrestrial orders (Primates, Peris-sodactyla, and Proboscidea) and two marine orders (Cetacea and Sirenia) require immediate conservation efforts. Within the remaining 21 orders, ca. 30% of Old World and 15% of New World families are at risk. Additionally, almost 15% of the worlds species are rated as endangered or vulnerable, and another ca. 10% are categorized as potentially vulnerable; these species warrant conservation strategies. The areas of the world with the greatest mammalian diversity are also the most poorly known, so conservation needs may be under-represented in those regions.

Geographic Variation in Sea Otters, Enhydra lutris

Univariate and multivariate analyses of 20 skull characters of 304 adult sea otters from throughout the geographic range strongly suggest that three subspecies should be recognized. The nominate form, Enhydra lutris lutris , occurs from the Kuril Islands north to the Commander Islands in the western Pacific Ocean. Individuals of E. l. lutris are characterized by large size and wide skulls with short nasal bones. E. l. nereis is found along the California coast and off San Nicolas Island, where the species recently has been reintroduced from coastal California. Specimens of E. l. nereis have narrow skulls with a long rostrum and small teeth, and usually lack the characteristic notch in the postorbital region found in most specimens of the other two subspecies. A new subspecies described by Don E. Wilson in this report, occurs throughout the Aleutian Islands and southward in the eastern Pacific to Washington. Specimens of the new subspecies are intermediate in size in most, but not all, characters and have longer mandibles than either of the other two subspecies.

Taxonomic revision of the olingos (Bassaricyon), with description of a new species, the Olinguito

Abstract We present the first comprehensive taxonomic revision and review the biology of the olingos, the endemic Neotropical procyonid genus Bassaricyon, based on most specimens available in museums, and with data derived from anatomy, morphometrics, mitochondrial and nuclear DNA, field observations, and geographic range modeling. Species of Bassaricyon are primarily forest-living, arboreal, nocturnal, frugivorous, and solitary, and have one young at a time. We demonstrate that four olingo species can be recognized, including a Central American species (Bassaricyon gabbii), lowland species with eastern, cis-Andean (Bassaricyon alleni) and western, trans-Andean (Bassaricyon medius) distributions, and a species endemic to cloud forests in the Andes. The oldest evolutionary divergence in the genus is between this last species, endemic to the Andes of Colombia and Ecuador, and all other species, which occur in lower elevation habitats. Surprisingly, this Andean endemic species, which we call the Olinguito, has never been previously described; it represents a new species in the order Carnivora and is the smallest living member of the family Procyonidae. We report on the biology of this new species based on information from museum specimens, niche modeling, and fieldwork in western Ecuador, and describe four Olinguito subspecies based on morphological distinctions across different regions of the Northern Andes.

Natural urine concentrations and composition in neotropical bats

Abstract 1. 1. Among neotropical bats with subdivided renal medullae, some natural urine samples are equal in concentration to mean maximum calculated levels. 2. 2. Natural urine osmotic pressures in frugivorous phyllostomids are less than in other phyllostomids which, in turn, are less than in insectivorous bats. 3. 3. Urinary sodium (Na+) concentrations show no difference between frugivorous. insectivorous, and others, but urinary potassium (K+) levels in frugivores are higher than in other bats. 4. 4. Natural urine concentrations are primarily related to diet and secondarily to environmental dehydration pressure.