Adaptations to Aquatic, Arboreal, Fossorial and Cursorial Habits in Mammals. II. Arboreal Adaptations

Abstract

IN THE struggle for existence it is apparent that single forms and whole groups of forms would independently become modified to a life off the ground. Very often only by such an adaptation could small defenseless animals save themselves from the attacks of larger and speedier carnivores. In addition, there is the question of food. The larger animals to whom the bulk of terrestrial food naturally goes are virtually absent from the trees. We accordingly find a multitude of animals that have made this region their abode where, freed from their enemies and with an abundance of food they have prospered. PARTIAL LIST OF ARBOREAL MIAMMALS. Order MARSUPIALIA. Family Didelphyid-e (all except Chironectes). Phalangericdm Macropodcicke (Dencirolagus only). Dasyuridxe (Dasyurus and Phascologale only).

Anatomical Basis of Differences in Locomotor Behavior in Martens: AComparison of the Forelimb Musculature Between Two Sympatric Species of Martes

“…In addition, the limbs of arboreal species need to allow an animal to move against gravity, imposing strong selective pressures on the forelimb which, during climbing, becomes the dominant limb. In general, the functional requirements are reflected in skeletal traits of the animal, such as elongated and/or clawed digits for grasping, the characteristic orientation of the glenoid cavity of the scapula facilitating shoulder mobility, and relatively longer and more robust forelimbs relative to the hindlimbs (Dublin, ; Ashton and Oxnard, 1964; van Valkenburgh, ; Hildebrand and Goslow, ).…”

Anatomical adaptations of the hind limb musculature of tree-kangaroos for arboreal locomotion (Marsupialia : Macropodinae)

“…Adaptation to an arboreal lifestyle has taken place in a number of mammalian groups including Primates, Carnivora, 'Insectivora', Rodentia, Xenarthra and various families of Marsupialia (Dublin 1903). The uneven and discontinuous nature of the arboreal realm imposes strong selective pressure on animals towards maintaining contact with the substrate, maintaining balance, and providing propulsion on flexible, discontinuous and inclined branch substrates (Grand 1990).…”

“…and Choloepus spp.) binturong (Arctictis binturong) and koala (Phascolarctos cinereus), tend to move relatively slowly and deliberately, and employ prehensile digits and/or large, grasping claws to provide increased resistance to slipping and to help maintain contact with the substrate (Dublin 1903;Cartmill 1979;Grand 1990a;Argot 2001). A long, muscular, nonprehensile tail may be employed as a counter balance; or a prehensile tail may function as a grasping organ (Organ, Teaford et al 2009;Organ 2010).…”

“…Further, a greater balance between pushing and pulling motions results in a trend towards a more even distribution of muscle mass between the fore-and hind-limbs in arboreal groups when compared to their terrestrial counterparts (Grand 1990b). Morphological variation between related species reflects the degree to which species inhabit the canopy (Dublin 1903). …”

Positional behaviour and tail use by the bare-tailed woolly opossum Caluromys philander (Didelphimorphia, Didelphidae)

“…Arboreal animals present many adaptations to safely use the vertical strata of the forest, such as elongation of the limbs, opposable hallux and pollex, prehensile tails, and specific locomotory modes, such as diagonal couplets (Dublin 1903;Lemelin 1999;Stevens 2008;Wallace and Demes 2008). Establishing the relationship between behaviour traits and morphological specializations, and determining converging adaptations, contribute to the comprehension of how natural selection operates in arboreal species.…”