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Gliding distance and height loss for the Mahogany Glider and the Sugar Glider. Note that this figure does not consider the initial drop in the glide after launch, only the overall glide.
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The gliding angle of the Mahogany Glider Petaurus gracilis and the Sugar Glider Petaurus breviceps was determined from field studies by measuring the height of launch and landing of glides and the distance travelled. This showed no significant difference between these two species in glide ratio, which averaged 1.91 and 1.82 m distance per 1 m loss...
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Context 1
... the Mahogany Glider or Sugar Glider (F 1,25 = 1.878, P > 0.05 and F 1,16 = 0.0001, P > 0.05, respectively). The distance travelled by individual Mahogany Gliders and Sugar Gliders against height loss can be seen in Fig. 2. Although it did not travel significantly further (t 42 = 0.711; P > 0.05), the Mahogany Glider was found to have a slightly greater glide ratio than the Sugar Glider (1.91 and 1.82, respectively). This, in turn, resulted in the Mahogany Glider having a slightly flatter angle of descent than the Sugar Glider (28.26 ± 0.84 degrees and ...
Citations
... Mahogany gliders (Petaurus gracillus-230-370 g) and brushtail possums (Trichosaurus vulpecula-1-3 kg) are phylogenetically distant and sympatric relatives, diverging an estimated 50 million years ago (Mitchell et al., 2014). Both are nocturnal, their ranges occupy open woodland environments of varying complexity and assemblage (Dettmann et al., 1995;Jackson, 2000aJackson, , 2000bJackson & Johnson, 2006). Their diet is generalist, both species have been observed eating a varied diet of foliage, nectar, pollen, plant exudates and arthropods; however, brushtail possums are noted to include a higher proportion of foliage into their diets than their gliding counterparts (Allan et al., 2019;Dettmann et al., 1995;Jackson & Johnson, 2006;Lindenmayer, 1997). ...
... Therefore, delegation of time to foraging efforts such as extending foraging ranges, would presumably be less in brushtail possums due to the abundance and distribution of foliage compared to exudates (Martin & Martin, 2007). This is not only reflected in the percentage difference of foraging behaviours like climbing, walking and jumping, but also representative of the species home ranges, where mahogany gliders have been observed to maintain larger areas (19-21 ha) (Jackson, 2000a(Jackson, , 2000b(Jackson, , 2011. A study on Malayan colugos (Galeopterus variegatus) corroborates our finding, identifying that the total gliding distance (7960 m) significantly exceeds the distance travelled (1342 m) . ...
Gliding has evolved independently as an isolated adaptive event within many vertebrate taxa. Yet, the underlying selection forces that led to these innovative adaptations remain ambiguous, especially in species that preclude direct observation. Our study utilized accelerometry and machine learning algorithms to compare the behavioural repertoires of two sympatric species, the Mahogany glider (Petaurus gracilis) and brushtail possum (Trichosaurus vulpecula), as to explore previously proposed selection pressures such as energy expenditure (VeBA), canopy use and ground avoidance measured by activity budgets. We found that mahogany gliders on average expend more activity‐related energy than brushtail possums but at different stages throughout the day. Canopy use was observed to be greater amongst mahogany gliders than brushtail possums, and we observed frequent ground use in brushtail possums yet none in mahogany gliders. The study found strong evidence to support ground avoidance as a potential driver for gliding evolution. The implications of these findings are important when considering the lack of knowledge surrounding evolved gliding behaviours in marsupials. Furthermore, the use of accelerometers and machine learning algorithms in behavioural studies has proven to be a robust and informative method and should be incorporated into future studies to understand the evolution of gliding behaviour.
... Globally, this pattern mirrors the overall reduction in faunal diversity in extratropical, colder regions; however, some temperate forests are surprisingly rich in gliding vertebrates. For instance, temperate and subtropical Australia supports a high diversity of gliding mammals (Jackson 2000, Cremona et al. 2020, McGregor et al. 2020. ...
... Gliding has been shown to be the most energy efficient form of locomotion when trees are further apart than half of the maximum distance an animal can glide (Norberg 1983, Norberg 1985; however, gliding capacity differs between taxa and effective glide distance is influenced by tree height. Amphibians, for example, are less apt as aerial acrobats than reptiles or mammals; they can glide up to 1.82 m distance per 1 m altitude loss (Jackson 2000, Dudley et al. 2007). Many amphibians use digital webbings to slow their descent without particular emphasis on moving horizontally (Dudley et al. 2007). ...
In vertebrates, gliding evolved as a mode of energy‐efficient locomotion to move between trees. Gliding vertebrate richness is hypothesised to increase with tree height and decrease with tree density but empirical evidence for this is scarce, especially at a global scale. Here, we test the ability of tree height and density to explain species richness of gliding vertebrates globally compared to richness of all vertebrates, while controlling for biogeographical and climatic factors. We compiled a global database of 193 gliding amphibians, mammals and reptiles and created maps of species richness from extent‐of‐occurrence range maps. We paired species richness of gliding vertebrates with spatial estimates of global tree height and density and biogeographical regions (BGRs) as covariates to account for ecological and historical differences among global regions. We used univariate linear and multivariate generalised linear mixed‐effect models to evaluate relationships between species richness and tree height and density, and the interaction between both variables. We found that richness of all gliding vertebrate species increased significantly with tree height, while results for richness of gliding amphibians, mammals and reptiles alone indicated mixed responses especially among different BGRs. Mixed‐effect models mirrored these results for richness of all gliding species combined, while also revealing the mixed response to tree height and denisyt of richness of gliding amphibians, mammals and reptiles. Richness of all vertebrate species – gliding and non‐gliding – also increased with tree height and density, but at a lesser rate than richness of gliding vertebrates, indicating a greater influence of forest structure on richness patterns of gliding vertebrates. Our results support hypotheses stating that gliding in vertebrates evolved globally in tall forests as energy‐efficient locomotion between trees, and provide further evidence for the importance of forest structure to explain the distribution of gliding vertebrates.
... gracilis) and Sugar Gliders have glide ratios of 1.9: 1 and 1.8:1 and glide angles of 28 and 30 , respectively, suggest they can glide twice Relationship for metabolic rate (ml O 2 g À1 h À1 ; black lines) and cost of transport (ml O 2 g À1 km À1 ; gray lines) with speed for a Red Kangaroo (Osphranter ¼ Macropus rufus; solid lines) walking pentapedally (four limbs and tail) and hopping bipedally, compared to cost for a quadrupedal mammal (dashed lines). Data from Dawson and Taylor (1973) and Taylor et al. (1982) as far as the distance climbed, with gliding requiring less energy than traveling the same distance quadrupedally (Jackson 1999). However, Flaherty (2002) concluded that gliding was generally not a cost-effective means of locomotion for the Squirrel Glider (Petaurus norfolcensis) with a mean glide angle of 37 , because the Gliders usually ran too fast, climbed too slowly, and glided too short a distance (mean glide distance ¼ 10 m) to realize any energetic advantages. ...
... Specification of the lateral patagium to the same coronal plane as the limbs is a functional necessity in both sugar gliders and bats, as a physical connection between these two morphological structures is ultimately required to regulate tension of the aerodynamic surface and to control direction during flight (32). In addition to a limb-like lateral position, it is notable that the lateral patagium's outgrowth also proceeds in a manner reminiscent to that of the limbs in both species. ...
Lateral flight membranes, or patagia, have evolved repeatedly in diverse mammalian lineages. While little is known about patagium development, its recurrent evolution may suggest a shared molecular basis. By combining transcriptomics, developmental experiments, and mouse transgenics, we demonstrate that lateral Wnt5a expression in the marsupial sugar glider (Petaurus breviceps) promotes the differentiation of its patagium primordium. We further show that this function of Wnt5a reprises ancestral roles in skin morphogenesis predating mammalian flight and has been convergently used during patagium evolution in eutherian bats. Moreover, we find that many genes involved in limb development have been redeployed during patagium outgrowth in both the sugar glider and bat. Together, our findings reveal that deeply conserved genetic toolkits contribute to the evolutionary transition to flight in mammals.
... gracilis) and Sugar Gliders have glide ratios of 1.9: 1 and 1.8:1 and glide angles of 28 and 30 , respectively, suggest they can glide twice Relationship for metabolic rate (ml O 2 g À1 h À1 ; black lines) and cost of transport (ml O 2 g À1 km À1 ; gray lines) with speed for a Red Kangaroo (Osphranter ¼ Macropus rufus; solid lines) walking pentapedally (four limbs and tail) and hopping bipedally, compared to cost for a quadrupedal mammal (dashed lines). Data from Dawson and Taylor (1973) and Taylor et al. (1982) as far as the distance climbed, with gliding requiring less energy than traveling the same distance quadrupedally (Jackson 1999). However, Flaherty (2002) concluded that gliding was generally not a cost-effective means of locomotion for the Squirrel Glider (Petaurus norfolcensis) with a mean glide angle of 37 , because the Gliders usually ran too fast, climbed too slowly, and glided too short a distance (mean glide distance ¼ 10 m) to realize any energetic advantages. ...
... Not to scale physical and physiological requirements, gliding flight has convergently evolved far more often than has flapping flight, in groups that include mammals, reptiles, amphibians, insects, arachnids, fishes, and cephalopods (Fig. 13.1), with body sizes spanning over 4 orders of magnitude (from~0.05 g in Cephalotes atratus (Yanoviak et al., 2005) ants to~3.2 kg in the red giant flying squirrel (Jackson, 2000), Petaurista petaurista). ...
Gliding locomotion has convergently evolved in multiple vertebrate and invertebrate taxa, spanning terrestrial and aquatic animals. The selective pressures attributed to the evolution of gliding include the topography of the environment as well as the capabilities for rapidly escaping predation, foraging over larger spatial areas, and landing safely after falling. Although gliding locomotion has likely evolved in response to these multiple factors in diverse lineages, extant taxa exhibit convergent morphologies and behaviors related to gliding. Understanding the relevance of specific gliding features is informed by the laws of physics: to successfully execute a glide, the animal must use a combination of body shape/size changes (morphology) along with attaining and modulating a favorable body posture (behavior) to generate sufficient aerodynamic forces to slow and control the descent. Gliding animals employ a diverse range of aerodynamic surfaces to generate lift and drag forces, from membrane wings in mammals, Draco lizards, fish, and squid, to smaller structures including skin flaps, flattened bodies, and appendages in geckos, snakes, frogs, spiders, and ants. These force-generating surfaces vary in their shape, size, and anatomical structure, but serve a common function of increasing the total body surface area of the animal compared to their non-gliding relatives, enabling them to produce significantly higher aerodynamic forces. Convergence is also observed in takeoff, gliding, and landing behaviors, necessary for the animal to execute a successful glide trajectory. Takeoff behaviors vary from jumping from vertical or horizontal substrates in terrestrial gliders, to launching from below or on top of the water surface in fish and squid. Once airborne, gliding animals produce and modulate aerodynamic forces of lift and drag through adjustments in their body-airfoil or posture, and/or interactive combinations of both. In some taxa, modulation of aerodynamic forces enables the animal to undertake aerial maneuvers to navigate spatially complex habitats and to land. The evolution of dedicated primary wings in mammalian gliders and Draco flying lizards allows them to substantially slow their descent and transition into a more upright position to land, mostly on vertical substrates. Gliders that lack wings, including snakes, geckos, ants, and spiders, use a landing strategy involving impact with the substrate without a significant reduction in speed, using a combination of the body and appendages to land. Flying fish and squid attain a more streamlined posture by tucking their fins to reduce drag while entering the water surface. In this chapter, we provide a broad overview of gliding in diverse lineages, highlighting the ecological and physical pressures that have shaped this form of aerial locomotion in the animal kingdom.
... Here, we use a BA design on the arboreal sugar glider (Petaurus breviceps) to assess the impact of habitat fragmentation and other landscape-scale movement barriers (i.e., highways, roads, and farmlands) prior to the establishment of a wildlife corridor in southeastern Australia. Sugar gliders are arboreal and rely on trees for movement; however, they can glide up to 30 m to move between trees and across gaps in canopy [36][37][38]. However, despite this adaptation, the species can still be impacted by barriers, such as roads [39], farmland [40], and urbanisation [37]. ...
... Additionally, we have shown in our other work that sugar gliders are highly mobile and able to move on the ground [45]. Thus, the species is likely be able to cross unsuitable habitat to access more suitable habitat, either by gliding (maximum glide distance of 30 m; [38]) or crossing the ground if needed. ...
Habitat loss and fragmentation contribute significantly to the decline of arboreal mammal populations. As populations become fragmented and isolated, a reduction in gene flow can result in a loss of genetic diversity and have an overall impact upon long-term persistence. Creating wildlife corridors can mitigate such effects by increasing the movement and dispersal of animals, thus acting to reduce population isolation. To evaluate the success of a corridor, a before–after experimental research framework can be used. Here, we report the genetic diversity and structure of sugar glider (Petaurus breviceps) sampling locations within a fragmented landscape prior to the implementation of a wildlife corridor. This study used 5999 genome-wide SNPs from 94 sugar gliders caught from 8 locations in a fragmented landscape in south-eastern New South Wales, Australia. Overall genetic structure was limited, and gene flow was detected across the landscape. Our findings indicate that the study area contains one large population. A major highway dissecting the landscape did not act as a significant barrier to dispersal, though this may be because of its relatively new presence in the landscape (completed in 2018). Future studies may yet indicate its long-term impact as a barrier to gene flow. Future work should aim to repeat the methods of this study to examine the medium-to-long-term impacts of the wildlife corridor on sugar gliders, as well as examine the genetic structure of other native, specialist species in the landscape.
... The gliding behavior and performance of Pteromyini has been studied in the field and in the laboratory for selected species (e.g., Ando & Shiraishi, 1993;Bahlman et al., 2013;Bishop & Brim-DeForest, 2008;Dolan & Carter, 1977;Jackson, 2000), but the morphofunctional principles of gliding are still barely understood (Socha et al., 2015). As all gliding mammals, these animals extend their legs to spread their patagium while gliding and are capable of navigating and actively changing direction and aerodynamic forces during flight, with observed gliding distances of up to 150 m in the largest species (Ando & Shiraishi, 1993;Krishna et al., 2016;Scholey, 1986). ...
Many of the squirrel‐related rodents (i.e., Sciuromorpha) are tree‐dwelling species known to be very agile climbers. This taxon also includes the most diverse clade of gliding (aerial) mammals that likely descended from a non‐gliding arboreal ancestor and evolved a patagium (i.e., a gliding membrane) to increase gliding performance. Glides can cover distances of up to 150 m and landing is typically accomplished by stalling the patagium to reduce impact velocity. It remains unclear if this behavior suffices to keep stresses on the locomotor apparatus similar to those experienced by their arboreal relatives or whether gliding behavior increases landing forces and stresses. The sparsely available support reaction force data are ambiguous, but bone microstructure is highly adaptable to changes in loading regime and likely provides insights into this question. Using μCT scans, we compared the cortical thickness of the glenoid fossa of the shoulder joint between arboreal and aerial Sciuromorpha using evolutionary model comparison, while also accounting for regional differences of the glenoid fossa. We did not find any differences between these locomotor behaviors, irrespective of the glenoid region. These findings agree with previous analyses of the microstructure of the femur in Sciuromorpha. We discuss different aspects that could explain the similarity in cortical thickness. According to our analysis of glenoid cortical thickness the loading regime appears not to have changed after the evolution of gliding locomotion, likely due to adjustments in landing performance.
... Flying squirrels face distinct challenges unlike other small mammals because of their specialized morphology. The evolutionary design of flying squirrels has allowed for energetically cheap gliding through use of a retractable patagium and development of longer humeri and femora [8][9][10][11]. However, flying squirrels are not efficient runners because of this design, and expend significantly more energy running when compared to other small mammals [12]. ...
... These ratios represent horizontal distance covered per unit of vertical drop and are highly variable, with higher ratios indicating longer glide distances. Southern Flying Squirrels have a ratio of 1.53 [83], Northern Flying Squirrels 1.98 [84], Siberian Flying Squirrels 1-1.5 [85], Red Giant Flying Squirrels (Petaurista petaurista) 3.1 [86], Japanese Giant Flying Squirrels (Petaurista leucogenys) 1.87 [87], Indian Giant Flying Squirrels (Petaurista philippensis) 2.32 [88], Squirrel Gliders 1.84 [81], Yellow-Bellied Gliders (Petaurus australis) 2.0 [89], and Sugar Gliders and Mahogany Gliders, 1.82 and 1.91 respectively [11]. When implementing gap crossing structures, the launch height must factor in the species' glide ratio. ...
Habitat fragmentation affects flying squirrels despite their ability to cross canopy gaps. If unable to cross gaps, flying squirrels may suffer from limited access to appropriate resources, inbreeding depression, and even extirpation. North American flying squirrels (Glaucomys) have been the focus of limited research on this issue when compared to other areas of the world tackling this problem. However, as all gliding mammals share similar conservation challenges, findings of other species on other continents can be applied to the Glaucomys species in North America. The
purpose of this review is to take a metapopulation approach to the problem of gap crossing. This review first discusses necessary habitat conservation strategies for Glaucomys within the patches they reside. The review then discusses patch size and configuration, honing in on maintaining connectivity between habitat patches. Different structures (natural and manmade) used to maintain connectivity are reviewed using gliding mammal literature from around the world. This information
is pertinent to North American conservation ecologists and landscape managers, who can use this information to improve habitat connectivity and facilitate crossings of Glaucomys flying squirrels within metapopulations.
... These trees are not currently mature (i.e. tall) enough to support the crossing of sugar gliders that require an average glide angle of 29.69° (Jackson 2000). In Lake Macquarie LGA the Pacific Motorway has been a dispersal barrier for the last 30-35 years, potentially impeding gene flow for ten generations of sugar gliders. ...
Arboreal gliders are vulnerable to habitat fragmentation and to barriers that extend their glide distance threshold. Habitat fragmentation through deforestation can cause population isolation and genetic drift in gliding mammals, which in turn can result in a loss of genetic diversity and population long-term persistence. This study utilised next generation sequencing technology to call 8784 genome-wide SNPs from 90 sugar gliders (Petaurus breviceps) sensu stricto. Samples were collected from 12 locations in the Lake Macquarie Local Government Area (New South Wales). The sugar gliders appeared to have high levels of gene flow and little genetic differentiation; however spatial least cost path analyses identified the Pacific Motorway as a potential barrier to their dispersal. This Motorway is still relatively new (<40 years old), so man-made crossing structures should be erected as a management priority to mitigate any long-term effects of population isolation by assisting in the dispersal and gene flow of the species.
