Skeletal morphology of bird wings is determined by thermoregulatory demand for heat dissipation in warmer climates

Weeks, Brian C.; Harvey, C. A.; Tobias, Joseph A.; Sheard, Catherine; Zhou, Zhizhuo; Fouhey, David F.

doi:10.1101/2023.02.06.527306

Cited by 3 publications

(2 citation statements)

References 52 publications

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“…These correlations, now known as Bergmann's rule (or intraspecifically, James' rule; Blackburn et al, 1999) and Allen's rule, have since been observed at both interspecific (e.g. Ashton et al, 2000;Meiri and Daya, 2003;Rodríguez et al, 2008;Symonds and Tattersall, 2010;Alhajeri et al, 2020;Benítez-López et al, 2021;McQueen et al, 2022;Weeks et al, 2023) and intra-specific levels (e.g. James, 1970;Ashton 2002;Freckleton et al, 2003;Benítez-López et al, 2021;McQueen et al, 2022).…”

Section: Introductionmentioning

confidence: 98%

Temperature-dependant, developmental plasticity and its effects on Allen’s and James’ rule in endotherms

Tabh¹,

Nord²

2023

Preprint

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Ecogeographical rules, describing common trends in animal form across space and time, have provided key insights into the primary factors driving species persistence on our planet. Among the most well-known ecogeographical rules are James’ rule (an intraspecific variant of Bergmann’s rule) and Allen’s rule, with each correlating ambient temperature to the size and shape of endotherms within a species. These two rules have recently gained renewed research attention, largely with the goal of understanding how they emerge (e.g. via natural selection or phenotypic plasticity), and thus, whether they may emerge quickly enough to facilitate species persistence in a warming world. Yet despite this attention, the precise proximate and ultimate drivers of James’ and Allen’s rules remain unresolved. In this paper, we review over a century of empirical literature surrounding these rules and ask whether each could be explained by plastic effects of developmental temperature on adult phenotype among endotherms. Across birds and mammals, studies strongly support developmental plasticity as a driver of James’ and Allen’s rules, particularly with regards to Allen’s rule and responses to heat. However, we find that plastic contributions toward each are non-linear and probably depend on: (1) efficiency of energy use at given ambient temperatures (James’ rule), and (2) thermal advantages at given ambient temperatures (Allen’s rule). These findings suggest that, among endotherms, rapid changes in body shape and size will continue to occur, but generalising the direction of responses across populations (e.g. as “shrinking” or “shape-shifting”) is likely naive.

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Section: Introductionmentioning

confidence: 98%

Temperature-dependant, developmental plasticity and its effects on Allen’s and James’ rule in endotherms

Tabh¹,

Nord²

2023

Preprint

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“…This is because these appendages are unfeathered, highly vascularized, and have a demonstrated role in thermoregulation, making them obvious locations for heat loss 39,40 . The undersides of wings are also highly vascularised and have been proposed to form another appendage which may conform to Allen's rule 31,41 , although the role of wing vascularity in shedding heat is poorly known (but see 42,43,44 ). However, if the wing functions as a heat-shedding appendage, we expect wing length relative to body size to increase in an Allen's rule-style response (sensu 31 ), rather than absolute wing length.…”

Section: Introductionmentioning

confidence: 99%

Pervasive morphological responses to climate change in bird body and appendage size

Ryding,

McQueen,

Klaassen

et al. 2023

Preprint

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Changes to body size and shape have been identified as potential adaptive responses to climate change, but the pervasiveness of these responses is questioned. To address this, we measured body and appendage size from 5013 museum bird skins of ecologically and evolutionary diverse species. We found that morphological change is a shared response to climate change across birds. Birds increased bill surface area, tarsus length, and relative wing length through time, consistent with expectations of increasing appendage size in warmer climates. Furthermore, birds decreased in absolute wing length, consistent with the expectation of decreasing body size in warmer climates. Interestingly, these trends were generally consistent across different diets, foraging habitats, and migratory and thermoregulatory behaviours. Shorter-term responses to hot weather were contrary to long-term effects for appendages. Overall, our findings support that morphological adaptation is a widespread response to climate change in birds that is independent of other ecological traits.

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Comparative Analysis of Morphometric, Densitometric, and Mechanical Properties of Skeletal Locomotor Elements in Three Duck Species (Anatidae: Anatinae)

Osiak-Wicha,

Tomaszewska,

Muszyński

et al. 2024

Animals

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Ducks (Anatinae) play a crucial role in wetland ecosystems, contributing to seed dispersal and nutrient cycling. This study investigates the skeletal adaptations of three duck species: the Mallard (Anas platyrhynchos), Tufted Duck (Aythya fuligula), and Green-Winged Teal (Anas crecca). The focus is on the tibiotarsus and humerus bones to understand how these adaptations support their different locomotion and habitat preferences. Bone samples n = 6 of deceased ducks (both male and female) from each species (for a total of 36 samples) were cleaned and measured for length, weight, and density. Dual-energy X-ray absorptiometry was used to determine bone mineral density (BMD) and bone mineral content (BMC), and mechanical properties like yield force and stiffness were tested using a 3-point bending test. The results show significant differences in body weight, bone weight, and bone length among the species, with Mallards being the largest and Teals the smallest. Male Teals displayed higher relative bone weight (RBW) in their tibia compared to male Mallards, and male Mallards had significantly lower RBW in the humerus compared to the other species. Female Teals had higher RBW than the other species. Teals also exhibited much lower BMD in the tibia, whereas female Mallards had lower BMD in the humerus. The Seedor index revealed that male Mallards had the highest values in the tibia, while female Teals had the lowest. Mechanical testing indicated that Teals had lower yield force and breaking force in the tibia, whereas Mallards showed the highest stiffness in both bones. Tufted Ducks had intermediate values, consistent with their diving behaviour. These findings suggest that the Mallard’s robust bones support its adaptability to various environments and diverse locomotion and foraging strategies. The Teal’s lighter and less dense bones facilitate rapid flight and agility in shallow wetlands. The Tufted Duck’s intermediate bone characteristics reflect its specialization in diving, requiring a balance of strength and flexibility. Understanding these skeletal differences may provide valuable insights into the evolutionary biology and biomechanics of these species, aiding in their conservation and enhancing our knowledge of their roles in wetland ecosystems. By exploring the functional morphology of these ducks, this study aims to shed light on the biomechanical mechanisms that underpin their locomotion and foraging behaviours.

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Skeletal morphology of bird wings is determined by thermoregulatory demand for heat dissipation in warmer climates

Cited by 3 publications

References 52 publications

Temperature-dependant, developmental plasticity and its effects on Allen’s and James’ rule in endotherms

Temperature-dependant, developmental plasticity and its effects on Allen’s and James’ rule in endotherms

Pervasive morphological responses to climate change in bird body and appendage size

Comparative Analysis of Morphometric, Densitometric, and Mechanical Properties of Skeletal Locomotor Elements in Three Duck Species (Anatidae: Anatinae)

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