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Colwell RK, Rangel TF, Fučíková K, Sustaita D, Yanega GM, Rico-Guevara A. Repeated Evolution of Unorthodox Feeding Styles Drives a Negative Correlation between Foot Size and Bill Length in Hummingbirds. Am Nat 2023; 202:699-720. [PMID: 37963119 DOI: 10.1086/726036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
AbstractDifferences among hummingbird species in bill length and shape have rightly been viewed as adaptive in relation to the morphology of the flowers they visit for nectar. In this study we examine functional variation in a behaviorally related but neglected feature: hummingbird feet. We gathered records of hummingbirds clinging by their feet to feed legitimately as pollinators or illegitimately as nectar robbers-"unorthodox" feeding behaviors. We measured key features of bills and feet for 220 species of hummingbirds and compared the 66 known "clinger" species (covering virtually the entire scope of hummingbird body size) with the 144 presumed "non-clinger" species. Once the effects of phylogenetic signal, body size, and elevation above sea level are accounted for statistically, hummingbirds display a surprising but functionally interpretable negative correlation. Clingers with short bills and long hallux (hind-toe) claws have evolved-independently-more than 20 times and in every major clade. Their biomechanically enhanced feet allow them to save energy by clinging to feed legitimately on short-corolla flowers and by stealing nectar from long-corolla flowers. In contrast, long-billed species have shorter hallux claws, as plant species with long-corolla flowers enforce hovering to feed, simply by the way they present their flowers.
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Easterling CM, Kolmann MA, O'Donnell MK. The Lesser-Known Transitions: Organismal Form and Function Across Abiotic Gradients. Integr Comp Biol 2022; 62:829-839. [PMID: 35927766 DOI: 10.1093/icb/icac133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/20/2022] [Accepted: 04/26/2022] [Indexed: 11/12/2022] Open
Abstract
From minute-to-minute changes, or across daily, seasonal, or geological timescales, animals are forced to navigate dynamic surroundings. Their abiotic environment is continually changing. These changes could include alterations to the substrates animals locomote on, flow dynamics of the microhabitats they feed in, or even altitudinal shifts over migration routes. The only constancy in any organism's day-to-day existence is the heterogeneity of the habitats they move through and the gradients in the physical media (e.g., air, water) they live in. We explored a broad range of organismal transitions across abiotic gradients and investigated how these organisms modify their form, function, and behavior to accommodate their surrounding media. We asked the following questions: (1) What are some challenges common to animals in changing media or moving between media? (2) What are common solutions to these recurring problems? (3) How often are these common solutions instances of either convergence or parallelism? Our symposium speakers explored these questions through critical analysis of numerous datasets spanning multiple taxa, timescales, and levels of analysis. After discussions with our speakers, we suggest that the role of physical principles (e.g., drag, gravity, buoyancy, viscosity) in constraining morphology and shaping the realized niche has been underappreciated. We recommend that investigations of these transitions and corresponding adaptations should include comparisons at multiple levels of biological organization and timescale. Relatedly, studies of organisms that undergo habitat and substrate changes over ontogeny would be worthwhile to include in comparisons. Future researchers should ideally complement lab-based morphological and kinematic studies with observational and experimental approaches in the field. Synthesis of the findings of our speakers across multiple study systems, timescales, and transitional habitats suggests that behavioral modification and exaptation of morphology play key roles in modulating novel transitions between substrates.
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Affiliation(s)
- C M Easterling
- Northwest University, Science Department, Kirkland, WA 98033
| | - M A Kolmann
- University of Michigan, Museum of Paleontology, Ann Arbor, MI 48109
| | - M K O'Donnell
- Lycoming College, Biology Department, Williamsport, PA 17701
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Sargent AJ, Groom DJE, Rico-Guevara A. Locomotion and Energetics of Divergent Foraging Strategies in Hummingbirds: A Review. Integr Comp Biol 2021; 61:736-748. [PMID: 34113992 DOI: 10.1093/icb/icab124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/02/2021] [Accepted: 06/08/2021] [Indexed: 11/13/2022] Open
Abstract
Hummingbirds have two main foraging strategies: territoriality (defending a patch of flowers) and traplining (foraging over routine circuits of isolated patches). Species are often classified as employing one or the other. Not only have these strategies been inconsistently defined within the behavioral literature, but this simple framework also neglects the substantial evidence for flexible foraging behavior displayed by hummingbirds. Despite these limitations, research on hummingbird foraging has explored the distinct avenues of selection that proponents of either strategy presumably face: trapliners maximizing foraging efficiency, and territorialists favoring speed and maneuverability for resource defense. In earlier studies, these functions were primarily examined through wing disc loading (ratio of body weight to the circular area swept out by the wings, WDL) and predicted hovering costs, with trapliners expected to exhibit lower WDL than territorialists and thus lower hovering costs. While these pioneering models continue to play a role in current research, early studies were constrained by modest technology, and the original expectations regarding WDL have not held up when applied across complex hummingbird assemblages. Current technological advances have allowed for innovative research on the biomechanics/energetics of hummingbird flight, such as allometric scaling relationships (e.g., wing area-flight performance) and the link between high burst lifting performance and territoriality. Providing a predictive framework based on these relationships will allow us to reexamine previous hypotheses, and explore the biomechanical trade-offs to different foraging strategies, which may yield divergent routes of selection for quintessential territoriality and traplining. With a biomechanical and morphofunctional lens, here we examine the locomotor and energetic facets that dictate hummingbird foraging, and provide (a) predictions regarding the behavioral, biomechanical, and morphofunctional associations with territoriality and traplining; and (b) proposed methods of testing them. By pursuing these knowledge gaps, future research could use a variety of traits to help clarify the operational definitions of territoriality and traplining, to better apply them in the field.
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Affiliation(s)
- A J Sargent
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA 98105, USA.,Burke Museum of Natural History and Culture, 4300 15th Ave NE, Seattle, WA 98105, USA
| | - D J E Groom
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA 98105, USA.,Burke Museum of Natural History and Culture, 4300 15th Ave NE, Seattle, WA 98105, USA.,Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - A Rico-Guevara
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA 98105, USA.,Burke Museum of Natural History and Culture, 4300 15th Ave NE, Seattle, WA 98105, USA
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Shankar A, Powers DR, Dávalos LM, Graham CH. The allometry of daily energy expenditure in hummingbirds: An energy budget approach. J Anim Ecol 2020; 89:1254-1261. [DOI: 10.1111/1365-2656.13185] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 12/06/2019] [Indexed: 01/21/2023]
Affiliation(s)
| | | | | | - Catherine H. Graham
- Stony Brook University Stony Brook NY USA
- Swiss Federal Research Institute (WSL) Birmensdorf Switzerland
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Wang Y, Yin Y, Ge S, Li M, Zhang Q, Li J, Wu Y, Li D, Dudley R. Limits to load-lifting performance in a passerine bird: the effects of intraspecific variation in morphological and kinematic parameters. PeerJ 2019; 7:e8048. [PMID: 31741797 PMCID: PMC6858814 DOI: 10.7717/peerj.8048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 10/16/2019] [Indexed: 11/20/2022] Open
Abstract
Although more massive flight muscles along with larger wings, higher wingbeat frequencies and greater stroke amplitudes enhance force and power production in flapping flight, the extent to which these parameters may be correlated with other morphological features relevant to flight physiology and biomechanics remains unclear. Intraspecifically, we hypothesized that greater vertical load-lifting capacity would correlate with higher wingbeat frequencies and relatively more massive flight muscles, along with relatively bigger hearts, lungs, and stomachs to enhance metabolic capacity and energy supply, but also with smaller body size given the overall negative allometric dependence of maximum flight performance in volant taxa. To explore intraspecific correlates of flight performance, we assembled a large dataset that included 13 morphological and kinematic variables for a non-migratory passerine, the Eurasian tree sparrow (Passer montanus). We found that heavier flight muscles and larger wings, heavier stomachs and shorter bills were the most important correlates of maximum load-lifting capacity. Surprisingly, wingbeat frequency, wing stroke amplitude and masses of the heart, lungs and digestive organs (except for the stomach) were non-significant predictor variables relative to lifting capacity. The best-fit structural equation model (SEM) indicated that load-lifting capacity was positively correlated with flight muscle mass, wing area and stomach mass, but was negatively correlated with bill length. Characterization of individual variability in flight performance in a free-ranging passerine indicates the subtlety of interaction effects among morphological features, some of which differ from those that have been identified interspecifically for maximum flight performance in birds.
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Affiliation(s)
- Yang Wang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Yuan Yin
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Shiyong Ge
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Mo Li
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Qian Zhang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Juyong Li
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Yuefeng Wu
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Dongming Li
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, China
| | - Robert Dudley
- Department of Integrative Biology, University of California, Berkeley, CA, USA
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Shankar A, Graham CH, Canepa JR, Wethington SM, Powers DR. Hummingbirds budget energy flexibly in response to changing resources. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13404] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Anusha Shankar
- Stony Brook University Stony Brook NY USA
- WSL Birmensdorf Switzerland
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Groom DJE, Toledo MCB, Powers DR, Tobalske BW, Welch KC. Integrating morphology and kinematics in the scaling of hummingbird hovering metabolic rate and efficiency. Proc Biol Sci 2019; 285:rspb.2017.2011. [PMID: 29491168 DOI: 10.1098/rspb.2017.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 02/01/2018] [Indexed: 11/12/2022] Open
Abstract
Wing kinematics and morphology are influential upon the aerodynamics of flight. However, there is a lack of studies linking these variables to metabolic costs, particularly in the context of morphological adaptation to body size. Furthermore, the conversion efficiency from chemical energy into movement by the muscles (mechanochemical efficiency) scales with mass in terrestrial quadrupeds, but this scaling relationship has not been demonstrated within flying vertebrates. Positive scaling of efficiency with body size may reduce the metabolic costs of flight for relatively larger species. Here, we assembled a dataset of morphological, kinematic, and metabolic data on hovering hummingbirds to explore the influence of wing morphology, efficiency, and mass on hovering metabolic rate (HMR). We hypothesize that HMR would decline with increasing wing size, after accounting for mass. Furthermore, we hypothesize that efficiency will increase with mass, similarly to other forms of locomotion. We do not find a relationship between relative wing size and HMR, and instead find that the cost of each wingbeat increases hyperallometrically while wingbeat frequency declines with increasing mass. This suggests that increasing wing size is metabolically favourable over cycle frequency with increasing mass. Further benefits are offered to larger hummingbirds owing to the positive scaling of efficiency.
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Affiliation(s)
- Derrick J E Groom
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada, M1C 1A4 .,Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3G5
| | - M Cecilia B Toledo
- Instituto Bàsico de Biociências, Universidade de Taubaté, Taubaté, SP, 12010-180, Brazil
| | - Donald R Powers
- Department of Biology, George Fox University, Newberg, OR 97132, USA
| | - Bret W Tobalske
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Kenneth C Welch
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada, M1C 1A4.,Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3G5
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