Submission Type
Poster
Abstract
Palaeognathae is a group of flightless birds classified by the absence of the keeled sternum (breastbone) present in flighted birds. As they diverged from their flighted ancestors, palaeognaths developed cursorial traits such as greater body mass and elongated hindlimbs, and concomitant with this was the reduction of the forelimbs, which were no longer needed for flight. Among living paleognaths, most species exhibit extreme forelimb reduction, such as that seen in the ostrich (Struthio camelus). This study investigates the variation betweenS. camelusindividuals to provide clues as to which behaviors and environmental pressures may have contributed most to forelimb morphology. Differences in the forelimb elements of males and females, indicating sexual dimorphism in the wing, would suggest variation results from sex-specific functions such as mating displays. Comparison between captive and wild populations could show variation resulting from presence of competition, predation, and other environmental factors. Using geometric morphometric software principal component (PC) data was analyzed to investigate variation between forelimb elements and test adherence to the hypothesized pattern of limb reduction in which reduction occurs distal to proximal. The aim of this project is to investigate the current variation in morphology of the palaeognath taxa using geometric morphometrics, which quantifies the shape of the bones. These methods will allow us to contrast interspecies and intraspecies variation to quantify how functional demands on the wing affect morphological variation of the bones, and thus better understand the evolutionary relationship between form and function in cases of limb reduction.
Recommended Citation
Marzec, Isabel, "080-Investigating Reduction of the Ostrich Forelimb: Palaeognathae (Aves)" (2024). GREAT Day Posters. 20.
https://knightscholar.geneseo.edu/great-day-symposium/great-day-2024/posters-2024/20
080-Investigating Reduction of the Ostrich Forelimb: Palaeognathae (Aves)
Palaeognathae is a group of flightless birds classified by the absence of the keeled sternum (breastbone) present in flighted birds. As they diverged from their flighted ancestors, palaeognaths developed cursorial traits such as greater body mass and elongated hindlimbs, and concomitant with this was the reduction of the forelimbs, which were no longer needed for flight. Among living paleognaths, most species exhibit extreme forelimb reduction, such as that seen in the ostrich (Struthio camelus). This study investigates the variation betweenS. camelusindividuals to provide clues as to which behaviors and environmental pressures may have contributed most to forelimb morphology. Differences in the forelimb elements of males and females, indicating sexual dimorphism in the wing, would suggest variation results from sex-specific functions such as mating displays. Comparison between captive and wild populations could show variation resulting from presence of competition, predation, and other environmental factors. Using geometric morphometric software principal component (PC) data was analyzed to investigate variation between forelimb elements and test adherence to the hypothesized pattern of limb reduction in which reduction occurs distal to proximal. The aim of this project is to investigate the current variation in morphology of the palaeognath taxa using geometric morphometrics, which quantifies the shape of the bones. These methods will allow us to contrast interspecies and intraspecies variation to quantify how functional demands on the wing affect morphological variation of the bones, and thus better understand the evolutionary relationship between form and function in cases of limb reduction.