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A Novel Method for Tracking Individuals of Fruit Fly Swarms Flying in a Laboratory Flight Arena.

Cheng XE, Qian ZM, Wang SH, Jiang N, Guo A, Chen YQ - PLoS ONE (2015)

Bottom Line: We found that there exists an asymptotic distance between fruit flies in swarms as the population density increases.Further, we discovered the evidence for repulsive response when the distance between fruit flies approached the asymptotic distance.Overall, the proposed tracking system presents a powerful method for studying flight behaviours of fruit flies in a three-dimensional environment.

View Article: PubMed Central - PubMed

Affiliation: School of Computer Science, Shanghai Key Laboratory of Intelligent Information Processing, Fudan University, Shanghai, China; Jingdezhen Ceramic Institute, Jingdezhen, China.

ABSTRACT
The growing interest in studying social behaviours of swarming fruit flies, Drosophila melanogaster, has heightened the need for developing tools that provide quantitative motion data. To achieve such a goal, multi-camera three-dimensional tracking technology is the key experimental gateway. We have developed a novel tracking system for tracking hundreds of fruit flies flying in a confined cubic flight arena. In addition to the proposed tracking algorithm, this work offers additional contributions in three aspects: body detection, orientation estimation, and data validation. To demonstrate the opportunities that the proposed system offers for generating high-throughput quantitative motion data, we conducted experiments on five experimental configurations. We also performed quantitative analysis on the kinematics and the spatial structure and the motion patterns of fruit fly swarms. We found that there exists an asymptotic distance between fruit flies in swarms as the population density increases. Further, we discovered the evidence for repulsive response when the distance between fruit flies approached the asymptotic distance. Overall, the proposed tracking system presents a powerful method for studying flight behaviours of fruit flies in a three-dimensional environment.

No MeSH data available.


Statistics of fruit flies’ kinematics.The measured data of different configurations are color coded. The upper row shows the PDFs of measured z-scores z and the lower panel shows the measured mean μ and standard deviation σ. (a) The PDFs of z-scores of speed, zs, of all configurations. The black arrow shows the direction of growing population size. The inset shows the polarisation value in six seconds (more data is not present). (b, c) The PDFs of z-scores of velocity components: (b) the horizontal component, zvy, and (c) the vertical direction, zvz, of all configurations. The distributions are nearly Gaussian (an empirical Gaussian curve is shown in grey), with small deviation in the tails. (d) The PDFs of z-scores of angular velocity, zav, of all configurations. The dashed-line shows the nearly exponential long tails on the high angular velocity.
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pone.0129657.g006: Statistics of fruit flies’ kinematics.The measured data of different configurations are color coded. The upper row shows the PDFs of measured z-scores z and the lower panel shows the measured mean μ and standard deviation σ. (a) The PDFs of z-scores of speed, zs, of all configurations. The black arrow shows the direction of growing population size. The inset shows the polarisation value in six seconds (more data is not present). (b, c) The PDFs of z-scores of velocity components: (b) the horizontal component, zvy, and (c) the vertical direction, zvz, of all configurations. The distributions are nearly Gaussian (an empirical Gaussian curve is shown in grey), with small deviation in the tails. (d) The PDFs of z-scores of angular velocity, zav, of all configurations. The dashed-line shows the nearly exponential long tails on the high angular velocity.

Mentions: Since each fruit fly’s motion data has been obtained through time, we can thereby compute fruit flies’ kinetic measurement, such as velocity v, angular velocity av and speed s which is the magnitude of velocity v at each moment. Fig 6a shows the statistics of speed. It shows that the measured mean speed μs is greater than 400 mm/s (see the lower panel of Fig 6a), while the measured standard deviation σs increases from 200 mm/s to 400 mm/s as the population size increases. Considering the z-score (a.k.a the standard score) of speed denotes the fluctuation of speed, we computed the z-scores of all configurations and reported the PDFs of z-scores of each configuration in Fig 6a (the upper panel). The z-score of speed zs is computed as zs = (s−μs)/σs. Fig 6a shows the fluctuation of fruit flies’ speed usually narrows down (i.e. the amplitude of fluctuation decreases) as the population size increases. That is, the flight of fruit flies in a denser population environment is less volatile than those in a less dense environment. It suggests fruit flies have probably awareness of the environment. The black arrow in Fig 6a (the upper panel), which points to the direction of growing population size, shows the long tails of speed fluctuation. These tails are nearly exponential and grow monotonically with the population size, which suggest that fruit flies in a denser population environment perform faster manoeuvres. It probably are these long tails which cause the standard deviation of speed increases as the population size increases. On the other hand, previous studies [36, 37] have demonstrated that the fruit fly exhibits a flight pattern in which straight flight sequence interspersed with rapid turn called saccades. Fig 6d shows the statistic of angular velocity. The measured mean angular velocity μav is greater than 400 degree/s (see the lower panel of Fig 6d), while Fig 6d (the upper panel) shows that the angular velocity av is less than the mean μav in most of moments. That is, the angular velocity is usually less than 400° per seconds. But the nearly exponential tails (indicated by dashed-line in grey) suggest that fruit flies have also often taken the rapid turn.


A Novel Method for Tracking Individuals of Fruit Fly Swarms Flying in a Laboratory Flight Arena.

Cheng XE, Qian ZM, Wang SH, Jiang N, Guo A, Chen YQ - PLoS ONE (2015)

Statistics of fruit flies’ kinematics.The measured data of different configurations are color coded. The upper row shows the PDFs of measured z-scores z and the lower panel shows the measured mean μ and standard deviation σ. (a) The PDFs of z-scores of speed, zs, of all configurations. The black arrow shows the direction of growing population size. The inset shows the polarisation value in six seconds (more data is not present). (b, c) The PDFs of z-scores of velocity components: (b) the horizontal component, zvy, and (c) the vertical direction, zvz, of all configurations. The distributions are nearly Gaussian (an empirical Gaussian curve is shown in grey), with small deviation in the tails. (d) The PDFs of z-scores of angular velocity, zav, of all configurations. The dashed-line shows the nearly exponential long tails on the high angular velocity.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4470659&req=5

pone.0129657.g006: Statistics of fruit flies’ kinematics.The measured data of different configurations are color coded. The upper row shows the PDFs of measured z-scores z and the lower panel shows the measured mean μ and standard deviation σ. (a) The PDFs of z-scores of speed, zs, of all configurations. The black arrow shows the direction of growing population size. The inset shows the polarisation value in six seconds (more data is not present). (b, c) The PDFs of z-scores of velocity components: (b) the horizontal component, zvy, and (c) the vertical direction, zvz, of all configurations. The distributions are nearly Gaussian (an empirical Gaussian curve is shown in grey), with small deviation in the tails. (d) The PDFs of z-scores of angular velocity, zav, of all configurations. The dashed-line shows the nearly exponential long tails on the high angular velocity.
Mentions: Since each fruit fly’s motion data has been obtained through time, we can thereby compute fruit flies’ kinetic measurement, such as velocity v, angular velocity av and speed s which is the magnitude of velocity v at each moment. Fig 6a shows the statistics of speed. It shows that the measured mean speed μs is greater than 400 mm/s (see the lower panel of Fig 6a), while the measured standard deviation σs increases from 200 mm/s to 400 mm/s as the population size increases. Considering the z-score (a.k.a the standard score) of speed denotes the fluctuation of speed, we computed the z-scores of all configurations and reported the PDFs of z-scores of each configuration in Fig 6a (the upper panel). The z-score of speed zs is computed as zs = (s−μs)/σs. Fig 6a shows the fluctuation of fruit flies’ speed usually narrows down (i.e. the amplitude of fluctuation decreases) as the population size increases. That is, the flight of fruit flies in a denser population environment is less volatile than those in a less dense environment. It suggests fruit flies have probably awareness of the environment. The black arrow in Fig 6a (the upper panel), which points to the direction of growing population size, shows the long tails of speed fluctuation. These tails are nearly exponential and grow monotonically with the population size, which suggest that fruit flies in a denser population environment perform faster manoeuvres. It probably are these long tails which cause the standard deviation of speed increases as the population size increases. On the other hand, previous studies [36, 37] have demonstrated that the fruit fly exhibits a flight pattern in which straight flight sequence interspersed with rapid turn called saccades. Fig 6d shows the statistic of angular velocity. The measured mean angular velocity μav is greater than 400 degree/s (see the lower panel of Fig 6d), while Fig 6d (the upper panel) shows that the angular velocity av is less than the mean μav in most of moments. That is, the angular velocity is usually less than 400° per seconds. But the nearly exponential tails (indicated by dashed-line in grey) suggest that fruit flies have also often taken the rapid turn.

Bottom Line: We found that there exists an asymptotic distance between fruit flies in swarms as the population density increases.Further, we discovered the evidence for repulsive response when the distance between fruit flies approached the asymptotic distance.Overall, the proposed tracking system presents a powerful method for studying flight behaviours of fruit flies in a three-dimensional environment.

View Article: PubMed Central - PubMed

Affiliation: School of Computer Science, Shanghai Key Laboratory of Intelligent Information Processing, Fudan University, Shanghai, China; Jingdezhen Ceramic Institute, Jingdezhen, China.

ABSTRACT
The growing interest in studying social behaviours of swarming fruit flies, Drosophila melanogaster, has heightened the need for developing tools that provide quantitative motion data. To achieve such a goal, multi-camera three-dimensional tracking technology is the key experimental gateway. We have developed a novel tracking system for tracking hundreds of fruit flies flying in a confined cubic flight arena. In addition to the proposed tracking algorithm, this work offers additional contributions in three aspects: body detection, orientation estimation, and data validation. To demonstrate the opportunities that the proposed system offers for generating high-throughput quantitative motion data, we conducted experiments on five experimental configurations. We also performed quantitative analysis on the kinematics and the spatial structure and the motion patterns of fruit fly swarms. We found that there exists an asymptotic distance between fruit flies in swarms as the population density increases. Further, we discovered the evidence for repulsive response when the distance between fruit flies approached the asymptotic distance. Overall, the proposed tracking system presents a powerful method for studying flight behaviours of fruit flies in a three-dimensional environment.

No MeSH data available.