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Arată versiune Óntreagă : Geometria naturii



Marcel TUDOR
27.07.2013, 18:30
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These underwater crop circles are highly complex and can measure an astonishing six feet in diameter.

This behaviour was first reported last year, but the paper was only published earlier this month. It's open access, so check it out here: http://bit.ly/15mVe1X (http://www.facebook.com/l.php?u=http%3A%2F%2Fbit.ly%2F15mVe1X&h=PAQFAvs_x&s=1)

Original image by Yoji Ookata, alterations and edits courtesy of Hannah Stevens.


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Role of Huge Geometric Circular Structures in the Reproduction of a Marine Pufferfish

Hiroshi Kawase (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#auth-1),
Yoji Okata (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#auth-2)
& Kimiaki Ito (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#auth-3)



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Scientific Reports 3, Article number: 2106 doi:10.1038/srep02106Received 19 April 2013 Accepted 13 June 2013 Published 01 July 2013Article tools

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We report that male pufferfishes (Torquigener sp., Tetraodontidae) constructed large geometric circular structures on the seabed that played an important role in female mate choice. Males dug valleys at various angles in a radial direction, constructing nests surrounded by radially aligned peaks and valleys. Furthermore, they created irregular patterns in the nest comprising fine sand particles. The circular structure not only influences female mate choice but also functions to gather fine sand particles in nests, which are important in female mate choice. Strangely enough, the males never reuse the nest, always constructing a new circular structure at the huge cost of construction. This is because the valleys may not contain sufficient fine sand particles for multiple reproductive cycles.

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Biodiversity (http://www.nature.com/search/executeSearch?sp-advanced=true&sp-m=0&siteCode=srep&sp-p=all&sp-q-9[SREP]=1&sp-p-2=all&sp-p-3=all&subject=/631/158/670&sp-s=date_descending&sp-c=25&facets=new)
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http://www.nature.com/srep/2013/130701/srep02106/carousel/srep02106-f2.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F2.html)Figure 2
http://www.nature.com/srep/2013/130701/srep02106/carousel/srep02106-f3.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F3.html)Figure 3
http://www.nature.com/srep/2013/130701/srep02106/carousel/srep02106-f4.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F4.html)Figure 4
http://www.nature.com/srep/2013/130701/srep02106/carousel/srep02106-f5.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F5.html)Figure 5
http://www.nature.com/srep/2013/130701/srep02106/carousel/srep02106-f6.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F6.html)Figure 6
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Introduction

Introduction•
Results (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#results)•
Discussion (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#discussion)•
Methods (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#methods)•
References (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#references)•
Acknowledgements (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#acknowledgments)•
Author information (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#author-information)•
Supplementary information (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#supplementary-information)

Sex differences in size, shape, colouration and behaviour arise from differences in reproductive success caused by competition over mates. Male weapons evolve through contests over females, and male ornaments evolve through sexual selection by female mate choice (sexual selection)1 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref1), 2 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref2). These hypotheses proposed by Darwin have been demonstrated in various organisms, providing an increasingly realistic picture of sexual selection in nature3 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref3), 4 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref4), 5 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref5), 6 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref6), 7 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref7), 8 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref8), 9 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref9), 10 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref10). Although selective mechanisms and characteristics have been studied in fishes, our knowledge is still limited to specific groups: tropical freshwater fishes such as guppy and swordtail (Poeciliidae), which are easy to use for aquarium experiments11 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref11), 12 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref12), 13 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref13), and shallow reef fishes such as wrasse (Labridae) and damselfish (Pomacentridae), which are easy to observe underwater14 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref14), 15 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref15), 16 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#ref16).
A geometric circular structure measuring approximately 2 m in diameter was found in 1995 on the seabed near southern Amami-Oshima Island in subtropical Japan. Subsequently, the circular structure was sporadically observed by native recreational divers. The origin of the structure was unclear, and it was unknown whether it had been created by a natural phenomenon or by an organism. The divers named the structure a ‘mystery circle’. We identified a small male pufferfish,Torquigener sp. (Tetraodontidae) (Fig. 1 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#f1)), measuring approximately 120 mm in total length, constructing the circular structure on the seabed for the first time in 2011. Here we describe how the males construct the structure and discuss reasons for their construction based on underwater observations and the results of a hydrodynamic experiment. Furthermore, we discuss the structure's function and the reasons behind the male's construction of a new structure during each reproductive cycle, instead of repairing and reusing the previous structure.
Figure 1: Male pufferfish, Torquigener sp.http://www.nature.com/srep/2013/130701/srep02106/images_article/srep02106-f1.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F1.html)The male is digging a valley with its fins and body. Photograph by K. Ito at Seisui on 23 April 2012.



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Results

Introduction (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#introduction)•
Results•
Discussion (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#discussion)•
Methods (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#methods)•
References (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#references)•
Acknowledgements (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#acknowledgments)•
Author information (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#author-information)•
Supplementary information (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#supplementary-information)

A total of 10 male reproductive processes (the process of preparing for spawning and subsequently performing egg care) were observed in 2 observation areas set up on the sandy bottom off Seisui and Katetsu (Fig. 2 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#f2)). Two males appeared in each observation area, and no other male was observed in these areas. Although they were not tagged, at least the males at S1 and S3 and K1 and K3 were identified as the same individuals by the presence of lateral body scars in the former and the construction of another new circular structure during egg-care in the latter (Fig. 2 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#f2)). This is to say the actual number of male individuals in the study areas ranged from 4 (in the case that males at S1, S3 and S5; S2, S4 and S6; K1 and K3; and K2 and K4 were the same individuals, respectively) to 8 (in the case that all males except those at S1 and S3, and K1 and K3 were different individuals). Each of the males constructed a circular structure on the seabed (Fig. 3 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#f3)), which required 7–9 days to complete (Fig. 2 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#f2); K1, K3 and K4). The behavioural patterns of the males changed during construction (Fig. 4 (http://www.nature.com/srep/2013/130701/srep02106/full/srep02106.html#f4)).
Figure 2: Reproductive process of male pufferfish.http://www.nature.com/srep/2013/130701/srep02106/images_article/srep02106-f2.jpg (http://www.nature.com/srep/2013/130701/srep02106/fig_tab/srep02106_F2.html)S1–6 and K1–4 indicate circular structures found at Seisui and Katetsu, respectively. Columns of light green, green and blue indicate the duration of the early, middle and final stage of circular structure construction, respectively. Refer the text for the definitions of the 3 construction stages. Light blue columns indicate the duration of egg care. White stars indicate spawning, solid triangles indicate hatching. N, R, and r indicate the number of peaks and valley pairs, radius, and radius of the central zone of the circular structure, respectively.



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Figure 3: Changes in the circular structure constructed by male pufferfish.



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Marcel TUDOR
27.07.2013, 19:00
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