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Love thy neighbour: group properties of gaping behaviour in mussel aggregations.

Nicastro KR, Zardi GI, McQuaid CD, Pearson GA, Serrão EA - PLoS ONE (2012)

Bottom Line: Although made up of individual members, an aggregation often displays novel effects that do not manifest at the level of the individual organism.P. perna gaping behaviour had no effect on body temperatures of isolated individuals, while it led to increased humidity and decreased temperatures in dense groups (beds).Gaping resulted in cooler body temperatures for P. perna than M. galloprovincialis when in aggregations, while solitary individuals exhibited the highest temperatures.

View Article: PubMed Central - PubMed

Affiliation: CCMAR-CIMAR Laboratório Associado, Universidade do Algarve, Faro, Portugal.

ABSTRACT
By associating closely with others to form a group, an animal can benefit from a number of advantages including reduced risk of predation, amelioration of environmental conditions, and increased reproductive success, but at the price of reduced resources. Although made up of individual members, an aggregation often displays novel effects that do not manifest at the level of the individual organism. Here we show that very simple behaviour in intertidal mussels shows new effects in dense aggregations but not in isolated individuals. Perna perna and Mytilus galloprovincialis are gaping (periodic valve movement during emersion) and non-gaping mussels respectively. P. perna gaping behaviour had no effect on body temperatures of isolated individuals, while it led to increased humidity and decreased temperatures in dense groups (beds). Gaping resulted in cooler body temperatures for P. perna than M. galloprovincialis when in aggregations, while solitary individuals exhibited the highest temperatures. Gradients of increasing body temperature were detected from the center to edges of beds, but M. galloprovincialis at the edge had the same temperature as isolated individuals. Furthermore, a field study showed that during periods of severe heat stress, mortality rates of mussels within beds of the gaping P. perna were lower than those of isolated individuals or within beds of M. galloprovincialis, highlighting the determinant role of gaping on fitness and group functioning. We demonstrate that new effects of very simple individual behaviour lead to amelioration of abiotic conditions at the aggregation level and that these effects increase mussel resistance to thermal stress.

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Results of solitary gaping experiments (trials pooled).Average temperatures of mussels at (a) 19°C or (b) 25°C and maximum temperatures of mussels at (c) 19°C or (d) at 25°C. Post hoc results are included in the figure.
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pone-0047382-g002: Results of solitary gaping experiments (trials pooled).Average temperatures of mussels at (a) 19°C or (b) 25°C and maximum temperatures of mussels at (c) 19°C or (d) at 25°C. Post hoc results are included in the figure.

Mentions: Only Perna perna gaped at either temperature. Body temperature increased when the experimental chamber was set at the higher temperature (Fig. 2; df = 1, p<0.001, see supporting information Table S1, Table S2), but gaping had no effect on maximum or average body temperatures (df = 1, p>0.05 in all cases). No pre-treatment effects were detected.


Love thy neighbour: group properties of gaping behaviour in mussel aggregations.

Nicastro KR, Zardi GI, McQuaid CD, Pearson GA, Serrão EA - PLoS ONE (2012)

Results of solitary gaping experiments (trials pooled).Average temperatures of mussels at (a) 19°C or (b) 25°C and maximum temperatures of mussels at (c) 19°C or (d) at 25°C. Post hoc results are included in the figure.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3472978&req=5

pone-0047382-g002: Results of solitary gaping experiments (trials pooled).Average temperatures of mussels at (a) 19°C or (b) 25°C and maximum temperatures of mussels at (c) 19°C or (d) at 25°C. Post hoc results are included in the figure.
Mentions: Only Perna perna gaped at either temperature. Body temperature increased when the experimental chamber was set at the higher temperature (Fig. 2; df = 1, p<0.001, see supporting information Table S1, Table S2), but gaping had no effect on maximum or average body temperatures (df = 1, p>0.05 in all cases). No pre-treatment effects were detected.

Bottom Line: Although made up of individual members, an aggregation often displays novel effects that do not manifest at the level of the individual organism.P. perna gaping behaviour had no effect on body temperatures of isolated individuals, while it led to increased humidity and decreased temperatures in dense groups (beds).Gaping resulted in cooler body temperatures for P. perna than M. galloprovincialis when in aggregations, while solitary individuals exhibited the highest temperatures.

View Article: PubMed Central - PubMed

Affiliation: CCMAR-CIMAR Laboratório Associado, Universidade do Algarve, Faro, Portugal.

ABSTRACT
By associating closely with others to form a group, an animal can benefit from a number of advantages including reduced risk of predation, amelioration of environmental conditions, and increased reproductive success, but at the price of reduced resources. Although made up of individual members, an aggregation often displays novel effects that do not manifest at the level of the individual organism. Here we show that very simple behaviour in intertidal mussels shows new effects in dense aggregations but not in isolated individuals. Perna perna and Mytilus galloprovincialis are gaping (periodic valve movement during emersion) and non-gaping mussels respectively. P. perna gaping behaviour had no effect on body temperatures of isolated individuals, while it led to increased humidity and decreased temperatures in dense groups (beds). Gaping resulted in cooler body temperatures for P. perna than M. galloprovincialis when in aggregations, while solitary individuals exhibited the highest temperatures. Gradients of increasing body temperature were detected from the center to edges of beds, but M. galloprovincialis at the edge had the same temperature as isolated individuals. Furthermore, a field study showed that during periods of severe heat stress, mortality rates of mussels within beds of the gaping P. perna were lower than those of isolated individuals or within beds of M. galloprovincialis, highlighting the determinant role of gaping on fitness and group functioning. We demonstrate that new effects of very simple individual behaviour lead to amelioration of abiotic conditions at the aggregation level and that these effects increase mussel resistance to thermal stress.

Show MeSH
Related in: MedlinePlus