The Company of Biologists

Table 2.

Characteristics of the discontinuous gas exchange cycle from the anterior and posterior spiracles of four dung beetle species

	P. femoralis			S. gariepinus			S. striatum			C. bacchus^{^*}
Species	Mesothoracic spiracles	Posterior spiracles	Mesothoracic spiracles	Elytral case	Mesothoracic spiracles	Elytral case	Mesothoracic spiracles	Elytral case
Closed period
sV̇_CO₂(μl g^-1)	0.16±0.06	0.44±0.24	0.70±0.6	2.64±3.2	6.33±8.8^{^†}	1.91±1.4^{^†}	0.57±0.22^{^†}	—
Duration (s)	307.2±102.5		1620.8±1265.3		604.7±187.6^{^†}		1858.3±917.1^{^†}	—
%DGC duration	20.7±5.5		42.7±16.4		34.2±11.9^{^†}		42.9±10.4^{^†}	—
Flutter period
sV̇_CO₂(μl g^-1)	0.60±0.4	4.44±2.6	1.01±0.9	—
Duration (s)	496.4±290.1		534.7±353.0
%DGC duration	29.0±9.8		17.52±12.4
Burst period
sV̇_CO₂(μl g^-1)	2.40±2.3	35.86±13.7	7.47±3.9	44.26±16.83	14.89±12.5	17.62±12.9	36.1±15.5	—
Duration (s)	785.7±288.6		1301±455.4	1836±533.2	1194.7±331.2		2230.4±325.1	—
%DGC duration	50.3±5.6		17.5±12.4	57.2±17.5	66.6±11.2		55.2±12.0	—

	P. femoralis			S. gariepinus			S. striatum			C. bacchus^{^*}
Species	Mesothoracic spiracles	Posterior spiracles	Mesothoracic spiracles	Elytral case	Mesothoracic spiracles	Elytral case	Mesothoracic spiracles	Elytral case
Closed period
sV̇_CO₂(μl g^-1)	0.16±0.06	0.44±0.24	0.70±0.6	2.64±3.2	6.33±8.8^{^†}	1.91±1.4^{^†}	0.57±0.22^{^†}	—
Duration (s)	307.2±102.5		1620.8±1265.3		604.7±187.6^{^†}		1858.3±917.1^{^†}	—
%DGC duration	20.7±5.5		42.7±16.4		34.2±11.9^{^†}		42.9±10.4^{^†}	—
Flutter period
sV̇_CO₂(μl g^-1)	0.60±0.4	4.44±2.6	1.01±0.9	—
Duration (s)	496.4±290.1		534.7±353.0
%DGC duration	29.0±9.8		17.52±12.4
Burst period
sV̇_CO₂(μl g^-1)	2.40±2.3	35.86±13.7	7.47±3.9	44.26±16.83	14.89±12.5	17.62±12.9	36.1±15.5	—
Duration (s)	785.7±288.6		1301±455.4	1836±533.2	1194.7±331.2		2230.4±325.1	—
%DGC duration	50.3±5.6		17.5±12.4	57.2±17.5	66.6±11.2		55.2±12.0	—

`—' Denotes a negligible amount. Data shown are mean ± s.d.

From Duncan and Byrne(2002)

Note that these are the measurements for combined closed and flutter periods