Biology Reference
In-Depth Information
(a)
(b)
C
B
Group size
Group size
Fig. 6.17
The idea of optimal group size. (a) As group size increases both benefits and
costs increase. However, in theory the increase in benefits will be a decelerating function
(with each added individual having less effect than the last), while the increase in costs
will accelerate (each added individual having more effect than the last). Therefore, costs
will eventually exceed the benefits at large group sizes. (b) In theory, there will be an
optimal group size (benefits - costs a maximum) at an intermediate group size. After
Krause and Ruxton (2002).
(b)
(a)
50
250
10
40
200
8
30
150
6
20
100
4
10
50
2
1
2345
678
1
2345
678
Lion group size
Lion group size
Fig. 6.18
Caraco and Wolf's calculation of optimal hunting group size for lions when
hunting wildebeest in the Serengeti. (a) With increasing lion group size, capture success
increases (solid circles) but if a kill is made, then food per lion decreases (open triangles).
(b) This results in an optimal group size of two lions, to maximize food per lion per
chase. Observed group sizes, however, are larger, on average three to four lions per
hunt. From Caraco and Wolf (1975).
