9780521861724htl 1..2

systems, discrete and surrounded by inimical habitat. They have relatively

low persistence on both ecological and geological timescales compared with

marine systems, which are also highly connected (Moss,1998). In addition,

marine populations might be viewed as effectively open systems, with lower

probabilities of local extinctions occurring, especially in species dispersing

planktonically (Eckert,2003). Marine habitats have historically been more

stable and less disturbed than terrestrial or freshwater systems (Moss,1998),

and may therefore be less shaped overall by dispersal patterns modes and hence

by body sizes. However, the parallel between the two systems may be most valid

at the level of dispersal viewed as a lottery with a high risk associated. The greater

the number of tickets a species buys, the greater the probability of success, thus

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Planktotrophs Lecithotrophs Non-planktonic

(b)

0

20

40

60

80

100

120

Body length (mm)

Developmental mode

Planktotrophs Lecithotrophs Non-planktonic

(a)

Proportional site occupancy

Figure 10.7Mean (SE)

proportional site

occupancy (F2,125¼1.66,

ns) (a) and body length

(F2,125¼0.69, ns) (b) of

planktotrophic (n¼66),

lecithotrophic (n¼34)

and non-planktonic

(n¼26) polychaetes.

Planktotrophic taxa are

more widespread (ANOVA

p<0.05, data subjected to

Asinp(x) transformation

to normalize variances)

than non-planktonic

dispersers, and tend to be

larger. Data from Foggo

et al. (unpublished).

202 S. D. RUNDLEET AL.