PMC

(a) Cumulative frequency distributions for (i) the distances between newly infectious burrow systems and burrow systems known to contain infectious gerbils the previous month (—), and (ii) the distances between occupied burrow systems and burrow systems known to be occupied the previous month (········). (b) An example of the spatial arrangement of empty (○), susceptible () and seropositive (◆) burrow systems at site 1 where data from the winter months of 2002 and 2003 were pooled to classify each burrow system. (c) The cumulative nearest-neighbour distribution function for the set of seropositive burrow systems shown in (b), together with upper and lower envelopes from 99 simulations of complete spatial randomness (points were restricted to be a random subset of the set of occupied burrow systems).

Burrow systems of M201, F478 and M023 (partly excavated only) are depicted in real spatial configuration, for the true position of burrow systems of F222 and F416 see . The burrow system of F478 was not included into analyses since the female was predated at the very beginning of the study. Red lines represent tunnels backfilled at a time of mapping, dashed lines are most probable connections not found. Green circles encompass nest sites. A dash-dot line indicates the expected boundary between the territories of males M201 and M023.

Each triad of male burrow systems (M379, M737, M843) and female burrow systems (F460, F367, F796) is depicted in the real spatial configuration. Red lines represent tunnels backfilled at a time of mapping, dash lines are most probable connections not found. Green circles encompass nest sites.

Photograph of the narrow aquarium and burrow system, with the bioturbating ghost shrimp visible.