Brother, Can You Share a Hollow?

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Science  18 Feb 2011:
Vol. 331, Issue 6019, pp. 823
DOI: 10.1126/science.331.6019.823-c

Tree hollows are a key resource for numerous forest-dwelling species. Hollow reductions that result from forest harvest and management practices are a significant threat to forest species worldwide. Although the reduction of hollows has generally been followed by a decline in dependent species, two species of Australian possum (Gymnobelidus leadbeateri and Trichosurus cunninghami) have not followed this trend. By tracking the denning behavior of individuals of known genetic relatedness, Banks et al. show that this resilience is largely due to a change in social behavior. When hollows are plentiful, possums use a large number of dens, have overlapping home ranges, and prefer to share hollows with unrelated individuals. When hollows are scarce, the animals show increased aggression and defense of hollows and instead prefer to nest with relatives. Thus, when resources are scarce, animals obtain an inclusive fitness benefit of sharing with relatives and excluding nonrelatives, whereas when resources are plentiful, inclusive fitness is less important than other considerations, such as inbreeding or pathogen avoidance.

Proc. R. Soc. London Ser. B 278, 10.1098/rspb.2010.2657 (2011).

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