Latitudinal variation in allocation to reproduction by the Antarctic oribatid mite, Alaskozetes antarcticus

The oribatid mite Alaskozetes antarcticus is found over a wide range of southern latitudes, between the cool temperate Falkland Islands (51–52°S) and Alexander Island (71–72°S). It is one of the largest terrestrial invertebrates found in Antarctica, where it dominates certain communities. Female A. antarcticus mature a single batch of eggs. Samples of A. antarcticus from seven sites in the maritime Antarctic and one in the sub-Antarctic, covering a latitudinal range of ca. 15° (53–68°S), were used to obtain measures of reproductive allocation, approximated by individual egg size and relative total egg to female body volume. Both measures suggest that mites from sub-Antarctic South Georgia showed considerably higher levels of reproductive allocation than those from any site in the maritime Antarctic. However, no consistent trends in any investment measure with increasing southerly latitude were found within the maritime Antarctic. These differences between the two Antarctic regions support, in general terms, the hypothesis that increased investment in survival traits in the harsher maritime Antarctic climate reduces the resources that can be committed to activities such as reproduction