Th. Worthy et al., AN ANALYSIS OF SKELETAL SIZE VARIATION IN MYSTACINA-ROBUSTA DWYER, 1962 (CHIROPTERA, MYSTACINIDAE), New Zealand journal of zoology, 23(2), 1996, pp. 99-110
Size variation within the presumably extinct greater short-tailed bat
Mystacina robusta is described from a variety of teeth and longbone me
asurements. Data from recent specimens collected from Big South Cape a
nd Solomon Islands are compared with those from fossil bones, mainly o
f Holocene age, from the Waitomo - Hawkes Bay and Martinborough region
s of the North Island, and Takaka, North Canterbury and South Canterbu
ry in the South Island, New Zealand. Variation is clinal, with size de
creasing significantly southwards. The hypothesis is proposed that thi
s clinal variation is a net response to two selection pressures. First
ly, it was advantageous for M. robusta to be relatively large to explo
it the abundant macro-invertebrates and microvertebrates available on
the forest floor. Secondly, large size would have been increasingly co
ld-limited towards the south, where the energy required to rewarm the
animals from the near-ambient temperatures reached during torpor was g
reatest.