Biology Reference
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time available to develop as adult before autumn) (
Gotthard, Nylin, &
Wiklund, 1999
). Similar regulation also occurs in the nympahalid
Lasiommata
petropolitana
whose larvae finely adjust their growth rate in advance of dia-
pause onset. In fact, larvae set for pupal diapause (short days) exhibit faster
larval development and a higher larval growth rate, quickly pupating with
a smaller size than those set for “long-day” development (about 40 days
vs. 70 days to reach pupation) (
Gotthard, 1998; Leimar, 1996; Nylin,
Gotthard, &Wiklund, 1996
). Thus, larvae carefully adjust their growth rate
before and after diapause with respect to the predicted time available for
growth (
Gotthard, 2008
).
7. SEASONAL POLYPHENISMS CORRELATE WITH
DIAPAUSE
Seasonal polymorphisms (polyphenism) in moths and butterflies often
correlate with diapause trajectory and their specification occurs coincidentally
to dormancy induction. Developmentally, changes in a hormone-sensitive
period or modifications in the strength, or in the timing, of hormone signaling
are pivotal in orchestrating these seasonal polyphenisms (
Nijhout, 2003;
Saunders et al., 2002
). Photoperiodic changes also play a fundamental role
in such phenomena as reliable cues of the time of the year and, as described
above, are used by the larvae to finely adjust their growth rate in advance of
diapause onset. As an example, the nymphalid
Anaea andria
exhibits a strong
seasonal polyphenism in wing shape that is coincidental with diapause trajec-
tory. The fifth instar larvae (
4-5 days prior to pupation) grown under long
days (
>
16 h of light) develop into a “summer” form that has blunt forewing
apex tails and decreased posterior projection on the hind wing. Conversely,
short photoperiods (
<
12 h of light) induce the appearance of “autumnal/win-
ter” morphs that exhibit forewing apices developed as recurved tails and an
increased anal projection on the hind wing. The two forms also differ in
the dorsal pigmentation of the wings and in the cryptic color of ventral wing
surface, with the “winter” morphs that are darker (mostly brown) than the
“summer” ones. Interestingly, the twomorphs are also different in their devel-
opmental time (at 27
C) since the “summer” form needs 25-45 days to
emerge as a butterfly while the “winter” form requires roughly 5 days more
than the time of the summer form (
Riley, 1980
). Since this species also exhibits
adult diapause (reproductive diapause) (
Scott, 1979
and references therein), the
seasonal polyphenism might be hormonally linked to diapausing functions so
