| 總結: | <p>Biparental care is a longstanding evolutionary conundrum. Why should parents continue to
invest in their offspring cooperatively, when by abandoning their partner they can reap all the
benefits with none of the work? Since the 1970s, several models have attempted to explain the
evolution and maintenance of biparental care in animals, eventually converging on the solution of
conditional cooperation: a parent’s behaviour should depend on the investment decisions of its
partner. This responsive strategy can lead to apparent coordination between parents, and many
empirical examples have since been reported. However, it is difficult to determine whether there
is active behavioural coordination between parents, or indeed the mechanisms underlying it. This
thesis uses two long-lived, monogamous seabird species, the Manx shearwater <em>Puffinus puffinus</em>
and the black-browed albatross <em>Thalassarche melanophris</em>, to investigate the occurrence and
mechanisms of coordinated parental behaviour. Using both experimental field manipulations and
quantitative observations I investigated the evidence for parental coordination in these species, and
the mechanisms and information parents may use to achieve it. Firstly, I examined the incubation
behaviour of parent Manx shearwaters, and found that their investment decisions were underlain
largely by their available body mass reserves, matching life-history predictions that long-lived
species should be selected to prioritise their own condition. Specifically, foraging birds determined
how long they should spend at sea by the amount of mass gains they needed to make on their trip,
with lighter birds spending proportionally more time foraging. However, I found that this decision
was modulated by the partner’s condition, with birds curtailing their trips when their partner
was in poor condition, suggesting that cooperative processes, perhaps facilitated by a process
of negotiation, may drive the coordination of care during incubation in this species. For chickrearing
shearwaters, I examined whether direct communication, or indirect information garnered
from the behaviour of the chick, might facilitate the coordination of nest visitation. Neither
putative sources of information appeared necessary for coordination in this species, and it was
not possible to determine conclusively what information drives provisioning behaviour. Instead,
I introduced the possibility that coordination at this breeding stage emerges passively through
an entrainment process during incubation. Finally, I investigated the potential role of intra-pair
display in facilitating coordination in the black-browed albatross, with a focus on allopreening. I
report tentative evidence that display forms part of an assessment process whereby the outgoing
parent determines its partner’s willingness to invest in care, which may ultimately contribute to
decision-making processes relating to foraging trip duration. Overall, I present evidence that
biparental care in these species may be underlain by nuanced systems of intra-pair coordination,
giving further insight into why and how animals are able to achieve cooperative behaviour.</p>
|
|---|