Effects of climate change on pup growth and survival in a cooperative mammal, the meerkat

1.    Breeding systems in which group members
help to raise the offspring of co-members are associated with arid,
unpredictable environments. Cooperative rearing may mitigate the effects
of adverse environmental conditions on pup growth and survival. However,
few studies have explored the relationship between environmental variation
and breeding success, and the role of helpers. 
2.    Here we show that increases in daily
maximum air temperatures (Tmax) in the southern Kalahari over the last
twenty years have been associated with reductions in the growth and
survival of meerkat (Suricata suricatta) pups. 
3.    On days when Tmax was high, meerkat pups
gained less body mass than on cooler days. Reductions in the diurnal body
mass gain (ΔMb) of pups on hotter days were not a consequence of
reductions in the frequency with which pups were fed by adults as feeding
rate increased with Tmax, suggesting that the reductions in ΔMb by pups on
hot days reflected a decrease in water content of the food items or an
increased water and energy cost of thermoregulation. 
4.    Reductions in pup ΔMb on hot days were
smaller in larger groups, in which helper-to-pup ratios were relatively
high. 5.    As further increases in air
temperature are predicted with climate change, further reductions in
meerkat pup growth and survival seem inevitable.

1. 群体成员协助抚育其他成员后代的繁育系统，与干旱且环境不可预测的生境高度相关。合作抚育可缓解不利环境条件对幼崽生长与存活的负面影响。然而，目前鲜有研究探讨环境波动与繁育成功率之间的关联，以及协助者在其中发挥的作用。
2. 本研究表明，过去二十年间，喀拉哈里南部地区的每日最高气温（daily maximum air temperature, Tmax）持续升高，与狐獴（Suricata suricatta）幼崽的生长发育及存活率下降显著相关。
3. 当每日最高气温偏高时，狐獴幼崽的体质量增长幅度低于气温较低的时日。高温时日幼崽的日体质量增量（diurnal body mass gain, ΔMb）下降，并非源于成年个体投喂频率降低——事实上投喂频率随Tmax升高而增加，这表明幼崽在高温时日的ΔMb下降，反映出食物的含水量降低，或是体温调节所需的水分与能量成本上升。
4. 群体规模越大、协助者与幼崽的比例越高时，高温时日幼崽ΔMb的下降幅度越小。
5. 随着气候变化预测显示气温将进一步升高，狐獴幼崽的生长与存活率或将进一步下降，这一趋势似乎难以避免。