Coexistence of bisexual and unisexual populations of Nysius groenlandicus in the Zackenberg Valley, Northeast Greenland
Coexistence of bisexual and unisexual populations of Nysius groenlandicus in the Zackenberg Valley, Northeast Greenland
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DOI：
10.1111/j.1570-7458.2011.01153.x
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发表时间：
2011-09-01
影响因子：
1.9
通讯作者：
Nachman, Gosta
中科院分区：
文献类型：
--
作者：
Bocher, Jens;Nachman, Gosta
以种子为食的真虫 Nysius groenlandicus (Zetterstedt)（异翅目：Lygaeidae）与许多沙漠栖息的昆虫具有相似的温度和湿度偏好。然而，它在格陵兰岛广泛分布，甚至在北极高海拔地区也有出现。这种看似悖论意味着该物种已经发展出生理、生态和行为机制，使其能够应对极端的北极环境。这些适应之一是它有性和无性繁殖的能力。有性生殖在沿海人群中最常见，而无性生殖（孤雌生殖）主要发生在内陆人群中。来自格陵兰岛东北部扎肯伯格山谷的初步数据表明，这两种繁殖策略都发生在同一地区。因此，我们决定重点关注这一领域，寻找以下证据：（1）单性恋和双性恋群体共存，（2）与两种生殖类型分布相关的因素，以及（3）有性群体和无性群体的雌性之间的形态差异。我们在扎肯伯格地区的 51 个地点对格罗恩兰迪斯猪笼草进行了采样。仅在四个样本中发现雄性和雌性的数量几乎相等，并且仅在靠近海岸线的样本中发现，而来自山谷内部的样本几乎全部由雌性组成。因此，当地范围内单性恋和双性恋人口的分布与之前在整个格陵兰岛发现的模式一致。利用该地区两个气候站获得的数据，我们发现山谷内部的夏季平均气温比海岸更有利于格罗恩兰迪斯猪笼草。内陆种群居住在孤立的小块地区，而有性种群则分布在沿海更均匀的地区。数据支持这样的假设，即两种生殖类型的共存是通过环境变异性和以频繁灭绝和重新殖民为特征的集合种群动态的结合来维持的，环境变异性使有性繁殖具有优势，而集合种群动态则以频繁的灭绝和重新殖民为特征，有利于无性繁殖。单性恋人群中女性的头宽平均比双性恋人群中的女性大 7%。这种形态差异背后的机制需要进一步研究。
The seed-feeding true bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae) has temperature and humidity preferences similar to many desert-inhabiting insects. Nevertheless, it is widely distributed in Greenland and occurs even in high arctic areas. This seeming paradox implies that the species has developed physiological, ecological, and behavioral mechanisms that enable it to cope with the extreme arctic environment. One of these adaptations is its ability to reproduce both sexually and asexually. Sexual reproduction is most common in coastal populations, whereas asexual reproduction (parthenogenesis) occurs mainly in inland populations. Preliminary data from the Zackenberg Valley in Northeast Greenland indicated that both reproductive strategies occurred within the same area. We therefore decided to focus on this area to find evidence of (1) coexistence of unisexual and bisexual populations, (2) factors that correlate with the distribution of the two reproductive types, and (3) morphological differences between females from sexual and asexual populations. We sampled N. groenlandicus at 51 sites within the Zackenberg area. Males and females were found in almost equal numbers in only four of the samples, and only in samples taken close to the coast line, whereas samples from the inner part of the valley consisted almost entirely of females. Thus, the distribution of uni- and bisexual populations at the local scale agreed with the pattern previously found for Greenland as a whole. Using data obtained from two climate stations operated in the area, we showed that average summer temperatures tend to be more favorable for N. groenlandicus in the inner part of the valley than at the coast. The inland populations inhabited small isolated patches, whereas the sexual populations were found in the more homogeneous areas along the coast. Data support the hypothesis that coexistence of the two reproductive types is maintained by a combination of environmental variability, which gives sexual reproduction an advantage, and metapopulation dynamics characterized by frequent extinctions and re-colonizations, which favors asexual reproduction. Head width of females from unisexual populations was on average 7% larger than that of females from bisexual populations. The mechanism behind this morphological difference needs further investigation.