Solignac Michel
Laboratoire de Biologie et Génétique Evolutives, Centre National de la Recherche Scientifique, F-91190, Gif-sur-Yvette, France.
Laboratoire d'Evolution des Etres Organisés, 105, Boulevard Raspail, F-75006, Paris, France.
Oecologia. 1976 Mar;26(1):33-52. doi: 10.1007/BF00345651.
A demographic study was carried out on two closely related species of the isopods Jaera (albifrons) ischiosetosa and J. (a.) albifrons and their F hybrids. The results from the 16 possible combinations of crosses have permitted an analysis of the nature of the mechanisms assuring the isolation of the species studied. Although intraspecific crosses yield an immediate success, interspecific crosses in the absence of choice of mates progress only slowly during the course of weeks. The results of both crosses between hybrids and back-crosses turn out to be intermediate between those of intra- and interspecific crosses. The hybrids of the first generation are perfectly viable and their survival curves are identical to those of the parents. The fertility of parents in intra- and interspecific crosses is comparable, with the exception of the fragility of female descendants (heterogametic sex) in one direction of crossing. The fertility of the F hybrids, however, crossed either among themselves or with their parents, is quite noticeably decreased: the time needed to double the size of the population is 2.5 times longer for the hybrids than for the parents. This hybrid breakdown completes the pre-fertilization isolating mechanisms: partial ecological isolation, and especially ethological isolation, is practically total when a choice of mates exists. The two species studied, for which demographic parameters are quite close, were raised together for ten generations and yielded only exceptional hybrids with a frequency which does not exceed that found under natural conditions.
对等足目动物耶尔虾属（Jaera）的两个近缘物种耶尔虾（Jaera (albifrons) ischiosetosa）和耶尔虾（J. (a.) albifrons）及其F1杂种进行了种群统计学研究。16种可能的杂交组合结果使得对确保所研究物种隔离的机制性质进行分析成为可能。虽然种内杂交能立即成功，但在没有配偶选择的情况下，种间杂交在数周内进展缓慢。杂种与回交的杂交结果均介于种内杂交和种间杂交结果之间。第一代杂种完全可存活，其存活曲线与亲本相同。种内和种间杂交中亲本的繁殖力相当，但在一个杂交方向上雌性后代（异配性别）较为脆弱。然而，F1杂种之间或与亲本杂交时，其繁殖力明显下降：杂种使种群数量翻倍所需的时间是亲本的2.5倍。这种杂种衰败完善了受精前的隔离机制：当存在配偶选择时，部分生态隔离，尤其是行为隔离，实际上是完全的。所研究的两个物种的种群统计学参数相当接近，将它们一起饲养了十代，只产生了极少数杂种，其频率不超过在自然条件下发现的频率。
