Stojković Biljana, Đorđević Mirko, Janković Jelena, Savković Uroš, Tucić Nikola
Department of Evolutionary Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade; Institute of Zoology, Faculty of Biology, University of Belgrade, Belgrade, Serbia.
Insect Sci. 2015 Apr;22(2):295-309. doi: 10.1111/1744-7917.12115. Epub 2014 Apr 29.
We tested mutation accumulation hypothesis for the evolution of senescence using short-lived and long-lived populations of the seed-feeding beetle, Acanthoscelides obtectus (Say), obtained by selection on early- and late-life for many generations. The expected consequence of the mutation accumulation hypothesis is that in short-lived populations, where the force of natural selection is the strongest early in life, the late-life fitness traits should decline due to genetic drift which increases the frequency of mutations with deleterious effects in later adult stages. Since it is unlikely that identical deleterious mutations will increase in several independent populations, hybrid vigor for late-life fitness is expected in offspring obtained in crosses among populations selected for early-life fitness traits. We tested longevity of both sexes, female fecundity and male reproductive behavior for hybrid vigor by comparing hybrid and nonhybrid short-lived populations. Hybrid vigor was confirmed for male virility, mating speed and copulation duration, and longevity of both sexes at late ages. In contrast to males, the results on female fecundity in short-lived populations did not support mutation accumulation as a genetic mechanism for the evolution of this trait. Contrary to the prediction of this hypothesis, male mating ability indices and female fecundity in long-lived populations exhibited hybrid vigor at all assayed age classes. We demonstrate that nonhybrid long-lived populations diverged randomly regarding female and male reproductive fitness, indicating that sexually antagonistic selection, when accompanied with genetic drift for female fecundity and male virility, might be responsible for overriding natural selection in the independently evolving long-lived populations.
我们利用以取食种子的甲虫豆象（Acanthoscelides obtectus (Say)）的短命和长寿种群，通过对早龄期和晚龄期进行多代选择获得的种群，来检验衰老进化的突变积累假说。突变积累假说的预期结果是，在短命种群中，自然选择的力量在生命早期最强，由于遗传漂变，晚龄期的适合度性状应该会下降，而遗传漂变会增加成年后期具有有害效应的突变的频率。由于相同的有害突变不太可能在几个独立的种群中增加，因此在为早龄期适合度性状选择的种群之间杂交获得的后代中，预期会出现晚龄期适合度的杂种优势。我们通过比较杂种和非杂种短命种群，来检验两性的寿命、雌性繁殖力和雄性生殖行为的杂种优势。在雄性活力、交配速度和交配持续时间以及晚龄期两性的寿命方面，杂种优势得到了证实。与雄性不同，短命种群中雌性繁殖力的结果不支持突变积累是该性状进化的遗传机制这一观点。与该假说的预测相反，长寿种群中雄性交配能力指标和雌性繁殖力在所有测定的年龄组中都表现出杂种优势。我们证明，非杂种长寿种群在雌性和雄性生殖适合度方面随机分化，这表明当伴随着雌性繁殖力和雄性活力的遗传漂变时，性拮抗选择可能是导致在独立进化的长寿种群中自然选择被推翻的原因。
