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- P-ISSN2765-2203
- E-ISSN2765-2211
- KCI Candidate
Abstract
Detrimental effects of inbreeding have been studied by many researchers for a long time. However, only a few studies have shown the occurrence of inbreeding depression due to evolutionary changes as a purging process. In this study, two different populations (inbreeding and outbreeding) of Drosophila melanogaster were compared to assess inbreeding effects on artificial population bottlenecks. For inbreeding conditions, a couple of D. melanogaster (one virgin and one male) were selected from an inbred population and cultured in a vial. For outbreeding conditions, a couple of D. melanogaster were selected from different populations and cultured in a vial. There were significant differences in body lengths of adults, but not in other parameters such as the total number of adults, the rate of survival, and the rate of wing mutants. The mean body length of adults of outbreeding populations was longer than that of inbreeding populations in the first generation (G1; P = 0.004), but not in the second generation (G2; P = 0.066). Although the other three parameters (total number of adults, rate of survival, and rate of wing mutants) showed differences in their mean values between inbreeding and outbreeding populations, these differences were not statistically significant. This might be due to genetic purging. This study demonstrated one additional experimental case related to inbreeding depression in artificial bottlenecked populations. Further studies are necessary to confirm the clear interaction between inbreeding depression and genetic purging using more generations and replicates (or samples) of D. melanogaster.
Abstract
Reproduction and molt are costly processes in avian life histories. These two fitness-related traits are expected to be under one of physiological trade-offs. Age-related molt is known to be higher in young birds than that in adults presumably due to the cost of reproduction in adults. The present study partially replicated a previous study using a non-invasive method of seasonal wing feather loss instead of capture-inspection for molting progress in oriental storks (Ciconia boyciana). We first examined characteristics of the known six wing feather types (i.e., primaries [P], primary coverts [PC], secondaries [S], secondary coverts [SC], and tertials [T]) from two specimens with four wings. Results were utilized as references for further investigation. We then collected a total of 3,807 wing feathers shedded by 61 captive storks for one year and classified them into six wing feather types based on the reference with structures of vane (i.e., how asymmetrical) and calamus (i.e., how rigidly attached to skin) of wing feathers. Our results indicated that annual losses of all six-type wing feathers decreased with increasing ages, ranging from 29% to 58% for PC, alula, SC, P, S, and T in order. Our results were also comparable to those of a former study, suggesting that the pattern of age-specific molt might be associated with the cost of reproduction in adults. However, juveniles might shed more wing feathers with low quality formed during the previous development stage than older birds.
