Internal selection against the evolution of left-right reversal.

Autor: Utsuno H; Department of Biology, Shinshu University, Matsumoto 390-8621, Japan. hirokiiii@hotmail.com, Asami T, Van Dooren TJ, Gittenberger E
Jazyk: angličtina
Zdroj: Evolution; international journal of organic evolution [Evolution] 2011 Aug; Vol. 65 (8), pp. 2399-411. Date of Electronic Publication: 2011 Apr 29.
DOI: 10.1111/j.1558-5646.2011.01293.x
Abstrakt: Among metazoan species, left-right reversals in primary asymmetry have rarely gone to fixation. This suggests that a general mechanism suppresses the evolution of polarity reversal. Most metazoans appear externally symmetric and reproduce by external fertilization or copulation with genitalia located in the midline. Thus, reversal should generate little exogenous disadvantage when interacting with the external environment or in mating with the common wild-type. Accordingly, an endogenously caused fitness reduction may be responsible for the general absence of reversed species. However, how this selection operates is little understood. Phenotypic changes associated with reversal are usually inseparable from zygotic pleiotropy. By exploiting hermaphroditism and the maternal inheritance of left-right polarity, we generated dextral and sinistral snails that share the same zygotic genotype. Before hatching, these sinistrals developed lethal morphological anomalies more frequently than dextrals. Their shell shape at maturity differed from the mirror image of the dextral shell. These interchiral differences demonstrate pleiotropy in maternal effects of the polarity or linked genes. Variation in interchiral differences between parental crosses suggests the presence of epistatic variation in relative performance of sinistrals. Our results show that internal selection operates against polarity reversal, and we suggest that this is due to changes in blastomere configuration.
(© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.)
Databáze: MEDLINE
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