TY - JOUR
T1 - Early evolution of reproductive isolation
T2 - A case of weak inbreeder/strong outbreeder leads to an intraspecific hybridization barrier in Arabidopsis lyrata
AU - İltaş, Ömer
AU - Svitok, Marek
AU - Cornille, Amandine
AU - Schmickl, Roswitha
AU - Lafon Placette, Clément
N1 - Publisher Copyright:
© 2021 The Authors. Evolution © 2021 The Society for the Study of Evolution.
PY - 2021/6
Y1 - 2021/6
N2 - Reproductive strategies play a major role in plant speciation. Notably, transitions from outcrossing to selfing may lead to relaxed sexual selection and parental conflict. Shifts in mating systems can affect maternal and paternal interests, and thus parent–specific influence on endosperm development, leading to reproductive isolation: if selfing and outcrossing species hybridize, the resulting seeds may not be viable due to endosperm failure. Nevertheless, it remains unclear how the switch in mating systems can impact reproductive isolation between recently diverged lineages, that is, during the process of speciation. We investigated this question using Arabidopsis lyrata, which recently transitioned to selfing (10,000 years ago) in certain North American populations, where European populations remain outcrossing. We performed reciprocal crosses between selfers and outcrossers, and measured seed viability and endosperm development. We show that parental genomes in the hybrid seed negatively interact, as predicted by parental conflict. This leads to extensive hybrid seed lethality associated with endosperm cellularization disturbance. Our results suggest that this is primarily driven by divergent evolution of the paternal genome between selfers and outcrossers. In addition, we observed other hybrid seed defects, suggesting that sex-specific interests are not the only processes contributing to postzygotic reproductive isolation.
AB - Reproductive strategies play a major role in plant speciation. Notably, transitions from outcrossing to selfing may lead to relaxed sexual selection and parental conflict. Shifts in mating systems can affect maternal and paternal interests, and thus parent–specific influence on endosperm development, leading to reproductive isolation: if selfing and outcrossing species hybridize, the resulting seeds may not be viable due to endosperm failure. Nevertheless, it remains unclear how the switch in mating systems can impact reproductive isolation between recently diverged lineages, that is, during the process of speciation. We investigated this question using Arabidopsis lyrata, which recently transitioned to selfing (10,000 years ago) in certain North American populations, where European populations remain outcrossing. We performed reciprocal crosses between selfers and outcrossers, and measured seed viability and endosperm development. We show that parental genomes in the hybrid seed negatively interact, as predicted by parental conflict. This leads to extensive hybrid seed lethality associated with endosperm cellularization disturbance. Our results suggest that this is primarily driven by divergent evolution of the paternal genome between selfers and outcrossers. In addition, we observed other hybrid seed defects, suggesting that sex-specific interests are not the only processes contributing to postzygotic reproductive isolation.
KW - Arabidopsis lyrata
KW - endosperm balance number
KW - gray zone of speciation
KW - Hybrid seed lethality
KW - mating system divergence
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U2 - 10.1111/evo.14240
DO - 10.1111/evo.14240
M3 - Article
C2 - 33900634
AN - SCOPUS:85105494013
SN - 0014-3820
VL - 75
SP - 1466
EP - 1476
JO - Evolution
JF - Evolution
IS - 6
ER -