Exogenous selection shapes germination behaviour and seedling traits of populations at different altitudes in a Senecio hybrid zone.

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Serval ID
serval:BIB_2B46EF3B107D
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Exogenous selection shapes germination behaviour and seedling traits of populations at different altitudes in a Senecio hybrid zone.
Journal
Annals of Botany
Author(s)
Ross R.I., Agren J.A., Pannell J.R.
ISSN
1095-8290 (Electronic)
ISSN-L
0305-7364
Publication state
Published
Issued date
2012
Peer-reviewed
Oui
Volume
110
Number
7
Pages
1439-1447
Language
english
Abstract
BACKGROUND AND AIMS: The Senecio hybrid zone on Mt Etna, Sicily, is characterized by steep altitudinal clines in quantitative traits and genetic variation. Such clines are thought to be maintained by a combination of 'endogenous' selection arising from genetic incompatibilities and environment-dependent 'exogenous' selection leading to local adaptation. Here, the hypothesis was tested that local adaptation to the altitudinal temperature gradient contributes to maintaining divergence between the parental species, S. chrysanthemifolius and S. aethnensis.
METHODS: Intra- and inter-population crosses were performed between five populations from across the hybrid zone and the germination and early seedling growth of the progeny were assessed.
KEY RESULTS: Seedlings from higher-altitude populations germinated better under low temperatures (9-13 °C) than those from lower altitude populations. Seedlings from higher-altitude populations had lower survival rates under warm conditions (25/15 °C) than those from lower altitude populations, but also attained greater biomass. There was no altitudinal variation in growth or survival under cold conditions (15/5 °C). Population-level plasticity increased with altitude. Germination, growth and survival of natural hybrids and experimentally generated F(1)s generally exceeded the worse-performing parent.
CONCLUSIONS: Limited evidence was found for endogenous selection against hybrids but relatively clear evidence was found for divergence in seed and seedling traits, which is probably adaptive. The combination of low-temperature germination and faster growth in warm conditions might enable high-altitude S. aethnensis to maximize its growth during a shorter growing season, while the slower growth of S. chrysanthemifolius may be an adaptation to drought stress at low altitudes. This study indicates that temperature gradients are likely to be an important environmental factor generating and maintaining adaptive divergence across the Senecio hybrid zone on Mt Etna.
Keywords
Senecio aethnensis, S. chrysanthemifolius, hybrid, germination, exogenous selection, early life history, temperature
Pubmed
Web of science
Open Access
Yes
Create date
17/07/2012 7:09
Last modification date
25/09/2019 6:08
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