February paper discussion (Jitka’s pick)

February 1st, 2010

Kochanek Jitka., Buckley Y.M., Probert R.J., Adkins S.W. & Steadman K.J. (2010).

Pre-zygotic parental environment modulates seed longevity.

Austral Ecology, (In press).

The environment that a plant experiences prior to seed set can have a major role in determining the quality and longevity of its progeny seeds.  We found that the environment a maternal plant experienced prior to setting seeds changed the potential lifespan of the seeds by at least a factor of two for an arid to semi-arid species, Wahlenbergia tumidifructa (Figure 1).

Figure 1. Wahlenbergia tumidifructa in the field.

Mean seed longevity was similar for seeds produced by plants that grew in warm-wet, warm-dry and cool-dry but longevity increased for seeds of plants in cool-wet conditions (Figure 2). We think it likely that a parental effect modified seed longevity as the maternal plant had visible phenotypic changes in response to environmental conditions that correlated with longevity and quality of the progeny seeds. Given that seed longevity is likely to be an important contributor to stable species coexistence, the novel environmental conditions expected with climate change may thus potentially alter the storage effect for this species.

Figure 2. W. tumidifructa in glasshouse experiment (cool-wet, cool-dry, warm-wet, warm-dry)

In our discussion of this paper it was suggested that the interpretation of the results is complex and warrants further research, for example, reduced seed longevity is not necessarily maladaptive, but may be adaptive under certain conditions. Also it is unclear whether the parental effect on progeny seeds is transient or reappears in subsequent generations. Possible avenues of research may be:

1) To construct a stochastic matrix model parameterised from different environmental conditions (spatially and/or temporally) to test the effect of seed longevity on population growth rate in different environmental contexts;

2)  Determine whether variable field environmental conditions give similar results as under controlled glasshouse and laboratory conditions used in this study. Reciprocal transplant studies may be particularly useful; and

3) Determine whether the response shown by W. tumidifructa is unique, given that it is amazingly plastic, or whether other, perhaps endangered species, respond in a similar way. Jitka is currently compiling another paper which shows the same results for Plantago cunninghamii, also a highly plastic species.

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