HighlightsComparing the copy number variations of DNA repair genes in diverse plant species PARP gene family showed higher copy number in trees compared to herbs There was negative correlation between copy number of PARP1 and growth rate in trees Increased copy number of PARP would be evolutionary favored in plant longevity
Background and Aims
Is there selection minimizing the costs of ovule production? Such selection should lead to a smaller ovule size in relation to seed size and, at the same time, smaller variation in ovule size within plants, the latter because the minimum structures and resources for functioning of ovules should be the same among ovules. Additionally, within species, ovule size should not depend on the plant’s resource status.
Methods
To confirm these predictions, we examined ovule and seed production for a variety of species.
Key Results
Among the 27 species studied, we found a significant negative dependence of the species mean of the coefficient of variation for plant ovule size on the ratio of the mean species seed size/mean species ovule size. Thus, the smaller the ovule size as compared with seed size, the smaller the degree of variation in ovule size. Among the 49 species studied, only two species showed significant positive dependence of mean ovule size on plant size. Although larger plants should have greater resources for ovule production, selection has not enhanced the production of large ovules in most species.
Conclusions
These results suggest that there is selection minimizing the costs of ovule production.
When the abundance and the composition of pollinators are unpredictable, exploitation of a diverse assemblage of pollinators is important for plant reproduction. To examine the role of floral traits in attracting diverse pollinators, we performed a field study using the zygomorphic flowers of Isodon trichocarpus. We investigated variation in floral traits among flowers and seasonal variation in pollinator assemblage and determined whether pollinator behaviour is linked to floral traits. We compared pollinator diversity among flowers by flower-based rarefaction and extrapolation. Pollinator diversity increased with span of corolla opening. The number of bumble bee visits increased with upper lip height. During the flowering period, there were only 2 days when all pollinator groups (wasps, bumble bees, small bees and hoverflies) were observed, and there were 4 days when only one group was observed. Thus, the degree of generalization was not similar for all flowers because pollinator visits differed according to floral traits and some pollinator groups were observed in only part of the flowering season. Our results show that floral form increased attractiveness to diverse pollinators and that different flower traits were associated with different pollinator visits. Thus, pollinator assemblage in this species is related to floral traits.
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