Pollination mode and life form strongly affect the relation between mating system and pollen to ovule ratios

Abstract

Summary• Pollen to ovule (P : O) ratios have been hypothesized to correlate with the degree of outcrossing and thus with the mating system of a plant. Also, P : O ratios are likely to vary with respect to pollination mode (i.e. wind pollination or animal pollination). Furthermore, constraints on the evolution of mating systems depending on life form may affect P : O ratios.• We compiled P : O ratios and outcrossing rates for 107 angiosperm species and analyzed the relation between these traits considering pollination mode, life form and phylogenetic relatedness among species.• In general, P : O ratios correlated significantly with outcrossing rates. However, when taking additional factors into account, the relation became ambiguous. The correlation was significantly positive in wind-pollinated species, but only marginally so in animal-pollinated species. Wind-pollinated species had higher P : O ratios than animal-pollinated taxa. In woody perennials, outcrossing was the predominant mating system and outcrossing rates did not correlate with P : O ratios. The results were not altered by accounting for phylogenetic relatedness among species.• The results indicate that P : O ratios vary more strongly with pollination mode and life form than with the mating system.

Primary floral allocation per flower in 12 Pedicularis (Orobanchaceae) species: significant effect of two distinct rewarding types for pollinators

“…In other words, the sex allocation in nectarless rewarding species is expected to be male biased. Few studies explore, however, that the effect of rewarding type on pattern of sex allocation thoroughly despite strong appeal to investigate it (Cruden 2000;Michalski and Durka 2009). To our knowledge, only two studies referred it so far (Pellmyr 1985;Mione and Anderson 1992).…”

“…the pollen:ovule ratio, or the ratio of androecium mass to gynoecium mass) may evolve by natural selection in response to changes in pollinator behavior or abundance, pollen vector (e.g. animals vs. wind), or mating system (Cruden 1977;Charlesworth and Charlesworth 1981;Charnov 1982;McKone 1987;Mione and Anderson 1992;Cruden 2000;Jürgens et al 2002;Friedman and Barrett 2008;Michalski and Durka 2009). …”

Phylogenetically balanced evidence for structural and carbon isotope responses in plants along elevational gradients

“…Wind-pollinated species are characterized by high pollen production. The maintenance of reproductive allometries in wind-pollinated species may also be a result of the constrained possibilities of mating system evolution as wind-pollinated species are generally less variable than insect-pollinated species (Michalski and Durka 2009). The patterns seen in Saxifraga and Potentilla conWrm the trend found in a non-phylogenetically-balanced sample by Fabbro and Körner (2004).…”

Assessment of provenance delineation by genetic differentiation patterns and estimates of gene flow in the common grassland plant Geranium pratense

“…Significant deviation from zero expectations is indicated for each distance interval (*** P \ 0.001, ** P \ 0.01, * P \ 0.05). Also, the degree of spatial genetic structure is given for each population by the Sp statistic Confidence intervals in (A) were derived by jackknifing loci and in (B) by jackknifing populations been shown to correlate positively with the outcrossing rate (Cruden 1977;Michalski and Durka 2009), a relationship that has often more explanatory power within lineages of closely related species. However, outcrossing rates have not been quantified by molecular analysis of progeny arrays in species of Geranium, except for unpublished results for G. maculatum, a perennial species with large showy flowers similar to G. pratense, showing similarly high outcrossing rates (cited in Chang 2007).…”