mating systems

I am interested in the evolution of mating systems in long-lived, rhizomatous plants that exhibit adaptations to outcrossing (i.e., zygomorphic floral symmetry, poricid anther dehiscence and “buzz” pollination, etc.) but are thought to undergo a lot of selfing via fertilization  (a) within an inflorescence (e.g., geitonogamy) and (b) among inflorescences arising from the rhizome of a single individual. Understanding the mating systems employed by members of the P. picta species complex is key to understanding how reproductive isolation is maintained…. and how it breaks down!

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Figure 1: Bombus occidentale visiting flowers of Pyrola dentata near Burnt Lava Flow (Siskiyou County, California).

To understand mating systems better, I have concentrated my efforts on two experiments. The first is observation-based and involves tracking differences in flowering phenology among species growing in sympatry to test, statistically, whether relative reproductive isolation (and minimal hybridization) is maintained temporally at different locations (differing in latitude and elevation) at different times in the flowering season. Figure 2 shows the stages of floral maturation that frequency estimates (Fig. 3) were based on, which track stages of anther maturation most closely.

Figure 2: A typical raceme of P. picta, with stages of floral maturation used for analyses of phenological differences among sympatric species,
Figure 2: A typical raceme of P. picta, with stages of floral maturation used for analyses of phenological differences among sympatric species.
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Figure 3: Bar graphs showing frequency distributions of flowering stages in sympatric species at different populations in northern California.

The other kind of experiment I have focused on is manipulative and involved conducting multiple kinds of fertilizations among species in sympatry to understand how different species respond (measured in terms of fertile, viable seeds produced) to heterospecific and conspecific crosses, fertilization by selfing (same flower) or by autogamy in comparison with controls (i.e., inflorescences that bumble bees can access).

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