Nectar Guide Patterns on Developmentally Homologous Regions of the Subtribe Ligeriinae (Gesneriaceae)

Homology is a crucial concept that should be considered while conducting a comparative analysis between organisms. In particular, in the subtribe Ligeriinae, the nectar guide pattern is associated with high diversity in petal shapes and sizes. This largely limits researchers to exclusively examining the interspecific variation in nectar guide patterns on the developmentally homologous region. Thus, to solve this problem, we proposed an approach for defining a homologous region of interest (ROI) that aligns the petal image between specimens based on petal contours and vasculatures. We identified petal contours and vasculatures from the fresh petal image and its histological image through image processing. The homologous ROI was subsequently obtained by applying geometric transformation to the contour and vasculature. The qualification and quantification of nectar guide patterns were subsequently performed based on the homologous ROI. Four patterning modes, namely vascular, random, distal, and proximal, were defined for the qualitative analysis of nectar guide patterns. In the quantitative analysis, principal component (PC) analysis was applied to homologous ROIs, and the PC score of each specimen served as the trait values of nectar guide patterns. The results of the two analyses coincided, and both showed significant associations between nectar guide patterns and pollination types. The proximal mode (corresponding to PC1) and distal mode (corresponding to PC2) together showed the strongest association with pollination types. Species exhibiting the hummingbird and bee pollination types tended to recruit the distal and proximal modes, respectively. Our study conducted a comparative analysis of nectar guide patterns on the developmentally homologous region and provided a comprehensive view of the variation in the nectar guide patterns of Ligeriinae.

Flower, fruit phenology and flower traits inCordia boissieri(Boraginaceae) from northeastern Mexico

We characterized variations inCordia boissieriflowers and established if these variations occur between plants or between flowering events. Flowering and fruiting was measured for 256 plants. A GLM test was used to determine the relationship between flowering and fruit set processes and rainfall. We performed measurements of floral traits to detect variations within the population and between flowering events. The position of the anthers with respect to the ovary was determined in 1,500 flowers. Three out of four flowering events of >80%C. boissieriplants occurred after rainfall events. Only one flowering event occurred in a drought. Most plants flowered at least twice a year. The overlapping of flowering and fruiting only occurred after rainfall. Anthesis lasted three-to-five days, and there were two flower morphs. Half of the plants had longistylus and half had brevistylus flowers. Anacahuita flower in our study had 1–4 styles; 2–9 stamens; 6.5–41.5 mm long corolla; sepals from 4.5–29.5 mm in length; a total length from 15.5–59 mm; a corolla diameter from 10.5–77 mm. The nectar guide had a diameter from 5–30.5 mm; 4–9 lobes; and 5 distinguishable nectar guide colors. The highest variation of phenotypic expression was observed between plants.

Pollination of Diuris maculata (Orchidaceae) by male Trichocolletes venustus bees

In a previous study, the Australian terrestrial orchid Diuris maculata sensu lato, from a site near Melbourne in Victoria, was suggested to be a floral mimic of several sympatric legume species. The widespread distribution of this orchid species (or species complex) suggests that there may be a number of different model and pollinator species throughout this range, and that additional studies are necessary to characterise its pollination adequately. In this study, the pollination of D. maculata in the Sydney region, mainly at Scheyville National Park, was compared with the results previously obtained in Victoria. At Scheyville National Park, Trichocolletes venustus was the only native bee species found in significant numbers, and the flowers it visited were almost exclusively the legumes Hardenbergia violacea and Daviesia ulicifolia ssp. ulicifolia. Fifty per cent (14 of 28) of captured male bees carried D. maculata orchid pollinaria, or remnants, which were identified by AFLP fingerprinting. Female bees, which appeared about 10–14 days after males, were not observed visiting the orchid or carrying orchid pollinaria. We confirmed that D. maculata flowers lack nectar, and noted that the pea-like flowers possess an UV false nectar guide comparable to the true UV nectar guide of the legume flowers. Colorimetric analysis showed the colour separation between D. ulicifolia ssp. ulicifolia and the orchid is small enough to be likely to produce foraging errors, consistent with mimicry. We conclude that guild mimicry of a diversity of ‘egg and bacon’ legumes best explains the pollination of D. maculata s.l., rather than precise mimicry of any one pea species. Preliminary observations suggest that pea-flower mimicry may range from being highly precise in some species, through to being much more generalised, but still retaining elements of mimicry. The novel finding of comparable UV patterns in Diuris species and putative pea models applies to most species in the genus and we found that the rare D. aequalis shows remarkable similarity in colour, shape and UV patterns to the sympatric legume Gompholobium huegelii, and is likely to be a mimic of this species.