Demonstration of pollinator-mediated competition between two native Impatiens species, Impatiens noli-tangere and I. textori (Balsaminaceae).

Plant-plant interspecific competition via pollinators occurs when the flowering seasons of two or more plant species overlap and the pollinator fauna is shared. Negative sexual interactions between species (reproductive interference) through improper heterospecific pollen transfer have recently been reported between native and invasive species demonstrating pollination-driven competition. We focused on two native Impatiens species (I. noli-tangere and I. textori) found in Japan and examined whether pollinator-mediated plant competition occurs between them. We demonstrate that I. noli-tangere and I. textori share the same pollination niche (i.e., flowering season, pollinator fauna, and position of pollen on the pollinator's body). In addition, heterospecific pollen grains were deposited on most stigmas of both I. noli-tangere and I. textori flowers that were situated within 2 m of flowers of the other species resulting in depressed fruit set. Further, by hand-pollination experiments, we show that when as few as 10% of the pollen grains are heterospecific, fruit set is decreased to less than half in both species. These results show that intensive pollinator-mediated competition occurs between I. noli-tangere and I. textori. This study suggests that intensive pollinator-mediated competition occurs in the wild even when interacting species are both native and not invasive.

Relationship between seminal plasma lactoferrin and gonadal function in horses.

Total 78 semen samples were obtained from 27 Thoroughbred stallions (aged 6 to 27 years), and were subjected to quantification of lactoferrin (Lf) in seminal plasma and examination of the seminal properties. The seminal plasma Lf concentration varied from 21 to 689 microg/ml, with a mean value of 244 +/- 151 microg/ml (S.D.). The seminal plasma Lf concentration and total seminal plasma Lf positively correlated with the sperm concentration (r=0.5938, P<0.001) and with the total sperm number (r=0.6959, P<0.001), respectively. There was no correlation between seminal plasma Lf and sperm motility. These results suggest that seminal plasma Lf reflects gonadal function.