Marking live conifer pollen for long-distance dispersal experiments

Abstract

Long-distance dispersal (LDD) theory requires a method for marking live LDD pollen. Such a method must complement more intensive sampling methods inclusive of molecular cytogenetics, proteomics and genomics. We developed a new method for marking live Pinus taeda pollen using two dyes, rhodamine 123 and aniline blue, dissolved in a sucrose solution. Marked and unmarked pollen were compared with respect to in vitro germination, storage, terminal velocity, and in vivo pollen tube penetration of ovules. We found that: (1) both types of marked pollen retained their capacity for germination, (2) both types of marked pollen had similar aerodynamic properties when compared to unmarked pollen controls, (3) marked pollen retained its germination capacity for 48 h, and (4) of the marked pollen, only the aniline-marked pollen penetrated ovules during pollination. Germination declined rapidly for both types of marked pollen after 48 h and before 37 days at -20°C storage, while unmarked pollen lots retained 93% germination at all stages. This method for marking live P. taeda pollen is feasible for tracing LDD pollen only if released and deposited within 48 h of dye treatment.

Competition and facilitation may lead to asymmetric range shift dynamics with climate change

“…Second, although our focal populations spanned large climatic gradients, they are located fairly short geographic distances from one another (maximum 27 kilometers – Fig. S1), especially relative to potential pollen dispersal distances: Conifer pollen can disperse and remain viable for distances at least as great as 36–75 km (DiGiovanni et al ., ; Williams & von Aderkas, ). This suggests that local adaptation to climate may be less important for altitudinal range shifts than for latitudinal range shifts.…”