Prezygotic barriers to gene flow between <Emphasis Type="Italic">Taraxacum ceratophorum</Emphasis> and the invasive <Emphasis Type="Italic">Taraxacum officinale</Emphasis> (Asteraceae) |
| |
Authors: | Marcus T Brock |
| |
Institution: | (1) Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA;(2) Present address: Department of Botany, University of Wyoming, Laramie, WY 82071, USA |
| |
Abstract: | Prezygotic reproductive barriers limit interspecific gene flow between congeners. Here, I examine the strength of floral isolation
and interspecific pollen-pistil barriers between an invasive apomictic, Taraxacum officinale, and the indigenous sexual alpine dandelion, Taraxacum ceratophorum. Experimental arrays of either native inflorescences or a mixture of native and exotic inflorescences were used to examine
insect preference and to track movement of a pollen analog. Using hand-pollinations, conspecific and heterospecific pollen
germination success on native stigmas was compared. To additionally test for interspecific pollen competition, T. ceratophorum plants received one of three possible hand-pollinations: control conspecific pollination, concomitant conspecific and heterospecific
pollination (mixed), or conspecific pollen followed by heterospecific pollen 15 min later (staggered). Floral isolation was
negligible as no insect preference was detected. On a presence/absence basis, florets on native inflorescences received slightly
less pollen analog from heterospecific donors than from conspecific donors; however, the amount of dye particles transferred
from either Taraxacum species to stigmas on recipient T. ceratophorum inflorescences was equivalent. In contrast to weak floral isolation, strong pollen germination and pollen competition barriers
should reduce the potential for hybridization. Heterospecific T. officinale pollen exhibited reduced germination success on T. ceratophorum stigmas in comparison to conspecific pollen. Furthermore, a significant pollen-competition effect on the percentage of hybrid
offspring was detected only when T. officinale preceded T. ceratophorum pollen by 15 min. This result indicates that conspecific pollen out-competes heterospecific pollen but further suggests that
biotic and abiotic factors reducing pollen accrual rates may partially remove barriers to natural hybridization. |
| |
Keywords: | Hybridization Floral isolation Insect preference Pollen competition Pollen– pistil Interactions |
本文献已被 SpringerLink 等数据库收录! |
|