Reproductive Biology Research
The reproductive biology of rare plants species has implications for conservation management plans because
the breeding system of a species influences the genetic diversity within and among populations of
that species. For example, a species that is primarily self-fertilizing may have less genetic variation
within populations, but more variation among populations. Conservation management plans have to
consider this fact and capture as much of this variation as possible.
Mating Systems and Hybridization of Long’s Braya and Fernald’s Braya
Research (including by-hand-pollination, and analysis of floral morphology) was conducted in 2000 to
determine the mating systems of Long’s Braya and Fernald’s Braya. This work showed that both species are primarily
autogamous (ie. self-fertilizing), but that Long's
Braya has a higher potential for outcrossing
(the opposite of "inbreeding") than does Fernald's Braya.
This means that recovery efforts for both Long’s Braya and Fernald’s Braya should focus on preserving the
entire geographical range of the existing population of both species, so that no variation is lost.
Some plants were found to have intermediate floral characters (indicating hybridization between the two species). Indeed,
hybrid by-hand-pollinations resulted in seeds being produced.
This means that conservation efforts should also
focus on minimizing hybridization between Long’s Braya and Fernald’s Braya in order to prevent the potential loss
of both of these rare species.
Mating Systems and Hybridization of Barrens Willow
Barrens willow can reproduce both sexually and asexually.
Asexual reproduction (ie. reproduction without sex)
seems to be the
predominate form of successful reproduction for Barrens Willow. As a result of wind and frost
erosion, the main root collar of the typically horizontal parent plant degrades
as young branches produce
roots (ie. roots growing from unusual places, such as along stems and branches), eventually resulting in
a radially distributed collection of young plants that are
Male Barrens Willow develop catkins and begin to
release pollen in June. Female Barrens Willow develop catkins by July, undergo fertilization,
and then release seeds in late July and early August. The amount of sexual reproduction
(including the number of catkins produced per plant), and the sex
ratio, varies significantly among populations.
Germination trials indicate that the germination success
of Barrens Willow seeds is high. However, seedlings are rarely if ever found in the wild. Moreover, seeds do not
grow when planted within experimental seed addition plots. Seedling success is even lower when the population is growing on human-disturbed
Willows are known to hybridize easily and therefore the Barrens Willow may well hybridize with other
willows found on the "Limestone Barrens". Research efforts to determine such hybridization potential,
as well as resulting genetic variation, are ongoing.
The reproductive biology of a rare plant species has important implications for conservation management plans.
Experimental pollinations: Long's Braya with and without pollination bags.
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