Abstract Detail



Reproductive Processes

Sturges, Lucia [1], Schenk, John [2].

Staminodial Evolution in Mentzelia Section Bartonia and Their Impact on the Male Fitness of Flowers.

Among the evolutionary changes that have occurred in flowers across angiosperms, the co-option of stamens from reproductive to non-reproductive structures represent one of the most drastic modifications from a functional standpoint.  Staminodial flowers are present in clades across angiosperms, and in groups, such as Mentzelia section Bartonia (Loasaceae), staminodes are common.  We studied the evolution of staminodes in section Bartonia by first asking how many times staminodes have been gained or lost.  A maximum likelihood approach identified ten transitions, which included staminodes independently evolving at least four times.  We then examined the fitness consequences of staminode evolution by quantifying how pollinator visitation rates are effected by the presence or absence of staminodes.  Populations of M. multiflora from Bernalillo County, New Mexico, U.S.A., were used in an experimental study to measure how staminodes impact floral visitation rates.  Pairwise comparisons were made of control flowers—those with staminodes and petals present—and treatment flowers—those with staminodes removed and petals present.  We hypothesized that if staminodes increased the male fitness of flowers, staminodial flowers would have significantly more pollinators.  Observations were made for the type of pollinator, pollinator action (hovering or landing), number of visits, location of landing, arrival and departure time, and duration of visit.  The most frequent pollinator was Apis mellifera (Apidae), the European honey bee, who landed on the petals and staminodes and quickly moved towards the center of the flower to collect nectar and pollen.  Pollinators significantly hovered above and landed on control flowers more often than treatment flowers.  The time that pollinators spent on flowers after they landed was equal, despite their preference to land on control flowers.  We concluded that the evolution of staminodes has been dynamic in section Bartonia, with multiple gains and losses.  A clear benefit to male fitness was identified by increased number of pollinators that visited staminodial flowers, suggesting that the fitness loss of reproductive function of stamens might be offset by the higher fitness advantage associated with increased rates of pollinator visitors.


Related Links:
Schenk lab webpage


1 - Georgia Southern University, Department of Biology, 4324 Old Register Road, Statesboro, GA, 30458, USA
2 - Georgia Southern University, Department Of Biology, 4324 Old Register Road, Biological Sciences Building, Statesboro, GA, 30458, United States

Keywords:
Ancestral character estimation
Androecium
European honey bee
fitness
Floral evolution
co-option
pollination
staminode
Loasaceae
Mentzelia.

Presentation Type: Poster
Number: PRP003
Abstract ID:245
Candidate for Awards:None


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