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Abstract Detail

Ecological Section

Rippel, Tyler M [1], Oremus, Joseph T [1], Philips, Robert W [1], Trygg, Matthew R [1], BYERS , DIANE L [1].

Soil Characteristics Effects on Female Frequency in Lobelia spicata.

Today, the remaining prairie habitat in Midwestern North America is fragmented into patches, with most being isolated from other prairies and surrounded by intensive agriculture. This fragmentation can negatively impact the reproductive success of species when genetic drift determines the dynamics of the breeding system instead of negative frequency dependent selection. We have been examining the consequences of prairie fragmentation on female frequency variation of a gynodioecious native prairie plant, Lobelia spicata. Initially, this species sparked our research efforts in testing for genetic drift due to the varying frequency of females, particularly in smaller populations (2% to 85%). While we found support for genetic drift influencing the breeding system, we also found the type of prairie appeared to impact female frequency. Tallgrass prairies with rich black soils usually had over 40% female plants while hill prairies with loess soil typically had less than 20% females. Given this information, we now propose environmental sexual specific selection is also occurring in this species, where the female plants are favored in the higher nutrient soils associated with particular prairie types. Thus we propose that soil characteristics, in addition to genetic drift, contribute to the variation in female frequency among the prairie fragments. To test if variation in the female frequency can be attributed to soil characteristics, we collected soil samples from a diversity of prairie types in 20 sites. We also determined female frequency and reproductive success of L. spicata populations in these sites. The prairie types included; moist sand prairies and savannas, loess and dolomite hill prairies, and moist tallgrass prairies. The soil samples were analyzed for physical texture, nitrate, organic matter, phosphorous, potassium, and pH levels. Our analysis showed that as the amount of clay increased in the soil, the female frequency increased. Sand and silt differed across sites but was not associated with changes in female frequency. Higher nitrate and greater organic matter were associated with increased female frequency, while other soil nutrients and pH were not associated with changes in female frequency. These results provide support for sex specific selection. We are planning to follow up this field survey with a greenhouse study that will experimentally alter the availability of soil nutrients to establish the cause of sex specific selection. As seed production by females declines with more females in the population this environmental effect on female frequency has consequences for conservation of diversity in tallgrass prairies.

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1 - IL State Univ, School Of Biological Sciences, Campus Box 4120, Normal, IL, 61790, USA

sex specific selection
sex ratio
habitat fragmentation.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PEC026
Abstract ID:535
Candidate for Awards:Ecological Section Best Undergraduate Presentation Award

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