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Dissertation Information for Janice Alers-Garcia

NAME:
- Janice Alers-Garcia

DEGREE:
- Ph.D.

DISCIPLINE:
- Biology

SCHOOL:
- Indiana University (USA) (2005)

ADVISORS:
- James D. Bever

COMMITTEE MEMBERS:
- Keith Clay
- Lynda Delph
- Curtis Lively
- Maxine Watson

MPACT Status: Incomplete - Not_Inspected

Title: Active host choice and parasitism by Cuscuta gronovii: Its effects on host individuals, populations and mutualistic interactions

Abstract: Parasitic plants constitute a diverse group of organisms regarding their germination requirements, growth form, dispersal, mode of parasitism and foraging behavior. Several studies have shown that parasitic plants affect the fitness of their host by controlling water or nutrient uptake, inducing physiological changes and/or altering allocation patterns. However less is known of how parasitic plants affect the population properties of their host plants. My dissertation research focuses on the genus Cuscuta (dodder), a highly holoparasitic plant that exhibits active host choice. I particularly examined: (1) the patterns and mechanisms underlying the development of size inequality of parasitized populations, (2) the mechanisms underlying active host choice of dodder, and (3) the dynamics of the tri-trophic interaction between mycorrhizal fungi, dodder and their plant hosts. I've examined these questions on a series of greenhouse experiments using the following systems: Cuscuta gronovii-Pilea pumila and Cuscuta gronovii-Bidens cernua-Glomus claroideum . The results of these studies show that size dependent parasitism and compensation at the population level are the mechanisms underlying the increase of size inequality on parasitized plant populations. Dodder is able to discriminate among potential hosts and choose the tallest ones within the population at least fifteen days prior to parasitism. By means of host choice experiments I was able to document that active host choice occurs toward tall hosts; and that the extend of parasitism and of dodder fitness increased in tall and non mycorrhizal hosts. The effects of dodder on host individuals are dependent on the length of parasitism; dodder causes a drastic reduction on vegetative and reproductive parameters on early attacked hosts compared to those attacked later. This clearly indicates that active host choice, time of parasitism and the responses of unaffected plants constitute important factors on the evaluation of the effects of parasitism at the individual and population levels.

MPACT Scores for Janice Alers-Garcia

A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2010-09-13 16:42:08

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