Biology ETDs

Publication Date

Summer 5-1-2017

Abstract

Plant-microbial interactions are ubiquitous and yet the consequences of these interactions on plant population and community dynamics are relatively unknown. Here, we used two different classes of plant-microbial interactions to examine their effects on key plant population and community characteristics such as commonness and rarity, competition and coexistence, as well as community stability.

Vertically-transmitted endophytes had stage-dependent effects on the population growth of two grass species Poa sylvestris and Poa alsodes, and generally increased host population growth rates. However, it was the intrinsic demographic advantage of P. sylvestris that allowed its population to grow at a much faster rate compared to P. alsodes rather than endophyte benefits.

In a greenhouse experiment, we showed that plant-soil microbial feedbacks were important in regulating the strength of self-limitation, or negative frequency dependence, of a strong competitor Bouteloua gracilis. These negative feedbacks increased the potential for its coexistence with Bouteloua eriopoda.

In a field experiment, we showed that fungal-driven plant-soil feedbacks between B. gracilis and B. eriopoda may help explain long term patterns of spatial variation in temporal stability between these two species. Negative plant-soil feedbacks for B. gracilis could promote locally stable plant communities, and this effect was stronger when it was at low frequency in the community.

Finally, next-generation sequencing of root-associated fungal communities from the two preceding studies revealed strong differences in composition among different growth conditions as well as cultivation periods. In addition, experimental inoculation methods in the greenhouse and field reliably altered the root-associated fungal communities of test plants.

Keywords

plant-microbial interactions, community ecology, population ecology, symbioses, semiarid grassland

Document Type

Dissertation

Degree Name

Biology

Level of Degree

Doctoral

Department Name

UNM Biology Department

First Committee Member (Chair)

Jennifer Rudgers

Second Committee Member

Scott Collins

Third Committee Member

Robert Sinsabaugh

Fourth Committee Member

Thomas Miller

Fifth Committee Member

Andrea Porras-Alfaro

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