Biology subjects

Laport, R. G.

Publications and source records attributed to Laport, R. G..

2 recordsLinked to original sources

bioRxiv2022

Differentiation of rhizosphere fungal assemblages by host ploidy level in mixed-ploidy Larrea tridentata populations

Polyploidy--whole genome duplication--is common in plants. Studies over the last several decades have documented numerous mixed-ploidy populations. Whether arising via recurrent whole genome duplication events within a population, or from secondary contact, the persistence of mixed populations depends on the ability of the minority cytotype to overcome the negative frequency dependent effects of outcrossing with other ploidies, known as Minority Cytotype Exclusion. One mechanism of overcoming Minority Cytotype Exclusion is microbially-mediated niche differentiation (MMND), wherein cytotypes occupy different niches via interactions with different sets of microbes. Inherently cryptic, MMND is underexplored in polyploid plant populations. Here, we search for evidence of MMND in creosotebush (Larrea tridentata), a dominant desert shrub of the southwestern U.S. and northern Mexico. We sequenced fungi from rhizosphere soils of diploid, autotetraploid, and autohexaploid plants growing in two naturally-occurring mixed-cytotype populations. Within populations, we found substantial fungal assemblage overlap across host plant cytotypes. However, using indicator species analysis, we identified some fungi that are differentiated by host plant cytotype, satisfying a precondition for MMND. Future study is needed to determine the degree of niche differentiation conferred, if any, and whether the identified fungi play a role in the long-term persistence of multiple cytotypes within populations.

evolutionary biology↗

bioRxiv2021

Environmental niche and demographic modeling of American chestnut near its southwestern range limit

AO_SCPLOWBSTRACTC_SCPLOWThe inadvertent introduction and rapid spread of chestnut blight (caused by Cryphonectria parasitica (Murr.) Barr) in the early 20th century resulted in the demise of American chestnut (Castanea dentata (Marsh.) Borkh.; Fagaceae) as a major component of forest canopies and had negative impacts on eastern forest communities. Research efforts over the last century have documented the persistence of occasional trees and root crown/stump sprouts throughout much of the species historic range providing the basis for ongoing breeding of blight-resistant stock and restoration efforts. Unfortunately, it remains unclear how much of the historic range remains climatically suitable for remnant trees that may harbor unique genetic variation for successful reintroduction efforts. Here we investigate whether the southwestern portion of the historical range remains environmentally suitable for undiscovered remnant populations of C. dentata using environmental niche modeling. We also use stage-structured matrix projection models to investigate the potential demographic future of C. dentata in W Tennessee, N Mississippi, SW Kentucky, and NW Alabama based upon observations of American chestnut in these areas over the last several decades. We found that suitable habitat associated with higher elevations and areas of high forest canopy cover occurs throughout much of the southwestern portion of the historical range and that populations of American chestnut in these areas are predicted to drastically decline over the next ~100-200 years without conservation interventions to mitigate the negative consequences of chestnut blight.

ecology↗