more of what we do

Species are the product of generations of mutation, migration, genetic drift, and natural selection. As a result of these evolutionary processes within a variable environment, established plants are imbued with genes that reflect the long-term average of past environmental conditions. Yet, an individual's life span is relatively short and it must cope with short-term environmental fluctuations, such as an unusual drought or cold period. If the short-term environmental fluctuations are too extreme, the individual, and perhaps even the population of individuals, may die. But how extreme is too extreme? If the individual possesses uncommon characteristics that allow it to persist and reproduce in extraordinary conditions when others do not, what will be the genetic consequences for the population? Of all of the avenues available for adaptation, how do particular species adapt and how rapidly does this adaptation occur?

polyploid evolution

We are addressing these questions in a number of on-going studies. Kandres Halbrook is studying the evolution of polyploidy in the Bouteloua curtipendula (sideoats grama) complex by examining the cellular morphometrics of present-day B. curtipendula specimens with those obtained from packrat middens spanning the past 44,000 years. She is elucidating the relationship between the onset of polyploidy in this complex and post-Pleistocene climate change. Is polyploidy a mechanism to cope with aridity?

native grasses for low-input turf

Steve Smith and Kandres Halbrook are working with Dave Kopec (School of Plant Sciences) on a project with the goal of identifying accessions of native grasses that could be used in low-input turf situations in the Southwest. An example of this would be "rough" areas along desert golf courses. Using native grasses could greatly reduce water use and maintenace costs in these areas. We are specifically targeting populations of low-growing grass species that have survived long-term exposure to grazing animals. Our work involves targeted collection followed by propagation and evaluation under typical turf management conditions. We believe this work could lead to cultivars of native grasses useful both under intensive management but also as low-input turfs in landscape settings.

cool-season drought

Most climate change models predict future reductions in winter precipitation in the Southwest. Steve Smith is examining how winter drought affects warm-season grasses. This project considers the relationship between tissue moisture content and tiller survival in perennial tillers of the C4 grass Digitaria californica (Arizona cottontop) during extended cool-season drought. Results from this research allow us to address many questions related to adaptation to climate change in warm-season perennial grasses: What tissue moisture threshold results in mortality? Does heritable genetic variation for this threshold exist? How effective may natural selection be in affecting this trait? Can we predict mid-summer tiller survival based on winter or spring tiller moisture content?

buffelgrass control

Travis Bean is involved in research that addresses population biological parameters associated with plant invasions. This is done within the context of a buffelgrass (Pennisetum ciliaris) management program for southern Arizona that Travis leads at the Desert Laboratory in Tucson. His research considers how seed movement in fragmented landscapes and climate affect the establishment of invasive plants, how relationships between climate and phenology can be used in managing invasive plants, and how climate and remnant vegetation affect changes in post-disturbance vegetation.

evaluating salt tolerance in alfalfa

Since the early 1990s we have been involved in evaluating tolerance to salinity in alfalfa. We regularly conduct greenhouse and laboratory trials to evaluate this trait in alfalfa cultivars and experimental populations. Contact Steve Smith If you have questions about these trials.