Dr. Ross A. McCauley


Associate Professor of Biology

Curator, Fort Lewis College Herbarium (FLD)

Fort Lewis College

Department of Biology

1000 Rim Dr.

Durango, Colorado 81301 USA


Office: 447 Berndt Hall

Phone: 970-247-7338

Email: mccauley_r@fortlewis.edu




Plant Systematics, Evolutionary Ecology, and Conservation

2014 - Associate Professor of Biology, Fort Lewis College

2008 - 2014 Assistant Professor of Biology, Fort Lewis College

2005-2008 Postdoctoral Researcher, Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México

2003-2004 Visiting Assistant Professor of Biology, Denison University

2002 Ph.D. Ohio University, Botany (Plant Systematics)

1999 M.S. Ohio University, Botany (Plant Ecology)

1995 B.S. Northland College, Environmental Studies and Biology





Fort Lewis College Courses


Bio 112: Intro. to Organismic & Evolutionary Biology (Syllabus, Winter 2013


Bio 202: Plant and Human Affairs(Syllabus, Spring 2015


Bio 206: General Botany (Syllabus, Spring 2015)


Bio 302: Systematic Botany (Syllabus, Summer 2015; Fall 2014)


Bio 390 (408): Plant Speciation and Evolution (Syllabus, Winter 2010)


Bio 407: Evolution (Syllabus, Spring 2014)


Bio 496/497: Senior Thesis: Quercus Hybridization (Fall 2009/Winter 2010)


Bio 496/497: Senior Thesis: Viola ecotypes (Winter 2011/Fall 2011



Workshop: Universidad Nacional Autónoma de México (Summer 2009):

Introdución a la Ecología Molecular en Plantas






Department of Biology


Research Summary

I'm interested in developing a broad understanding of the ecological and organismal factors which contribute to the creation and maintenance of plant biodiversity.  Much of my work has involved the application of population genetics in a phylogeographic, phylogenetic or ecological context to  identify lineages and explore the evolutionary forces maintaining these lineages.  Currently I am involved in a variety of projects focusing on the evolution of plant biodiversity through reciprocal hybridization in Mexican Quercus, the evolution and conservation of rare taxa, the evolution of chromosomal races in widespread species, and ecotypic differentiation controlled by elevational gradients in the Southern Rockies.

Secondarily I am interested in traditional taxonomic studies focused on the circumscription and identification of taxa and using the available data to complete revisionary taxonomic treatments.  I have been working extensively on a monographic review of the genus Froelicha in the Amaranthaceae and am currently involved in the production of other taxonomic treatments and assisting with various flora projects. 

Student Research & Work Opportunities

Students interested in plants are encouraged to look into developing independent studies with me on the flora of SW Colorado.  These could be floristic-based studies or evolutionary-based studies. Work (funded via Financial Aid's work study program) is additionally available to work caring for plants in the college greenhouse.   Limited opportunities are available for paid work in the college herbarium assisting in the development of a digital publically-accessible database of the herbarium collections.

Current Research

Studies of Quercus biogeography and hybridization in Mexico and the S.W. United States

The genus Quercus is well known for frequent hybridization among closely related species and recurrent hybridization is an important evolutionary process in the generation of species biodiversity.  I have been studying the effects of this recurrent hybridization in one of the "hotspots" of oak diversity in the world. Of the approximately 500 species of Quercus Mexico shows a very high level of both species diversity at 160 along with a high level of species endimism.  Much of this diversity is likely due to recurrent hybridization and habitat changes during evolutionary history.

As a means of studying these processes I have been working with a natural group of red oaks known as the Subsection Racemiflorae consisting of four species (Q. conzattii Trel., Q. radiata Trel., Q. tarahumara Spellenb., J.R. Bacon, & Breedlove, Q. urbanii Trel.) which are united by the characteristic of producing acorns on racemose inflorescences. These species form a natural group of red oaks restricted to the western Sierra Madre and southern Cordillera of Mexico. There is an apparent segregation of the species based on edaphic factors and elevation with the more restricted species (Q. radiata, Q. tarahmara, Q. urbanii) being more or less specialists on highly sterile, often mineralized soils.


Q. conzattii                                                   Q. radiata

Q. tarahumara                                               Q. urbanii

Of particular interest in the group is the bicentric distribution of both Q. urbanii and Q. conzattii. Quercus urbanii is disjunct by approximately 700 km from mountain slopes near the Balsas Depression to the western Sierra Madre in Sinaloa and adjacent Durango. Across this distribution it occurs mostly in small "islands" of monospecific stands, however there are no quantifiable differences in morphology between the northern and southern portions of the range and there are no reports of it hybridizing with other oak species. Extending this pattern of range disjunction is Q. conzattii which is disjunct by approximately 850 km between its northern and southern regions of distribution. While occurring in ecologically similar habitats and often as the first black oak above xeric tropical or desert scrub, its large disjunction has resulted in slight morphological differences between the two portions of its range, although almost all differences can be viewed as a continuum of variation from south to north. An additional resulting characteristic of its wide disjunction is the presence of a different composition of sympatric species, particularly other Quercus.

Given the combination of broad and narrow range species, the clear range disjunction, and occasional gene flow through hybridization present within the subsection Racemiflorae it is thought that this group can act as a good model system within the Mexican oaks for the detection of historical patterns of gene flow and past species distributions. I have collected and analyzed the genetic structure of 49 populations of the group throughout its range using a combination of nuclear and chloroplast microsatellites. Results indicate recurent gene flow via hybridization and genome sharing among at least three of the species. Bayesian admixture analysis also suggests extensive hybridization, likely with other species, particularly in the most widespread Q. conzattii

Poster Presentation presented at the IVIII Botanical Congress, Melbourne Australia: "Genetic Structure and Speciation in a Lineage of Mexican Red Oaks: A Phylogeographic Study of Quercus Section Lobatae Subsection Racemiflorae.


Closer to home I have been working to understand patterns of hybridization among the oak species of the Four Corners region which is principally dominated by Q. gambelii, Q. turbinella, and Q. havardii.  Initial work with Senior Thesis students during the 2009-2010 school year compared populations of pure and mixed species using a combination of detailed morphometric analysis and Inter-simple sequence repeat (ISSR) genetic markers. This work showed a high level of gene exchange among the taxa, most evident in lower elevation zones, while morphological characters were consistent and taxon-specific - even in the light of high levels of gene sharing. Further work is hoped to identify a set of specific genetic traits which identify specific taxon groups. For more information on this project see the Senior Seminar page under the heading teaching to the left.

Poster Presentation presented at Evolution 2011, Norman, OK: "Influence of relictual species on the morphology of a hybridizing oak complex: an analysis of the Quercus x undulata complex in the Four Corners Region."

Biogeography and conservation genetics of Guaiacum (Zygophyllaceae) in Western Mexico

The genus Guaiacum or Lignum Vitae is a group of six species native to the dry forests of the American tropics and subtropics which have been used for a variety of purposes spanning from medicinal to timber products for centuries. Today utilization of Guaiacum is principally for its wood which is one of the heaviest currently in trade with a mass of approximately 1303 kg/m3 and has a self-lubricating quality making it useful for mechanical purposes. Past overexploitation in conjunction with habitat loss and a slow rate of regeneration has left most species of Guaiacum threatened and are today listed on the IUCN Red List of Threatened Species and their trade controlled under CITES. Two species of Guaiacum occur in western Mexico G. coulteri, a shrub to small tree endemic to the seasonally dry forests of the Pacific Coast of Mexico ranging from Sonora to Oaxaca and G. unijugum, a small shrub endemic to the Cape of Baja California.

To date my work with western Mexican Guaiacum has identified the evolutionary relationships of the Baja California endemic and surveyed the genetic diversity and structure of G. coulteri to assist in conservation measures. The work with G. coulteri has additionally uncovered potential instances of cryptic speciation within the species range likely do to chromosomal rearrangements. 




Systematics and Phylogeography of Ostrya (Betulaceae) in North America

Ostrya is a small genus of understory tree in North America and Asia commonly known as hop-hornbean. In North America the genus ranges from southern Canada to Honduras. While the group shows much morphological variation most of the variation has been included within a single species, O. virginiana which has a distribution covering the entire range of the genus. Various segregations have been proposed, particularly in Mexico, but the characters for recognizing species segregation have been inconsistent and thus have not been maintained. Some recognition of species segregation has also been variously proposed and supported for the taxa in the SW United States. I am working on a comprehensive systematic revision of the genus across its North American range to determine the number of distinct species, the phylogenetic relationship among them, and reconstruct the continental patterns of migration.

My initial work with the genus is focusing on determining the distinctions of the taxa in the southwest US. In this region the genus Ostrya has a very restricted distribution to the Chisos Mountains in SW Texas, the Guadalupe and adjacent Sacramento Mountains in W Texas and S New Mexico, and the drainage of the Colorado River in N Arizona and S Utah. One to three species have been recognized. The most segregated view could recognize O. chisosensis restricted to the Chisos Mountains, O. baileyi in the Guadalupe Mts. and O. knowltonii in the Colorado River drainage. The most inclusive includes all taxa within O. knowltonii. Along with students I have been performing field studies, herbarium investigations of morphological variation, ecological niche analysis, and completing a detailed DNA barcoding study to determine the circumscription of species across the region. Future work will involve the examination of species circumscription in other regions of North America and the development of chloroplast microsatellite markers to serve as a marker for phylogeographic reconstruction.

Results of preliminary morphological investigation of species circumscription of Ostrya in the American Southwest (Collaborative Student/Faculty Research: Stephanie Dykema and Ross McCauley "A taxonomic reevaluation of the genus Ostrya (Betulaceae) in the Southwestern United States based on leaf morphology"


Studies in Western North American Viola

In Viola I have been working on two projects. One is a biosystematic study of the Viola adunca complex in the San Juan Mountains of SW Colorado. In the local area V. adunca appears to be speciating along elevational and ecological gradients into discrete ecotypes. This work is being performed with undergraduate students (see Senior Thesis Viola ecotypes for more info) and has focused on studies of plant phenology, pollinator behavior, and population genetics using microsatellites.  

Results of local level genetic differentiation between two ecotypes of Viola adunca suggesting segregation and potential gene sharing in intermediate environments (Collaborative Student/Faculty Research: Ethan Hainey and Ross McCauley "Differentiation of Montane and Alpine Ecotypes of Viola adunca in Southwestern Colorado Using Microsatellite DNA Analysis"


Secondly I have been working to describe a new species of Viola endemic to the Guadalupe Mountains of SE New Mexico and SW Texas. This new species, just published this past year as V. calcicola R.A. McCauley & H.E. Ballard, is restricted to cracks of limestone along the southeastern extent of the range.


Systematics and Conservation of the Endemic Hawaiian Arborescent Amaranthaceae (Charpentiera and Nototrichium)

The Amaranthaceae s.s. is family of approximately 70 genera and 1000 species distributed across varying, primarily tropical environments worldwide. While the family is large and diverse in terms of distribution and ecological adaptations, morphological divergence from annual or perennial herbs is very rare. Most of the incidences of woodiness within the family are restricted to island species of more widespread genera. Some examples include the shrubby species of Achyranthes on Norfolk Island, Alternanthera, Pleuropetalum, Froelichia, and Lithophilla of the Galápagos Islands and Henonia of Madagascar. True arborescence in the Amaranthaceae is only foundin the two genera Nototrichium and Charpetiera of the Hawaiian, Austral, and Cook Islands. Together with my collaborator Dr. J. Christopher Havran at Campbell University we are investigating the phylogeny and origin of these unique genera in the Hawaiian Islands. Our studies are initially focusing on the development of a molecular phylogeny for the two groups to understand the dynamics of species relatedness and origin. Our work to date has uncovered a close relationship between the widespread genus Achyranthes and Nototrichium, a potential intergeneric hibridizaiton between Charpentiera and Achyranthes prior to long-distance dispersal, and a number of instances of paraphyly in the evolution of these groups. Our future work seeks to investigate at a more in-depth scale the patterns of evolution and corresponding classification of these species in the islands.

Poster Presentation presented at Botany 2014: "Paraphyly, hybridization, and multiple introductions in the origin and evolution of the endemic Amaranthaceae of the Hawaiian Islands (genera Achyranthes, Charpentiera and Nototrichium)


Systematics of the genus Froelichia (Amaranthaceae)

Froelichia interrupta inflorescence

The genus Froelichia is a group of 16 species of small herbs and shrubs native to a variety of habitats in the Western Hemisphere. I have worked extensively with this group over the past ten years on topics ranging from taxonomic description of new species, to biogeography, population ecology, and phylogenetic reconstructions and am currently working on a taxonomic monograph of the group.  




© 2015 Ross A McCauley