Zachary Culumber

Zach Culumber

Department of Biology
Texas A&M University 

3258 TAMU
College Station, TX 77843 

Tel: 979.845.3614 


Ph. D. Zoology (In Progress)
Texas A&M University 

Curriculum Vitae (updated Feb 2011)

Zachary Culumber

Zach is now the coordinator of CICHAZ. Check out his research page.

Education: B.S. with High Distinction - University of Illinois (Urbana) – Kim Hughes (Advisor), Undergraduate Thesis: “No associations between an MHC class-II gene and parasite resistance in guppies (Poecilia reticulata)”

Research Interests: Evolutionary genetics of sexual selection, population genetics/genomics, phylogeography, mechanisms maintaining genetic variation. I have broad interests in the areas of behavior and ecological and evolutionary genetics. In particular, I am interested in the evolutionary genetics of sexual selection and the role of ecology in evolution/speciation (from the genetic perspective).

The current focus of my dissertation is an investigation of population genetics in Xiphophorus hybrid zones of eastern Mexico and of the evolutionary genetics of sexual selection in this system. Single nucleotide polymorphism (SNP) genotyping and DNA sequencing of a limited number of loci have shown significant spatial variation in population structure among hybrid zones found along replicated ecological gradients in at least six stream reaches. The goal of my dissertation is to understand how genetic variation is distributed along the hybrid zones and the mechanisms that maintain population structure.

Figure 1

The goal of my dissertation research is to test as many reproductive isolating mechanisms as possible along the breadth of pre- to post-zygotic mechanisms that could be maintaining significant population structure (subpopulations of both parentals and hybrids) in some localities, while other populations appear to be random mating hybrid swarms. Combining population genetic tests using SNP markers with behavioral experiments is providing the basis to better understand what mechanisms may be involved in the hybrid zones’ dynamics and population structure.

figure 2

Soon genotyping of hundreds of single nucleotide polymorphisms (SNP) derived from transcriptome sequencing of X. birchmanni and X. malinche will be the foundation for population genomics in the hybrid zone. From this we can look for patterns of genetic introgression across multiple tributaries and identify areas of the genome that may be important in the reproductive isolation observed in some populations, as well as genomic islands involved in reproductive isolation of the two parental species.

I am currently collaborating with Michi Tobler of Oklahoma State University on phylogeographic projects of other Poeciliid species, as well as within the Xiphophorus hybrid zone. Over the last two years, I have also collaborated with Christian Bautista-Hernandez of the Universidad Autonoma del Estado de Hidalgo (UAEH) in Pachuca, HGO. Her studies of the parasite fauna in structured Xiphophorus populations combined with SNP genotyping demonstrates that parasitism is significantly different among X. birchmanni, X. malinche and hybrids within single populations.

I am also currently an NSF IGERT trainee through the interdisciplinary Applied Biodiversity Science program at Texas A&M. As a part of the ABS program, my goal is to better understand water quality issues in the Huasteca of Mexico as it appears not only to serve as a conduit to hybridization is Xiphophorus but has clear public health implications for local communities. I will be collecting water quality parameters in multiple streams in collaboration with Professor Scott Monks from UAEH, and collaborating with masters student Kristin Wilcox from Recreation Parks and Tourism at TAMU on applied social side of water quality issues. I am also associated with the Ecology and Evolutionary Biology group at A&M.


  1. J.B. Johnson, Z.W. Culumber and G.G. Rosenthal , 2015. Boldness and predator evasion in naturally hybridizing swordtails (Teleostei: Xiphophorus). Curr. Zool. 61: 596-603. [PDF]
  2. Z.W. Culumber, O.M. Ochoa and G.G. Rosenthal , 2014. Assortative mating and the maintenance of population structure in a natural hybrid zone. Am. Nat. 184:225-232. [PDF]
  3. Z.W. Culumber and G.G. Rosenthal, 2013. Mating preferences do not maintain the tailspot polymorphism in the platyfish, Xiphophorus variatus. Behav. Ecol. 24:1286-1291. [PDF]
  4. Z.W. Culumber and G.G. Rosenthal, in press. Population-level mating patterns and fluctuating asymmetry in swordtail hybrids. Naturwissenschaften. [PDF]
  5. Z.W. Culumber, D.B. Shepard, S.W. Coleman, G.G. Rosenthal and M. Tobler, 2012. Physiological adaptation along environmental gradients and replicated hybrid zone structure in swordtails (Teleostei: Xiphophorus). J. Evol. Biol. [PDF]
  6. M.N. Verzijden, Z.W. Culumber and G.G. Rosenthal, In press. Opposite effects of learning cause asymmetric mate preferences in hybridizing species. Behav. Ecol.. [PDF]
  7. J.B. Johnson, Z.W. Culumber and G.G. Rosenthal., In preparation. Boldness and anti-predator behavior in naturally hybridizing swordtail fish.
  8. Z.W. Culumber, H.S. Fisher, M. Tobler, M. Mateos, P.H. Barber, M.D. Sorenson and G.G. Rosenthal, 2011. Replicated hybrid zones of Xiphophorus swordtails along an elevational gradient. Mol. Ecol. [PDF]
  9. M. Tobler, Z.W. Culumber, M. Plath, K.O. Winemiller and G.G. Rosenthal, 2010. An indigenous religious ritual selects for resistance to a toxicant in a livebearing fish. Biol. Lett. [PDF]
  10. S.W. Coleman, Z.W. Culumber, A. Meaders, J. Henson and G.G. Rosenthal, 2009. Inducible molecular defenses, ultraviolet radiation, and melanomagenesis in natural Xiphophorus hybrids - a field-based investigation of lab-based cancer models. Env. Biol. Fish. [PDF]
  11. K.R. Purdy Drew, L.K. Sanders, Z.W. Culumber, O. Zribi and G.C.L. Wong, 2008. Cationic amphiphiles increase activity of aminoglycoside antibiotic tobramycin in the presence of airway polyelectrolytes. J Am. Chem. Soc. 131 (2):486-93.