Resume

• 2017

  Texas A&M University

  The University of Texas at Arlington

  University of Minnesota

  Bryan/College Station

  Texas Area

  Assistant Professor

  Texas A&M University

• 2013

  NESCent (National Evolutionary Synthesis Center)

  Saint Paul

  Development and implementation of new approaches to the inference ploidy level from chromosome number data

  and investigations of the consequences of polyploidy and relationship to the evolution of sexual systems.

  Postdoctoral Scholar

  University of Minnesota

  The evolutionary dynamics of sex chromosomes are unique because they have smaller effective population sizes than autosomes and do not spend equal time in males and females. However

  our understanding of the rates and patterns of sex chromosome evolution come from very few model organisms. The Proposed research will synthesize data from decades of cytogenetic work and phylogenetic studies and will use Bayesian comparative phylogenetic methods to estimate the rate at which sex limited chromosomes decay and how frequently sex chromosome systems experience turnover. This project will allow us to determine how broadly applicable our understanding of sex chromosome evolution is and how variable the rate of sex chromosome turnover and decay is across some of the most speciose groups of animals

  and which groups exhibit patterns that may be worthy of further research. Completion of this project will also lead to useful comparative phylogenetic tools that can be used to perform posterior predictive simulations

  Graduate Fellow

  Raleigh-Durham

  North Carolina Area

  NESCent (National Evolutionary Synthesis Center)

  Arlington

  Texas

  Dissertation research consisted of the collection of over 4

  000 karyotype records for beetles from existing literature. Were used in conjunction with genetic data from Genbank to apply compartive methods to investigate the tempo and mode of sex chromosome and chromosome number evolution.

  Doctoral Student

  The University of Texas at Arlington

• 2010

  Hands on science activities for 1-8th grade students. Activities focus on introducing the scientific process and evolution using fossils

  skulls

  and other specimens.

  Fort Worth ISD

  Statistics

  Phylogenetics

  Scientific Writing

  Research

  Science

  Coding Languages

  Project Management

  Data Analysis

  Genetics

  Comparative Methods

  University Teaching

  Entomology

  Evolutionary Biology

  Statistical Data Analysis

  Molecular Evolution

  Leadership

  Public Speaking

  Microsoft Office

  Higher Education

  Teaching

  Genomic origins of insect sex chromosomes

  Recent efforts to catalog the diversity of sex chromosome\nsystems coupled with genome sequencing projects are adding\na new level of resolution to our understanding of insect sex\nchromosome origins. Y-chromosome degeneration makes\nsequencing difficult and may erase homology so rapidly that\ntheir origins will often remain enigmatic. X-chromosome origins\nare better understood

  but thus far prove to be remarkably\nlabile

  often lacking homology even among close relatives.\nFurthermore

  evidence now suggests that differentiated X or\nY-chromosomes may both revert to autosomal inheritance.\nData for ZW systems is scarcer

  but W and Y-chromosomes\nseem to share many characteristics. Limited evidence\nsuggests that Z-chromosome homology is more conserved\nthan X counterparts

  but broader sampling of both sex\nchromosome systems is needed.

  Genomic origins of insect sex chromosomes

  Chromosomal sex determination is phylogenetically widespread

  having arisen independently in many lineages. Decades of theoretical work provide predictions about sex chromosome differentiation that are well supported by observations in both XY and ZW systems. However

  the phylogenetic scope of previous work gives us a limited understanding of the pace of sex chromosome gain and loss and why Y or W chromosomes are more often lost in some lineages than others

  creating XO or ZO systems. To gain phylogenetic breadth we therefore assembled a database of 4724 beetle species’ karyotypes and found substantial variation in sex chromosome systems. We used the data to estimate rates of Y chromosome gain and loss across a phylogeny of 1126 taxa estimated from seven genes. Contrary to our initial expectations

  we find that highly degenerated Y chromosomes of many members of the suborder Polyphaga are rarely lost

  and that cases of Y chromosome loss are strongly associated with chiasmatic segregation during male meiosis. We propose the “fragile Y” hypothesis

  that recurrent selection to reduce recombination between the X and Y chromosome leads to the evolution of a small pseudoautosomal region (PAR)

  which

  in taxa that require XY chiasmata for proper segregation during meiosis

  increases the probability of aneuploid gamete production

  with Y chromosome loss. This hypothesis predicts that taxa that evolve achiasmatic segregation during male meiosis will rarely lose the Y chromosome. We discuss data from mammals

  which are consistent with our prediction.

  Estimating tempo and mode of Y chromosome turnover: explaining Y chromosome loss with the fragile Y hypothesis

  Cytogenetic research has a long history in Coleoptera taxonomy and evolutionary biology. The last synthesis of beetle karyotypes was completed in 1978 when only 2

  160 beetles had been studied (Smith and Virkki 1978). Since this compilation

  the number of beetles that have been targeted by cytogenetic studies has doubled. However

  karyotype records are scattered among hundreds of journal articles often with narrow taxonomic or geographic focus. This has made it difficult to analyze large-scale patterns of karyotype evolution across Coleoptera or even determine what data is available for a clade. To eliminate this barrier

  we created the Coleoptera karyotype database (www.uta.edu/karyodb/). The database currently contains 4

  797 records

  but we envision it as a long-term repository that will be regularly updated. This will allow open access to data that were previously scattered and often available only through subscriptionbased publications.

  Coleoptera Karyotype Database

  Blackmon

  Heath

• 2008

  Bachelor of Science (B.S.)

  Environmental Science: Fisheries and Wildlife Management

  Environmental Science - Fish and Wildlife Management

  Oregon State University

  Summa Cum Laude

• 4.0

  Genetic Society of America

  English

  Doctor of Philosophy (Ph.D.)

  Quantitative biology: focusing on comparative analyses of genome evolution in invertebrates.

  Quantitative Biology

  The University of Texas at Arlington

• The fragile Y hypothesis: Y chromosome aneuploidy as a selective pressure in sex chromosome and meiotic mechanism evolution - Blackmon - 2015 - BioEssays - Wiley Online Library

  Loss of the Y-chromosome is a common feature of species with chromosomal sex determination. However

  our understanding of why some lineages frequently lose Y-chromosomes while others do not is limited. The fragile Y hypothesis proposes that in species with chiasmatic meiosis the rate of Y-chromosome aneuploidy and the size of the recombining region have a negative correlation.

  The fragile Y hypothesis: Y chromosome aneuploidy as a selective pressure in sex chromosome and meiotic mechanism evolution - Blackmon - 2015 - BioEssays - Wiley Online Library