Karen Crow

Karen Crow

( She/Her/Hers )
Associate Professor
University of California, Santa Cruz
Phone: (415) 405-2760
Email: crow@sfsu.edu
Location: HH 708

Fields: Marine Biology, Ecology and Evolution

At SF State Since: 2007

Specialties: Evolution and ecology of fishes, Ichthyology, Molecular evolution of duplicate Hox genes, Evolutionary Developmental Biology (Evo-Devo)

External Personal Website:

My research interests lie squarely in the fields of Evolutionary Developmental Biology (EvoDevo) and the use of Genetics/Genomics to answer questions about the evolution of diversity in vertebrates, which are mostly fishes. I use molecular approaches to understand the evolutionary forces that generate biological diversity, novelty, and reproductive isolation.

Much of my work is focused on a family of genes that specify body plan features called Hox genes. Specifically, I have focused on the molecular evolution of HoxA11 and HoxA13 in the cartilaginous (Barry and Crow 2017, Swenson et al.2018) and ray-finned fishes (Metscher et al. 2005, Crow et al. 2009, Archambeault et al. 2015, Crow et al. 2020), Hox cluster duplication in paddlefish (Crow et al. 2012) and teleosts (Crow et al. 2006), and the putative relationship between genome duplication and the evolution of complexity and diversity in vertebrates (Crow and Wagner 2006).

Based on this work, I proposed a novel hypothesis that genome duplication may play a role in reduced probability of extinction. This hypothesis predicts a latent effect on species diversity, which is more consistent with observed patterns of vertebrate diversity than previously proposed hypotheses (Crow and Wagner 2006). I have investigated questions varying in scale from paternity (Crow et al. 1997, LaBrecque et al. 2014, Izumiyama et al. 2020a, Izumiyama et al. 2020b) to genomics in ray-finned fishes (Crow et al, 2012) including genetic differentiation of sub-populations for conservation designation (Nielsen et al. 1999), estimating phylogenetic relationships (Crow et al. 2004, Maxfield et al. 2012, Chiquillo et al. 2014, Hamilton et al. 2017), conflict between hybridization and the maintenance of species boundaries (Crow et al. 2007), sympatric speciation (Crow et al. 2010), and alternative reproductive strategies (Crow et al. 1997, Crow et al. 2010, Maxfield et al. 2012, Chiquillo et al.2014, Crow et al. 2017, Izumiyama et al. 2020a, Izumiyama et al. 2020b, Awata et al. 2020 submitted, Hansen et al. 2020 submitted) to evaluate how they may contribute to species diversity. 

While my research spans a range of topics, the underlying theme is to understand the evolutionary forces that generate novelty, diversity, and what Darwin called “the mystery of mysteries” -the evolution of reproductive isolation.

My recent work has focused on investigating the role of Hox genes in the evolution and development of novel morphological domains such as claspers in cartilaginous fishes (Barry and Crow 2017), cephalic lobes in manta rays (Swenson et al. 2018), the brood pouch in male pipefishes (Hamilton et al. 2016), paddlefish barbels (which are not homologous with zebrafish barbels, Archambeault et al. 2014), and distal elements of the gut of zebrafish and gobies (Archambeault et al. 2014, Crow et al. 2020). Additional projects have centered on aspects of reproductive strategies including sexual selection and the evolution of female Bateman gradients in surfperches (LaBrecque et al. 2014, Izumiyama et al. 2020a, Izumiyama et al. 2020b), multiple embryos per egg capsule in skates (Chiquillo et al. 2014), and the evolution of sex allocation plasticity in gobies (Maxfield et al. 2012)Over the past few years I have discovered amazing secrets about body plan evolution in batoids, which in rough terms can be described as “How you go from a shark, to a skate, to a ray”. An unexpected caveat indicates that strong selection on modes of locomotion has been a driving force in the evolution and development of this group. For example, the expanded pectoral fins that fuse anteriorly in batoids facilitate undulatory swimming in these benthic dwellers (Hall et al. 2018), and the expanded crura in the pelvic fins of skates allowed “punting” in the same environment (Barry and Crow 2017). In manta rays and their relatives, partitioning the anterior pectoral fins allowed separation of feeding and locomotory functions, and the genetic program separating these pectoral fin domains was likely co-opted from a similar pathway separating claspers from pelvic fin domains that arose approximately 200 million years earlier (Swenson et al. 2018).

  • Mandy Hansen, Karen D. Crow, and Katharyn Boyer. 2020. Invasive mangroves produce unsuitable habitat for endemic goby and burrowing shrimp pairs in Kāneʻohe Bay, Oahu, Hawai‘i. Sciencias Marinas. submitted
  • Karen D. Crow, Ara Sadakian, Noelle Kassly2020. The role of the 5’ HoxA genes in the development of the hindgut, vent, and a novel sphincter in a derived teleost (bluebanded goby, Lythrypnus dalli). Journal of Experimental Zoology-B: Molecular and Developmental Evolution 08102020, DOI: 10.1002/jez.b.22982
  • Michael Izumiyama, Satoshi Awata, Karen D. Crow. 2020. Evaluating the reproductive strategy and correlation between mating success and reproductive success of Ditrema temminckii: Is the number of fathers a good approximation for the number of mates? Copeia. In press. 
  • Michael Izumiyama, Michael Westphal, Karen D. Crow. 2020. In the surf zone: Reproductive strategy of the calico surfperch (Amphistichus koelzi)in a comparative contextJournal of Fish Biology 2020; 96: 939–949.
  • John D. Swenson, Jeff Klomp, Robert A. Fisher, Karen D. Crow. 2018. How the Devil Ray Got Its Horns: The Evolution and Development of Cephalic Lobes in Myliobatid Stingrays (Batoidea: Myliobatidae)Frontiers in Ecology and Evolution.
  • Kayla Hall, Peter Hundt, John Swenson, Adam Summers, Karen D. Crow. 2018. Evolution of radial distribution in pectoral appendages of pelagic rays (Myliobatidae)-a derived group of batoids that evolved cephalic lobes in association with a shift from undulatory to oscillatory swimming. Journal of Morphology. doi: 10.1002/jmor.20837
  • Shannon Barry, Karen D. Crow. 2017. The role of HoxA11 and HoxA13 in the evolution of novel fin morphologies in a representative batoid (Leucoraja erinacea). EvoDevo: 8, 24.
  • Owens, MT, Seidel, SB, Wong, M, Bejines, TE, Lietz, S, Perez, JR, Sit, S, Subedar, ZS, Acker, GN, Akana, SF, Balukjian, B, Benton, HP, Blair, JR, Boaz, SM, Boyer, KE, Bram, JB, Burrus, LW, Byrd, DT, Caporale, N, Carpenter, EJ, Chan, YHM, Chen, L, Chovnick, A, Chu, DS, Clarkson, BK, Cooper, SE, Creech, C, Crow, KD, de la Torre, JR, Denetclaw, WF, Duncan, KE, Edwards, AS, Erickson, KL, Fuse, M, Gorga, JJ, Govindan, B, Green, LJ, Hankamp, PZ, Harris, HE, He, ZH, Ingalls, S, Ingmire, PD, Jacobs, JR, Kamakea, M, Rhea R. Kimpo, Knight, JS, Krause, SK, Krueger, LE, Light, TL, Lund, L, Márquez-Magaña, LM, McCarthy, BK, McPheron, LJ, Miller-Sims, VC, Moffatt, CA, Muick, PC, Nagami, PH, Nusse, GL, Okimura, KM, Pasion, SG, Patterson, R, Pennings, PS, Riggs, BE, Romeo, J, Roy, SW, Russo-Tait, T, Schultheis, LM, Sengupta, L, Small, R, Spicer, GS, Stillman, JH, Swei, A, Wade, JM, Waters, SB, Weinstein, SL, Willsie, JK, Wright, DW, Harrison, CD, Kelley, LA, Trujillo, G, Domingo, CD, Schinske, JN, Tanner, KD. 2017. Classroom Sound Can Be Used To Classify Teaching Practices in College Science Courses, Proceedings of the National Academy of Sciences, 114(12) 3085–3090. 
  • Healy Hamilton, Norah Saarman, Graham Short, Beth Moore, Tinya Hoang, Chris Grace, Martin Gomon, Karen Crow, W. Brian Simison. 2016. Molecular phylogeny and patterns of diversification in syngnathid fishes. Molecular Phylogenetics and Evolution. 107 (2017) 388-403 
  • Sophie Archambeault, Julia Taylor, Karen D. Crow. 2014. HoxA and HoxD expression in a variety of vertebrate body plan features reveals an ancient origin for the reverse collinear expression pattern. EvoDevo 5:44 (19 November 2014).
  • Sophie Archambeault, Eric Ng, Lyle Rapp, David Cerino, Bradford Bourque, Tessa Solomon-Lane, Matthew S. Grober, Andrew Rhyne, and Karen D. Crow. 2014. Reproduction, larviculture, and early development of the Bluebanded goby, Lythrypnus dalli, an emerging model organism for studies in evolutionary developmental biology and sexual plasticity. Aquaculture Research. doi:10.1111/are.12648. Online 1-5-15
  • John R. LaBrecque, Yvette R. Alva-Campbell, Sophie Archambeault, Karen D. Crow. 2014. Multiple paternity is a shared reproductive strategy in the live-bearing surfperches (Embiotocidae) that may be associated with female fitness. Ecology and Evolution4(12) 2316-2329.
  • Kelcie Chiquillo, David A. Ebert, Christina Slager, Karen D. Crow. 2014. The secret of the mermaid's purse: Phylogenetic affinities within the Rajidae and the evolution of a novel reproductive strategy in skates. Molecular Phylogenetics and Evolution. 75 (2014) 245–251.
  • Crow, Karen D., Christopher D. Smith, Jan-Fang Cheng, Günter P. Wagner and Chris T. Amemiya. 2012. An independent genome duplication inferred from Hox paralogs in the American paddlefish-a representative basal ray-finned fish and important comparative reference. Genome Biology and Evolution.  
  • Jessica M. Maxfield, James L. Van Tassell, Colette M. St. Mary, Jean-Christophe Joyeux, Karen D. Crow.  2012.  Extreme gender flexibility: Using a phylogenetic framework to infer the evolution of variation in sex allocation, phylogeography, and speciation in a genus of bidirectional sex changing fishes (Lythrypnus, Gobiidae). Molecular Phylogenetics and Evolution: 64 (2012) 416–427.
  • Crow, Karen D., Hiroyuki Munehara, Giacomo Bernardi.  2010. Sympatric speciation in a genus of marine reef fishes.  Molecular Ecology. 19:10 2089-2105.
  • Crow, Karen D., Chris Amemiya, Jutta Roth and Günter P. Wagner.  2009. Hypermutability of HoxA13a and functional divergence from its paralog are associated with the origin of a novel developmental feature in zebrafish and related taxa (Cypriniformes). Evolution.  63(6): 1574-1592.
  • Crow, Karen D., Hiroyuki Munehara, Ziyusei Kanamoto, Andrey Balanov, Dmitriy Antonenko, and Giacomo Bernardi.  2007.  Maintenance of species boundaries despite rampant hybridization between three species of reef fishes (Hexagrammidae): Implications for the role of selection.  Biological Journal of the Linnean Society.  91: 135-147.
  • Crow, Karen D. and Günter P. Wagner.  2006.  What is the role of genome duplication in the evolution of complexity and diversity in vertebrates?  Molecular Biology and Evolution.  23(5): 887-892.
  • Crow, Karen D., Peter F. Stadler, Vincent J. Lynch, Chris Amemiya, and Günter P. Wagner.  2006. The “fish specific” Hox cluster duplication is coincident with the origin of teleosts.  Molecular Biology and Evolution.  23(1): 121-136.
  • Metscher, B. D., K. Takahashi, K. D. Crow, C. Amemiya, D. F. Nonaka, and G. P. Wagner. 2005. Expression of Hoxa-11 and Hoxa-13 in the pectoral fin of a basal ray finned fish, Polyodon spathula: implications for the origin of tetrapod limbs. Evolution and Development.  7:186-195.
  • Crow, Karen D., Ziyusei Kanamoto and Giacomo Bernardi.  2004.  Molecular phylogeny of the hexagrammid fishes using a multi-locus approach.  Molecular Phylogenetics and Evolution.  32(3):986-997.
  • Balanov, A.A., A.I. Markevich, D.V. Antonenko, and K.D. Crow.  2001.  The first occurrence of hybrids of Hexagrammos otakiiH. octogrammus and description of H. otakii (Hexagrammidae) from Peter the Great Bay (Sea of Japan).  Journal of Ichthyology.  41(9):28-738. 
  • Nielsen, J.L., K.D. Crow and M.C. Fountain. 1999.  Microsatellite diversity and conservation of a relic trout population:  McCloud River redband trout.  Molecular Ecology.  8  (S12, Dec. 1999):129-142.
  • Crow, K.D., L. Barbieri and S. Lowerre-Barbieri.  1999.  "Sex, Lies, and Audiotape" or Variation in diel periodicity of courtship sound production in spotted seatrout, Cynoscion nebulosus.  Georgia Journal of Science.  57(2):143-144.
  • Crow, K.D., D.A. Powers and G. Bernardi.  1997.  Evidence for multiple maternal contributors in nests of kelp greenling (Hexagrammos decagrammus, Hexagrammidae).  Copeia.  1997(1):9-15.