Species & Speciation

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There are thousands of species of true crickets (family Gryllidae); no one knows how many because many groups are poorly known, at least in some parts of the world.  The songs of crickets are species-specific (at least within a fauna), and females typically show strong preferences for their own species’ song.  Because song simultaneously affects assortative mating and both sexual and natural selection, understanding song evolution is central to understanding each of these processes, given constraints of the others.

Song is energetically expensive to produce, and can increase risk of death from predators and/or parasitoids (see Crickets & Flies research page).  The major risk factor, however, appears to be how much and when males call, but song structure, e.g. frequency and the numbers, rate, and pattern of song pulses, can also play a role increasing or decreasing risk. Female crickets appear to strongly favor species specific pulse rates; this seems true for all species tested to date.  However in some species females prefer songs with more pulses per chirp or trill, and/or faster repetition rate of chirps or trills – but these preferences are not shared among all species tested.  Sometimes the detailed features of cricket song appear to indicate something about male quality; potential benefits to females from mating with preferred males may include genetic and/or direct benefits.

Current Projects:

I am currently working on aspects of species divergence and song evolution in North American Gryllus, especially those species in the western USA.

With Dave Weissman and Jeff Cole, I am collaborating on various aspects of taxonomy and molecular phylogenetics of North American Gryllus.  This work will result in a comprehensive revision and production of a multi-locus molecular hypothesis of species relationships.

I am collaborating with Matthias Hennig and his lab on detailed multivariate preference function tests for a number of species.  This work will inform our understanding of proximate mechanisms of song recognition and will also provide a foundation for comparative studies of preference evolution.

I am also part of the large GenArt collaboration examining the genetics of speciation; Frieder Mayer heads this group.

Papers about female preference evolution:

Gray, D. A., Gabel, E., Blankers, T., & Hennig, R. M. 2016. Multivariate female preference tests reveal latent perceptual biases. Proceedings of the Royal Society of London B. .

Gabel, E., Gray, D. A., & Hennig, R. M. 2016. How the ‘what’ and ‘where’ of male acoustic signals drive the choice for a mating partner in chirping and trilling field crickets. J. Comparative Physiology A 202: 823-837

Hennig, R. M., Blankers, T., & Gray, D. A. 2016. Divergence in male cricket song and female preference functions in three allopatric sister species. J. Comparative Physiology A: 202:347-360.

Blankers, T., Hennig, R. M. & Gray, D. A. 2015. Conservation of multivariate female preference functions and preference mechanisms in three species of trilling field crickets. Journal of Evolutionary Biology 28: 630-641.

Rodríguez, R. L., Araya-Salas, M., Gray, D. A, Reichert, M. S., Symes, L. B., Wilkins, M. R., Safran, R. J. & Höbel. G. 2015. How acoustic signals scale with individual body size: common trends across diverse taxa. Behavioral Ecology 26: 168-177 doi: 10.1093/beheco/aru174.

Gray, D. A. & Eckhardt, G. 2001.  Is cricket courtship song condition dependent? Animal Behaviour 62: 871-877.

Gray, D. A. 1999. Intrinsic factors affecting female choice in house crickets: time cost, female age, nutritional condition, body size, and size-relative reproductive investment. Journal of Insect Behavior 12: 691-700.

Gray, D. A. & Cade, W. H. 1999. Quantitative genetics of sexual selection in the field cricket, Gryllus integer. Evolution 53: 848-854.

Gray, D. A. 1997. Female house crickets, Acheta domesticus, prefer the chirps of large males.  Animal Behaviour 54: 1553-1562.

Papers about species divergence/speciation:

Blankers, T., Gray, D. A, & Hennig, R. M. 2016. Multivariate phenotypic evolution: divergent acoustic signals and sexual selection in Gryllus field crickets. Evolutionary Biology doi:10.1007/s11692-016-9388-1

Gray, D. A., * Gutierrez, N. J., * Chen, T. L., * Gonzalez, C., Weissman, D. B., & Cole, J. A. 2016. Species divergence in field crickets: genetics, song, ecomorphology, and pre- and postzygotic isolation. Biological Journal of the Linnean Society 117: 192-205. DOI: 10.1111/bij.12668

Rodríguez, R. L., Boughman, J. W., Gray, D. A., Hebets, E. A., Höbel, G. & Symes, L. B. 2013. Diversification under sexual selection: the relative roles of mate preference strength and the degree of divergence in mate preferences. Ecology Letters 16: 964-974.

Gray, D. A. 2011. Speciation, divergence, and the origin of Gryllus rubens: behavior, morphology, and molecules. Insects 2: 195-209.

Izzo, A. S. & D. A. Gray 2011. Heterospecific courtship and sequential mate choice in sister species of field crickets. Animal Behaviour 81: 259-264.

Gray, D. A., Huang, H. & Knowles, L. L. 2008. Molecular evidence of a peripatric origin for two sympatric species of field cricket (Gryllus rubens and G. texensis) revealed from coalescent simulations and population genetic tests. Molecular Ecology 17: 3836-3855.

Gray, D. A., Barnfield, P., Seifried, M. & Richards, M. 2006. Molecular divergence between Gryllus rubens and Gryllus texensis, a cryptic species-pair of field crickets (Orthoptera: Gryllidae). Canadian Entomologist 138: 305-313.

Gray, D. A. 2005. Does courtship behavior contribute to species-level reproductive isolation in field crickets? Behavioral Ecology 16: 201-206.

Izzo, A. S. & Gray, D. A. 2004. Cricket song in sympatry: examining reproductive character displacement and species specificity of song in Gryllus rubens. Annals of the Entomological Society of America 97: 831-837.

Fitzpatrick, M. J. & Gray, D. A 2001.  Divergence in the courtship songs of the field crickets Gryllus texensis and G. rubens (Orthopera, Gryllidae). Ethology 107: 1075-1085

Gray, D. A. & Cade, W. H. 2000.  Sexual selection and speciation in field crickets.  Proceedings of the National Academy of Sciences, USA 97: 14449-14454.

Papers about taxonomy:

Weissman, D. B., Gray, D. A., Pham, H. T. & Tijssen, P. 2012. Billions and billions sold: Pet-feeder crickets (Orthoptera: Gryllidae), commercial cricket farms, an epizootic densovirus, and government regulations make for a potential disaster. Zootaxa 3504: 67-88.

Weissman, D. B., Walker, T. J. & Gray, D. A. 2009. The Jamaican field cricket Gryllus assimilis and two new sister species (Orthoptera: Gryllidae). Annals of the Entomological Society of America 102: 367-380.

Gray, D. A., Walker, T. J., Conley, B. E. & Cade, W. H. 2001. A morphological means of distinguishing females of the cryptic field cricket species, Gryllus rubens and G. texensis (Orthoptera: Gryllidae). Florida Entomologist 84: 314-315.

2 thoughts on “Species & Speciation

  1. Judith Duckhorn McNally

    I am fascinated to have found this line of information!!!!!!!!! Thank you so much for being there and doing this.
    My husband and I (in Sunland, CA) noticed a hugely dramatic fall-off of bug population(s) in our yard and gardens this year. There were almost no flies, similarly no ants, no Japanese beetles, no June bugs, and very few of these “blond” crickets, very few bees, too. It was a stunning change.

    We are just one block from the Big Tujunga Wash, and usually get some centipedes, tons of roly-poly bugs, earwigs, some butterflies, etc., etc. They were nearly non-existent this year.
    The only critters that seemed to be of a normal population size were the spiders and the tiny red spider mites. Oh–and some small moths.
    Do you think this is just a local thing, and temporary? Did the wild climate ups and downs do something? Have you heard of this insect-loss phenomenon from others?

    We do not use ANY pesticides or herbicides on our little property. (Less than 1/4 acre.) Not in the house, either.

    If you care to reply (which we would love), your first email will end up in my spamblocker, because I do not have your email address in my virtual address book. But I will watch carefully and fish your email out!)

    Thank you,
    Judith and Gerald McNally 818 352-6492

    P.S. If you ever want to read a stingingly funny little novel, get ahold of Bill Fitzhugh’s PEST CONTROL. I chuckled almost nonstop and I am sure an entomologist would get ten times more fun out of it. –jm

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    Reply
    1. Dr. Dave Gray Post author

      Hi – thanks for the interest and for being such a good observer of natural patterns. I don’t have any data, but I think that your observations are probably correct and may be related to drought.

      Like

      Reply

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