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Tombak KJ, Gersick AS, Reisinger LV, Larison B, Rubenstein DI. Zebras of all stripes repel biting flies at close range. Sci Rep 2022; 12:18617. [PMID: 36329147 DOI: 10.1038/s41598-022-22333-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 10/13/2022] [Indexed: 11/05/2022] Open
Abstract
The best-supported hypothesis for why zebras have stripes is that stripes repel biting flies. While this effect is well-established, the mechanism behind it remains elusive. Myriad hypotheses have been suggested, but few experiments have helped narrow the field of possible explanations. In addition, the complex visual features of real zebra pelage and the natural range of stripe widths have been largely left out of experimental designs. In paired-choice field experiments in a Kenyan savannah, we found that hungry Stomoxys flies released in an enclosure strongly preferred to land on uniform tan impala pelts over striped zebra pelts but exhibited no preference between the pelts of the zebra species with the widest stripes and the narrowest stripes. Our findings confirm that zebra stripes repel biting flies under naturalistic conditions and do so at close range (suggesting that several of the mechanisms hypothesized to operate at a distance are unnecessary for the fly-repulsion effect) but indicate that interspecific variation in stripe width is associated with selection pressures other than biting flies.
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Larison B, Kaelin CB, Harrigan R, Henegar C, Rubenstein DI, Kamath P, Aschenborn O, Smith TB, Barsh GS. Population structure, inbreeding and stripe pattern abnormalities in plains zebras. Mol Ecol 2020; 30:379-390. [PMID: 33174253 DOI: 10.1111/mec.15728] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/23/2020] [Accepted: 10/30/2020] [Indexed: 01/14/2023]
Abstract
One of the most iconic wild equids, the plains zebra occupies a broad region of sub-Saharan Africa and exhibits a wide range of phenotypic diversity in stripe patterns that have been used to classify multiple subspecies. After decades of relative stability, albeit with a loss of at least one recognized subspecies, the total population of plains zebras has undergone an approximate 25% decline since 2002. Individuals with abnormal stripe patterns have been recognized in recent years but the extent to which their appearance is related to demography and/or genetics is unclear. Investigating population genetic health and genetic structure are essential for developing effective strategies for plains zebra conservation. We collected DNA from 140 plains zebra, including seven with abnormal stripe patterns, from nine locations across the range of plains zebra, and analyzed data from restriction site-associated and whole genome sequencing (RAD-seq, WGS) libraries to better understand the relationships between population structure, genetic diversity, inbreeding, and abnormal phenotypes. We found that genetic structure did not coincide with described subspecific variation, but did distinguish geographic regions in which anthropogenic habitat fragmentation is associated with reduced gene flow and increased evidence of inbreeding, especially in certain parts of East Africa. Further, zebras with abnormal striping exhibited increased levels of inbreeding relative to normally striped individuals from the same populations. Our results point to a genetic cause of stripe pattern abnormalities, and dramatic evidence of the consequences of habitat fragmentation.
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Affiliation(s)
- Brenda Larison
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA.,Center for Tropical Research, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - Christopher B Kaelin
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA.,Department of Genetics, Stanford University, Stanford, CA, USA
| | - Ryan Harrigan
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA.,Center for Tropical Research, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | | | - Daniel I Rubenstein
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Pauline Kamath
- School of Food and Agriculture, University of Maine, Orono, ME, USA
| | - Ortwin Aschenborn
- School of Veterinary Medicine, University of Namibia, Neudamm Windhoek, Namibia
| | - Thomas B Smith
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA.,Center for Tropical Research, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - Gregory S Barsh
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA.,Department of Genetics, Stanford University, Stanford, CA, USA
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