09/05/2026
Hoffnung für die bedrohten Wüstenfische.
Conservation genomics offers new hope for the Pecos pupfish (𝐶𝑦𝑝𝑟𝑖𝑛𝑜𝑑𝑜𝑛 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠), a vulnerable species uniquely adapted to the harsh, salty springs and gypsum sinkholes of the Chihuahuan Desert in Texas and New Mexico, USA. Facing habitat loss, water scarcity, and hybridisation with invasive sheepshead minnows (𝐶𝑦𝑝𝑟𝑖𝑛𝑜𝑑𝑜𝑛 𝑣𝑎𝑟𝑖𝑒𝑔𝑎𝑡𝑢𝑠) via live bait release, this species has seen its range shrink dramatically.
Here, researchers use DNA sequencing to map the genetic diversity, population structure, and admixture of these pupfish across wild and refuge populations. The work reveals how isolated habitats have created distinct genetic groups with limited gene flow, with some populations showing signs of reduced diversity - warning signs of inbreeding and vulnerability to further decline. By documenting ongoing hybridisation threats and assessing effective population sizes, the researchers provide critical data for managers. These findings will help prioritise habitat protection, guide captive breeding programs, and support “genetic rescue” efforts to keep this desert icon swimming into the future.
𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵 𝗧𝗶𝘁𝗹𝗲
Conservation genomics of Pecos pupfish (𝐶𝑦𝑝𝑟𝑖𝑛𝑜𝑑𝑜𝑛 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠)
Open-access - https://onlinelibrary.wiley.com/doi/10.1111/jfb.70486
𝗖𝗶𝘁𝗮𝘁𝗶𝗼𝗻
Dolan, E. P., Fields, A. T., Bean, M. G., Doege, R. L., Hatt, J. L., Conway, K. W., & Portnoy, D. S. (2026). Conservation genomics of Pecos pupfish (𝐶𝑦𝑝𝑟𝑖𝑛𝑜𝑑𝑜𝑛 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠). Journal of Fish Biology, 1–15. https://doi.org/10.1111/jfb.70486
𝗔𝗯𝘀𝘁𝗿𝗮𝗰𝘁
The Pecos pupfish, 𝐶𝑦𝑝𝑟𝑖𝑛𝑜𝑑𝑜𝑛 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠, is an imperilled freshwater fish found in arid regions of Texas and New Mexico (USA). The species faces multiple challenges to persistence including reductions in suitable habitat, water shortages, as well as hybridization and competition with an introduced congener (sheepshead minnow, 𝐶. 𝑣𝑎𝑟𝑖𝑒𝑔𝑎𝑡𝑢𝑠).
As part of the current management strategy, refuge populations, seeded with non-introgressed individuals collected from Texas, are maintained at the Fort Worth Zoo and on private property in West Texas. Therefore, assessments of standing genetic variation within and among wild and refuge populations and levels of admixture in the wild are critical for future conservation and management planning. Fin clips were acquired in 10 locations in the wild, five in Texas, five in New Mexico and from two refuge populations in Texas (one maintained by Fort Worth Zoo and another on a private property in West Texas).
In Texas, non-introgressed 𝐶. 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠 were found in the wild at only one location Upper Salt Creek (USC); all other locations were composed of admixed individuals or non-introgressed 𝐶. 𝑣𝑎𝑟𝑖𝑒𝑔𝑎𝑡𝑢𝑠. No admixed individuals were found in New Mexico. Significant genetic heterogeneity was detected between all locations of non-introgressed 𝐶. 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠, including the refuge populations, and estimates of divergence between Texas locations (USC and refuge populations) and New Mexico locations were relatively large (FST: 0.23–0.32). Estimates of contemporary effective population size for USC and the two refuge populations were less than 50, but greater than 500 for all New Mexico populations.
In summation, while New Mexico populations look secure, the data suggest that 𝐶. 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠 in Texas is currently imperilled by the threat of hybridization, as well as potential loss of genetic diversity on contemporary time scales. Deep divergence between Texas (including refuge populations) and New Mexico suggests that further study would be needed prior to any management plans that would involve assisted gene flow between the regions.
𝗣𝗵𝗼𝘁𝗼 𝗖𝗿𝗲𝗱𝗶𝘁
Photographs of select individuals of 𝐶𝑦𝑝𝑟𝑖𝑛𝑜𝑑𝑜𝑛 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠 (a–f, males on left, females on right), a potential hybrid between 𝐶. 𝑝𝑒𝑐𝑜𝑠𝑒𝑛𝑠𝑖𝑠 x 𝐶. 𝑣𝑎𝑟𝑖𝑒𝑔𝑎𝑡𝑢𝑠 (g), and 𝐶. 𝑣𝑎𝑟𝑖𝑒𝑔𝑎𝑡𝑢𝑠 (h–i, male on left, female on right). (a, b) TCWC 20594.01, private ranch, Reeves Co., TX; C, D, TCWC 20596.01, Salt Creek at private ranch, Reeves Co., TX (USC); (e) F, Bitter Lake, Chaves Co., NM (AMN), not preserved; (g) TCWC 20597.01, female, Salt Creek, Reeves Co., TX (LSC); (h, i) TCWC uncat., Balmorhea Lake, Reeves Co., TX.
© 2026 the Author(s). Published in the Journal of Fish Biology. This paper is released under a Creative Commons Attribution 4.0 International (CC-BY-4.0) licence.
