Evaluating otter reintroduction outcomes using genetic spatial capture–recapture modified for dendritic networks

Sean M. Murphy, Jennifer R. Adams, Lisette P. Waits, John J. Cox

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Monitoring the demographics and genetics of reintroduced populations is critical to evaluating reintroduction success, but species ecology and the landscapes that they inhabit often present challenges for accurate assessments. If suitable habitats are restricted to hierarchical dendritic networks, such as river systems, animal movements are typically constrained and may violate assumptions of methods commonly used to estimate demographic parameters. Using genetic detection data collected via fecal sampling at latrines, we demonstrate applicability of the spatial capture–recapture (SCR) network distance function for estimating the size and density of a recently reintroduced North American river otter (Lontra canadensis) population in the Upper Rio Grande River dendritic network in the southwestern United States, and we also evaluated the genetic outcomes of using a small founder group (n = 33 otters) for reintroduction. Estimated population density was 0.23–0.28 otter/km, or 1 otter/3.57–4.35 km, with weak evidence of density increasing with northerly latitude (β = 0.33). Estimated population size was 83–104 total otters in 359 km of riverine dendritic network, which corresponded to average annual exponential population growth of 1.12–1.15/year since reintroduction. Growth was ≥40% lower than most reintroduced river otter populations and strong evidence of a founder effect existed 8–10 years post-reintroduction, including 13–21% genetic diversity loss, 84%–87% genetic effective population size decline, and rapid divergence from the source population (FST accumulation = 0.06/generation). Consequently, genetic restoration via translocation of additional otters from other populations may be necessary to mitigate deleterious genetic effects in this small, isolated population. Combined with non-invasive genetic sampling, the SCR network distance approach is likely widely applicable to demogenetic assessments of both reintroduced and established populations of multiple mustelid species that inhabit aquatic dendritic networks, many of which are regionally or globally imperiled and may warrant reintroduction or augmentation efforts.

Original languageEnglish
Pages (from-to)15047-15061
Number of pages15
JournalEcology and Evolution
Volume11
Issue number21
DOIs
StatePublished - Nov 2021

Bibliographical note

Funding Information:
Primary funding was provided by New Mexico Department of Game & Fish’s Share with Wildlife Program (Grants: T-32-5, #7; and W-151-R-3); supplemental funding was provided by University of Kentucky Department of Forestry and Natural Resources, and University of Idaho College of Natural Resources. We thank Brian Long, Daniel Boyes, Connor Steckel, Chyna Dixon, and Kris Malone for collecting fecal samples in New Mexico; Rich Beausoleil and Washington Department of Fish and Wildlife for providing tissue samples from the source population in Washington; Shannon Romeling and Amigos Bravos for providing some locations of active latrines and allowing the use of their watercrafts for sampling; Digpal Singh Gour, Nicole Recla, and Hannah Elfering at University of Idaho for expedient genotyping; Virginia Seamster, Jim Stuart, Rick Winslow, David Wilckens, and Elise Goldstein at New Mexico Department of Game & Fish for providing support; and Murray Efford at University of Otago for assisting with modification of SCR goodness-of-fit testing for models with the linear network distance function. We also thank the anonymous reviewers who provided constructive comments and suggestions that improved this manuscript. Staff at Rio Grande del Norte National Monument, Questa Ranger District of the Carson National Forest, and private landowners in Taos County granted access for sample collections.

Funding Information:
Primary funding was provided by New Mexico Department of Game & Fish’s Share with Wildlife Program (Grants: T‐32‐5, #7; and W‐151‐R‐3); supplemental funding was provided by University of Kentucky Department of Forestry and Natural Resources, and University of Idaho College of Natural Resources. We thank Brian Long, Daniel Boyes, Connor Steckel, Chyna Dixon, and Kris Malone for collecting fecal samples in New Mexico; Rich Beausoleil and Washington Department of Fish and Wildlife for providing tissue samples from the source population in Washington; Shannon Romeling and Amigos Bravos for providing some locations of active latrines and allowing the use of their watercrafts for sampling; Digpal Singh Gour, Nicole Recla, and Hannah Elfering at University of Idaho for expedient genotyping; Virginia Seamster, Jim Stuart, Rick Winslow, David Wilckens, and Elise Goldstein at New Mexico Department of Game & Fish for providing support; and Murray Efford at University of Otago for assisting with modification of SCR goodness‐of‐fit testing for models with the linear network distance function. We also thank the anonymous reviewers who provided constructive comments and suggestions that improved this manuscript. Staff at Rio Grande del Norte National Monument, Questa Ranger District of the Carson National Forest, and private landowners in Taos County granted access for sample collections.

Publisher Copyright:
© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Keywords

  • Lontra canadensis
  • dendritic network
  • founder effect
  • population density
  • recapture
  • river otter
  • spatially explicit capture

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation

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