The effects of controlled propagation on an endangered species: Genetic differentiation and divergence in body size among native and captive populations of the Socorro Isopod (Crustacea: Flabellifera)

Stephen M Shuster, Mark P. Miller, Brian K. Lang, Nathan Zorich, Lynn Huynh, Paul S Keim

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The endangered Socorro Isopod, Thermosphaeroma thermophilum, is endemic to a single thermal spring in Socorro, NM. This species is cannibalistic, with males more cannibalistic than females, and with females and juveniles more vulnerable than males as prey. In 1990, the New Mexico Department of Game and Fish, created the Socorro Isopod Propagation Facility (SIPF) near the natural habitat, Sedillo Spring (SS), to increase total population size and to examine the effects of habitat heterogeneity on population growth. We report the genetic and morphological effects of this experiment, using the natural population as a control. Captive subpopulations experienced bottlenecks of known intensity and duration, as well as different intensities of cannibalism. Using 57 AFLP markers, we show that in 6 years (1990-1996), captive subpopulations diverged significantly from the natural population. Also during this 6-year period, body lengths of captive isopods diverged nearly 2-fold from the natural population, evidently because cannibalism and thus selection favoring large size was more intense in captive subpopulations than in nature. This hypothesis is supported by the fact that cannibalism and the apparent response to selection on body size became variable among captive subpopulations when physical structure was added to three of the four SIPF pools in April 1997. As expected if cannibalism was the source of selection for large body size, by August 1998 (15 months = 7-8 generations), the rate at which body size increased became inversely proportional to the amount of physical structure within pools. Although we are unable to separate the specific effects of population subdivision and cannibalism, our results show that these conditions in combination caused rapid changes in genetic variation and the external morphology of these captive subpopulations. Our results have important implications for future attempts to manage and propagate endangered species.

Original languageEnglish (US)
Pages (from-to)355-368
Number of pages14
JournalConservation Genetics
Volume6
Issue number3
DOIs
StatePublished - May 2005

Fingerprint

Cannibalism
Isopoda
Crustacea
captive population
Endangered Species
cannibalism
isopod
Body Size
subpopulation
endangered species
genetic differentiation
body size
divergence
genetic variation
Population
Ecosystem
hot springs
Population Growth
founder effect
habitat

Keywords

  • AFLP
  • Bottleneck
  • Cannibalism
  • Crustacea
  • Selection
  • Thermal springs

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Genetics
  • Genetics(clinical)
  • Nature and Landscape Conservation

Cite this

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title = "The effects of controlled propagation on an endangered species: Genetic differentiation and divergence in body size among native and captive populations of the Socorro Isopod (Crustacea: Flabellifera)",
abstract = "The endangered Socorro Isopod, Thermosphaeroma thermophilum, is endemic to a single thermal spring in Socorro, NM. This species is cannibalistic, with males more cannibalistic than females, and with females and juveniles more vulnerable than males as prey. In 1990, the New Mexico Department of Game and Fish, created the Socorro Isopod Propagation Facility (SIPF) near the natural habitat, Sedillo Spring (SS), to increase total population size and to examine the effects of habitat heterogeneity on population growth. We report the genetic and morphological effects of this experiment, using the natural population as a control. Captive subpopulations experienced bottlenecks of known intensity and duration, as well as different intensities of cannibalism. Using 57 AFLP markers, we show that in 6 years (1990-1996), captive subpopulations diverged significantly from the natural population. Also during this 6-year period, body lengths of captive isopods diverged nearly 2-fold from the natural population, evidently because cannibalism and thus selection favoring large size was more intense in captive subpopulations than in nature. This hypothesis is supported by the fact that cannibalism and the apparent response to selection on body size became variable among captive subpopulations when physical structure was added to three of the four SIPF pools in April 1997. As expected if cannibalism was the source of selection for large body size, by August 1998 (15 months = 7-8 generations), the rate at which body size increased became inversely proportional to the amount of physical structure within pools. Although we are unable to separate the specific effects of population subdivision and cannibalism, our results show that these conditions in combination caused rapid changes in genetic variation and the external morphology of these captive subpopulations. Our results have important implications for future attempts to manage and propagate endangered species.",
keywords = "AFLP, Bottleneck, Cannibalism, Crustacea, Selection, Thermal springs",
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T1 - The effects of controlled propagation on an endangered species

T2 - Genetic differentiation and divergence in body size among native and captive populations of the Socorro Isopod (Crustacea: Flabellifera)

AU - Shuster, Stephen M

AU - Miller, Mark P.

AU - Lang, Brian K.

AU - Zorich, Nathan

AU - Huynh, Lynn

AU - Keim, Paul S

PY - 2005/5

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N2 - The endangered Socorro Isopod, Thermosphaeroma thermophilum, is endemic to a single thermal spring in Socorro, NM. This species is cannibalistic, with males more cannibalistic than females, and with females and juveniles more vulnerable than males as prey. In 1990, the New Mexico Department of Game and Fish, created the Socorro Isopod Propagation Facility (SIPF) near the natural habitat, Sedillo Spring (SS), to increase total population size and to examine the effects of habitat heterogeneity on population growth. We report the genetic and morphological effects of this experiment, using the natural population as a control. Captive subpopulations experienced bottlenecks of known intensity and duration, as well as different intensities of cannibalism. Using 57 AFLP markers, we show that in 6 years (1990-1996), captive subpopulations diverged significantly from the natural population. Also during this 6-year period, body lengths of captive isopods diverged nearly 2-fold from the natural population, evidently because cannibalism and thus selection favoring large size was more intense in captive subpopulations than in nature. This hypothesis is supported by the fact that cannibalism and the apparent response to selection on body size became variable among captive subpopulations when physical structure was added to three of the four SIPF pools in April 1997. As expected if cannibalism was the source of selection for large body size, by August 1998 (15 months = 7-8 generations), the rate at which body size increased became inversely proportional to the amount of physical structure within pools. Although we are unable to separate the specific effects of population subdivision and cannibalism, our results show that these conditions in combination caused rapid changes in genetic variation and the external morphology of these captive subpopulations. Our results have important implications for future attempts to manage and propagate endangered species.

AB - The endangered Socorro Isopod, Thermosphaeroma thermophilum, is endemic to a single thermal spring in Socorro, NM. This species is cannibalistic, with males more cannibalistic than females, and with females and juveniles more vulnerable than males as prey. In 1990, the New Mexico Department of Game and Fish, created the Socorro Isopod Propagation Facility (SIPF) near the natural habitat, Sedillo Spring (SS), to increase total population size and to examine the effects of habitat heterogeneity on population growth. We report the genetic and morphological effects of this experiment, using the natural population as a control. Captive subpopulations experienced bottlenecks of known intensity and duration, as well as different intensities of cannibalism. Using 57 AFLP markers, we show that in 6 years (1990-1996), captive subpopulations diverged significantly from the natural population. Also during this 6-year period, body lengths of captive isopods diverged nearly 2-fold from the natural population, evidently because cannibalism and thus selection favoring large size was more intense in captive subpopulations than in nature. This hypothesis is supported by the fact that cannibalism and the apparent response to selection on body size became variable among captive subpopulations when physical structure was added to three of the four SIPF pools in April 1997. As expected if cannibalism was the source of selection for large body size, by August 1998 (15 months = 7-8 generations), the rate at which body size increased became inversely proportional to the amount of physical structure within pools. Although we are unable to separate the specific effects of population subdivision and cannibalism, our results show that these conditions in combination caused rapid changes in genetic variation and the external morphology of these captive subpopulations. Our results have important implications for future attempts to manage and propagate endangered species.

KW - AFLP

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KW - Selection

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