The Age of Plethodontid Salamanders: A Short Review on Longevity

Staub, Nancy L.

doi:10.1643/ot-14-200

Cited by 19 publications

(16 citation statements)

References 47 publications

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“…One very large individual (42 mm SVL at time of initial capture, 30% greater than the VB asymptotic size) from a cave population had been repeatedly captured over a 14‐year period (A. Gluesenkamp and M. Sanders, personal communication), although individuals in caves may live longer than their surface counterparts. Longevity estimates of wild plethodontid salamanders range from 7 to 36 years (Staub, ) although estimates have not been reported previously for central Texas Eurycea species. Several longevity records exist for captive populations (e.g., Herald, ) including the City of Austin's captive refugium, where several E. tonkawae are over 11 years of age, while the oldest E. sosorum is 17.5 years old (D. Chamberlain, personal communication; City of Austin, unpublished data).…”

Section: Discussionmentioning

confidence: 97%

“…One very large individual (42 mm SVL at time of initial capture, 30% greater than the VB asymptotic size) from a cave population had been repeatedly captured over a 14-year period (A. Gluesenkamp and M. Sanders, personal communication), although individuals in caves may live longer than their surface counterparts. Longevity estimates of wild plethodontid salamanders range from 7 to 36 years (Staub, 2016) Temporary emigration can result in biased parameter estimates of the JS model when the pattern of emigration is Markovian (Kendall et al, 1997). In one study, JS estimates of population size were found to be generally unbiased when animals had a high probability of returning to the study area, but were negatively biased when they had a low probability of returning (Zehfuss, Hightower, & Pollock, 1999).…”

Section: Discussionmentioning

confidence: 99%

“…Determination of longevity is difficult, particularly given that the oldest individuals in a population are encountered with low frequency. In this case, the VB asymptotic size estimate does not represent the maximum size achieved, but the mean maximum size (e.g., see Staub () for a discussion of longevity estimation using VB models), and many individuals in the population were larger. For example, 59 E. tonkawae were at or above the mean asymptotic size when initially captured and were later recaptured up to six years later.…”

Section: Discussionmentioning

confidence: 99%

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Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae)

Bendik¹

2017

Ecology and Evolution

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Insights into the ecology and natural history of the neotenic salamander, Eurycea tonkawae, are provided from eight years of capture‐recapture data from 10,041 captures of 7,315 individuals at 16 sites. Eurycea tonkawae exhibits seasonal reproduction, with peak gravidity occurring in the fall and winter. Size frequency data indicated recruitment occurred in the spring and summer. Open‐population capture‐recapture models revealed a similar seasonal pattern at two of three sites, while recruitment was dependent on flow at the third site. Females can reach sexual maturity within one year, and oviposition likely takes place below ground. The asymptotic body length of 1,290 individuals was estimated as 31.73 mm (at ca. two years of age), although there was substantial heterogeneity among growth trajectories. Longevity was approximately eight years, and the median age for a recaptured adult was 2.3 years. Abundance estimated from closed‐population and robust‐design capture‐recapture models varied widely within and among sites (range 41–834), although, surprisingly, dramatic changes in abundance were not observed following prolonged dry periods. Seasonal migration patterns of second‐year and older adults may help explain lower ratios of large individuals and higher temporary emigration during the latter half of the year, but further study is required. Low numbers of captures and recaptures precluded the use of open‐population models to estimate demographic parameters at several sites; therefore, closed‐population (or robust‐design) methods are generally recommended. Based on observations of their life history and population demographics, E. tonkawae seems well adapted to conditions where spring flow is variable and surface habitat periodically goes dry.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae)

Bendik¹

2017

Ecology and Evolution

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“…Species of the P. jordani complex are unfortunately lacking in all three attributes. They have relatively narrow thermal performance windows (Clay and Gifford 2018), long generation times (Staub 2016), and small and geographically isolated populations with limited gene flow (Highton and Peabody 2000), emphasizing their conservation concern. Our regional, multispecies model demonstrates that temperature, precipitation, and vapor pressure strongly influence surface activity probability, and without physiological or behavioral changes, these salamanders will exhibit higher levels of surface activity during their peak active season under future climate conditions.…”

Section: Discussionmentioning

confidence: 99%

Predicted alteration of surface activity as a consequence of climate change

Gade

Connette

Crawford

et al. 2020

Ecology

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Wildlife are faced with numerous threats to survival, none more pressing than that of climate change. Understanding how species will respond behaviorally, physiologically, and demographically to a changing climate is a cornerstone of many contemporary ecological studies, especially for organisms, such as amphibians, whose persistence is closely tied to abiotic conditions. Activity is a useful parameter for understanding the effects of climate change because activity is directly linked to fitness as it dictates foraging times, energy budgets, and mating opportunities. However, activity can be challenging to measure directly, especially for secretive organisms like plethodontid salamanders, which only become surface active when conditions are cool and moist because of their anatomical and physiological restrictions. We estimated abiotic predictors of surface activity for the seven species of the Plethodon jordani complex. Five independent data sets collected from 2004 to 2017 were used to determine the parameters driving salamander surface activity in the present day, which were then used to predict potential activity changes over the next 80 yrs. Average active seasonal temperature and vapor pressure deficit were the strongest predictors of salamander surface activity and, without physiological or behavioral modifications, salamanders were predicted to exhibit a higher probability of surface activity during peak active season under future climate conditions. Temperatures during the active season likely do not exceed salamander thermal maxima to cause activity suppression and, until physiological limits are reached, future conditions may continue to increase activity. Our model is the first comprehensive field‐based study to assess current and future surface activity probability. Our study provides insights into how a key behavior driving fitness may be affected by climate change.

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“…From such metrics, one can derive stable age distribution, age at maturity, and longevity, all of which strongly influence estimates of population growth rates from viability analyses [57]. Stage-structured organisms pose a real challenge to this end, and as a result, previous studies are largely limited to species without distinct lifestages [22,[58][59][60][61], or for which homogenous data across stages can be collected [25,62]. For all other circumstances, the tendency is to ignore stage-structure or to omit non-conforming data.…”

Section: Plos Onementioning

confidence: 99%

Reconciling larval and adult sampling methods to model growth across life-stages

et al. 2020

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Individual growth rates are intrinsically related to survival and lifetime reproductive success and hence, are key determinants of population growth. Efforts to quantify age-size relationships are hampered by difficulties in aging individuals in wild populations. In addition, species with complex life-histories often show distinct shifts in growth that cannot be readily accommodated by traditional modelling techniques. Amphibians are often characterized by rapid larval growth, cessation of growth prior to metamorphosis, and resumption of growth in the adult stage. Compounding issues of non-linear growth, amphibian monitoring programs typically sample larval and adult populations using dissimilar methods. Here we present the first multistage growth model that combines disparate data collected across life-history stages. We model the growth of the endangered Reticulated Flatwoods Salamander, Ambystoma bishopi, in a Bayesian framework, that accounts for unknown ages, individual heterogeneity, and reconciles dip-net and drift fence sampling designs. Flatwoods salamanders achieve 60% of growth in the first 3 months of life but can survive for up to 13 years as a terrestrial adult. We find evidence for marked variability in growth rate, the timing and age at metamorphosis, and maximum size, within populations. Average size of metamorphs in a given year appeared strongly dependent on hydroperiod, and differed by >10mm across years with successful recruitment. In contrast, variation in the sizes of emerging metamorphs appeared relatively constant across years. An understanding of growth will contribute to the development of population viability analyses for flatwoods salamanders, will guide management actions, and will ultimately aid the recovery of the species. Our model formulation has broad applicability to amphibians, and likely any stage-structured organism in which homogenous data cannot be collected across life-stages. The tendency to ignore stagestructure or omit non-conforming data in growth analyses can no longer be afforded given the high stakes of management decisions, particularly for endangered or at-risk populations.

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The Age of Plethodontid Salamanders: A Short Review on Longevity

Cited by 19 publications

References 47 publications

Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae)

Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae)

Predicted alteration of surface activity as a consequence of climate change

Reconciling larval and adult sampling methods to model growth across life-stages

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