Application of Life-History Theory and Population Model Analysis to Turtle Conservation

Heppell, Selina S.

doi:10.2307/1447430

Cited by 395 publications

(353 citation statements)

References 24 publications

Supporting

Mentioning

331

Contrasting

Unclassified

Order By: Relevance

“…Simultaneously, by limiting development within these zones, female turtles undergoing nesting migrations will experience reduced risk of individual mortality. Population persistence is unlikely with additive mortality of sexually mature females concurrent with loss of nesting areas (e.g., Heppell, 1998).…”

Section: Discussionmentioning

confidence: 99%

“…Turtle demography is characterized by relatively high nest and embryonic mortality, delayed sexual maturity, and high adult survivorship (Congdon et al, 1993(Congdon et al, , 1994, rendering populations particularly sensitive to decline when there is a loss of sexually mature individuals (Brooks et al, 1991;Gibbs and Shriver, 2002;Heppell, 1998). Thus, a synopsis of distances traveled overland by nesting females could generate useful targets for conservation planning to protect critical population segments.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Terrestrial habitat requirements of nesting freshwater turtles

Steen

Gibbs

Buhlmann

et al. 2012

Biological Conservation

View full text Add to dashboard Cite

Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of > 8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8 m forMalaclemys to nearly 1400 m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage = 93 m, 75% = 154 m, 90% = 198 m, 95% = 232 m, 100% = 942 m. Approximately 6-98 m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424 m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (zones) for 95% nest coverage (Actinemys, Apalone, Chelydra, Chrysemys, Clemmys,Glyptemys, Graptemys, Macrochelys, Malaclemys, Pseudemys, Sternotherus), whereas other genera require larger zones (Deirochelys, Emydoidea, Kinosternon, Trachemys). Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings. Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Terrestrial habitat requirements of nesting freshwater turtles

Steen

Gibbs

Buhlmann

et al. 2012

Biological Conservation

View full text Add to dashboard Cite

show abstract

“…This genetic situation is analogous to the demographic situation facing long-lived organisms where adults are targeted for removal. Delayed sexual maturity of these organisms provides a juvenile pool that can buffer the chronic disturbance, but can also mask the inevitable population extinction (Congdon et al 1993;Congdon et al 1994;Heppell 1998).…”

Section: Discussionmentioning

confidence: 99%

“…This finding suggests that the current 150-ha habitat of the IL population might be adequate to support the desirable census population size of 700. Previous studies identified adult survival as being vital in the management of declining populations of long-lived organisms (Lande 1988;Congdon et al 1993;Congdon et al 1994;Heppell 1998;Belzer 2002). Mortality of the species is high at the juvenile stage, but declines substantially when the animals reach maturation: survivorship of adults is estimated at 81-96% year À1 (Blair 1976;Metcalf and Metcalf 1985;Doroff and Keith 1990).…”

Section: Conservation Guidelines For the Il Populationmentioning

confidence: 99%

Genetic Effects of a Persistent Bottleneck on a Natural Population of Ornate Box Turtles (Terrapene ornata)

Kuo

Janzen

2004

Conservation Genetics

139

105

View full text Add to dashboard Cite

Human activities in the past few hundred years have caused enormous impacts on many ecosystems, greatly accelerating the rate of population decline and extinction. In addition to habitat alteration and destruction, the loss of genetic diversity due to reduced population size has become a major conservation issue for many imperiled species. However, the genetic effects of persistent population bottlenecks can be very different for long-lived and short-lived species when considering the time scale of centuries. To investigate the genetic effects of persistent population bottlenecks on long-lived species, we use microsatellite markers to assess the level of genetic diversity of a small ornate box turtle population that has experienced a persistent bottleneck in the past century, and compare it to a large relatively undisturbed population. The genetic signature of a recent bottleneck is detected by examining the deviation from mutation-drift equilibrium in the small population, but the bottleneck had little effect on its level of genetic diversity. Computer simulations combined with information on population structure suggest that an effective population size of 300, which results in a census population size of 700, would be required for the small population to maintain 90% of the average number of alleles per locus in the next 200 years. The life history of long-lived species could mask the accelerated rate of genetic drift, making population recovery a relatively slow process. Statistical analysis of genetic data and empirical-based computer simulations can be important tools to facilitate conservation planning.

show abstract

“…It leads to sexual size dimorphism (Gibbons & Lovich 1990;Lefebvre et al 2011) and the smaller body size may influence mortality, which in turn can skew the sex ratio of a population (Hellgren et al 2000). Data on species' demography are integral to conservation assessments and hence management strategies, particularly in view of climate change (Heppell 1998;Scott et al 2012). Chelonians have a high extinction risk (Rhodin et al 2011), and climate change will aggravate declines, leading to a reduction in species richness (Ihlow et al 2012).…”

mentioning

confidence: 99%

Population ecology ofPsammobates oculiferin a semi-arid environment

Keswick

Hofmeyr

2013

African Journal of Herpetology

View full text Add to dashboard Cite

We studied the ecology of Psammobates oculifer over 13 months near Kimberley, South Africa, to ascertain if the population's life history traits conform to chelonian patterns in arid environments. Capture rates were highest in spring and lowest in winter when environmental conditions were respectively most and least favourable for tortoise activity. Body condition did not change from autumn to spring, but reached lower values during the summer drought. Capture effort averaged 5 hours/tortoise, which corresponds closely to that of species with low population densities in arid regions. Population size structure was skewed towards adults, indicative of low recruitment and/or low juvenile survivorship. Females were larger and heavier than males, confirming sexual dimorphism in this species. Body size of cohorts scaled to annuli counts, indicating a close correspondence between body size and age. Telemetered adults deposited one or no growth ring in the year of study; consequently, annuli counts could underestimate adult age. Regression analyses showed that male and female growth rates did not differ, but males matured at a smaller size and younger age than females. The smallest male showing reproductive behaviour had 12 annuli and a shell volume of 157 cm 3 , while similar measures for females were 14 annuli and 185 cm 3 . The sex ratio of the population did not differ from 1:1 but the bias towards males in spring, and towards females in autumn, indicates that studies limited to particular seasons can misrepresent life history traits of populations. We concluded that the life history of P. oculifer conforms to chelonian patterns in arid regions.

show abstract

Application of Life-History Theory and Population Model Analysis to Turtle Conservation

Cited by 395 publications

References 24 publications

Terrestrial habitat requirements of nesting freshwater turtles

Terrestrial habitat requirements of nesting freshwater turtles

Genetic Effects of a Persistent Bottleneck on a Natural Population of Ornate Box Turtles (Terrapene ornata)

Population ecology ofPsammobates oculiferin a semi-arid environment

Contact Info

Product

Resources

About