Climate-induced variation in vital rates of an unharvested large-herbivore population

2003 ◽  
Vol 81 (1) ◽  
pp. 33-45 ◽  
Author(s):  
Robert A Garrott ◽  
L Lee Eberhardt ◽  
Patrick J White ◽  
Jay Rotella
Keyword(s):  
Cervus Elaphus ◽  
Dynamic Equilibrium ◽  
Survival Rates ◽  
Vital Rates ◽  
Large Herbivore ◽  
Stochastic Effects ◽  
Resource Limited ◽  
Historic Data ◽  
Reproductive Rates ◽  
Variable Recruitment

Variation in vital rates of an unharvested elk (Cervus elaphus) population was studied using telemetry for 7 consecutive years, 1991–1998. We found pronounced senescence in survival rates, but no evidence for reproductive senescence. Prime-age females (<10 years old) experienced very high annual survival rates (mean = 0.97, SE = 0.02), with lower survival rates for senescent animals ([Formula: see text]10 years old; mean = 0.79, SE = 0.06). There was evidence that the severity of snowpack conditions had little effect on survival of prime-age animals except during the most extreme winter, while survival of senescent animals was progressively depressed as the severity of snowpack conditions increased. Reproductive rates remained essentially constant, near their biological maxima (mean = 0.91, SE = 0.02). Annual re cruitment was highly variable. Snowpack had a pronounced effect on recruitment (r2 = 0.91), the most severe snowpack conditions resulting in the virtual elimination of a juvenile cohort. Population estimates and recruitment rates obtained during this investigation and historic data collected from 1965 to 1980 support the premise that the population has been maintained in a dynamic equilibrium for at least three decades despite the stochastic effects of climate variation on vital rates. We conclude that the population is resource-limited, with variation about the equilibrium caused primarily by variable recruitment driven by stochastic annual snowpack.

scholarly journals Demographic cost and mechanisms of adaptation to environmental stress in resurrected Daphnia

2016 ◽  
Vol 75 (s2) ◽  
Author(s):  
Stefan Sommer ◽  
Roberta Piscia ◽  
Marina M. Manca ◽  
Diego Fontaneto ◽  
Arpat Ozgul
Keyword(s):  
Population Growth ◽  
Life Table ◽  
Survival Rates ◽  
Copper Tolerance ◽  
Lower Probability ◽  
Vital Rates ◽  
Population Growth Rates ◽  
Life Table Response Experiments ◽  
Reproductive Rates ◽  
Table Data

A characteristic feature of the <em>Daphnia</em> (Crustacea: Cladocera) life cycle are the so-called ephippia, which are fertilised eggs that need to undergo diapause. When they are shed by the female, they sink to the lake bottom, where they may become embedded in the sediment and may remain viable for decades. Extracting and hatching ephippia in the laboratory and subjecting resurrected lineages to conditions representative of historic lake environments allows retrospective investigation of life-history responses to environmental change. Here we reanalyse data from such a resurrection experiment (Piscia <em>et al.</em>, 2015: Bull. Environ. Contam. Toxicol. 94:46–51). Contemporary and past lineages of <em>Daphnia galeata</em> Sars 1863 were obtained from Lake Orta (Italy), a deep, subalpine lake with a well-documented history of industrial copper pollution. Experimental <em>Daphnia</em> were subjected to three copper treatments representative of two levels of historic as well as to current (i.e., unpolluted) lake conditions, and life-table data were collected. With these data at hand, we first estimated vital rates (survival, maturation, and reproduction) and used these rates to project the asymptotic population growth rates (<em>λ</em>) for each population-by-treatment combination. Next, we performed life-table response experiments (LTRE) to estimate the contributions of the vital rates to observed differences in <em>λ</em>. Finally, we used elasticity analysis to explore the functional relationship between <em>λ</em> and each of the vital rates. We found that survival rates were only compromised at elevated copper levels. Moreover, past, resurrected <em>Daphnia</em> had a higher <em>λ</em> at low copper concentrations compared to unpolluted conditions, but a lower <em>λ</em> when exposed to high copper levels. Contemporary <em>Daphnia</em>, on the other hand, only reproduced successfully in unpolluted water. Under these conditions, however, they had a higher population growth rate than the past <em>Daphnia</em>, suggesting a cost of copper tolerance in the latter. This cost was mainly due to a lower probability of reproduction and reduced fecundity, whereas survival remained largely unaffected. Finally, we found higher elasticity values of <em>λ</em> to survival than to reproductive rates. This suggests that any change in the environment that will affect survival rather than reproductive parameters will have a much larger impact on Lake Orta’s current <em>Daphnia</em> population.<em></em>

scholarly journals Factors Influencing Survival of Female Elk in a Harvested Population

2012 ◽  
Vol 3 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Jonathan M. Conard ◽  
Brett K. Sandercock ◽  
Philip S. Gipson ◽  
Warren B. Ballard
Keyword(s):  
Cervus Elaphus ◽  
Radio Telemetry ◽  
Survival Rates ◽  
Negative Relationship ◽  
Parameter Estimates ◽  
Vital Rates ◽  
Hunting Season ◽  
Management Actions ◽  
Study Population ◽  
Old Females

Abstract Understanding the influence of management actions and environmental conditions on demographic vital rates is important for effective conservation and management of wildlife populations. We used radio-telemetry to monitor annual and seasonal survival of 34 female elk Cervus elaphus at Fort Riley, Kansas in a 3.5-y field study (November 2003 to February 2007). We modeled the relationship between individual and environmental covariates and survival rates of female elk. We observed eight mortalities, and harvest was the primary cause of mortality in our study population. Annual survival rates of female elk in Kansas (0.76) were similar to other harvested populations of elk. Among the candidate model set, models that included age as a covariate were most supported. Parameter estimates from top models provided support for a slight negative relationship between age and survival. Monthly survival estimates during hunting season declined with age from 0.98 for 1.5-y-old females to 0.80 for 16.5-y-old females.

Low recruitment not mortality limits growth of peripheral populations of Silene spaldingii

Botany ◽  
2014 ◽  
Vol 92 (5) ◽  
pp. 340-347 ◽  
Author(s):  
Peter Lesica
Keyword(s):  
Population Viability ◽  
Plant Population ◽  
Range Limits ◽  
Peripheral Populations ◽  
Vital Rates ◽  
Plateau Region ◽  
Columbia Plateau ◽  
Central Population ◽  
Variable Recruitment ◽  
Eastern Washington

Populations at the periphery of a species range are thought to be less viable than those in the center because they are at the limit of their ecological tolerances. Plant population viability is determined primarily by mortality and recruitment, thus knowing differences in vital rates between central and peripheral populations is key to understanding range limits. Silene spaldingii S. Watson is a long-lived iteroparous plant that occurs throughout the eastern Columbia Plateau region of eastern Washington and adjacent Idaho and Oregon and is disjunct in northwest Montana. I recorded the fate of mapped S. spaldingii plants annually for 10 years in four populations, two from eastern Washington and two from Montana. Recruitment averaged three times higher and relatively constant at two central populations in Washington compared with two peripheral sites in Montana. Mortality was three times higher at one of the central populations compared with the remaining three sites due to vole predation. Vole activity was observed at the second central population but came too late in the study to be certain that it resulted in mortality. Vole predation was not observed in the peripheral populations. My results suggest that peripheral populations of S. spaldingii may only be able to persist as long as predation or other sources of mortality remain low and that intrinsic low and variable recruitment rates coupled with predation may help define the eastern range margin of this species.

scholarly journals ETMR-07. ETANTR: A RARE TUMOR IN A RESOURCE-LIMITED SETTING

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii324-iii324
Author(s):  
Julieta Hoveyan ◽  
Manushak Avagyan ◽  
Anna Avagyan ◽  
Ruzanna Papyan ◽  
Samvel Iskanyan ◽  
...  
Keyword(s):  
Survival Rates ◽  
Tumor Resection ◽  
Large Mass ◽  
Intrathecal Methotrexate ◽  
High Dose ◽  
Ongoing Research ◽  
Resource Limited ◽  
The Right ◽  
Immunohistochemical Analyses ◽  
Limited Setting

Abstract INTRODUCTION Embryonal tumor with abundant neuropil and true rosettes (ETANTR) is a rare aggressive brain tumor with low survival rates. There are about 80 cases reported in literature since 2000 when it was first described. There is no standard treatment scheme for ETANTR yet. CASE REPORT: A 2 years old boy presented with a month-long of headache and inability to hold his head. CT scan and MRI revealed a large mass in the right frontal lobe with midline shift. Subtotal tumor resection was done. Histological and immunohistochemical analyses was consistent with ETANTR in one laboratory and PNET in another. The second opinion suggested by the Center of Pediatric Oncology, Hematology and Immunology in Moscow the diagnosis ETANTR was confirmed. Taking into account certain similarities with medulloblastoma was decided to provide treatment according to HIT-2014 protocol. Control MRI done after 2 cycles of Block SKK Carboplatin/Etoposide found tumor progression and for that reason patient underwent second surgical resection. Considering the age of the child radiation therapy was not expedient and the decision was to continue treatment with HIT 2014 intensified regimen, which includes Cisplatin, Vincristine, Etoposide, Cyclophosphamide and intravenous High dose Methotrexate with intrathecal Methotrexate. Aiming to evaluate the effectiveness of treatment we are planning to perform MRI after this 2nd cycle of intensified regimen. DISCUSSION There are difficulties in diagnosis of rare types of cancers in Armenia. Since there is no approved treatment for ETANTR, there is a need for ongoing research to improve its prognosis.

scholarly journals Experts correctly describe demography associated with historical decline of the endangered Indiana bat, but not recent period of stationarity

2017 ◽  
Author(s):  
Wayne Thogmartin ◽  
Carol Sanders-Reed ◽  
Jennifer Szymanski ◽  
Lori Pruitt ◽  
Michael Runge
Keyword(s):  
Population Decline ◽  
Survival Rates ◽  
Clear Understanding ◽  
Myotis Sodalis ◽  
Indiana Bat ◽  
White Nose Syndrome ◽  
Demographic Behavior ◽  
Pup Survival ◽  
Survival And Reproduction ◽  
Reproductive Rates

Demographic characteristics of bats are often insufficiently described for modeling populations. In data poor situations, experts are often relied upon for characterizing ecological systems. In concert with the development of a matrix model describing Indiana bat (Myotis sodalis) demography, we elicited estimates for parameterizing this model from 12 experts. We conducted this elicitation in two stages, requesting expert values for 12 demographic rates. These rates were adult and juvenile seasonal (winter, summer, fall) survival rates, pup survival in fall, and propensity and success at breeding. Experts were most in agreement about adult fall survival (3% Coefficient of Variation) and least in agreement about propensity of juveniles to breed (37% CV). The experts showed greater concordance for adult ( mean CV, adult = 6.2%) than for juvenile parameters ( mean CV, juvenile = 16.4%), and slightly more agreement for survival (mean CV, survival = 9.8%) compared to reproductive rates ( mean CV, reproduction = 15.1%). However, survival and reproduction were negatively and positively biased, respectively, relative to a stationary dynamic. Despite the species exhibiting near stationary dynamics for two decades prior to the onset of a potential extinction-causing agent, white-nose syndrome, expert estimates indicated a population decline of -11% per year (95% CI = -2%, -20%); quasi-extinction was predicted within a century ( mean = 61 years to QE, range = 32, 97) by 10 of the 12 experts. Were we to use these expert estimates in our modeling efforts, we would have errantly trained our models to a rapidly declining demography asymptomatic of recent demographic behavior. While experts are sometimes the only source of information, a clear understanding of the temporal and spatial context of the information being elicited is necessary to guard against wayward predictions.

Blood proteins of red deer introduced to Patagonia: genetic origins and variability

2011 ◽  
Vol 51 (4) ◽  
pp. 359 ◽  
Author(s):  
Werner T. Flueck ◽  
Jo Anne M. Smith-Flueck
Keyword(s):  
Superoxide Dismutase ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Large Body ◽  
Climatic Conditions ◽  
Glucose Phosphate Isomerase ◽  
Blood Proteins ◽  
Herd Health ◽  
Glucose Phosphate ◽  
Reproductive Rates

A small group of European red deer (Cervus elaphus elaphus) was introduced into the foothills of the Andes in Patagonia in the early 1920s. This species adapted well to the habitat and climatic conditions in the area and presently may number over 100 000 animals. Several indices commonly used to evaluate the fitness of a species in its environment indicate that red deer thrive under very favourable conditions in Patagonia; for example, body size, antler development, reproductive rates, herd health, and longevity are near the maximum described for the species. Furthermore, some local populations occur at densities much higher than encountered in their native ranges. The objective was to examine several biological enzyme systems to test for variance in protein polymorphism in comparison to populations of red deer in other parts of the world. The protein systems examined by electrophoresis in the plasma included: post-transferrin, transferrin, vitamin D binding protein, plasminogen, and complement component; and in the erythrocytes: hemoglobin, superoxide dismutase, glucose phosphate isomerase, and diaphorase I. Variation in plasminogen was lower than is typical for red deer, and glucose phosphate isomerase showed no variation. Furthermore, some occurrences of alleles typical for North American wapiti (Cervus elaphus canadensis) indicate that the introduced deer originated from English or European deer parks which have had a history of introductions of wapiti in the past. In New Zealand, the superoxide dismutase allele typical for wapiti was found in 1% of red deer, whereas it occurred in 11% of animals in the present study. Polymorphism measured across the nine examined protein systems was 2.0 alleles per locus with an overall heterozygosity of 0.30. The low variations are likely the result of the introduction based on few individuals. However, the outstanding performance of the present population contradicts the existence of any overt impact from this founder effect. The observed large body sizes may not only be due to good environmental conditions, but also due to previous hybridisation with wapiti. Several specimens were heterozygous and one specimen was homozygous for wapiti hemoglobin.

scholarly journals Hibernation is associated with increased survival and the evolution of slow life histories among mammals

2011 ◽  
Vol 278 (1723) ◽  
pp. 3355-3363 ◽  
Author(s):  
Christopher Turbill ◽  
Claudia Bieber ◽  
Thomas Ruf
Keyword(s):  
Life Histories ◽  
Survival Rates ◽  
Diverse Range ◽  
Annual Survival ◽  
Active Season ◽  
Evolutionary Theories ◽  
Generation Times ◽  
Evolution Of Life ◽  
Reproductive Rates ◽  
Similar Survival

Survival probability is predicted to underlie the evolution of life histories along a slow–fast continuum. Hibernation allows a diverse range of small mammals to exhibit seasonal dormancy, which might increase survival and consequently be associated with relatively slow life histories. We used phylogenetically informed GLS models to test for an effect of hibernation on seasonal and annual survival, and on key attributes of life histories among mammals. Monthly survival was in most cases higher during hibernation compared with the active season, probably because inactivity minimizes predation. Hibernators also have approximately 15 per cent higher annual survival than similar sized non-hibernating species. As predicted, we found an effect of hibernation on the relationships between life history attributes and body mass: small hibernating mammals generally have longer maximum life spans (50% greater for a 50 g species), reproduce at slower rates, mature at older ages and have longer generation times compared with similar-sized non-hibernators. In accordance with evolutionary theories, however, hibernating species do not have longer life spans than non-hibernators with similar survival rates, nor do they have lower reproductive rates than non-hibernators with similar maximum life spans. Thus, our combined results suggest that (i) hibernation is associated with high rates of overwinter and annual survival, and (ii) an increase in survival in hibernating species is linked with the coevolution of traits indicative of relatively slow life histories.

scholarly journals Cyclic dynamics of snowshoe hares on a small island in the Yukon

2002 ◽  
Vol 80 (8) ◽  
pp. 1442-1450 ◽  
Author(s):  
Charles J Krebs ◽  
Todd N Zimmerling ◽  
Claire Jardine ◽  
Kim A Trostel ◽  
Alice J Kenney ◽  
...  
Keyword(s):  
Population Decline ◽  
Survival Rates ◽  
Ground Squirrels ◽  
Adult Survival ◽  
Small Island ◽  
Juvenile Survival ◽  
Lower Amplitude ◽  
Arctic Ground Squirrels ◽  
Reproductive Rates ◽  
Survival Differences

Snowshoe hare (Lepus americanus) populations were monitored from 1977 to 2001 on Jacquot Island (5 km2) in Kluane Lake, southwestern Yukon, and on nearby mainland sites. Jacquot Island hares averaged twice the density of mainland control populations and, although they show 10-year cycles, fluctuate with much lower amplitude than mainland populations. Three separate intensive studies over 6 years attempted to determine what caused these differences. We tested two hypotheses to explain the dynamics. Reproductive rates of hares were similar on Jacquot Island and the mainland. Adult survival rates were higher on the island in most years, with the exception of years of population decline. Juvenile survival rates from 0 to 30 days of life were much higher on the island than on the mainland except for decline summers. The adult- and juvenile-survival differences between the island and the mainland were explained most consistently by predation. Improved survival on the island is correlated with a reduction in the numbers and types of predators found on Jacquot Island compared with the mainland. In particular, red squirrels were rare on Jacquot Island, arctic ground squirrels were absent, and the larger predators, like lynx and great-horned owls, were sporadic in occurrence on this small island.

Effects of adults on the demography of fox squirrels (Sciurus niger)

1985 ◽  
Vol 63 (4) ◽  
pp. 861-867 ◽  
Author(s):  
Lonnie P. Hansen ◽  
Charles M. Nixon
Keyword(s):  
Home Range Size ◽  
Adult Males ◽  
Sciurus Niger ◽  
Age Classes ◽  
Control Grid ◽  
Local Populations ◽  
Adult Females ◽  
Resource Limited ◽  
Fox Squirrels ◽  
Reproductive Rates

As a test of the hypothesis that adult fox squirrels (Sciurus niger) regulate the number of immature and adult squirrels entering a population, each fall from 1979 to 1981 adult males were removed from two grids (male-removal grids, MRGs), adult females from two grids (female-removal grids, FRGs), all adults from one grid (adult-removal grid, ARG), and one grid was maintained as a control (control grid, CG). The number of previously uncaptured juveniles and subadults (both sexes) and yearling–adult females was greater on FRGs than on the CG and MRGs, especially during the fall. The number of new adult males captured during the fall was higher where adult males had been removed. During spring, reproductive rates (percent lactating) were higher on grids from which females had been removed (FRGs and the ARG), but this was not so during fall. Length of residency was shorter for juvenile–subadult and adult fox squirrels and longer for yearling females where adult females had been removed. Movement patterns in response to removal of adults suggested resident adult females influenced home range size of all sex classes and age-classes. We conclude that the presence of adult females is important in limiting recruitment in local populations of fox squirrels and that this strategy likely evolved in response to resource-limited environments.

Effect of Temperature and Size on Development, Mortality, and Survival Rates of the Pelagic Early Life History Stages of Marine Fish

1991 ◽  
Vol 48 (3) ◽  
pp. 503-518 ◽  
Author(s):  
Pierre Pepin
Keyword(s):  
Early Life ◽  
Survival Rates ◽  
Early Life History ◽  
Mortality Rates ◽  
Yolk Sac ◽  
Vital Rates ◽  
Daily Mortality ◽  
Cumulative Mortality ◽  
Life History Stages ◽  
Size Dependent

This paper presents a comprehensive summary of development, mortality, and survival rates of fish eggs, yolk-sac larvae, and postlavae in relation to temperature and size. The general temperature- and, where applicable, size-dependent models explained 30–81% of the variance in vital rates. Daily development and mortality rates generally increased with increasing temperature. Temperature had an equal but opposite effect on stage-specific cumulative mortality rates of eggs and yolk-sac larvae. Stage-specific (length-dependent) cumulative mortality rates of postlarval fish were independent of temperature due to equal effects of temperature on daily growth and daily mortality rates. Size had no significant effect on daily or cumulative mortality rates of egg and yolk-sac stages. Daily mortality rates of postlarval fish were significantly influenced by mean size (i.e. length). The compensation of temperature effects between stages and/or vital rates may reduce the impact of environmental uncertainty on survival rates. It is suggested that the general temperature- and/or size-dependent relationships described in this study can serve as basic frameworks to assess whether there are significant effects resulting from species/stock-specific characteristics or environmental factors on the vital rates of the early life history stages of fish.

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