Age structure, mortality and breeding in a population of agile wallabies (Macropus agilis)

2008 ◽  
Vol 56 (6) ◽  
pp. 431 ◽  
Author(s):  
Simon C. Stirrat
Keyword(s):  
Sex Ratio ◽  
Age Structure ◽  
Mortality Rates ◽  
Adult Mortality ◽  
Study Data ◽  
Life Table Analysis ◽  
Wet Season ◽  
Age Classes ◽  
Table Analysis ◽  
Annual Mortality

Aspects of the demography of the agile wallaby (Macropus agilis) were investigated in an overabundant population in East Point Reserve, Darwin. The maximum wet-season population size was relatively stable for several years before, and during, this study. Data suggest that the population fluctuated in size seasonally. Life table analysis indicated that mortality of animals up to 18 months old (including pouch young and young-at-foot) was high compared with adult mortality rates. After 18 months of age, mortality rates of males increased throughout life whereas those of females declined slightly and were relatively stable in older age classes. Females reproduced throughout the year, but more large pouch young were observed in the wet season than at other times of the year. The sex ratio of the population was female-biased, probably a result of higher mortality of males in the dry season. Predation by dogs was documented but contributed a relatively small fraction of total annual mortality.

The age structure of a striped maple population

1979 ◽  
Vol 9 (4) ◽  
pp. 504-508 ◽  
Author(s):  
David E. Hibbs
Keyword(s):  
Structure Analysis ◽  
High Mortality ◽  
Age Structure ◽  
Mortality Rates ◽  
Population Age Structure ◽  
Survivorship Curve ◽  
Age Dependent ◽  
Gap Phase ◽  
Annual Mortality

Cohort and population age structure analysis showed that, after the initially high mortality rates of the 1st year (87.5%), striped maple seedlings (Acerpensylvanicum L.) underwent practically no mortality until the age of 15. Annual mortality was up (3.8%) between the ages of 16 and 40, then dropped to a lower level (1.6%). Mortality was age dependent and generally density independent. The survivorship curve agrees well with a pattern that could be expected of a species whose strategy is gap phase replacement.

scholarly journals Age-Independent Adult Mortality in a Long-Lived Herb

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 187 ◽  
Author(s):  
Edelfeldt ◽  
Lindell ◽  
Dahlgren
Keyword(s):  
General Pattern ◽  
Cost Of Reproduction ◽  
Mortality Rates ◽  
Adult Mortality ◽  
Trade Offs ◽  
Age Dependent ◽  
Annual Mortality ◽  
Age Independent ◽  
Long Term Studies

Relative to mammals and birds, little is known about the mortality trajectories of perennial plants, as there are few long-term demographic studies following multiple yearly cohorts from birth to death. This is particularly important because if reproductively mature individuals show actuarial senescence, current estimations of life spans assuming constant survival would be incorrect. There is also a lack of studies documenting how life history trade-offs and disturbance influence the mortality trajectories of plants. We conducted Bayesian survival trajectory analyses (BaSTA) of a 33-year individual-based dataset of Pulsatilla vulgaris ssp. gotlandica. Mortality trajectories corresponded to “Type III” survivorship patterns, with rapidly decreasing annual mortality rates for young plants, but with constant mortality for reproductively mature individuals. We found trade-off effects resulting in a cost of growth for non-reproductive plants but no apparent cost of reproduction. Contrarily to our expectation, young plants that had previously shrunk in size had a lower mortality. However, accounting for trade-offs and disturbance only had minor effects on the mortality trajectories. We conclude that BaSTA is a useful tool for assessing mortality patterns in plants if only partial age information is available. Furthermore, if constant mortality is a general pattern in polycarpic plants, long-term studies may not be necessary to assess their age-dependent demography.

Comparative mortality rates of Bos indicus and Bos taurus cattle in central Queensland

1973 ◽  
Vol 13 (61) ◽  
pp. 127 ◽  
Author(s):  
JE Frisch
Keyword(s):  
Birth Weight ◽  
First Generation ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Mortality Rates ◽  
Adult Mortality ◽  
The Difference ◽  
Annual Mortality ◽  
Zebu Breed ◽  
Zebu Cows

A study was made over several years of lifetime mortality rates of both purebred Bos taurus and Bos indicus breeds and of several generations of crosses between the breeds. Of 4,678 calves born during the period, 4.7 per cent died at or within one week of birth. A further 2.3 per cent of those remaining died before weaning and a further 1.1 per cent died from weaning to 15 months. Sixteen of 22 calves born as twins were perinatal mortalities. Perinatal losses were highest in purebred Zebus (Africander and Brahman) and in first generation Brahman crossbred (BX) calves. Africander crossbreds (AX) generally had the lowest mortality rates of all crossbreds at each stage of the life cycle. Perinatal mortalities were however high in both F1 AX and F1 BX calves born to primiparous purebred British (Hereford and Shorthorn) heifers. Over all crossbred generations, perinatal mortalities were highest in calves from 3-year-old heifers and decreased with age of dam. More males (4.7 per cent) than females (2.9 per cent) died at or near birth. Mortalities in F1 BX males (10.3 per cent) were the highest of all groups. Relatively high or low birth weight was associated with high perinatal mortalities in the crossbreeds. Losses of stock after weaning were generally higher in the British breed-types than in the Zebu breed-types with the greatest differences in adult mortality rates. Annual mortality rates of breeding cows of each breed were studied over a similar period. 9,537 cow years were involved in the study. Mortality rates of both purebred and crossbred British cows were higher than for purebred and crossbred Zebu cows. One contributing cause was the difference in numbers of cows of each breed that died while calving. In all, 1.4 per cent of British crossbred calvings resulted in the death of the cow compared with 0.6 and 0.3 per cent for comparable AX and BX cows. Losses were negligible in purebred Zebus. Mortality rates in adults generally increased slowly with age and were highest in 8 - 10-year-old cows.

scholarly journals Ground survey of red lechwe in the Linyanti swamps and Chobe floodplains, northern Botswana

Koedoe ◽  
2017 ◽  
Vol 59 (2) ◽  
Author(s):  
Phemelo Gadimang ◽  
Gaseitsiwe S. Masunga
Keyword(s):  
Sex Ratio ◽  
Age Structure ◽  
National Park ◽  
Local Communities ◽  
Dry Season ◽  
Wet Season ◽  
Seasonal Shift ◽  
Ground Survey ◽  
Significant Difference ◽  
Tourism Potential

A ground survey of red lechwe was carried out in the Linyanti swamps and the Chobe floodplains of northern Botswana in the dry and wet seasons of 2012 and 2013, respectively. We documented numbers, sex ratio and age structure of red lechwe within the linear strips of 25 km × 300 m along the Linyanti swamps and the Chobe floodplains. Results indicated a significant difference in the numbers of red lechwe between sites and seasons. About 66 and 755 red lechwe were estimated for Chobe in the dry and wet season, respectively, with 343 and 261 of them estimated for Linyanti in the dry and wet season, respectively. In Chobe, the red lechwe densities varied widely between seasons (9 red lechwe/km2 – 101 red lechwe/km2 ) compared with Linyanti, where the densities did not vary much between seasons (35 red lechwe/km2 – 46 red lechwe/km2 ). The lower densities of red lechwe in Chobe in the dry season when compared with the wet season suggest a possible seasonal shift in the distribution of red lechwe to the nearby Zambezi floodplains in Namibia.Conservation implications: The higher number of red lechwe in the Chobe floodplains in the wet season indicates the potential of the floodplains as a habitat for this species in that season. The dry season shift in the distribution of red lechwe in Chobe presents an opportunity for local communities in Namibia to engage in tourism, whereas the return of the red lechwe to the floodplains in the wet season ensures protection of the animals as well as boosts the tourism potential of the Chobe National Park.

Root sprouting in American beech: production, survival, and the effect of parent tree vigor

1987 ◽  
Vol 17 (6) ◽  
pp. 539-544 ◽  
Author(s):  
Robert H. Jones ◽  
Dudley J. Raynal
Keyword(s):  
Life Table ◽  
Mortality Rates ◽  
Beech Bark Disease ◽  
Age Classes ◽  
American Beech ◽  
Parent Tree ◽  
Age Class ◽  
Per Capita ◽  
Individual Parent ◽  
Annual Mortality

Root sprout age-class distributions around American beech trees were measured to characterize production of sprouts under closed canopies. Annual mortality of root sprouts was estimated by static and cohort life table analyses. Sprouts around parent trees with and without beech bark disease were compared to test for effects of lowered parent vigor on sprout production and vigor. Age-class distributions were highly variable, indicating episodic production of sprouts. Trends in the data suggested that (i) for individual parent beech trees, the number of sprouts per age-class decreased exponentially as sprout age increased; and (ii) parent trees with larger diameters had more sprouts, more sprout age-classes, but greater variability in age-class distribution. Life table analyses indicated uniform per capita mortality rates for clumps of sprouts but decreasing mortality with age for individual sprouts within clumps. Low parent vigor, due in part to beech bark disease, was weakly correlated with reduced sprout production, but diseased trees maintained populations of older sprouts that differed little from sprouts associated with nondiseased trees.

scholarly journals Towards a replicator dynamics model of age structured populations

2021 ◽  
Vol 82 (5) ◽  
Author(s):  
K. Argasinski ◽  
M. Broom
Keyword(s):  
Sex Ratio ◽  
Age Structure ◽  
Replicator Dynamics ◽  
Structured Populations ◽  
Reproductive Value ◽  
Leslie Matrix ◽  
Age Classes ◽  
Structured Population Model ◽  
Age Class ◽  
Age Structured

AbstractWe present a new modelling framework combining replicator dynamics, the standard model of frequency dependent selection, with an age-structured population model. The new framework allows for the modelling of populations consisting of competing strategies carried by individuals who change across their life cycle. Firstly the discretization of the McKendrick von Foerster model is derived. We show that the Euler–Lotka equation is satisfied when the new model reaches a steady state (i.e. stable frequencies between the age classes). This discretization consists of unit age classes where the timescale is chosen so that only a fraction of individuals play a single game round. This implies a linear dynamics and individuals not killed during the round are moved to the next age class; linearity means that the system is equivalent to a large Bernadelli–Lewis–Leslie matrix. Then we use the methodology of multipopulation games to derive two, mutually equivalent systems of equations. The first contains equations describing the evolution of the strategy frequencies in the whole population, completed by subsystems of equations describing the evolution of the age structure for each strategy. The second contains equations describing the changes of the general population’s age structure, completed with subsystems of equations describing the selection of the strategies within each age class. We then present the obtained system of replicator dynamics in the form of the mixed ODE-PDE system which is independent of the chosen timescale, and much simpler. The obtained results are illustrated by the example of the sex ratio model which shows that when different mortalities of the sexes are assumed, the sex ratio of 0.5 is obtained but that Fisher’s mechanism, driven by the reproductive value of the different sexes, is not in equilibrium.

Variation and dynamics of a fossil antelope population

Paleobiology ◽  
1983 ◽  
Vol 9 (1) ◽  
pp. 62-69 ◽  
Author(s):  
Björn Kurtén
Keyword(s):  
Mortality Rate ◽  
Life Table ◽  
Ontogenetic Development ◽  
Stabilizing Selection ◽  
Life Table Analysis ◽  
Dental Wear ◽  
Table Analysis ◽  
Mortality Life Table ◽  
Annual Mortality

656 mandibles and isolated teeth of the bovid Pachytragus solignaci Robinson from two localities in the Miocene Beglia Formation, Gafsa, Tunisia, have been individually aged on the basis of ontogenetic development and state of dental wear. The sample probably represents normal but seasonally restricted mortality. Life table analysis indicates an annual mortality rate of 25–30%, increasing in old animals. Dental dimensions are affected by stabilizing selection which sets in as the tooth comes into function, earlier mortality being nonselective in that respect.

scholarly journals Tenth Revision Mortality Rates and Niosh Life Table Analysis

2006 ◽  
Vol 163 (suppl_11) ◽  
pp. S211-S211
Author(s):  
C F Robinson ◽  
TM Schnorr ◽  
RT CassinelliII ◽  
GM Calvert ◽  
K Steenland ◽  
...  
Keyword(s):  
Life Table ◽  
Mortality Rates ◽  
Life Table Analysis ◽  
Table Analysis
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