scholarly journals Genetic relatedness reveals total population size of white sharks in eastern Australia and New Zealand

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
R. M. Hillary ◽  
M. V. Bravington ◽  
T. A. Patterson ◽  
P. Grewe ◽  
R. Bradford ◽  
...  
Keyword(s):  
New Zealand ◽  
Population Size ◽  
Total Population ◽  
Genetic Relatedness ◽  
Total Population Size ◽  
Eastern Australia

scholarly journals Demographic rates of northern royal albatross at Taiaroa Head, New Zealand

2014 ◽  
Author(s):  
Yvan Richard ◽  
Lyndon Perriman ◽  
Chris Lalas ◽  
Edward R. Abraham
Keyword(s):  
New Zealand ◽  
Survival Rate ◽  
Population Size ◽  
Total Population ◽  
Adult Survival ◽  
Total Population Size ◽  
Annual Survival ◽  
Demographic Rates ◽  
Age At First Breeding ◽  
The Mean

Demographic rates, such as annual survival rate, are generally difficult to estimate for long-lived seabirds, because of the length of time required for this kind of study and the remoteness of colonies. However, a small colony of northern royal albatross (Diomedea sanfordi) established itself on the mainland of New Zealand at Taiaroa Head, making possible regular banding and monitoring of its individuals since the first chick fledged, in 1938. Data on the presence/absence of birds, as well as on breeding outcomes, were available for the period from 1989–90 to 2011–12, and included 2128 annual resightings of 355 banded individuals of known age. The main goal of the present study was to estimate the annual survival rate of juveniles, pre-breeders, and adults at Taiaroa Head. These rates were estimated simultaneously in a single Bayesian multi-state capture-recapture model. Several models were fitted to the data, with different levels of complexity. From the most parsimonious model, the overall annual adult survival rate was estimated as 0.950 (95% c.i.: 0.941–0.959). In this model, adult survival declined with age, from 0.976 (95% c.i.: 0.963–0.988) at 6 years, the minimum age at first breeding, to 0.915 (95% c.i.: 0.879–0.946) at 40 years. Mean annual survival of pre-breeders was 0.966 (95% c.i.: 0.950–0.980), and 0.933 (95% c.i.: 0.908–0.966) for juveniles. There was no discernible difference in survival between males and females, and there was no apparent trend in survival over time. Estimates of other demographic rates were also obtained during the estimation process. The mean age at first return of juveniles to the colony was estimated as 4.8 years (95% c.i.: 4.6–5.1), and the mean age at first breeding as 8.9 years (95% c.i.: 8.5–9.3). Because all the birds of the colony were banded, it was possible to estimate the total population size. The number of northern royal albatross present annually at the Taiaroa Head colony has doubled since 1989–90, and the current total population size was estimated to be over 200 individuals. The ratio of the total population size to the number of annual breeding pairs varied from 5 to 12 among years, with an overall mean of 7.65 (95% c.i.: 7.56–7.78), and this high variability highlights the need for a sufficient number of surveys of seabird breeding populations before reliable conclusions on population trends can be made. Although long-term data allowed estimates of demographic rates of northern royal albatross at Taiaroa Head, the location of the colony and the ongoing management by staff mean that the population dynamics may differ from those of the main population on the Chatham Islands.

scholarly journals Demographic rates of northern royal albatross at Taiaroa Head, New Zealand

2014 ◽  
Author(s):  
Yvan Richard ◽  
Lyndon Perriman ◽  
Chris Lalas ◽  
Edward R. Abraham
Keyword(s):  
New Zealand ◽  
Survival Rate ◽  
Population Size ◽  
Total Population ◽  
Adult Survival ◽  
Total Population Size ◽  
Annual Survival ◽  
Demographic Rates ◽  
Age At First Breeding ◽  
The Mean

Demographic rates, such as annual survival rate, are generally difficult to estimate for long-lived seabirds, because of the length of time required for this kind of study and the remoteness of colonies. However, a small colony of northern royal albatross (Diomedea sanfordi) established itself on the mainland of New Zealand at Taiaroa Head, making possible regular banding and monitoring of its individuals since the first chick fledged, in 1938. Data on the presence/absence of birds, as well as on breeding outcomes, were available for the period from 1989–90 to 2011–12, and included 2128 annual resightings of 355 banded individuals of known age. The main goal of the present study was to estimate the annual survival rate of juveniles, pre-breeders, and adults at Taiaroa Head. These rates were estimated simultaneously in a single Bayesian multi-state capture-recapture model. Several models were fitted to the data, with different levels of complexity. From the most parsimonious model, the overall annual adult survival rate was estimated as 0.950 (95% c.i.: 0.941–0.959). In this model, adult survival declined with age, from 0.976 (95% c.i.: 0.963–0.988) at 6 years, the minimum age at first breeding, to 0.915 (95% c.i.: 0.879–0.946) at 40 years. Mean annual survival of pre-breeders was 0.966 (95% c.i.: 0.950–0.980), and 0.933 (95% c.i.: 0.908–0.966) for juveniles. There was no discernible difference in survival between males and females, and there was no apparent trend in survival over time. Estimates of other demographic rates were also obtained during the estimation process. The mean age at first return of juveniles to the colony was estimated as 4.8 years (95% c.i.: 4.6–5.1), and the mean age at first breeding as 8.9 years (95% c.i.: 8.5–9.3). Because all the birds of the colony were banded, it was possible to estimate the total population size. The number of northern royal albatross present annually at the Taiaroa Head colony has doubled since 1989–90, and the current total population size was estimated to be over 200 individuals. The ratio of the total population size to the number of annual breeding pairs varied from 5 to 12 among years, with an overall mean of 7.65 (95% c.i.: 7.56–7.78), and this high variability highlights the need for a sufficient number of surveys of seabird breeding populations before reliable conclusions on population trends can be made. Although long-term data allowed estimates of demographic rates of northern royal albatross at Taiaroa Head, the location of the colony and the ongoing management by staff mean that the population dynamics may differ from those of the main population on the Chatham Islands.

scholarly journals Carrying Capacity of a Population Diffusing in a Heterogeneous Environment

Mathematics ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 49 ◽  
Author(s):  
D.L. DeAngelis ◽  
Bo Zhang ◽  
Wei-Ming Ni ◽  
Yuanshi Wang
Keyword(s):  
Population Size ◽  
Carrying Capacity ◽  
Heterogeneous System ◽  
Total Population ◽  
Reaction Diffusion ◽  
Maximum Growth ◽  
Reaction Diffusion Equations ◽  
Logistic Growth ◽  
Chemostat Model ◽  
Total Population Size

The carrying capacity of the environment for a population is one of the key concepts in ecology and it is incorporated in the growth term of reaction-diffusion equations describing populations in space. Analysis of reaction-diffusion models of populations in heterogeneous space have shown that, when the maximum growth rate and carrying capacity in a logistic growth function vary in space, conditions exist for which the total population size at equilibrium (i) exceeds the total population that which would occur in the absence of diffusion and (ii) exceeds that which would occur if the system were homogeneous and the total carrying capacity, computed as the integral over the local carrying capacities, was the same in the heterogeneous and homogeneous cases. We review here work over the past few years that has explained these apparently counter-intuitive results in terms of the way input of energy or another limiting resource (e.g., a nutrient) varies across the system. We report on both mathematical analysis and laboratory experiments confirming that total population size in a heterogeneous system with diffusion can exceed that in the system without diffusion. We further report, however, that when the resource of the population in question is explicitly modeled as a coupled variable, as in a reaction-diffusion chemostat model rather than a model with logistic growth, the total population in the heterogeneous system with diffusion cannot exceed the total population size in the corresponding homogeneous system in which the total carrying capacities are the same.

Isolation by distance in a hierarchically clustered population

1983 ◽  
Vol 20 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Stanley Sawyer ◽  
Joseph Felsenstein
Keyword(s):  
Total Population ◽  
Genetic Relatedness ◽  
Isolation By Distance ◽  
Random Mating ◽  
Physical Distance ◽  
Population Densities ◽  
Total Population Size ◽  
Biological Population ◽  
Equilibrium Probability ◽  
Different Levels

A biological population with local random mating, migration, and mutation is studied which exhibits clustering at several different levels. The migration is determined by the clustering rather than actual geographic or physical distance. Darwinian selection is assumed to be absent, and population densities are such that nearby individuals have a probability of being related. An expression is found for the equilibrium probability of genetic relatedness between any two individuals as a function of their clustering distance. Asymptotics for a small mutation rate u are discussed for both a finite number of clustering levels (and of total population size), and for an infinite number of levels. A natural example is discussed in which the probability of heterozygosity varies as u to a power times a periodic function of log(l/u).

Bionomics of Dytiscus alaskanus J. Balfour-Browne (Coleoptera: Dytiscidae) in a central Alberta lake

1985 ◽  
Vol 63 (6) ◽  
pp. 1316-1323 ◽  
Author(s):  
R. B. Aiken ◽  
C. W. Wilkinson
Keyword(s):  
Life History ◽  
Life Cycle ◽  
North America ◽  
Population Growth ◽  
Population Size ◽  
Total Population ◽  
Eutrophic Lake ◽  
North Central ◽  
Total Population Size

There are few studies of life history and population growth of large dytiscid beetles in North America. We sampled populations of Dytiscus alaskanus in a eutrophic lake in north central Alberta weekly in the summers of 1982 and 1983. Like many other temperate zone dytiscids, D. alaskanus has a univoltine life cycle. Dytiscus alaskanus prefers the area at the limit of emergent vegetation in the lake and is most often associated with shoreline vegetation of cattail and sedge. Populations of adult D. alaskanus are at a peak in the late spring and decline throughout the summer. Mark–recapture experiments allowed determination of total population size and monitoring of movement patterns in the lake. Data are discussed with reference to the relatively short summer with which these beetles must cope.

Estimation of the parameters of a branching process from migrating binomial observations

1998 ◽  
Vol 30 (4) ◽  
pp. 948-967 ◽  
Author(s):  
C. Jacob ◽  
J. Peccoud
Keyword(s):  
Confidence Interval ◽  
Asymptotic Behaviour ◽  
Population Size ◽  
Branching Process ◽  
Total Population ◽  
Initial Population ◽  
Asymptotic Confidence Interval ◽  
Total Population Size ◽  
Initial Population Size ◽  
Watson Process

This paper considers a branching process generated by an offspring distribution F with mean m < ∞ and variance σ2 < ∞ and such that, at each generation n, there is an observed δ-migration, according to a binomial law Bpvn*Nnbef which depends on the total population size Nnbef. The δ-migration is defined as an emigration, an immigration or a null migration, depending on the value of δ, which is assumed constant throughout the different generations. The process with δ-migration is a generation-dependent Galton-Watson process, whereas the observed process is not in general a martingale. Under the assumption that the process with δ-migration is supercritical, we generalize for the observed migrating process the results relative to the Galton-Watson supercritical case that concern the asymptotic behaviour of the process and the estimation of m and σ2, as n → ∞. Moreover, an asymptotic confidence interval of the initial population size is given.

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