I use the North American Breeding Bird Survey (Sauer et al. 2017) to construct 462 population tra... more I use the North American Breeding Bird Survey (Sauer et al. 2017) to construct 462 population trajectories with about 50 yearly abundance estimates each. Applying AIC model-selection, I find that selection-regulated population dynamics is 25,000 (95%:0.42-1.7e17) times more probable than density-regulated growth. Selection is essential in 94% of the best models explaining 82% of the population dynamics variance across the North American continent. Similar results are obtained for 111, 215, and 420 populations of British birds (BTO 2020), Danish birds (DOF 2020), and birds and mammals in the Global Population Dynamic Database (GPDD 2010). The traditional paradigm---that the population dynamic growth rate is a function of the environment, with maximal per-capita growth at low population densities, and sub-optimal reproduction from famine at carrying capacities with strong competition for limited resources---is not supported. Selection regulation generates a new paradigm where the worl...
In their Science paper, Desforges et al. (2018) address PCB pollution in killer whales, predictin... more In their Science paper, Desforges et al. (2018) address PCB pollution in killer whales, predicting a decline in calf survival and an associated collapse of killer whale populations worldwide. I refute the collapse, showing that it follows from a flawed model parametrisation. The result is not questioning contamination problems in killer whales, but only the bold prediction of global collapse.
ABSTRACTThis paper combines a catch allocation model for narwhals in East Canada and West Greenla... more ABSTRACTThis paper combines a catch allocation model for narwhals in East Canada and West Greenland with Bayesian population modelling of the eight summer aggregations of narwhals in the region. The catch allocation model allocates the catches in different hunting areas and seasons to the different summer aggregations, and the population models analyse the impact of these catches on the population dynamics of the eight narwhal aggregations.The population models run from 1970, and the catch allocation model needs population trajectories from 1970 to the present in order to estimate the catches taken from the different summer aggregations during this period. In an initial run it uses linear transitions between the available abundance estimates; but more elaborate population trajectories are estimated by the fit of the population models to the abundance data. The two models are therefore run in an iterative manner until the catch histories that are estimated by the allocation model, an...
The natural selection of metabolism and mass can explain inter-specific allometries from prokaryo... more The natural selection of metabolism and mass can explain inter-specific allometries from prokaryotes to mammals (Witting 2017a), with exponents that depend on the selected metabolism and the spatial dimensionality (2D/3D) of intra-specific behaviour. The predicted 2D-exponent for total metabolism increases from 3/4 to 7/4 when the fraction of the inter-specific body mass variation that follows from primary variation in metabolism increases from zero to one.A 7/4 exponent for mammals has not been reported from inter-specific comparisons, but I detect the full range of allometries for evolution in the fossil record. There are no fossil data for allometric correlations between metabolism and mass, but I estimate life history allometries from the allometryfor the rate of evolutionin mass (w) in physical time (t).Theexponent describes the curvature of body mass evolution, with predicted values being: 3/2 (2D) for within niche evolution in small horses over 54 million years. 5/4 (2D) and ...
The critically endangered Spitsbergen stock of bowhead whale (Balaena mysticetus) seems to be inc... more The critically endangered Spitsbergen stock of bowhead whale (Balaena mysticetus) seems to be increasing. However, research effort has also been increasing confounding a firm conclusion. A systematic aerial survey for walrus (Odobaenus rosmarus), applying distance sampling methodology in part of the Northeast Water Polynya (NEW), revealed a ‘bycatch’ of several observations of bowhead whales, which resulted in an estimated abundance of 102 (95 % CI 32–329) individuals. This is the largest abundance of bowhead whales reported from the Greenland Sea since the days of whaling in the sixteenth to seventeenth centuries. The NEW was inaccessible to vessels during the whaling period because of heavy pack ice, and it is only recently that researchers have visited this area; thus only a few sightings of bowhead whales within the NEW exist prior to the survey in 2009. The NEW may nevertheless be one of the most important summering grounds for the Spitsbergen stock, and the whales may benefit from advection of calanoid copepods from the productive deep basins along the coast of Svalbard east of the NEW. This discovery provides renewed hope for the Spitsbergen stock of bowhead whales that until now has shown only inconclusive signs of recovery despite more than 100 years of protection from whaling.
During evolution on Earth there has been a directional change where simple self-replicators have ... more During evolution on Earth there has been a directional change where simple self-replicators have evolved into large multi-cellular organisms with high metabolic rates and complex be-havioural interactions. Associated with this increase there has been a transition from an asomatic, non-senescing, haploid, and asexually reproducing organism to a somatic, senesc-ing, diploid, and sexually reproducing organism. In a few special cases there have been an additional transition to two different forms of eusociality. A new theory of natural selection (Witting, 1997a) suggests that this directional increase in complexity is the evolutionary process to be expected in a stable environment. An essential component of the theory is selection by density dependent competitive interactions, a factor that is not included in clas-sical life-history theories. It is discussed how it is possible to integrate the classical and the proposed theory to obtain a more general theory of evolution.
The relationship between Fisher's fundamental theorem of natural selection and the ecological... more The relationship between Fisher's fundamental theorem of natural selection and the ecological environment of density regulation is examined. Using a linear model, it is shown that the theorem holds when density regulation is caused by exploitative competition and that the theorem fails with interference competition. In the latter case the theorem holds only at the limit of zero population density and/or at the limit where the competitively superior individuals cannot monopolize the resource. The results are discussed in relation to population dynamics and life history evolution, where evidence suggests that the level of interference competition in natural populations is so high that the fundamental theorem does not apply.
This paper uses the population perturbation caused by the whaling industry during the 19th and 20... more This paper uses the population perturbation caused by the whaling industry during the 19th and 20th centuries to examine whether the population dynamics of the summer,aggregation of humpback whales o,West Greenland is best described by direct density regulation and an abundance that returns monotonically towards an equilibrium state, or by inertia dynamics that include also delayed density dependence by density dependent selection generating a cyclic population response. When abundance data from the last two decades are combined with the historical catches from 1664 to the present, it is shown that an estimated current population production of 6% per year (90% CI:3 9%) is inconsistent with direct density regulation given relatively stable environmental conditions and that no more than ten percent of the historical catches in the West Indies were taken from the West Greenland summer aggregation. The current abundance increase is instead consistent with a cyclic response by inertia dy...
While it is known that population cycles are driven by delayed density-dependent feedbacks, the s... more While it is known that population cycles are driven by delayed density-dependent feedbacks, the search for a common feedback mechanism in natural populations with cyclic dynamics has remained unresolved for almost a century. To identify the existence and cause of delayed feedbacks I apply six age- and sex-structured population dynamics models to seven species of baleen whales (suborder Mysticeti) that were heavily depleted by past commercial whaling. The six models include a predator–prey model with killer whale (Orcinus orca) as the predator, and five singe-species models based on (1) exponential growth, (2) density-regulated growth, (3) density-regulated growth with depensation, (4) delayed density-regulated growth and (5) selection-delayed dynamics. The latter model has a density-regulated growth rate that is accelerated and decelerated by the intra-specific natural selection that arises from the density-dependent competitive interactions between the individuals in the population. Essential parameters are estimated by a Bayesian statistical framework, and it is shown that baleen whales have a delayed recovery relative to density-regulated growth. The time-lag is not explained by depensation, or by interactions with prey or predators. It is instead resolved by a selection-delayed acceleration of the intrinsic growth rate. The results are discussed in relation to the literature on cyclic dynamics, and it is noted (1) that selection-delayed dynamics is both theoretically and empirically sufficient for cyclic population dynamics, (2) that it is widespread in natural populations owing to the widespread occurrence of otherwise unexplained phenotypic cycles in populations with cyclic dynamics, and (3) that there is a lack of empirical evidence showing that predator–prey interactions is a sufficient cause for the cyclic dynamics of natural populations. The conclusion stresses the importance of intra-specific delays in cyclic dynamics, and suggests that it is the acceleration of the growth rate, and not the growth rate itself, that is determined by the density-dependent environment.
I use the North American Breeding Bird Survey (Sauer et al. 2017) to construct 462 population tra... more I use the North American Breeding Bird Survey (Sauer et al. 2017) to construct 462 population trajectories with about 50 yearly abundance estimates each. Applying AIC model-selection, I find that selection-regulated population dynamics is 25,000 (95%:0.42-1.7e17) times more probable than density-regulated growth. Selection is essential in 94% of the best models explaining 82% of the population dynamics variance across the North American continent. Similar results are obtained for 111, 215, and 420 populations of British birds (BTO 2020), Danish birds (DOF 2020), and birds and mammals in the Global Population Dynamic Database (GPDD 2010). The traditional paradigm---that the population dynamic growth rate is a function of the environment, with maximal per-capita growth at low population densities, and sub-optimal reproduction from famine at carrying capacities with strong competition for limited resources---is not supported. Selection regulation generates a new paradigm where the worl...
In their Science paper, Desforges et al. (2018) address PCB pollution in killer whales, predictin... more In their Science paper, Desforges et al. (2018) address PCB pollution in killer whales, predicting a decline in calf survival and an associated collapse of killer whale populations worldwide. I refute the collapse, showing that it follows from a flawed model parametrisation. The result is not questioning contamination problems in killer whales, but only the bold prediction of global collapse.
ABSTRACTThis paper combines a catch allocation model for narwhals in East Canada and West Greenla... more ABSTRACTThis paper combines a catch allocation model for narwhals in East Canada and West Greenland with Bayesian population modelling of the eight summer aggregations of narwhals in the region. The catch allocation model allocates the catches in different hunting areas and seasons to the different summer aggregations, and the population models analyse the impact of these catches on the population dynamics of the eight narwhal aggregations.The population models run from 1970, and the catch allocation model needs population trajectories from 1970 to the present in order to estimate the catches taken from the different summer aggregations during this period. In an initial run it uses linear transitions between the available abundance estimates; but more elaborate population trajectories are estimated by the fit of the population models to the abundance data. The two models are therefore run in an iterative manner until the catch histories that are estimated by the allocation model, an...
The natural selection of metabolism and mass can explain inter-specific allometries from prokaryo... more The natural selection of metabolism and mass can explain inter-specific allometries from prokaryotes to mammals (Witting 2017a), with exponents that depend on the selected metabolism and the spatial dimensionality (2D/3D) of intra-specific behaviour. The predicted 2D-exponent for total metabolism increases from 3/4 to 7/4 when the fraction of the inter-specific body mass variation that follows from primary variation in metabolism increases from zero to one.A 7/4 exponent for mammals has not been reported from inter-specific comparisons, but I detect the full range of allometries for evolution in the fossil record. There are no fossil data for allometric correlations between metabolism and mass, but I estimate life history allometries from the allometryfor the rate of evolutionin mass (w) in physical time (t).Theexponent describes the curvature of body mass evolution, with predicted values being: 3/2 (2D) for within niche evolution in small horses over 54 million years. 5/4 (2D) and ...
The critically endangered Spitsbergen stock of bowhead whale (Balaena mysticetus) seems to be inc... more The critically endangered Spitsbergen stock of bowhead whale (Balaena mysticetus) seems to be increasing. However, research effort has also been increasing confounding a firm conclusion. A systematic aerial survey for walrus (Odobaenus rosmarus), applying distance sampling methodology in part of the Northeast Water Polynya (NEW), revealed a ‘bycatch’ of several observations of bowhead whales, which resulted in an estimated abundance of 102 (95 % CI 32–329) individuals. This is the largest abundance of bowhead whales reported from the Greenland Sea since the days of whaling in the sixteenth to seventeenth centuries. The NEW was inaccessible to vessels during the whaling period because of heavy pack ice, and it is only recently that researchers have visited this area; thus only a few sightings of bowhead whales within the NEW exist prior to the survey in 2009. The NEW may nevertheless be one of the most important summering grounds for the Spitsbergen stock, and the whales may benefit from advection of calanoid copepods from the productive deep basins along the coast of Svalbard east of the NEW. This discovery provides renewed hope for the Spitsbergen stock of bowhead whales that until now has shown only inconclusive signs of recovery despite more than 100 years of protection from whaling.
During evolution on Earth there has been a directional change where simple self-replicators have ... more During evolution on Earth there has been a directional change where simple self-replicators have evolved into large multi-cellular organisms with high metabolic rates and complex be-havioural interactions. Associated with this increase there has been a transition from an asomatic, non-senescing, haploid, and asexually reproducing organism to a somatic, senesc-ing, diploid, and sexually reproducing organism. In a few special cases there have been an additional transition to two different forms of eusociality. A new theory of natural selection (Witting, 1997a) suggests that this directional increase in complexity is the evolutionary process to be expected in a stable environment. An essential component of the theory is selection by density dependent competitive interactions, a factor that is not included in clas-sical life-history theories. It is discussed how it is possible to integrate the classical and the proposed theory to obtain a more general theory of evolution.
The relationship between Fisher's fundamental theorem of natural selection and the ecological... more The relationship between Fisher's fundamental theorem of natural selection and the ecological environment of density regulation is examined. Using a linear model, it is shown that the theorem holds when density regulation is caused by exploitative competition and that the theorem fails with interference competition. In the latter case the theorem holds only at the limit of zero population density and/or at the limit where the competitively superior individuals cannot monopolize the resource. The results are discussed in relation to population dynamics and life history evolution, where evidence suggests that the level of interference competition in natural populations is so high that the fundamental theorem does not apply.
This paper uses the population perturbation caused by the whaling industry during the 19th and 20... more This paper uses the population perturbation caused by the whaling industry during the 19th and 20th centuries to examine whether the population dynamics of the summer,aggregation of humpback whales o,West Greenland is best described by direct density regulation and an abundance that returns monotonically towards an equilibrium state, or by inertia dynamics that include also delayed density dependence by density dependent selection generating a cyclic population response. When abundance data from the last two decades are combined with the historical catches from 1664 to the present, it is shown that an estimated current population production of 6% per year (90% CI:3 9%) is inconsistent with direct density regulation given relatively stable environmental conditions and that no more than ten percent of the historical catches in the West Indies were taken from the West Greenland summer aggregation. The current abundance increase is instead consistent with a cyclic response by inertia dy...
While it is known that population cycles are driven by delayed density-dependent feedbacks, the s... more While it is known that population cycles are driven by delayed density-dependent feedbacks, the search for a common feedback mechanism in natural populations with cyclic dynamics has remained unresolved for almost a century. To identify the existence and cause of delayed feedbacks I apply six age- and sex-structured population dynamics models to seven species of baleen whales (suborder Mysticeti) that were heavily depleted by past commercial whaling. The six models include a predator–prey model with killer whale (Orcinus orca) as the predator, and five singe-species models based on (1) exponential growth, (2) density-regulated growth, (3) density-regulated growth with depensation, (4) delayed density-regulated growth and (5) selection-delayed dynamics. The latter model has a density-regulated growth rate that is accelerated and decelerated by the intra-specific natural selection that arises from the density-dependent competitive interactions between the individuals in the population. Essential parameters are estimated by a Bayesian statistical framework, and it is shown that baleen whales have a delayed recovery relative to density-regulated growth. The time-lag is not explained by depensation, or by interactions with prey or predators. It is instead resolved by a selection-delayed acceleration of the intrinsic growth rate. The results are discussed in relation to the literature on cyclic dynamics, and it is noted (1) that selection-delayed dynamics is both theoretically and empirically sufficient for cyclic population dynamics, (2) that it is widespread in natural populations owing to the widespread occurrence of otherwise unexplained phenotypic cycles in populations with cyclic dynamics, and (3) that there is a lack of empirical evidence showing that predator–prey interactions is a sufficient cause for the cyclic dynamics of natural populations. The conclusion stresses the importance of intra-specific delays in cyclic dynamics, and suggests that it is the acceleration of the growth rate, and not the growth rate itself, that is determined by the density-dependent environment.
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