Levels of Selection Are Artefacts of Different Fitness Temporal Measures

Bourrat, Pierrick

doi:10.1111/rati.12053

Cited by 31 publications

(30 citation statements)

References 24 publications

(27 reference statements)

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“…If we follow his reasoning, keeping the time over which fitness is assessed as a constant (meaning that the environment is the same at both levels), we predict no difference between a measure of selection made at the level of the organism and another one made at the level of the species. The simplest interpretation of difference in the direction of selection over time is that one and the same process of natural selection changes direction over time -not that two distinct processes are opposing each other (see also Bourrat 2015).…”

Section: When Time Makes a Differencementioning

confidence: 99%

Levels, Time and Fitness in Evolutionary Transitions in Individuality

Bourrat¹

2015

Philosophy and Theory in Biology

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In this paper, I identify two major problems with the model of evolutionary transitions in individuality (ETIs) developed by Michod and colleagues, and extended by Okasha, commonly referred to as the "export-of-fitness view". First, it applies the concepts of viability and fertility inconsistently across levels of selection. This leads Michod to claim that once an ETI is complete, lower-level entities composing higher-level individuals have nil fitness. I argue that this claim is mistaken, propose a correct way to translate the concepts of viability and fertility from one level to the other and show that once an ETI is complete, neither viability nor fertility of the lower level entities is nil. Second, the exportof-fitness view does not sufficiently take the parameter of time into account when estimating fitness across levels of selection. As a result fitness is measured over different periods of time at each level. This ultimately means that fitness is measured in different environmental conditions at each level and misleads Okasha into making the claim that the two levels are ontologically distinct levels of selection. I show that once fitness is measured over the same period of time across levels, the claim about two levels of selection can only be an epistemic one.

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Section: When Time Makes a Differencementioning

confidence: 99%

Levels, Time and Fitness in Evolutionary Transitions in Individuality

Bourrat¹

2015

Philosophy and Theory in Biology

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“…Problems can arise if the environment changes over this time period in a way that affects an individual's long-term reproductive output. [76,77] One way to sidestep this complication is by computing the exponential growth rate in an idealized "average" environment (i.e., averaging over all the environments encountered by the individuals, weighted by their relative frequency). In this section, we show how irreversible changes in the environment can preclude this approach.…”

Section: Problem 2: Environmental Averaging Can Limit Predictive Effimentioning

confidence: 99%

Taming fitness: Organism‐environment interdependencies preclude long‐term fitness forecasting

2020

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Fitness is a central but notoriously vexing concept in evolutionary biology. The propensity interpretation of fitness is often regarded as the least problematic account for fitness. It ties an individual's fitness to a probabilistic capacity to produce offspring. Fitness has a clear causal role in evolutionary dynamics under this account. Nevertheless, the propensity interpretation faces its share of problems. We discuss three of these. We first show that a single scalar value is an incomplete summary of a propensity. Second, we argue that the widespread method of "abstracting away" environmental idiosyncrasies by averaging over reproductive output in different environments is not a valid approach when environmental changes are irreversible. Third, we point out that expanding the range of applicability for fitness measures by averaging over more environments or longer time scales (so as to ensure environmental reversibility) reduces one's ability to distinguish selectively relevant differences among individuals because of mutation and eco-evolutionary feedbacks. This series of problems leads us to conclude that a general value of fitness that is both explanatory and predictive cannot be attained. We advocate for the use of propensity-compatible methods, such as adaptive dynamics, which can accommodate these difficulties.

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“…Thus, let me add a couple of words about fitness, in order to provide a background to help explain how to understand fitness in multispecies Darwinian populations. Philosophical (such as ‘what is?’) and practical questions (such as ‘how to count?’) concerning fitness are very complex and have been debated for decades (Abrams 2012 ; Bourrat 2015 ). However, I put them aside here, because for the purpose of this paper a few general remarks are sufficient.…”

Section: Fitness Incommensurabilitymentioning

confidence: 99%

“…Thus, let me start with a fundamental question: who or what is the bearer of fitness? This is not a trivial question, given that fitness is not very well defined, and has been ascribed to different types (or even groups, such as a given phenotype) of entities (Abrams 2012 ; Bourrat 2015 ). My answer to this question will not be surprising, since I have already answered it indirectly in this paper.…”

Section: Fitness Incommensurabilitymentioning

confidence: 99%

The relativity of Darwinian populations and the ecology of endosymbiosis

Stencel

2016

Biol Philos

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If there is a single discipline of science calling the basic concepts of biology into question, it is without doubt microbiology. Indeed, developments in microbiology have recently forced us to rethink such fundamental concepts as the organism, individual, and genome. In this paper I show how microorganisms are changing our understanding of natural aggregations and develop the concept of a Darwinian population to embrace these discoveries. I start by showing that it is hard to set the boundaries of a Darwinian population, and I suggest thinking of a Darwinian population as a relative property of a Darwinian individual. Then I argue, in contrast to the commonly held view, that Darwinian populations are multispecies units, and that in order to accept the multispecies account of Darwinian populations we have to separate fitness from natural selection. Finally, I show how all these ideas provide a theoretical framework leading to a more precise understanding of the ecology of endosymbiosis than is afforded by poetic metaphors such as ‘slavery’.

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Levels of Selection Are Artefacts of Different Fitness Temporal Measures

Cited by 31 publications

References 24 publications

Levels, Time and Fitness in Evolutionary Transitions in Individuality

Levels, Time and Fitness in Evolutionary Transitions in Individuality

Taming fitness: Organism‐environment interdependencies preclude long‐term fitness forecasting

The relativity of Darwinian populations and the ecology of endosymbiosis

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