Darwinism Evolution Natural selection

Researchers question Darwin’s theory of “fecundity selection”

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Is there an optimum number other than MORE!?/waldemarus, fotolia

It almost feels like researchers think it is okay now to just doubt Darwin. It seems, we’re a long way from the “Darwin himself said” rubbish that used to deface media releases even a few years ago.*

From ScienceDaily:

A key concept in Darwin’s theory of evolution which suggests nature favors larger females that can produce greater numbers of off-spring must be redefined according to scientists behind ground-breaking new research.

The study, published in the scientific journal Biological Reviews, concludes that the theory of ‘fecundity selection’ — one of Charles Darwin’s three main evolutionary principles, also known as ‘fertility selection’ — should be redefined so that it no longer rests on the idea that more fertile females are more successful in evolutionary terms. The research highlights that too many offspring can have severe implications for mothers and the success of their descendants, and that that males can also affect the evolutionary success of a brood.

Farmers could have told us that, but who listens to them?

Darwin’s theory of fecundity selection was postulated in 1874 and, together with the principles of natural selection and sexual selection, remains a fundamental component of modern evolutionary theory. It describes the process of reproductive success among organisms, defined by the number of successful offspring which reach breeding age.

How did a theory remain a fundamental component of evolution theory without taking into account factors like this: The more members of a species in a natural ecology who reach breeding age, the fiercer will be the competition for food—with serious effects on the offspring of the new adult generation.

To say nothing of th fact that, in times of hardship due to overgrazing or overhunting, herd or pack discipline could break down, with more species members lost in the chaos.

Note: A possible exception may exist when the life form succeeds via producing overwhelming numbers for a short time only, thus dislodging another life form. That is, it succeeds as a hort term, not a long term strategy.

So, did all those researchers just agree to be feckless in Darwin’s name?

After years of research, an evolutionary biologist from the University of Lincoln, UK, has proposed a revised version of the theory of fecundity selection which recommends an updated definition, adjusts its traditional predictions and incorporates important new biological terms.

More.

Why bother? Why not just say the theory is another Darwin dud and there is no sense trying to rescue it?

See also: Talk to the fossils: Let’s see what they say back

Here’s the abstract:

Fitness results from an optimal balance between survival, mating success and fecundity. The interactions between these three components of fitness vary depending on the selective context, from positive covariation between them, to antagonistic pleiotropic relationships when fitness increases in one reduce the fitness of others. Therefore, elucidating the routes through which selection shapes life history and phenotypic adaptations via these fitness components is of primary significance to understanding ecological and evolutionary dynamics. However, while the fitness components mediated by natural (survival) and sexual (mating success) selection have been debated extensively from most possible perspectives, fecundity selection remains considerably less studied. Here, we review the theoretical basis, evidence and implications of fecundity selection as a driver of sex-specific adaptive evolution. Based on accumulating literature on the life-history, phenotypic and ecological aspects of fecundity, we (i) suggest a re-arrangement of the concepts of fecundity, whereby we coin the term ‘transient fecundity’ to refer to brood size per reproductive episode, while ‘annual’ and ‘lifetime fecundity’ should not be used interchangeably with ‘transient fecundity’ as they represent different life-history parameters; (ii) provide a generalized re-definition of the concept of fecundity selection as a mechanism that encompasses any traits that influence fecundity in any direction (from high to low) and in either sex; (iii) review the (macro)ecological basis of fecundity selection (e.g. ecological pressures that influence predictable spatial variation in fecundity); (iv) suggest that most ecological theories of fecundity selection should be tested in organisms other than birds; (v) argue that the longstanding fecundity selection hypothesis of female-biased sexual size dimorphism (SSD) has gained inconsistent support, that strong fecundity selection does not necessarily drive female-biased SSD, and that this form of SSD can be driven by other selective pressures; and (vi) discuss cases in which fecundity selection operates on males. This conceptual analysis of the theory of fecundity selection promises to help illuminate one of the central components of fitness and its contribution to adaptive evolution. Open access – Daniel Pincheira-Donoso, John Hunt. Fecundity selection theory: concepts and evidence. Biological Reviews, 2015; DOI: 10.1111/brv.12232

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3 Replies to “Researchers question Darwin’s theory of “fecundity selection”

  1. 1
    ppolish says:

    Fecundity Selection is bogus, Natural Selection is destructive, and Sexual Selection is guided. Combine all three and you get Victorian Era pseudoscience.

  2. 2
    Andre says:

    Ppolish

    Correction, Victorian era scientific racism.

  3. 3
    Jack Jones says:

    The Question Mr Polish is why are evolutionists allowed to get away with sloppy language like “natural selection”?

    Biologist, Peter Corning “biologist Ernst Mayr informed us that “Natural selection does its best to favor the production of programs guaranteeing behavior that increases fitness”(1976:365). And Edward O. Wilson, in Sociobiology, assured us that “natural selection is the agent that molds virtually all of the characters of species”(1975:67).

    The problem is that natural selection is not a “mechanism.” Natural selection does not do anything; nothing is ever actively “selected” (although sexual selection and predator-prey interactions involve special cases). Nor can the sources of causation be localized either within an organism or externally in the environment. In fact, the term natural selection is a metaphor for an important aspect, or property of the ongoing evolutionary process. (Darwin’s inspiration for his metaphor was the “artificial selection” practiced by animal breeders.) Natural selection is really an “umbrella concept” that refers to whatever functionally-significant factors (as opposed to historical contingencies, fortuitous effects or physical laws) are responsible in a given context for causing differential survival and reproduction. Properly conceptualized, these causal factors are always relational; they are defined both by organism(s) and their environment(s), and by the interactions between them.

    This crucially important point can be illustrated with a textbook example of evolutionary change, “industrial melanism.” Until the Industrial Revolution, a “cryptic” (light-colored) strain of peppered moths called Biston betularia, predominated in the English countryside over a darker “melanic” form. The wing coloration of cryptic strain provided camouflage from avian predators (like thrushes) as the moths rested on the mottled trunks of lichen-encrusted trees. This gave them an advantage over the darker form (carbonaria), which stood out. As a result, the melanic form was relatively rare. But as soot progressively blackened the tree trunks in areas near England’s growing industrial cities, the relative frequency of the two forms was eventually reversed; the birds began to prey more heavily on the light, cryptic strain while the darker, melanic strain became less visible (Kettlewell 1955, 1973).

    The question is, where in this example was natural selection “located”? What was the “mechanism”? The short answer is that natural selection included the entire configuration of factors that combined to influence differential survival and reproduction. In this case, an alteration in the relationship between the coloration of the trees and the wing pigmentation of the moths, as a result of industrial pollution, was an important proximate factor. But this factor was important only because of the inflexible resting behavior of the moths and the feeding habits and perceptual abilities of the birds. If the moths had been subject only to insect-eating bats, which use “sonar” rather than a visual detection system to catch insects on the wing, the change in background coloration would not have made any difference. Nor would it have mattered if there were not genetically-based differences in wing coloration that allowed for “selection” between the two alternative forms.

    Hence, one cannot (technically) speak of “mechanisms” or fix on a particular “selection pressure” in explaining the workings of natural selection; these are really only shorthand expressions. One must focus on the interactions that occur within an organism and between the organism and its environment(s), inclusive of other organisms. Natural selection as a causal agency refers to the functional consequences produced by adaptively significant changes in a given organism-environment relationship.”

    If selection is a metaphor as Darwin admitted and Corning seems to confirm, then it cannot do anything, Darwin admitted that it is a metaphor, Corning seems to suggest that this metaphor is describing an outcome of other causes, it appears to be more of a hand waving term for the evolutionist than anything else.

    As for the peppered moth story, Even if it were true, The increase in the amount of dark moths does not provide a mechanism for moths to become anything other than moths, no matter how many generations are given.

    The Late Will Provine “Creationists have discovered our empty “natural selection” language, and the “actions” of natural selection make huge, vulnerable targets.[p.200]” Will Provine. The Origin of Theoretical Population Genetics (University of Chicago Press, 1971), reissued in 2001.

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