scholarly journals Natural Selection and Sex Change in Pandalid Shrimp: Test of a Life-History Theory

1979 ◽  
Vol 113 (5) ◽  
pp. 715-734 ◽  
Author(s):  
Eric L. Charnov
Keyword(s):  
Life History ◽  
Natural Selection ◽  
Life History Theory ◽  
Sex Change

Power and Evolutionary Fitness of Teleosts

1982 ◽  
Vol 39 (1) ◽  
pp. 3-13 ◽  
Author(s):  
D. M. Ware
Keyword(s):  
Life History ◽  
Natural Selection ◽  
Optimal Foraging ◽  
Evolutionary Biology ◽  
Life History Theory ◽  
A Priori ◽  
Empirical Work ◽  
Physiological Basis ◽  
Vital Functions ◽  
Surplus Power

The use of optimization arguments in evolutionary biology has been criticized because the methodology requires an assumption about what is being maximized by natural selection. As optimality arguments are often a priori and always speculative, the critics point out that there is no theoretical basis for any maximization principles in biology. They contend that only empirical work can establish if there are some properties of species that are generally maximized by natural selection. I accept this standard for evaluation, and argue that the concept of surplus power, which provides a physiological basis for optimal foraging and life history theory, is related to fitness. Evidence in the form of specific morphological and behavioral traits in teleost fishes is presented to demonstrate that natural selection has increased surplus power. Life history theory is concerned with how power is allocated by organisms to various vital functions; therefore, the specific problem of stock and recruitment in fisheries can be treated as a special application of life history theory. Some implications about the dynamics and possible survival value of different reproductive strategies exhibited by teleosts are discussed.Key words: surplus power, evolutionary biology, optimal foraging, life history theory, fitness

scholarly journals Fish ears are sensitive to sex change

2008 ◽  
Vol 5 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Stefan P.W Walker ◽  
Mark I McCormick
Keyword(s):  
Life History ◽  
Inner Ear ◽  
Fisheries Management ◽  
Life History Theory ◽  
Sex Change ◽  
Reproductive Mode ◽  
Reef Fishes ◽  
Otolith Growth ◽  
History Of ◽  
Complex Life History

Many reef fishes change sex during their life. The testing of life-history theory and effective fisheries management therefore relies on our ability to detect when this fundamental transition occurs. This study experimentally illustrates the potential to glean such information from the otolithic bodies of the inner-ear apparatus in the sex-changing fish Parapercis cylindrica . It will now be possible to reconstruct the complete, often complex life history of hermaphroditic individuals from hatching through to terminal reproductive status. The validation of sex-change associated otolith growth also illustrates the potential for sex-specific sensory displacement. It is possible that sex-changing fishes alter otolith composition, and thus sensory-range specificity, to optimize life history in accordance with their new reproductive mode.

Changeable Children

2020 ◽  
pp. 32-70
Author(s):  
David F. Bjorklund
Keyword(s):  
Life History ◽  
Natural Selection ◽  
Life History Theory ◽  
Homo Sapiens ◽  
Hunter Gatherers ◽  
Recent Advances ◽  
Human Functioning ◽  
The World ◽  
Important Evidence

Plasticity is an evolved feature of Homo sapiens and is greatest early in development. Plasticity permits children to adjust to diverse environments and still grow up to be productive members of their society. This can be seen from the variety of rearing environments found in cultures around the world, from the child-adoring hunter-gatherers to those that view children as drains on resources. Plasticity is not infinite, however, but declines with age. Natural selection has provided children with sensitivity to early environments and the plasticity to entrain their development in adaptive ways, as explained by life history theory. Recent advances have provided important evidence for the proximal causes of changes in behavior as a result of experience—epigenetics, how genes are expressed in different contexts. We can now begin to understand plasticity at the level of the gene, and this has implications for understanding all forms of human functioning.

Interrelationships of factors of social development are more complex than Life History Theory predicts

2019 ◽  
Vol 42 ◽  
Author(s):  
Boris Kotchoubey
Keyword(s):  
Life History ◽  
Social Development ◽  
Life History Theory ◽  
Strong Correlations ◽  
Behavioral Features

Abstract Life History Theory (LHT) predicts a monotonous relationship between affluence and the rate of innovations and strong correlations within a cluster of behavioral features. Although both predictions can be true in specific cases, they are incorrect in general. Therefore, the author's explanations may be right, but they do not prove LHT and cannot be generalized to other apparently similar processes.

scholarly journals Five reasons COVID-19 is less severe in younger age groups

2020 ◽  
Author(s):  
Paul W Turke
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Age Of Onset ◽  
Age Groups ◽  
Medical Community ◽  
System Function ◽  
The Third ◽  
Immune System Function ◽  
Age Related ◽  
Younger Age

Abstract The severity of COVID-19 is age-related, with the advantage going to younger age groups. Five reasons are presented. The first two are well-known, are being actively researched by the broader medical community, and therefore are discussed only briefly here. The third, fourth, and fifth reasons derive from evolutionary life history theory, and potentially fill gaps in current understanding of why and how young and old age groups respond differently to infection with SARS-CoV-2. Age of onset of generalized somatic aging, and the timing of its progression, are identified as important causes of these disparities, as are specific antagonistic pleiotropic tradeoffs in immune system function.

scholarly journals The earliest example of sexual dimorphism in bivalves—evidence from the astartid Nicaniella (Lower Jurassic, southern Germany)

2021 ◽  
pp. 1-10
Author(s):  
Baran Karapunar ◽  
Winfried Werner ◽  
Franz T. Fürsich ◽  
Alexander Nützel
Keyword(s):  
Principal Component Analysis ◽  
Life History ◽  
Shape Analysis ◽  
Principal Component ◽  
Sex Change ◽  
Lower Jurassic ◽  
Allocation Of Resources ◽  
Fourier Shape Analysis ◽  
Lower Height ◽  
Male To Female

Abstract Protandrous sex change (sex change from male to female) is one of the diverse sexual expressions exhibited by bivalves, but its expression in the shell is quite rare. Previous studies on living and fossil astartids suggest a relationship between protandrous sex change and the formation of crenulations on the ventral shell margin at later ontogenetic stages. Here we report the formation of such crenulations in the Early Jurassic astartid Nicaniella rakoveci (Kuhn, 1935) from the Amaltheenton Formation at Buttenheim, Franconia. This is the earliest known record of protandrous hermaphroditism in fossil bivalves, predating previous reports by at least 13 Myr. A principal component analysis of linear size measurements and Fourier shape analysis of the shell outlines revealed that the outline of Nicaniella rakoveci specimens varies from subquadrate to subcircular, but this variation is independent of the presence or absence of crenulations and therefore not associated with sex. Crenulated specimens exhibit a lower height/inflation ratio than non-crenulated ones, suggesting that the protandrous females have more inflated valves than the males. The formation of crenulations was probably related to allocation of resources for reproduction. The most likely function of the crenulations was to increase the internal shell volume in the female stage to accommodate more eggs rather than being an adaptation against predation as often assumed for other bivalves. The formation of crenulations is part of the protandrous life history and probably is controlled by a genetic mechanism that is also responsible for sex change.

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