Science Education and the Dominican Republic Project

Nehm, Ross H.; Luna, J. Gómez; Budd, Ann F.

doi:10.1007/978-1-4020-8215-3_12

Cited by 2 publications

(8 citation statements)

References 21 publications

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“…the variance in quantitative traits is small compared to the change in mean value that can occur following periods of rapid adaptation (Reznick and Ghalambor, 2001). Such homogeneity is common in static populations in stable environments or in environments that change without affecting the overall fitness of the population (Brady, 2003; Ellegren, 2010; Lundberg et al, 1986; Michener and Grimaldi, 1988; Nehm and Budd, 2008; Park et al, 1997; Phipps et al, 1998; Stanley and Yang, 1987). It has been argued that stasis is the predominant mode of evolution (Hansen and Houle, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…While the existence of static populations is usually regarded as a trivial consequence of stabilizing selection, explaining how they can respond quickly to sudden environmental challenges is one of the most important unsolved problems in evolutionary biology (Hansen and Houle, 2004). There are, in fact, many examples of species that have been remarkably static over long time periods, but have then undergone rapid phenotypic evolution and genetic differentiation (Eldredge et al, 2005; Estes and Arnold, 2007; Nehm and Budd, 2008). …”

Section: Introductionmentioning

confidence: 99%

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Degeneracy allows for both apparent homogeneity and diversification in populations

Whitacre

Atamas

2012

Biosystems

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Trait diversity – the substrate for natural selection – is necessary for adaptation through selection, particularly in populations faced with environmental changes that diminish population fitness. In habitats that remain unchanged for many generations, stabilizing selection maximizes exploitation of resources by reducing trait diversity to a narrow optimal range. One might expect that such ostensibly homogeneous populations would have a reduced potential for heritable adaptive responses when faced with fitness-reducing environmental changes. However, field studies have documented populations that, even after long periods of evolutionary stasis, can still rapidly evolve in response to changed environmental conditions. We argue that degeneracy, the ability of diverse population elements to function similarly, can satisfy both the current need to maximize fitness and the future need for diversity. Degenerate ensembles appear functionally redundant in certain environmental contexts and functionally diverse in others. We propose that genetic variation not contributing to the observed range of phenotypes in a current population, also known as cryptic genetic variation (CGV), is a specific case of degeneracy. We argue that CGV, which gradually accumulates in static populations in stable environments, reveals hidden trait differences when environments change. By allowing CGV accumulation, static populations prepare themselves for future rapid adaptations to environmental novelty. A greater appreciation of degeneracy’s role in resolving the inherent tension between current stabilizing selection and future directional selection has implications in conservation biology and may be applied in social and technological systems to maximize current performance while strengthening the potential for future changes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Degeneracy allows for both apparent homogeneity and diversification in populations

Whitacre

Atamas

2012

Biosystems

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“…Although selection-driven heritable phenotypic divergence is the key mechanism of adaptive evolution, prolonged evolutionary stasis is common in populations remaining in stable or near-stable environments [1-8]. Evolutionary stasis of populations is commonly associated with phenotypic trait homogeneity, or the relative rarity of outlying trait values [1-8].…”

Section: Introductionmentioning

confidence: 99%

“…Evolutionary stasis of populations is commonly associated with phenotypic trait homogeneity, or the relative rarity of outlying trait values [1-8]. Such populations converge towards the most adaptive trait values, allowing for maximal exploitation of the available resources.…”

Section: Introductionmentioning

confidence: 99%

“…Stabilizing selection is widely assumed to provide the best explanation of trait homogeneity in static populations, but the direct evidence for stabilizing selection in the wild is far from overwhelming and many stable traits persist even in widely varying environmental conditions [9]. Moreover, many species remain remarkably static over long time periods, but then undergo rapid phenotypic evolution and genetic differentiation, often only to transition to the next state of stasis [8,10-17]. Evoking stabilizing selection alone to explain stasis is insufficient, because it is difficult to reconcile the frequency with which evolutionary stasis is observed with the well-known abundance of genetic variation in traits, which ensures the capacity for evolvability [9].…”

Section: Introductionmentioning

confidence: 99%

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Non-local competition drives both rapid divergence and prolonged stasis in a model of speciation in populations with degenerate resource consumption

Atamas

Atamas³

et al. 2012

Theor Biol Med Model

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The theory of speciation is dominated by adaptationist thinking, with less attention to mechanisms that do not affect species adaptation. Degeneracy – the imperfect specificity of interactions between diverse elements of biological systems and their environments – is key to the adaptability of populations. A mathematical model was explored in which population and resource were distributed one-dimensionally according to trait value. Resource consumption was degenerate – neither strictly location-specific nor location-independent. As a result, the competition for resources among the elements of the population was non-local. Two modeling approaches, a modified differential-integral Verhulstian equation and a cellular automata model, showed similar results: narrower degeneracy led to divergent dynamics with suppression of intermediate forms, whereas broader degeneracy led to suppression of diversifying forms, resulting in population stasis with increasing phenotypic homogeneity. Such behaviors did not increase overall adaptation because they continued after the model populations achieved maximal resource consumption rates, suggesting that degeneracy-driven distributed competition for resources rather than selective pressure toward more efficient resource exploitation was the driving force. The solutions were stable in the presence of limited environmental stochastic variability or heritable phenotypic variability. A conclusion was made that both dynamic diversification and static homogeneity of populations may be outcomes of the same process – distributed competition for resource not affecting the overall adaptation – with the difference between them defined by the spread of trait degeneracy in a given environment. Thus, biological degeneracy is a driving force of both speciation and stasis in biology, which, by themselves, are not necessarily adaptive in nature.

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Science Education and the Dominican Republic Project

Cited by 2 publications

References 21 publications

Degeneracy allows for both apparent homogeneity and diversification in populations

Degeneracy allows for both apparent homogeneity and diversification in populations

Non-local competition drives both rapid divergence and prolonged stasis in a model of speciation in populations with degenerate resource consumption

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