64:", as being "Unity of Type" and went on to explain the phenomenon as existing because organisms do not start over from scratch, but have characteristics that are built upon already existing ones that were inherited from their ancestors; and these characteristics likely limit the amount of evolution seen in that new taxa due to these constraints.
92:. This may be considered to be a form of external constraint, in the sense that the organism is constrained not by its makeup or genetics, but by its environment. The implication would be that if the population was in a new environment, its previously constrained features would potentially begin to evolve.
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change. One proposed definition of constraint is "A property of a trait that, although possibly adaptive in the environment in which it originally evolved, acts to place limits on the production of new phenotypic variants." Constraint has played an important role in the development of such ideas as
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Although they are separate, the types of constraints discussed are nevertheless relatable to each other. In particular, stabilizing selection, mechanical, and physical constraints might lead through time to developmental integration and canalisation. However, without any clear idea of any of these
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If one sees particular features of organisms that have not changed over rather long periods of time (many generations), then this could suggest some constraint on their ability to change (evolve). However, it is not clear that mere documentation of lack of change in a particular character is good
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This class of constraint depends on certain types of phenotype not being produced by the genotype (compare stabilizing selection, where there is no constraint on what is produced, but rather on what is naturally selected). For example, for a highly homozygous organism, the degree of observed
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Any aspect of an organism that has not changed over a certain period of time could be considered to provide evidence for "constraint" of some sort. To make the concept more useful, it is therefore necessary to divide it into smaller units. First, one can consider the pattern of constraint as
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is that of the requirement that organisms function adequately in their environment. Thus, where stabilizing selection acts because of the particular niche that is occupied, mechanical and physico-chemical constraints act in a more general manner. For example, the acceleration caused by
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pointed out, this degree of functional constraint — or burden — generally varies according to position in the organism. Structures literally in the centre of the organism — such as the vertebral column — are often more burdened than those at the periphery, such as hair or toes.
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is involved in the muscle, nerve, and vascular systems as well as providing support and flexibility) and therefore cannot be radically altered without causing severe functional disruption. This may be viewed as one type of
183:. Despite mutations, certain character variants are never produced. These variants are therefore developmentally impossible to achieve and are never introduced into a population. This is implied by
60:, or phylogenetic constraint. It refers to the tendency of related taxa sharing traits based on phylogeny. Charles Darwin spoke of this concept in his 1859 book "
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Functional coupling takes the idea that organisms are integrated networks of functional interactions (for example, the vertebral column of
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phenotypic variability in its descendants would be lower than those of a heterozygous one. Similarly, developmental systems may be highly
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76:. It has often been considered more fruitful, to consider constraint in its causal sense: what are the causes of lack of change?
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Brakefield, P. M.; Roskam, J. C. (2006). "Exploring
Evolutionary Constraints is a Task for an Integrative Evolutionary Biology".
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Antonovics, Janis; Van
Tienderen, Peter H. (1991). "Ontoecogenophyloconstraints? The chaos of constraint terminology".
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acts on an organism to prevent it changing, for example, so that it can continue to function in a tightly-defined
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Garland, Jr., T., C. J. Downs, and A. R. Ives. (2022). Trade-offs (and constraints) in organismal biology.
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remains problematic. In addition, the terminology used to describe constraints has led to confusion.
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evidence for constraint in the sense of the character being unable to change. For example, long-term
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mechanisms, deducing them from mere patterns of stasis as deduced from phylogenetic patterns or the
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Biological factors limiting evolutionary change, impacting traits and species development.
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Schwenk, K. (1995). A utilitarian approach to evolutionary constraint.
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Schwenk K, Wagner GP (2003) "Constraint". In: Hall BK, Olson WM (eds)
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for an animal of a particular size. Similarly, the properties of
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and has been called both genetic and developmental constraint.”
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The most common explanation for biological constraint is that
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Keywords and
Concepts in Evolutionary Developmental Biology
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Order in Living organisms: a systems analysis of evolution
370:. Harvard University Press, Cambridge (MA), pp. 52–61.
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Lack of genetic variation and developmental integration
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Functional coupling and physico-chemical constraint
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72:related to stable environments might cause
128:properties in order to function properly.
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392:Physiological and Biochemical Zoology
231:Blomberg, S. P.; Garland, T. (2002).
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124:mean that tissues must have certain
162:Relationships of constraint classes
109:places constraints on the minimum
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334:Trends in Ecology & Evolution
272:Darwin, Charles (1859). "Ch. 6".
250:10.1046/j.1420-9101.2002.00472.x
54:phylogenetic comparative methods
237:Journal of Evolutionary Biology
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346:10.1016/0169-5347(91)90059-7
181:Variational inaccessibility
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404:. John Wiley & Sons.
275:On The Origin of Species
62:On the Origin of Species
52:analysis and the use of
291:The American Naturalist
100:Related to the idea of
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22:are factors which make
20:Biological constraints
102:stabilizing selection
86:stabilizing selection
80:Stabilizing selection
70:stabilizing selection
207:Carrier's constraint
202:Convergent evolution
58:phylogenetic inertia
43:Types of constraint
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142:Rupert Riedl
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50:phylogenetic
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133:vertebrates
24:populations
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297:: S4–S13.
218:References
37:body plans
397:, 82–112.
212:Trade-off
197:Allometry
156:canalised
138:trade-off
422:Category
354:21232448
319:40495719
311:17109328
259:16027791
191:See also
175:Examples
118:strength
33:homology
428:Biology
409:Zoology
126:osmotic
114:density
107:gravity
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74:stasis
315:S2CID
255:S2CID
140:. As
122:water
90:niche
372:ISBN
350:PMID
307:PMID
116:and
111:bone
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