Morphological trends and rates of evolution in arvicolids (arvicolidae, rodentia): Towards a punctuated equilibria/disequilibria model

1993 ◽  
Vol 19 ◽  
pp. 27-39 ◽  
Author(s):  
J. Chaline ◽  
B. Laurin ◽  
P. Brunet-Lecomte ◽  
L. Viriot
1998 ◽  
Vol 89 (3) ◽  
pp. 199-225 ◽  
Author(s):  
J. van der Made

AbstractThe Tetraconodontinae Lydekker, 1876 are a subfamily of pigs (Suidae) with a great variety of dental adaptations, such as greatly enlarged or reduced premolars, enlarged posterior molars, hypsodonty, enlarged incisors etc. The essence of most of these adaptations can be described very well by simple biometry. Size increase of the last molars has proved to be of importance in African biostratigraphy. However, it appears that members of different lineages have been mixed up.Tendencies in relative premolar size indicate that the 21 species known can be grouped in three tribes: (1) the Tetraconodontini, with very large or even extremely enlarged premolars and, in one of the lineages, a tendency to enlarge the posterior molars; (2) the Nyanzachoerini new tribe, characterised by moderately enlarged or even reduced premolars and with a tendency to increase the length of the posterior molars by the addition of distal cusps; and (3) the Parachleuastochoerini new tribe, with relatively long but narrower premolars. Both Nyanzachoerini and Tetraconodontini include species that were placed previously inConohyusandNyanzachoerus.A very long gradually evolving lineage in the Nyanzachoerini, spanning 13 Ma, is documented. In the last 5 Ma of this lineage, M3 length increased at such a rate that a (sub)species can be recognised about every 0·7 Ma. Slightly lesser rates of evolution are found in some other lineages, but still others experienced apparently long periods of stasis or very slow evolution. In a single case there is a period of stasis combined with a sudden evolutionary jump as in the punctuated equilibria model.In the cases of intercontinental dispersal events combined with cladogenesis, where the ancestor in the continent of origin could be identified, the cause of cladogenesis seems to have been geographical isolation. Two tetraconodont lineages were restricted to Eurasia for about 5 Ma. During the Late Miocene, members of these lineages dispersed repeatedly to Africa. The Vallesian is a period of profound climatic changes which are reflected in changes in biogeography of many taxa. It is assumed that these and later climatic changes enabled the dispersal of Tetraconodontinae to Africa.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yash Sondhi ◽  
Emily A. Ellis ◽  
Seth M. Bybee ◽  
Jamie C. Theobald ◽  
Akito Y. Kawahara

AbstractOpsins, combined with a chromophore, are the primary light-sensing molecules in animals and are crucial for color vision. Throughout animal evolution, duplications and losses of opsin proteins are common, but it is unclear what is driving these gains and losses. Light availability is implicated, and dim environments are often associated with low opsin diversity and loss. Correlations between high opsin diversity and bright environments, however, are tenuous. To test if increased light availability is associated with opsin diversification, we examined diel niche and identified opsins using transcriptomes and genomes of 175 butterflies and moths (Lepidoptera). We found 14 independent opsin duplications associated with bright environments. Estimating their rates of evolution revealed that opsins from diurnal taxa evolve faster—at least 13 amino acids were identified with higher dN/dS rates, with a subset close enough to the chromophore to tune the opsin. These results demonstrate that high light availability increases opsin diversity and evolution rate in Lepidoptera.


Science ◽  
2002 ◽  
Vol 295 (5563) ◽  
pp. 2270-2273 ◽  
Author(s):  
D. M. Lambert

1928 ◽  
Vol 1 (3) ◽  
pp. 485-497 ◽  
Author(s):  
C. R. Johnson

Abstract The rates of evolution of gas from carbon black with variation of time, temperature, and pressure have been determined. Complete analyses have been made of five types of carbon black, which involve an organic combustion of the original sample, an organic combustion of the sample after the gases have been removed, a determination of the loss in weight represented by the gases removed, analyses of the gases removed, and finally a complete accounting, or balance, of the carbon in the steps considered. In an attempt to supply some missing information not revealed by the foregoing, some special gas analyses under varying conditions were made. The relationship between the amount and composition of volatile matter evolved from carbon blacks and the properties imparted to vulcanized rubber when compounded with these blacks has been studied.


2011 ◽  
Vol 279 (1732) ◽  
pp. 1287-1292 ◽  
Author(s):  
Roi Holzman ◽  
David C. Collar ◽  
Samantha A. Price ◽  
C. Darrin Hulsey ◽  
Robert C. Thomson ◽  
...  

Morphological diversification does not proceed evenly across the organism. Some body parts tend to evolve at higher rates than others, and these rate biases are often attributed to sexual and natural selection or to genetic constraints. We hypothesized that variation in the rates of morphological evolution among body parts could also be related to the performance consequences of the functional systems that make up the body. Specifically, we tested the widely held expectation that the rate of evolution for a trait is negatively correlated with the strength of biomechanical trade-offs to which it is exposed. We quantified the magnitude of trade-offs acting on the morphological components of three feeding-related functional systems in four radiations of teleost fishes. After accounting for differences in the rates of morphological evolution between radiations, we found that traits that contribute more to performance trade-offs tend to evolve more rapidly, contrary to the prediction. While ecological and genetic factors are known to have strong effects on rates of phenotypic evolution, this study highlights the role of the biomechanical architecture of functional systems in biasing the rates and direction of trait evolution.


2021 ◽  
Author(s):  
Mauricio González-Forero ◽  
Andy Gardner

How development affects evolution. A mathematical framework that explicitly integrates development into evolution has recently been derived. Here we use this framework to analyse how development affects evolution. We show that, whilst selection pushes genetic and phenotypic evolution uphill on the fitness landscape, development determines the admissible evolutionary pathway, such that evolutionary outcomes occur at path peaks, which need not be peaks of the fitness landscape. Development can generate path peaks, triggering adaptive radiations, even on constant, single-peak landscapes. Phenotypic plasticity, niche construction, extra-genetic inheritance, and developmental bias variously alter the evolutionary path and hence the outcome. Selective development, whereby phenotype construction may point in the adaptive direction, may induce evolution either towards or away landscape peaks depending on the developmental constraints. Additionally, developmental propagation of phenotypic effects over age allows for the evolution of negative senescence. These results help explain empirical observations including punctuated equilibria, the paradox of stasis, the rarity of stabilizing selection, and negative senescence, and show that development has a major role in evolution.


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