Rates of Molecular Evolution Are Linked to Life History in Flowering Plants
Department of Ecology and Evolutionary Biology, 21 Sachem Street, Post Office Box 208105, Yale University, New Haven, CT 06520-8105, USA.Science (Impact Factor: 33.61). 11/2008; 322(5898):86-9. DOI: 10.1126/science.1163197
Variable rates of molecular evolution have been documented across the tree of life, but the cause of this observed variation within and among clades remains uncertain. In plants, it has been suggested that life history traits are correlated with the rate of molecular evolution, but previous studies have yielded conflicting results. Exceptionally large phylogenies of five major angiosperm clades demonstrate that rates of molecular evolution are consistently low in trees and shrubs, with relatively long generation times, as compared with related herbaceous plants, which generally have shorter generation times. Herbs show much higher rates of molecular change but also much higher variance in rates. Correlates of life history attributes have long been of interest to biologists, and our results demonstrate how changes in the rate of molecular evolution that are linked to life history traits can affect measurements of the tempo of evolution as well as our ability to identify and conserve biodiversity.
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- "If, in addition, the spontaneous mutation rate on the molecular level itself depends on ambient temperatures, then the probability and rate of evolutionary processes that involve mutations would further increase with a higher thermal regime. Strong support for the correlation of molecular evolution with generation time comes from comparative studies on vertebrates, plants and invertebrates89101112. However, these studies do not include temperature as a putative environmental driver of this correlation. "
ABSTRACT: The evolutionary speed hypothesis (ESH) proposes a causal mechanism for the latitudinal diversity gradient. The central idea of the ESH is that warmer temperatures lead to shorter generation times and increased mutation rates. On an absolute timescale, both should lead to an acceleration of selection and drift. Based on the ESH, we developed predictions regarding the distribution of intraspecific genetic diversity: populations of ectothermic species with more generations per year owing to warmer ambient temperatures should be more differentiated from each other, accumulate more mutations and show evidence for increased mutation rates compared with populations in colder regions.We used the multivoltine insect species Chironomus riparius to test these predictions with cytochrome oxidase I (COI) sequence data and found that populations from warmer regions are indeed significantly more differentiated and have significantly more derived haplotypes than populations from colder regions. We also found a significant correlation of the annual mean temperature with the population mutation parameter θ that serves as a proxy for the per generation mutation rate under certain assumptions. This pattern could be corroborated with two nuclear loci. Overall, our results support the ESH and indicate that the thermal regime experienced may be crucially driving the evolution of ectotherms and may thus ultimately govern their speciation rate.
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- "Although the generation time effect on molecular evolution in plants has been under debate (e.g. Whittle and Johnston 2003; Verdú et al. 2007; Soria-Hernanz et al. 2008), in the last few years, some robust analyses of the phylogenies of numerous lineages have undoubtedly shown higher rates of molecular changes associated with shorter generation times (Smith and Donoghue 2008; Müller and Albach 2010; Yue et al. 2010). With ca. "
ABSTRACT: The genus Erica represents the epitome of plant biodiversity in the South African Cape fynbos with over 700 species. This genus is composed of seeder and resprouter species, but both species diversity and endemism are strongly linked to the seeder habit and concentrated in the southwestern Cape Floristic Region (CFR). Erica coccinea is a relatively abundant and widespread fynbos species whose most remarkable morphological feature is the existence of distinct seeder and resprouter forms, frequently—but not always—in disjunct populations. Both higher within-population genetic diversity and among-population differentiation have been found in seeders, most likely as a consequence of the shorter generation times and faster population turnovers. Resprouters, despite being less diverse, are suspected to be ancestral. However, no solid evidence has yet been provided for the ancestrality of the resprouter form, or for the demographic processes that have determined the current distribution of genetic diversity in both regeneration forms. Here, we used microsatellites and sequences of the nuclear ribosomal internal transcribed spacers to describe the phylogeographic structure of seeder and resprouter E. c occinea populations and provide good evidence for the ancestral status of the resprouter form and the comparatively high rates of molecular evolution in derived seeder populations. We also reveal that mixed populations, where both seeder and resprouter individuals co-occur, were originated by secondary contacts. This study highlights the role of fire in driving accelerated diversification in seeder lineages of highly speciose CFR fynbos taxa.
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- "These results are unlikely to be due to the statistical errors of our method, because the estimated type I error is around 0.05 and the power is up to 80% for the mitochondrial results and the regression coefficients are consistently negative. The copy-frequency effect is a good explanation for many observed patterns in rate of molecular evolution, such as the widespread observation of a generation time effect (e.g., Mooers and Harvey 1994; Bromham et al. 1996; Smith and Donoghue 2008; Thomas et al. 2010), higher rates of molecular evolution in highly eusocial hymenopterans (Bromham and Leys 2005), faster rates of molecular evolution in shorter plants (Lanfear, Ho, et al. 2013; Bromham et al. 2015), and faster mutations in sequences that are carried more often in male germline than in female germline (Ellegren and Fridolfsson 1997; Whittle and Johnston 2002). So why do we not find evidence that the copy-frequency effect is a primary driver of differences in mutation rates between rockfish species? "
ABSTRACT: The mitochondrial theory of ageing proposes that the cumulative effect of biochemical damage in mitochondria causes mitochondrial mutations and plays a key role in ageing. Numerous studies have applied comparative approaches to test one of the predictions of the theory: that the rate of mitochondrial mutations is negatively correlated with longevity. Comparative studies face three challenges in detecting correlates of mutation rate: covariation of mutation rates between species due to ancestry, covariation between life history traits, and difficulty obtaining accurate estimates of mutation rate. We address these challenges using a novel Poisson regression method to examine the link between mutation rate and lifespan in rockfish (Sebastes). This method has better performance than traditional sister-species comparisons when sister species are too recently diverged to give reliable estimates of mutation rate. Rockfish are an ideal model system: they have long life spans with indeterminate growth and little evidence of senescence, which minimizes the confounding tradeoffs between lifespan and fecundity. We show that lifespan in rockfish is negatively correlated to rate of mitochondrial mutation, but not the rate of nuclear mutation. The life history of rockfish allows us to conclude that this relationship is unlikely to be driven by the tradeoffs between longevity and fecundity, or by the frequency of DNA replications in the germline. Instead the relationship is compatible with the hypothesis that mutation rates are reduced by selection in long-lived taxa to reduce the chance of mitochondrial damage over its lifespan, consistent with the mitochondrial theory of ageing. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org.