Fifty years of genetic studies: what to make of the large amounts of variation found within populations?

González‐Martínez, Santiago C.; Budde, Katharina B.; Lalagüe, Hadrien

doi:10.1007/s13595-015-0471-z

Cited by 42 publications

(37 citation statements)

References 77 publications

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“…In forest trees, high genetic diversity is better maintained within populations than among them (Hamrick 2004;Scotti et al 2016), and results from the current study M. dasyclada are in concordance with this notion. This characteristic could be due to having effective pollen dispersal, which facilities gene flow (Kremer et al 2012).…”

Section: Discussionsupporting

confidence: 88%

Genetic diversity in populations of Maytenus dasyclada (Celastraceae) in forest reserves and unprotected Araucaria forest remnants

et al. 2017

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Understanding the genetic structure and diversity of plants is fundamental to their conservation and permits their sustainable use by local communities. Th e genus Maytenus (Celastraceae) is composed of plants possessing pharmacological and antioxidant properties. However, the genetic and economic properties of the species M. dasyclada, a typical species of Araucaria forests in Brazil and Uruguay, have been little studied. In this work, the genetic structure and diversity of natural populations of M. dasyclada located in unprotected and preserved forest remnants were investigated using RAPD and isozymes markers. Th e results demonstrated that in areas of preservation, populations of M. dasyclada possess a relatively high degree of polymorphism and high values for Na, Ne, Shannon index, He and Ho, indicating high genetic variability. Moreover, these protected populations are very close to each other and potentially experience signifi cant gene fl ow. Th e results presented here highlight the relevance of preservation areas for the conservation of M. dasyclada, and that populations inhabiting these areas could serve as a genetic source for the recovery of populations in regions where genetic diversity has been lost.

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Section: Discussionsupporting

confidence: 88%

Genetic diversity in populations of Maytenus dasyclada (Celastraceae) in forest reserves and unprotected Araucaria forest remnants

et al. 2017

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“…Evolution by natural selection relies on the presence of standing variation but acts to diminish it. This conundrum drives the need to understand what forces maintain standing variation in nature (Mitchell‐Olds et al ., ) and has produced many studies investigating the circumstances under which heterozygosity at a locus is preserved through evolutionary time (Hedrick, , ; Delph & Kelly, ; Scotti et al ., ). Despite criticism stemming from previous theoretical models, our model demonstrates that variation in resource allocation can result in fitness trade‐offs in life‐history traits, and those trade‐offs can protect polymorphism, maintaining natural variation.…”

Section: Resultsmentioning

confidence: 97%

Antagonistic pleiotropy can maintain fitness variation in annual plants

Brown

Kelly

2017

J of Evolutionary Biology

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Antagonistic pleiotropy (AP) is a genetic trade-off between different fitness components. In annual plants, a trade-off between days to flower (DTF) and reproductive capacity often determines how many individuals survive to flower in a short growing season, and also influences the seed set of survivors. We develop a model of viability and fecundity selection informed by many experiments on the yellow monkeyflower, Mimulus guttatus, but applicable to many annual species. A viability/fecundity trade-off maintains stable polymorphism under surprisingly general conditions. We also introduce both spatial heterogeneity and temporal stochasticity in environmental parameters. Neither is necessary for polymorphism, but spatial heterogeneity allows polymorphism while also generating the often observed non-negative correlations in fitness components.

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“…However, increased potential for microevolution in trees contrasts with slow macroevolutionary rates (6). The current most-favored explanation for this paradox is that selection is not a major driver of genetic diversity (41). In nonsessile organisms, selection has been shown to contribute very little to phenotypic changes over time and changing climate (42).…”

Section: Discussionmentioning

confidence: 99%

Insect outbreak shifts the direction of selection from fast to slow growth rates in the long-lived conifer Pinus ponderosa

Mata

Hood

Sala

2017

Proc. Natl. Acad. Sci. U.S.A.

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Long generation times limit species' rapid evolution to changing environments. Trees provide critical global ecosystem services, but are under increasing risk of mortality because of climate changemediated disturbances, such as insect outbreaks. The extent to which disturbance changes the dynamics and strength of selection is unknown, but has important implications on the evolutionary potential of tree populations. Using a 40-y-old Pinus ponderosa genetic experiment, we provide rare evidence of context-dependent fluctuating selection on growth rates over time in a long-lived species. Fast growth was selected at juvenile stages, whereas slow growth was selected at mature stages under strong herbivory caused by a mountain pine beetle (Dendroctonus ponderosae) outbreak. Such opposing forces led to no net evolutionary response over time, thus providing a mechanism for the maintenance of genetic diversity on growth rates. Greater survival to mountain pine beetle attack in slow-growing families reflected, in part, a host-based life-history trade-off. Contrary to expectations, genetic effects on tree survival were greatest at the peak of the outbreak and pointed to complex defense responses. Our results suggest that selection forces in tree populations may be more relevant than previously thought, and have implications for tree population responses to future environments and for tree breeding programs.fluctuating selection | growth-survival trade-offs | selection response | Pinus ponderosa | Dendroctonus ponderosae U nderstanding the dynamics of selection over time is fundamental for understanding life-history evolution (1) and predicting evolutionary change under climate change (2, 3). To date, such understanding is based almost exclusively on data for relatively short-lived species (4, 5), but virtually nonexistent for long-lived organisms, such as trees (ref. 6; but see ref. 7). Trees and forests provide critical ecological and commercial services, including impacts on global carbon cycles, species diversity, water quality, and climate regulation (8). Recent forest mortality (9, 10) highlights the importance of understanding how climate change and climate change-driven disturbances may impact forests (11,12). Trees may live for hundreds of years and experience varying selection pressures associated with fluctuating climate (13), disturbance regimes (14), and biotic interactions (15), all of which may be magnified under climate change. The extent to which these events may change the strength and direction of selection and contribute to the maintenance of genetic diversity and evolutionary potential is unknown. Of special relevance are insect outbreaks, a biotic interaction expected to increase with climate change (16) but unaccounted for in models to predict the evolutionary potential of tree populations (17, 18).Mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) is a native, irruptive forest insect in western North America that uses numerous Pinus species as hosts. Via pheromone-mediated mass attacks that o...

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Fifty years of genetic studies: what to make of the large amounts of variation found within populations?

Abstract: International audienceNo abstract availabl

Cited by 42 publications

References 77 publications

Genetic diversity in populations of Maytenus dasyclada (Celastraceae) in forest reserves and unprotected Araucaria forest remnants

Genetic diversity in populations of Maytenus dasyclada (Celastraceae) in forest reserves and unprotected Araucaria forest remnants

Antagonistic pleiotropy can maintain fitness variation in annual plants

Insect outbreak shifts the direction of selection from fast to slow growth rates in the long-lived conifer Pinus ponderosa

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