scholarly journals An experimentally introduced population of Brassica rapa (Brassicaceae). 2. Rapid evolution of phenotypic traits

2018 ◽  
Vol 151 (3) ◽  
pp. 293-302 ◽  
Author(s):  
Michael R. Sekor ◽  
Steven J. Franks
Keyword(s):  
New York ◽  
Brassica Rapa ◽  
Rapid Evolution ◽  
Common Garden ◽  
Phenotypic Selection ◽  
Plant Size ◽  
Phenotypic Traits ◽  
Multiple Traits ◽  
Introduced Populations ◽  
Evolutionary Changes

Background and aims – Introduced populations can potentially experience strong selection and rapid evolution. While some retrospective studies have shown rapid evolution in introduced populations in the past, few have directly tested for and characterized evolution as it occurs. Here we use an experimental introduction to directly observe and quantify evolution of multiple traits in a plant population introduced to a novel environment. Methods – We experimentally introduced seeds of the annual plant Brassica rapa L. (Brassicaceae) from a location in southern California into multiple replicated plots in New York. We allowed the populations to naturally evolve for 3 years. Following the resurrection approach, we compared ancestors and descendants planted in common garden conditions in New York in multiple phenotypic traits. Key results – Within only three generations, there was significant evolution of several morphological, phenological, and fitness traits, as well as substantial variation among traits. Despite selection for larger size during the three years following introduction, there was evolution of smaller size, earlier flowering time, and shorter duration of flowering. Although there were rapid evolutionary changes in traits, descendants did not have greater fitness than ancestors in New York, indicating a lack of evidence for adaptive evolution, at least over the timeframe of the study. Conclusions – This study found rapid evolution of several morphological and phenological traits, including smaller plant size and shorter time to flowering, following introduction, confirming that evolution can rapidly occur during the early stages of colonization. Many traits evolved in the opposite direction predicted from phenotypic selection analysis, which suggests that the resurrection approach can reveal unanticipated evolutionary changes and can be very useful for studying contemporary evolution.

scholarly journals Effects of latitudinal variation on field and common garden comparisons between native and introduced groundsel (Senecio vulgaris) populations

2019 ◽  
Author(s):  
Bi-Ru Zhu ◽  
Xiao-Meng Li ◽  
Da-Yong Zhang ◽  
Wan-Jin Liao
Keyword(s):  
Plant Height ◽  
Rapid Evolution ◽  
Common Garden ◽  
Phenotypic Traits ◽  
Senecio Vulgaris ◽  
Chinese Populations ◽  
Introduced Populations ◽  
Native Populations ◽  
Latitudinal Clines ◽  
European Populations

Abstract Background: Field and common garden comparisons are commonly performed to test the rapid evolution of increased vigor in introduced plant populations. Latitudinal clines in phenotypic traits can obscure such evolutionary inferences, particularly when native or introduced populations are distributed across large geographic ranges. We tested whether the latitudinal clines influence the comparisons between introduced and native populations of Senecio vulgaris. We compared plant height, number of branches and number of capitula in the field in Europe and China, and in a common garden in Switzerland.Results: The Chinese introduced populations performed better than the European native populations in the field in terms of plant height and number of capitula, which was consistent with the prediction of the evolution of increased competitive ability (EICA) hypothesis. The Chinese populations exhibited more capitula than the European populations when the latitudinal cline was considered in the common garden comparison. When we compared the traits of the northeast Chinese, southwest Chinese and European populations in both the field and common garden, the northeast Chinese populations, at latitudes similar to those of the European populations, exhibited greater plant size and more capitula than the European populations in both the field and common garden. However, the southwest Chinese populations, at latitudes that are much lower than those of the European populations, did not perform better in terms of reproduction than the native populations.Conclusion: Latitudinal clines in phenotypic traits should be considered in field and common garden comparisons when introduced populations are geographically structured.

An experimentally introduced population of Brassica rapa (Brassicaceae). 1. Phenotypic selection over three years following colonization of a novel environment

2018 ◽  
Vol 151 (2) ◽  
pp. 209-218 ◽  
Author(s):  
Michael R. Sekor ◽  
Steven J. Franks
Keyword(s):  
New York ◽  
Brassica Rapa ◽  
Annual Variation ◽  
Phenotypic Selection ◽  
Direct Selection ◽  
Novel Environment ◽  
Weather Patterns ◽  
Early Stages ◽  
Selection For ◽  
Introduced Population

Background and aims – Despite the importance of selection in driving evolution, little is known about the consistency of selection, particularly in the early stages of colonization of novel environments. This study examines the targets and consistency of selection on an experimentally introduced population of the annual plant, Brassica rapa L., in its first three years following introduction to a novel environment. Methods – Phenotypic selection analyses were conducted on a variety of traits collected during the first three years following introduction from California to New York, and the consistency of the strength and direction of selection was examined. Key results – The introduced population experienced direct selection for increased overall size and earlier flowering in 2011 and 2012, and increased height, earlier flowering, and longer duration of flowering in 2013. While the direction of selection only varied for height, inter-annual variation in the strength of selection was observed for a variety of traits, possibly due to changing weather patterns in the introduced environment. Conclusions – The results suggest that selection is dynamic and can fluctuate over time. Thus multi-year assessments of selection are useful for predicting evolutionary responses, particularly in the early stages of colonization of a novel environment.

EICA 2.0: a general model of enemy release and defence in plant and animal invasions.

2020 ◽  
pp. 192-207
Author(s):  
Richard Honor ◽  
Robert I. Colautti
Keyword(s):  
Invasive Species ◽  
Natural Enemies ◽  
General Model ◽  
Rapid Evolution ◽  
Common Garden ◽  
Enemy Release ◽  
Introduced Populations ◽  
Introduced Range ◽  
Common Garden Experiments

Abstract Plants and animals have evolved a variety of strategies to limit the negative fitness consequences of natural enemies (i.e. herbivores, predators, parasites and pathogens). Demographic bottlenecks occurring during the invasion process reduce the number of co-introduced natural enemies, providing opportunities to study rapid evolution in environments with different or reduced enemy loads. Enemy release theory provides a set of hypotheses and predictions about the role of natural enemies in the proliferation of invasive species. This body of theory includes the Enemy Release Hypothesis (ERH) and the related Evolution of Increased Competitive Ability Hypothesis (EICA), but there is often confusion about these hypotheses and the data needed to test them. We introduce a simple, general model of enemy release to identify and clarify some of the key assumptions and predictions implicit in enemy release theory and its impacts on invasion. Although introduced populations likely benefit from a reduction in the direct fitness impacts of natural enemies in the early stages of invasion, an evolutionary shift in resource allocation from defence to growth and reproduction is much less likely and depends on a delicate balance between the fitness costs and benefits of defence and the fitness impacts of natural enemies in both the native and introduced ranges. Even when the abundance of natural enemies is lower in the introduced range, the majority of scenarios do not favour evolution of less defended genotypes that are more competitive or more fecund, contrary to predictions of EICA. Perhaps surprisingly, we find that the level of damage by natural enemies in field surveys is not generally a good parameter for testing enemy release theory. Instead, common garden experiments characterizing fitness reaction norms of multiple genotypes from the native and introduced range are crucial to estimate the historic rate of adaptive evolution or predict it into the future. Incorporating spatial autocorrelation and methods from population genetics can further improve our understanding of the role of enemy release and evolution in the proliferation of invasive species.

scholarly journals It is lonely at the front: contrasting evolutionary trajectories in male and female invaders

2016 ◽  
Vol 3 (12) ◽  
pp. 160687 ◽  
Author(s):  
Cameron M. Hudson ◽  
Gregory P. Brown ◽  
Richard Shine
Keyword(s):  
Sexual Dimorphism ◽  
Common Garden ◽  
Limb Length ◽  
Phenotypic Traits ◽  
Evolutionary Changes ◽  
Spatial Sorting ◽  
Significant Heritability ◽  
Selective Forces ◽  
Major Shift ◽  
Sex Disparity

Invasive species often exhibit rapid evolutionary changes, and can provide powerful insights into the selective forces shaping phenotypic traits that influence dispersal rates and/or sexual interactions. Invasions also may modify sexual dimorphism. We measured relative lengths of forelimbs and hindlimbs of more than 3000 field-caught adult cane toads ( Rhinella marina ) from 67 sites in Hawai'i and Australia (1–80 years post-colonization), along with 489 captive-bred individuals from multiple Australian sites raised in a ‘common garden’ (to examine heritability and reduce environmental influences on morphology). As cane toads spread from east to west across Australia, the ancestral condition (long limbs, especially in males) was modified. Limb length relative to body size was first reduced (perhaps owing to natural selection on locomotor ability), but then increased again (perhaps owing to spatial sorting) in the invasion vanguard. In contrast, the sex disparity in relative limb length has progressively decreased during the toads' Australian invasion. Offspring reared in a common environment exhibited similar geographical divergences in morphology as did wild-caught animals, suggesting a genetic basis to the changes. Limb dimensions showed significant heritability (2–17%), consistent with the possibility of an evolved response. Cane toad populations thus have undergone a major shift in sexual dimorphism in relative limb lengths during their brief (81 years) spread through tropical Australia.

scholarly journals Floral signals evolve in a predictable way under artificial and pollinator selection in Brassica rapa using a G-matrix

2019 ◽  
Author(s):  
Pengjuan Zu ◽  
Florian P. Schiestl ◽  
Daniel Gervasi ◽  
Xin Li ◽  
Daniel Runcie ◽  
...  
Keyword(s):  
Brassica Rapa ◽  
Resource Limitation ◽  
Floral Traits ◽  
Selection Experiment ◽  
Response To Selection ◽  
Multiple Traits ◽  
Floral Trait ◽  
Genetic Covariance ◽  
Evolutionary Changes ◽  
Evolutionary Trajectories

AbstractBackgroundAngiosperms employ an astonishing variety of visual and olfactory floral signals that are generally thought to evolve under natural selection. Those morphological and chemical traits can form highly correlated sets of traits. It is not always clear which of these are used by pollinators as primary targets of selection and which would be indirectly selected by being linked to those primary targets. Quantitative genetics tools for predicting multiple traits response to selection have been developed since long and have advanced our understanding of evolution of genetically correlated traits in various biological systems. We use these tools to predict the evolutionary trajectories of floral traits and understand the selection pressures acting on them.ResultsWe used data from an artificial and a pollinator (bumblebee, hoverfly) selection experiment with fast cycling Brassica rapa plants to predict evolutionary changes of 12 floral volatiles and 4 morphological floral traits in response to selection. Using the observed selection gradients and the genetic variance-covariance matrix (G-matrix) of the traits, we showed that the responses of most floral traits including volatiles were predicted in the right direction in artificial- and bumblebee-selection experiment, revealing direct and indirect targets of bumblebee selection. Genetic covariance had a mix of constraining and facilitating effects on evolutionary responses. We further revealed how G-matrices evolved in the selection processes.ConclusionsOverall, our integrative study shows that floral signals, and especially volatiles, evolve under selection in a mostly predictable way, at least during short term evolution. Evolutionary constraints stemming from genetic covariance affected traits evolutionary trajectories and thus it is important to include genetic covariance for predicting the evolutionary changes of a comprehensive suite of traits. Other processes such as resource limitation and selfing also needs to be considered for a better understanding of floral trait evolution.

Effects of latitudinal variation on field and common garden comparisons between native and introduced groundsel (Senecio vulgaris) populations

2020 ◽  
Author(s):  
Bi-Ru Zhu ◽  
Xiao-Meng Li ◽  
Da-Yong Zhang ◽  
Wan-Jin Liao
Keyword(s):  
Plant Height ◽  
Common Garden ◽  
Phenotypic Traits ◽  
Senecio Vulgaris ◽  
Chinese Populations ◽  
Introduced Populations ◽  
Native Populations ◽  
Latitudinal Clines ◽  
European Populations ◽  
Better Than

Abstract Aims Field and common garden comparisons are commonly performed to test the rapid evolution of increased vigor in introduced plant populations. Latitudinal clines in phenotypic traits can obscure such evolutionary inferences, particularly when native or introduced populations are distributed across large geographic ranges. We tested whether the latitudinal clines influence comparisons between introduced and native populations of Senecio vulgaris. Methods Senecio vulgaris is native to Europe but has been introduced in northeastern and southwestern China. To evaluate the performance in terms of growth and reproduction between native European populations and introduced Chinese populations, we compared plant height, number of branches and number of capitula in field populations in native and introduced ranges and in a common garden in Switzerland. Important Findings The introduced Chinese populations performed better than the native European populations in the field in terms of plant height and number of capitula, which was consistent with the prediction of the evolution of the increased competitive ability (EICA) hypothesis. The Chinese populations produced more capitula than the European populations when the latitudinal cline was considered in the common garden comparison. When we compared the traits of the northeastern Chinese, southwestern Chinese and European populations in both the field and common garden, the northeastern Chinese populations, at latitudes similar to those of the European populations, exhibited greater plant size and more capitula than the European populations in both the field and common garden. However, the southwestern Chinese populations, at latitudes much lower than those of the European populations, did not perform better than the native populations in terms of reproduction. In conclusion, our results suggest that latitudinal clines in phenotypic traits should be considered in field and common garden comparisons when introduced populations are geographically structured.

EICA 2.0: a general model of enemy release and defence in plant and animal invasions.

2020 ◽  
pp. 192-207
Author(s):  
Richard Honor ◽  
◽  
Robert L. Colautti ◽  
Keyword(s):  
Invasive Species ◽  
Natural Enemies ◽  
General Model ◽  
Rapid Evolution ◽  
Common Garden ◽  
Enemy Release ◽  
Introduced Populations ◽  
Introduced Range ◽  
Common Garden Experiments

Plants and animals have evolved a variety of strategies to limit the negative fitness consequences of natural enemies (i.e. herbivores, predators, parasites and pathogens). Demographic bottlenecks occurring during the invasion process reduce the number of co-introduced natural enemies, providing opportunities to study rapid evolution in environments with different or reduced enemy loads. Enemy release theory provides a set of hypotheses and predictions about the role of natural enemies in the proliferation of invasive species. This body of theory includes the Enemy Release Hypothesis (ERH) and the related Evolution of Increased Competitive Ability Hypothesis (EICA), but there is often confusion about these hypotheses and the data needed to test them. We introduce a simple, general model of enemy release to identify and clarify some of the key assumptions and predictions implicit in enemy release theory and its impacts on invasion. Although introduced populations likely benefit from a reduction in the direct fitness impacts of natural enemies in the early stages of invasion, an evolutionary shift in resource allocation from defence to growth and reproduction is much less likely and depends on a delicate balance between the fitness costs and benefits of defence and the fitness impacts of natural enemies in both the native and introduced ranges. Even when the abundance of natural enemies is lower in the introduced range, the majority of scenarios do not favour evolution of less defended genotypes that are more competitive or more fecund, contrary to predictions of EICA. Perhaps surprisingly, we find that the level of damage by natural enemies in field surveys is not generally a good parameter for testing enemy release theory. Instead, common garden experiments characterizing fitness reaction norms of multiple genotypes from the native and introduced range are crucial to estimate the historic rate of adaptive evolution or predict it into the future. Incorporating spatial autocorrelation and methods from population genetics can further improve our understanding of the role of enemy release and evolution in the proliferation of invasive species.

scholarly journals Resurrection approach shows evolutionary changes in drought responses in European plant species after two decades of climate change

2020 ◽  
Author(s):  
Robert Rauschkolb ◽  
Lisa Henres ◽  
Caroline Lou ◽  
Sandrine Godefroid ◽  
Lara Dixon ◽  
...  
Keyword(s):  
Climate Change ◽  
Plant Species ◽  
Seedling Survival ◽  
Global Climate ◽  
Common Garden ◽  
Extreme Weather Events ◽  
Phenotypic Traits ◽  
Plant Populations ◽  
Evolutionary Changes ◽  
Recent Climate

Plant populations must continuously adapt to the impacts of ongoing global climate change, including warmer temperatures and more extreme weather events. We can detect such evolutionary changes within plant populations through the resurrection approach whereby plants grown from seeds stored in seed banks (“ancestors”) are compared to freshly collected seeds from the same populations (“descendants”) in common garden experiments. In this study we used the resurrection approach in two multi-species experiments to investigate changes in phenotypic traits and drought tolerance of European plant species from two biogeographic regions. In the seedling survival experiment using seedlings of four Mediterranean species, watering was ceased and day of mortality recorded. We found that descendants survived significantly longer without any watering but these seedlings were smaller than the ancestral seedlings. In the watering response experiment we investigated phenotypic responses to drought in adult plants of nine species originating from temperate climatic regions in Europe. We found that descendant plants were significantly taller under well-watered conditions but smaller under drought than their ancestors, thus showing stronger plasticity. Our study suggests that plants have already evolved phenotypically, including through changes in trait means and plasticity, within the last decades. The observed evolutionary changes are consistent with adaptation to increased drought. More generally, the resurrection approach proved to be a useful tool to study rapid evolutionary processes in plants under climate change. Future studies should include fitness measures and comparative transplantations of descendants and ancestors into their original habitat to disentangle adaptive from non-adaptive responses to recent climate change.

scholarly journals Floral signals evolve in a predictable way under artificial and pollinator selection in Brassica rapa

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Pengjuan Zu ◽  
Florian P. Schiestl ◽  
Daniel Gervasi ◽  
Xin Li ◽  
Daniel Runcie ◽  
...  
Keyword(s):  
Brassica Rapa ◽  
Resource Limitation ◽  
Floral Traits ◽  
Response To Selection ◽  
Multiple Traits ◽  
Floral Trait ◽  
Genetic Covariance ◽  
Selection Gradients ◽  
Evolutionary Changes ◽  
Evolutionary Trajectories

Abstract Background Angiosperms employ an astonishing variety of visual and olfactory floral signals that are generally thought to evolve under natural selection. Those morphological and chemical traits can form highly correlated sets of traits. It is not always clear which of these are used by pollinators as primary targets of selection and which would be indirectly selected by being linked to those primary targets. Quantitative genetics tools for predicting multiple traits response to selection have been developed since long and have advanced our understanding of evolution of genetically correlated traits in various biological systems. We use these tools to predict the evolutionary trajectories of floral traits and understand the selection pressures acting on them. Results We used data from an artificial selection and a pollinator (bumblebee, hoverfly) evolution experiment with fast cycling Brassica rapa plants to predict evolutionary changes of 12 floral volatiles and 4 morphological floral traits in response to selection. Using the observed selection gradients and the genetic variance-covariance matrix (G-matrix) of the traits, we showed that the observed responses of most floral traits including volatiles were predicted in the right direction in both artificial- and bumblebee-selection experiment. Genetic covariance had a mix of constraining and facilitating effects on evolutionary responses. We further revealed that G-matrices also evolved in the selection processes. Conclusions Overall, our integrative study shows that floral signals, especially volatiles, evolve under selection in a mostly predictable way, at least during short term evolution. Evolutionary constraints stemming from genetic covariance affected traits evolutionary trajectories and thus it is important to include genetic covariance for predicting the evolutionary changes of a comprehensive suite of traits. Other processes such as resource limitation and selfing also need to be considered for a better understanding of floral trait evolution.

scholarly journals Multivariate phenotypic divergence along an urbanization gradient

2020 ◽  
Vol 16 (9) ◽  
pp. 20200511
Author(s):  
James S. Santangelo ◽  
L. Ruth Rivkin ◽  
Carole Advenard ◽  
Ken A. Thompson
Keyword(s):  
Urban Areas ◽  
Natural Populations ◽  
Common Garden ◽  
Urban Environments ◽  
Adaptive Divergence ◽  
Phenotypic Traits ◽  
The Novel ◽  
Multiple Traits ◽  
Urbanization Gradient ◽  
Urban Sites

Evidence suggests that natural populations can evolve to better tolerate the novel environmental conditions associated with urban areas. Studies of adaptive divergence in urban areas often examine one or a few traits at a time from populations residing only at the most extreme urban and nonurban habitats. Thus, whether urbanization drives divergence in many traits simultaneously in a manner that varies with the degree of urbanization remains unclear. To address this gap, we generated seed families of white clover ( Trifolium repens ) collected from 27 populations along an urbanization gradient in Toronto, Canada, grew them in a common garden, and measured 14 phenotypic traits. Families from urban sites had evolved later phenology and germination, larger flowers, thinner stolons, reduced cyanogenesis, greater biomass and greater seed set. Pollinator observations revealed near-complete turnover of pollinator morphological groups along the urbanization gradient, which may explain some of the observed divergences in floral traits and phenology. Our results suggest that adaptation to urban environments involves multiple traits.

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