scholarly journals Natural selection and outbreeding depression suggest adaptive differentiation in the invasive range of a clonal plant

2018 ◽  
Vol 285 (1882) ◽  
pp. 20181091 ◽  
Author(s):  
Pauline O. Pantoja ◽  
C. E. Timothy Paine ◽  
Mario Vallejo-Marín
Keyword(s):  
Natural Selection ◽  
Clonal Plant ◽  
Phenotypic Selection ◽  
Lateral Spread ◽  
Outbreeding Depression ◽  
Invasive Range ◽  
Introduced Populations ◽  
Introduced Range ◽  
Native Populations ◽  
Floral Displays

Analyses of phenotypic selection and demography in field populations are powerful ways to establishing the potential role of natural selection in shaping evolution during biological invasions. Here we use experimental F 2 crosses between native and introduced populations of Mimulus guttatus to estimate the pattern of natural selection in part of its introduced range, and to seek evidence of outbreeding depression of colonists. The F 2 s combined the genome of an introduced population with the genome of either native or introduced populations. We found that the introduced × introduced cross had the fastest population growth rate owing to increased winter survival, clonality and seed production. Our analysis also revealed that selection through sexual fitness favoured large floral displays, large vegetative and flower size, lateral spread and early flowering. Our results indicate a source-of-origin effect, consistent with outbreeding depression exposed by mating between introduced and native populations. Our findings suggest that well-established non-native populations may pay a high fitness cost during subsequent bouts of admixture with native populations, and reveal that processes such as local adaptation in the invasive range can mediate the fitness consequences of admixture.

Genetic comparison of introduced and native populations of common buckthorn (Rhamnus cathartica), a woody shrub introduced into North America from Europe

2020 ◽  
Vol 13 (2) ◽  
pp. 68-75
Author(s):  
Alexis Wafer ◽  
Theresa M. Culley ◽  
Kala Stephens ◽  
J. Ryan Stewart
Keyword(s):  
Genetic Variation ◽  
North America ◽  
The United States ◽  
Genetic Admixture ◽  
Biological Traits ◽  
Rhamnus Cathartica ◽  
Early 19Th Century ◽  
Introduced Populations ◽  
Introduced Range ◽  
Native Populations

AbstractIntroduced from Europe to North America in the early 19th century as an ornamental shrub and for medicinal purposes, common buckthorn (Rhamnus cathartica L.) has since spread and naturalized throughout regions of the United States and Canada. The purpose of this study was to investigate levels of genetic variation and population differentiation in R.cathartica in its introduced range in North America compared with its native range in Europe to better understand patterns of spread. By analyzing introduced and native populations using microsatellite markers, we found that introduced populations generally exhibited similar or slightly lower levels of genetic variation compared with native populations, consistent with a slight bottleneck effect. Introduced populations contained many different genotypes, indicating genetic admixture, rather than one or few genotypes. In a few cases, populations had been misidentified in the field and were glossy buckthorn (Frangula alnus Mill.; syn. Rhamnus frangula L.). Overall, there was no substantial genetic differentiation detected between native and introduced populations of R. cathartica. Invasive spread in this species is likely due to its past horticultural history as well as adaptive biological traits such as competitive behavior, potential allelopathy, and seed dispersal via birds.

scholarly journals Differential germination strategies of native and introduced populations of the invasive species Plantago virginica

NeoBiota ◽  
2019 ◽  
Vol 43 ◽  
pp. 101-118
Author(s):  
Xinyu Xu ◽  
Lorne Wolfe ◽  
Jeffrey Diez ◽  
Yi Zheng ◽  
Hui Guo ◽  
...  
Keyword(s):  
Plant Traits ◽  
Rapid Evolution ◽  
Climatic Conditions ◽  
Introduced Populations ◽  
Introduced Range ◽  
Native Populations ◽  
Selection For ◽  
Native North America ◽  
Germination Traits

Germination strategies are critically important for the survival, establishment and spread of plant species. Although many plant traits related to invasiveness have been broadly studied, the earliest part of the life cycle, germination, has received relatively little attention. Here, we compared the germination patterns between native (North America) and introduced (China) populations of Plantagovirginica for four consecutive years to examine whether there has been adaptive differentiation in germination traits and how these traits are related to local climatic conditions. We found that the introduced populations of P.virginica had significantly higher germination percentages and faster and shorter durations of germination than native populations. Critically, the native populations had a significantly larger proportion of seeds that stayed dormant in all four years, with only 60% of seeds germinating in year 1 (compared to >95% in introduced populations). These results demonstrate striking differences in germination strategies between native and introduced populations which may contribute to their successful invasion. Moreover, the germination strategy of P.virginica in their native range exhibited clear geographical variation across populations, with trends towards higher germination percentages at higher latitudes and lower annual mean temperatures and annual precipitation. In the introduced range, however, their germination strategies were more conserved, with less variation amongst populations, suggesting that P.virginica may have experienced strong selection for earlier life history characteristics. Our findings highlight the need to examine the role of rapid evolution of germination traits in facilitating plant invasion.

Outbreeding depression is uncommon and predictable

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Natural Selection ◽  
Genetic Differences ◽  
Outbreeding Depression ◽  
Isolated Populations ◽  
Large Populations

Crosses between populations within species sometimes result in reduced fitness, especially in F2 and later generations (outbreeding depression). The primary mechanisms causing outbreeding depression in crosses between populations are fixed chromosomal differences and adaptive genetic differences, especially for long-isolated populations. Outbreeding depression is usually observed after crossing populations with ploidy differences or fixed differences for translocations, inversions or centric fusions: the magnitudes are usually ploidy > translocations and monobrachial centric fusions > inversions and simple centric fusions. Populations adapted to different environments (but with the same karyotype) often exhibit outbreeding depression when crossed, especially in the F2 and later generations. Even if outbreeding depression occurs, it is often only temporary, as natural selection acts to remove it, especially in large populations.

scholarly journals Evidence of between-population differences in natural selection on extra-floral nectaries of the shrub Anemopaegma album (Bignoniaceae)

Botany ◽  
2016 ◽  
Vol 94 (3) ◽  
pp. 201-213
Author(s):  
Anselmo Nogueira ◽  
Pedro J. Rey ◽  
Julio M. Alcántara ◽  
Lúcia G. Lohmann
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Evolutionary Ecology ◽  
Common Garden ◽  
Phenotypic Selection ◽  
Population Differences ◽  
Wild Populations ◽  
Neotropical Savanna ◽  
Foliar Damage ◽  
Floral Nectaries

Extra-floral nectaries (EFNs) are thought to represent protective adaptations against herbivory, but studies on the evolutionary ecology of EFNs have seldom been conducted. Here we investigate the patterns of natural selection and genetic variation in EFN traits in two wild populations of Anemopaegma album Mart. ex DC. (Bignoniaceae) that have been previously described as contrasting EFN – ant adapted localities in the Neotropical savanna (Cristália and Grão Mogol). In each population, four EFN descriptors, foliar damage, and reproductive success variables were measured per plant (100–120 plants per population). To estimate the heritability of EFN traits, we crossed reproductive plants in the field, and grew offspring plants in a common garden. The results showed that ant assemblages differed between populations, as did the range of foliar herbivory. Genetic variation and positive phenotypic selection in EFN abundance were only detected in the Cristália population, in which plants with more EFNs were more likely to reproduce. An evaluation of putative causal links conducted by path analysis corroborated the existence of phenotypic selection on EFNs, which was mediated by the herbivory process in the Cristália population. While EFNs could be currently under selection in Cristália, it is possible that past selection may have driven EFN traits to become locally adapted to the local ant assemblage in the Grão Mogol population.

scholarly journals Root flavonoids are related to enhanced AMF colonization of an invasive tree

AoB Plants ◽  
2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yingchun Pei ◽  
Evan Siemann ◽  
Baoliang Tian ◽  
Jianqing Ding
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Invasive Plants ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Plant Invasions ◽  
Invasion Success ◽  
Chemical Mechanism ◽  
Introduced Populations ◽  
Native Populations ◽  
Invasive Tree

Abstract Arbuscular mycorrhizal fungi (AMF) are important mutualistic microbes in soil, which have capacity to form mutualistic associations with most land plants. Arbuscular mycorrhizal fungi play an important role in plant invasions and their interactions with invasive plants have received increasing attention. However, the chemical mechanisms underlying the interactions of AMF and invasive plants are still poorly understood. In this study we aim to test whether root secondary chemicals are related to enhanced AMF colonization and rapid growth in an invasive tree. We conducted a common garden experiment in China with Chinese tallow tree (Triadica sebifera) to examine the relationships among AMF colonization and secondary metabolites in roots of plants from introduced (USA) and native (China) populations. We found that AMF colonization rate was higher in introduced populations compared to native populations. Roots of plants from introduced populations had lower levels of phenolics and tannins, but higher levels of flavonoids than those of plants from native populations. Flavonoids were positively correlated with AMF colonization, and this relationship was especially strong for introduced populations. Besides, AMF colonization was positively correlated with plant biomass suggesting that higher root flavonoids and AMF colonization may impact plant performance. This suggests that higher root flavonoids in plants from introduced populations may promote AMF spore germination and/or attract hyphae to their roots, which may subsequently increase plant growth. Overall, our results support a scenario in which invasive plants enhance their AMF association and invasion success via genetic changes in their root flavonoid metabolism. These findings advance our understanding of the mechanisms underlying plant invasion success and the evolutionary interactions between plants and AMF. Understanding such mechanisms of invasive plant success is critical for predicting and managing plant invasions in addition to providing important insights into the chemical mechanism of AMF–plant interactions.

scholarly journals Natural selection on plant resistance to herbivores in the native and introduced range

AoB Plants ◽  
2015 ◽  
Vol 7 ◽  
pp. plv090 ◽  
Author(s):  
Pedro L. Valverde ◽  
Juan Arroyo ◽  
Juan Núñez-Farfán ◽  
Guillermo Castillo ◽  
Adriana Calahorra ◽  
...  
Keyword(s):  
Natural Selection ◽  
Plant Resistance ◽  
Introduced Range

scholarly journals Invasion but not hybridisation is associated with ecological niche shift in monkeyflowers

2019 ◽  
Author(s):  
Daniele Da Re ◽  
Angel P. Olivares ◽  
William Smith ◽  
Mario Vallejo-Marín
Keyword(s):  
New Zealand ◽  
Ecological Niche ◽  
Secondary Contact ◽  
Niche Shift ◽  
Ecological Niches ◽  
Introduced Populations ◽  
Niche Dynamics ◽  
Introduced Range ◽  
Niche Shifts ◽  
Native And Introduced Ranges

AbstractBackgroundThe ecological niche occupied by novel hybrids can influence their establishment as well as the potential to coexist with their parents. Hybridisation generates new phenotypic combinations, which, in some cases, may allow them to occupy ecological niches outside the environmental envelope of parental taxa. In other cases, hybrids may retain similar ecological niches to their parents, resulting in competition and affecting their coexistence. To date, few studies have quantitatively assessed niche shifts associated with hybridisation in recently introduced populations while simultaneously characterising the niche of parental species in both native and introduced ranges.AimsIn this study, we compared the ecological niche of a novel hybrid plant with the niches of its two parental taxa in the non-native geographic range. We also characterised and compared the parental taxa’s ecological niche of native and introduced populations in order to assess potential niche changes during the invasion process independent of hybridisation.MethodsWe studied monkeyflowers (Mimulus spp., Phrymaceae) that were introduced from the Americas to Europe and New Zealand in the last 200 years. We focused on a novel hybrid, triploid, asexual taxon (M. × robertsii) that occurs only in the British Isles where its two parents (M. guttatus and M. luteus) come into secondary contact. We assembled more than 12,000 geo-referenced occurrence records and eight environmental variables of the three taxa across native and introduced ranges, and conducted ecological niche model analysis using maximum entropy, principal component and niche dynamics analysis.ResultsWe found no evidence of niche shift in the hybrid, M. × robertsii compared to introduced populations of both of their parental taxa. The hybrid had a niche more similar to M. luteus, which is also the rarest of the parental taxa on the introduced range. Among parental monkeyflowers, M. guttatus showed niche conservatism in introduced populations in Europe, but a niche shift in New Zealand, while M. luteus showed a niche shift in Europe. However, the evidence of niche shift should be treated with caution due to the occurence of non-analog climatic conditions, small population size and unfilling niche dynamics.ConclusionsOur results suggest that hybridisation in non-native monkyeflowers did not result in a shift in ecological niche. This niche conservation could create competition between parental and derived taxa, the outcome of which will depend on relative competitive abilities. Further work is needed to establish if the expansion of the hybrid in the introduced range is causally related to the apparent rarity of one of the parents (M.luteus). Finally, the comparison of native and non-native populations of parental taxa, suggest that whether invasions result in niche shifts or not depends on both taxon and geographic region, highlighting the idiosyncratic nature of biological invasions.

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 Genome-wide selection scans integrated with association mapping reveal mechanisms of physiological adaptation across a salinity gradient in killifish

2018 ◽  
Author(s):  
Reid S. Brennan ◽  
Timothy M. Healy ◽  
Heather J. Bryant ◽  
Man Van La ◽  
Patricia M. Schulte ◽  
...  
Keyword(s):  
Natural Selection ◽  
Salinity Tolerance ◽  
Hypoxia Tolerance ◽  
Physiological Traits ◽  
Adaptive Divergence ◽  
Genome Wide ◽  
Native Populations ◽  
Genomic Regions ◽  
Insight Into ◽  
Freshwater Environments

AbstractAdaptive divergence between marine and freshwater environments is important in generating phyletic diversity within fishes, but the genetic basis of adaptation to freshwater habitats remains poorly understood. Available approaches to detect adaptive loci include genome scans for selection, but these can be difficult to interpret because of incomplete knowledge of the connection between genotype and phenotype. In contrast, genome wide association studies (GWAS) are powerful tools for linking genotype to phenotype, but offer limited insight into the evolutionary forces shaping variation. Here, we combine GWAS and selection scans to identify loci important in the adaptation of complex physiological traits to freshwater environments. We focused on freshwater (FW)-native and brackish water (BW)-native populations of the Atlantic killifish (Fundulus heteroclitus) as well as a population that is a natural admixture of these two populations. We measured phenotypes for multiple physiological traits that differ between populations and that may contribute to adaptation across osmotic niches (salinity tolerance, hypoxia tolerance, metabolic rate, and body shape) and used a reduced representation approach for genome-wide genotyping. Our results show patterns of population divergence in physiological capabilities that are consistent with local adaptation. Selection scans between BW-native and FW-native populations identified genomic regions that presumably aect fitness between BW and FW environments, while GWAS revealed loci that contribute to variation for each physiological trait. There was substantial overlap in the genomic regions putatively under selection and loci associated with the measured physiological traits, suggesting that these phenotypes are important for adaptive divergence between BW and FW environments. Our analysis also implicates candidate genes likely involved in physiological capabilities, some of which validate a priori hypotheses. Together, these data provide insight into the mechanisms that enable diversification of fishes across osmotic boundaries.Author SummaryIdentifying the genes that underlie adaptation is important for understanding the evolutionary process, but this is technically challenging. We bring multiple lines of evidence to bear for identifying genes that underlie adaptive divergence. Specifically, we integrate genotype-phenotype association mapping with genome-wide scans for signatures of natural selection to reveal genes that underlie phenotypic variation and that are adaptive in populations of killifish that are diverging between marine and freshwater environments. Because adaptation is likely manifest in multiple physiological traits, we focus on hypoxia tolerance, salinity tolerance, and metabolic rate; traits that are divergent between marine and freshwater populations. We show that each of these phenotypes is evolving by natural selection between environments; genetic variants that contribute to variation in these physiological traits tend to be evolving by natural selection between marine and freshwater populations. Furthermore, one of our top candidate genes provides a mechanistic explanation for previous hypotheses that suggest the adaptive importance of cellular tight junctions. Together, these data demonstrate a powerful approach to identify genes involved in adaptation and help to reveal the mechanisms enabling transitions of fishes across osmotic boundaries.

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