INCREASED PLANT SIZE IN EXOTIC POPULATIONS: A COMMON-GARDEN TEST WITH 14 INVASIVE SPECIES

Ecology ◽  
2007 ◽  
Vol 88 (11) ◽  
pp. 2758-2765 ◽  
Author(s):  
Dana M. Blumenthal ◽  
Ruth A. Hufbauer
Keyword(s):  
Invasive Species ◽  
Common Garden ◽  
Plant Size

scholarly journals Tolerance of Swallowworts (Vincetoxicum spp.) to Multiple Years of Artificial Defoliation and Clipping

2016 ◽  
Vol 9 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Lindsey R. Milbrath ◽  
Antonio DiTommaso ◽  
Jeromy Biazzo ◽  
Scott H. Morris
Keyword(s):  
North America ◽  
Seed Production ◽  
Aboveground Biomass ◽  
Root Biomass ◽  
Plant Competition ◽  
Common Garden ◽  
Plant Size ◽  
Tissue Loss ◽  
Defoliation Treatment ◽  
Growth And Reproduction

AbstractThe European vines pale swallowwort and black swallowwort are invading various habitats in northeastern North America. It is unclear how these plants might respond to potential biological control agents, as they experience little herbivore damage in North America, or longer durations of mowing given the reported lack of efficacy of mechanical control. We evaluated the effect of six seasons of artificial defoliation (50 or 100% defoliation once or twice per season) and clipping (once, twice, or four times at 8 cm above the soil level) on the survival, growth, and reproduction of mature plants of the two species grown in a common garden field experiment. No plants died from damage after 6 yr. Black swallowwort produced more aboveground biomass, whereas pale swallowwort produced more root biomass and root crown buds, compared with its congener species. For most damage treatments, root biomass and the number of crown buds and stems increased over time, whereas aboveground biomass and viable seeds per plant generally did not change. Substantial overlap in plant size and seed production occurred among damage treatments and species. The most severe defoliation treatment did not substantially limit growth and reproduction compared with undamaged plants. While two clippings per season sometimes prevented seed production, four clippings per season was the only type of damage that consistently prevented plant growth and eliminated seed production. Pale and black swallowwort display a high tolerance to aboveground tissue loss in high-light environments without plant competition. The annual increase in plant size calls into question the potential efficacy of a defoliating insect against field populations of swallowworts, and it seems likely the only benefits of a long-term mowing regime will be to eliminate seed production.

scholarly journals Evolution of increased vigour associated with allopolyploidization in the newly formed invasive species Salsola ryanii

AoB Plants ◽  
2019 ◽  
Author(s):  
Shana R Welles ◽  
Norman C Ellstrand
Keyword(s):  
Invasive Species ◽  
Common Garden ◽  
Plant Evolution ◽  
Seed Number ◽  
Testing Hypotheses ◽  
Fixed Heterozygosity ◽  
Study Support ◽  
A Site

Abstract A correlation between allopolyploidization and increased fitness is an explanation for the importance of allopolyploidy throughout evolution, specifically plant evolution. Although many authors have suggested correlation between allopolyploidy and increased fitness, common garden comparisons testing hypotheses about fitness shifts associated with allopolyploidy are lacking. In this study, we test the theory that allopolyploidy is associated with increased fitness in the newly formed allopolyploid weed Salsola ryanii. We conducted a common garden comparison over 2 years to determine how different fitness correlates (plant volume, plant mass and estimated seed number) of the newly formed allopolyploid species S. ryanii compares to its progenitors (S. tragus and S. australis) at a site within the range of all the newly formed allopolyploid and both of its progenitors. We document an increase in above-ground plant mass and above-ground volume in the newly formed allopolyploid compared to its progenitors. Plant mass and volume of the newly formed allopolyploid relative to its progenitors was dependent on year. The results of this study support the hypothesis that allopolyploidization is associated with increased growth, which is consistent with predictions that allopolyploid lineages experience vigour due to fixed heterozygosity.

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.

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 Herbivory may promote a non-native plant invasion at low but not high latitudes

2019 ◽  
Vol 124 (5) ◽  
pp. 819-827 ◽  
Author(s):  
Xinmin Lu ◽  
Minyan He ◽  
Saichun Tang ◽  
Yuqing Wu ◽  
Xu Shao ◽  
...  
Keyword(s):  
Invasive Species ◽  
Native Species ◽  
Invasive Plant ◽  
Field Survey ◽  
Common Garden ◽  
Middle Latitude ◽  
Plant Invasions ◽  
Alternanthera Philoxeroides ◽  
Native Plant ◽  
Low Latitude

Abstract Background and Aims The strengths of biotic interactions such as herbivory are expected to decrease with increasing latitude for native species. To what extent this applies to invasive species and what the consequences of this variation are for competition among native and invasive species remain unexplored. Here, herbivore impacts on the invasive plant Alternanthera philoxeroides and its competition with the native congener A. sessilis were estimated across latitudes in China. Methods An common garden experiment spanning ten latitudinal degrees was conducted to test how herbivore impacts on A. philoxeroides and A. sessilis, and competition between them change with latitude. In addition, a field survey was conducted from 21°N to 36.8°N to test whether A. philoxeroides invasiveness changes with latitude in nature as a result of variations in herbivory. Key Results In the experiment, A. sessilis cover was significantly higher than A. philoxeroides cover when they competed in the absence of herbivores, but otherwise their cover was comparable at low latitude. However, A. philoxeroides cover was always higher on average than A. sessilis cover at middle latitude. At high latitude, only A. sessilis emerged in the second year. Herbivore abundance decreased with latitude and A. philoxeroides emerged earlier than A. sessilis at middle latitude. In the field survey, the ratio of A. philoxeroides to A. sessilis cover was hump shaped with latitude. Conclusion These results indicate that herbivory may promote A. philoxeroides invasion only at low latitude by altering the outcome of competition in favour of the invader and point to the importance of other factors, such as earlier emergence, in A. philoxeroides invasion at higher latitudes. These results suggest that the key factors promoting plant invasions might change with latitude, highlighting the importance of teasing apart the roles of multiple factors in plant invasions within a biogeographic framework.

Differences in physiological integration between invasive and noninvasive introduced clonal species of Carpobrotus

2019 ◽  
Vol 12 (6) ◽  
pp. 972-981 ◽  
Author(s):  
Sergio R Roiloa ◽  
Peter Alpert ◽  
Rodolfo Barreiro
Keyword(s):  
Invasive Species ◽  
Division Of Labor ◽  
Clonal Growth ◽  
Sand Dunes ◽  
Natural Populations ◽  
Common Garden ◽  
Clonal Plants ◽  
Physiological Integration ◽  
Shoot Mass ◽  
Clonal Species

Abstract Aims Clonal growth is associated with invasiveness in introduced plant species, but few studies have compared invasive and noninvasive introduced clonal species to investigate which clonal traits may underlie invasiveness. To test the hypothesis that greater capacity to increase clonal growth via physiological integration of connected ramets increases invasiveness in clonal plants, we compared the effects of severing connections on accumulation of mass in the two species of the creeping, succulent, perennial, herbaceous genus Carpobrotus that have been introduced on sand dunes along the Pacific Coast of northern California, the highly invasive species Carpobrotus edulis and the co-occurring, noninvasive species Carpobrotus chilensis. Methods Pairs of ramets from four mixed populations of the species from California were grown in a common garden for 3 months with and without severing the stem connecting the ramets. To simulate the effect of clones on soils in natural populations, the older ramet was grown in sand amended with potting compost and the younger in sand alone. Important Findings Severance decreased net growth in mass by ~60% in C. edulis and ~100% in C. chilensis, due mainly to the negative effect of severance on the shoot mass of the younger ramet within a pair. Contrary to the hypothesis, this suggests that physiological integration increases growth more in the less invasive species. However, severance also decreased allocation of mass to roots in the older ramet and increased it in the younger ramet in a pair, and the effect on the younger ramet was about twice as great in C. edulis as in C. chilensis. This indicates that the more invasive species shows greater phenotypic plasticity in response to physiological integration, in particular greater capacity for division of labor. This could contribute to greater long-term growth and suggests that the division of labor may be a trait that underlies the association between clonal growth and invasiveness in plants.

scholarly journals Flight capacity increases then declines from the core to the margins of an invasive species' range

2019 ◽  
Vol 15 (11) ◽  
pp. 20190496 ◽  
Author(s):  
Andrew C. Merwin
Keyword(s):  
Invasive Species ◽  
Maternal Effects ◽  
Common Garden ◽  
Spatial Proximity ◽  
Dispersal Ability ◽  
Suitable Habitat ◽  
Dispersal Capacity ◽  
The Core ◽  
Spatial Sorting ◽  
Flight Capacity

Individuals that disperse farther than other individuals are more likely to be on the frontlines of spreading populations and may be more likely to mate with one another as a consequence of their spatial proximity. Over generations, this process—known as spatial sorting—can produce patterns of increasing dispersal ability from a population's core towards the spreading front. By contrast, when the spread of a population is limited by the availability of suitable habitat, theory predicts that range boundaries can select against more dispersive phenotypes and produce patterns of decreasing dispersal capacity towards population margins. In a common garden study of invasive kudzu bugs ( Megacopta cribraria )—which are limited by the availability of hostplants in their southern and western margins—I show that midrange individuals fly 49% farther than individuals in the core and 37% farther than individuals at margins. This result highlights that other processes, such as maternal effects or selection at range boundaries, may create more complicated patterns of dispersal ability across landscapes than predicted by models of spatial sorting alone.

scholarly journals Growing up in a new world: trait divergence between rural, urban, and invasive populations of an amphibian urban invader

NeoBiota ◽  
2021 ◽  
Vol 69 ◽  
pp. 103-132
Author(s):  
Max Mühlenhaupt ◽  
James Baxter-Gilbert ◽  
Buyisile G. Makhubo ◽  
Julia L. Riley ◽  
John Measey
Keyword(s):  
Invasive Species ◽  
Growth Rate ◽  
Swimming Performance ◽  
Common Garden ◽  
Developmental Rate ◽  
Invasion Success ◽  
Ontogenetic Changes ◽  
Urban Habitats ◽  
Trait Divergence ◽  
Larval Traits

Cities are focal points of introduction for invasive species. Urban evolution might facilitate the success of invasive species in recipient urban habitats. Here we test this hypothesis by rearing tadpoles of a successful amphibian urban coloniser and invader in a common garden environment. We compared growth rate, morphological traits, swimming performance, and developmental rate of guttural toad tadpoles (Sclerophrys gutturalis) from native rural, native urban, and non-native urban habitats. By measuring these traits across ontogeny, we were also able to compare divergence across different origins as the tadpoles develop. The tadpoles of non-native urban origin showed significantly slower developmental rate (e.g., the proportion of tadpoles reaching Gosner stage 31 or higher was lower at age 40 days) than tadpoles of native urban origin. Yet, tadpoles did not differ in growth rate or any morphological or performance trait examined, and none of these traits showed divergent ontogenetic changes between tadpoles of different origin. These findings suggest that prior adaptation to urban habitats in larval traits likely does not play an important role in facilitating the invasion success of guttural toads into other urban habitats. Instead, we suggest that evolutionary changes in larval traits after colonization (e.g., developmental rate), together with decoupling of other traits and phenotypic plasticity might explain how this species succeeded in colonising extra-limital urban habitats.

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.

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