scholarly journals Local differentiation in the defensive morphology of an invasive zooplankton species is not genetically based

2017 ◽  
Author(s):  
Giuseppe E. Fiorino ◽  
Andrew G. McAdam

AbstractEvolutionary changes in functional traits represent one possible reason why exotic species spread to become invasive, but empirical studies of the mechanisms driving phenotypic differentiation between populations of invasive species are rare. This study tested whether differences in distal spine length among populations of the invasive cladoceran, Bythotrephes longimanus, could be explained by local adaptation or phenotypic plasticity. We collected Bythotrephes from six lakes and found that distal spine lengths and natural selection on distal spine length differed among populations, but were unrelated to the gape-limitation of the dominant fish predator in the lake from which they were collected. A common garden experiment revealed significant genetic and maternal variation for distal spine length, but phenotypic differences among populations were not genetically based. Phenotypic differences among lakes in this ecologically important trait are, therefore, the result of plasticity and not local adaptation, despite spatially variable selection on this heritable trait. The ability of Bythotrephes to plastically adjust distal spine length may explain the success of this species at invading lake ecosystems with diverse biotic environments.

2021 ◽  
Author(s):  
Anna Kirschbaum ◽  
Oliver Bossdorf ◽  
J F Scheepens

Abstract Aims Plant populations in managed grasslands are subject to strong selection exerted by grazing, mowing and fertilization. Many previous studies showed that this can cause evolutionary changes in mean trait values, but little is known about the evolution of phenotypic plasticity in response to land use. In this study, we aimed to elucidate the relationships between phenotypic plasticity – specifically, regrowth ability after biomass removal – and the intensity of grassland management and levels of temporal variation therein. Methods We conducted an outdoor common garden experiment to test if plants from more intensively mown and grazed sites showed an increased ability to regrow after biomass removal. We used three common plant species from temperate European grasslands, with seed material from 58 – 68 populations along gradients of land-use intensity, ranging from extensive (only light grazing) to very intensive management (up to four cuts per year). Important findings In two out of three species, we found significant population differentiation in regrowth ability after clipping. While variation in regrowth ability was unrelated to the mean land-use intensity of populations of origin, we found a relationship with its temporal variation in P. lanceolata, where plants experiencing less variable environmental conditions over the last 11 years showed stronger regrowth in reproductive biomass after clipping. Therefore, while mean grazing and mowing intensity may not select for regrowth ability, the temporal stability of the environmental heterogeneity created by land use may have caused its evolution in some species.


2016 ◽  
Vol 283 (1831) ◽  
pp. 20160477 ◽  
Author(s):  
Denon Start ◽  
Benjamin Gilbert

Patch size and isolation are predicted to alter both species diversity and evolution; yet, there are few empirical examples of eco-evolutionary feedback in metacommunities. We tested three hypotheses about eco-evolutionary feedback in a gall-forming fly, Eurosta solidaginis and two of its natural enemies that select for opposite traits: (i) specialization and poor dispersal ability constrain a subset of natural enemies from occupying small and isolated patches, (ii) this constraint alters selection on the gall fly, causing phenotypic shifts towards traits resistant to generalist and dispersive enemies in small and isolated patches, and (iii) reduced dispersal evolves in small, isolated populations. We sampled patches in a natural metacommunity and found support for all hypotheses; Eurosta 's specialist wasp parasitoid attacked fewer galls in small and isolated patches, generating a selection gradient that favoured small galls resistant to predation by a dispersive and generalist bird predator. Phenotype distributions matched this selection gradient, and these phenotypic differences were maintained in a common garden experiment. Finally, we found lower dispersal abilities in small and isolated patches, a phenotypic shift that aids in the maintenance of local adaptation. We suggest that the trophic rank and the species traits of consumers are central to evolution in metacommunities.


2018 ◽  
Author(s):  
Sara Marin ◽  
Juliette Archambeau ◽  
Vincent Bonhomme ◽  
Mylène Lascoste ◽  
Benoit Pujol

ABSTRACTPhenotypic differentiation among natural populations can be explained by natural selection or by neutral processes such as drift. There are many examples in the literature where comparing the effects of these processes on multiple populations has allowed the detection of local adaptation. However, these studies rarely identify the agents of selection. Whether population adaptive divergence is caused by local features of the environment, or by the environmental demand emerging at a more global scale, for example along altitudinal gradients, is a question that remains poorly investigated. Here, we measured neutral genetic (FST) and quantitative genetic (QST) differentiation among 13 populations of snapdragon plants (Antirrhinum majus) in a common garden experiment. We found low but significant genetic differentiation at putatively neutral markers, which supports the hypothesis of either ongoing pervasive homogenisation via gene flow between diverged populations or reproductive isolation between disconnected populations. Our results also support the hypothesis of local adaptation involving phenological, morphological, reproductive and functional traits. They also showed that phenotypic differentiation increased with altitude for traits reflecting the reproduction and the phenology of plants, thereby confirming the role of such traits in their adaptation to environmental differences associated with altitude. Our approach allowed us to identify candidate traits for the adaptation to climate change in snapdragon plants. Our findings imply that environmental conditions changing with altitude, such as the climatic envelope, influenced the adaptation of multiple populations of snapdragon plants on the top of their adaptation to local environmental features. They also have implications for the study of adaptive evolution in structured populations because they highlight the need to disentangle the adaptation of plant populations to climate envelopes and altitude from the confounding effects of selective pressures acting specifically at the local scale of a population.


Author(s):  
Daniela Chequer Charan ◽  
Carolina Pometti ◽  
Mariano Cony ◽  
Juan Cesar Vilardi ◽  
Beatriz O Saidman ◽  
...  

Abstract Prosopis chilensis (Molina) Stuntz (Leguminosae) is a valuable native species in Argentina included in the Prosopis Management Programme. Natural provenances show important height and shape differentiation throughout their distribution in the Monte Desert. The availability of progeny trials provides an opportunity to quantify genetic differentiation among provenances and test the relative importance of demographic vs adaptive processes on morphological variation. We quantified both genetic and quantitative differentiation of neutral markers and five economically important traits, respectively, among four provenances in a provenance-progeny trial. We aimed to quantify the genetic basis of variations in height, basal diameter, tree shape, spine length and biomass. Two hypotheses were tested: (1) economically important traits have significant heritability, and (2) the phenotypic variation among provenances is the result of local adaptation to particular environmental conditions. Our results indicate that most morphological variation was found among individuals within families (~95 per cent). The h2 estimates were heterogeneous among traits and ranged from low (0 for number of stems) to moderate (0.22 and 0.28 for spine length and biomass, respectively). Variance among families (~5 per cent) was evenly distributed within and among provenances. Morphological differentiation among provenances was low, but significant, and could be attributed mainly to individuals from Villa Unión. Based on molecular markers, genetic differentiation among provenances was low and significant (FST = 0.03; P = 5 × 10−4) but was able to differentiate the groups from Villa Unión, Fiambalá and Mogna-Chilecito. Neutrality tests were conducted using the FST–QST test and DJSOST and δGREGORIUS alternative coefficients of differentiation. Neutrality tests yielded no evidence of local adaptation and were rather consistent in showing a trend toward stabilizing selection, particularly for spine length. The selection strategy for breeding programmes should depend on the trait to be improved and should consider both provenance and familiar information. Considering an intra-familiar ranking is encouraged in order to maximize the genetic gain. Additionally, in order to recover germplasm provenance diversity, based on morphological and microsatellite results, our recommendation would be to include seeds from individuals from at least the Villa Unión, Fiambalá and Mogna-Chilecito areas.


2011 ◽  
Vol 4 (4) ◽  
pp. 209-220 ◽  
Author(s):  
S. K. Ebeling ◽  
J. Stocklin ◽  
I. Hensen ◽  
H. Auge

2011 ◽  
Vol 279 (1727) ◽  
pp. 349-356 ◽  
Author(s):  
Morgan W. Kelly ◽  
Eric Sanford ◽  
Richard K. Grosberg

The extent to which acclimation and genetic adaptation might buffer natural populations against climate change is largely unknown. Most models predicting biological responses to environmental change assume that species' climatic envelopes are homogeneous both in space and time. Although recent discussions have questioned this assumption, few empirical studies have characterized intraspecific patterns of genetic variation in traits directly related to environmental tolerance limits. We test the extent of such variation in the broadly distributed tidepool copepod Tigriopus californicus using laboratory rearing and selection experiments to quantify thermal tolerance and scope for adaptation in eight populations spanning more than 17° of latitude. Tigriopus californicus exhibit striking local adaptation to temperature, with less than 1 per cent of the total quantitative variance for thermal tolerance partitioned within populations. Moreover, heat-tolerant phenotypes observed in low-latitude populations cannot be achieved in high-latitude populations, either through acclimation or 10 generations of strong selection. Finally, in four populations there was no increase in thermal tolerance between generations 5 and 10 of selection, suggesting that standing variation had already been depleted. Thus, plasticity and adaptation appear to have limited capacity to buffer these isolated populations against further increases in temperature. Our results suggest that models assuming a uniform climatic envelope may greatly underestimate extinction risk in species with strong local adaptation.


2008 ◽  
Vol 38 (6) ◽  
pp. 1690-1694 ◽  
Author(s):  
Megan K. Kanaga ◽  
Ronald J. Ryel ◽  
Karen E. Mock ◽  
Michael E. Pfrender

Genetic diversity within populations is an important component of adaptive evolution, and recent research has demonstrated that genetic variation within plant populations can have important ecological effects. In this study, we investigate quantitative-genetic variation in several traits within a quaking aspen ( Populus tremuloides Michx.) population. A common garden experiment was planted with replicates of 13 aspen genotypes collected from wet and dry sites within a population in southern Utah, USA. Ten growth, leaf, physiological, and structural traits were measured. There were significant, heritable phenotypic differences among genotypes in every measured trait and differences in 4 of the 10 traits among genotypes originating from wet and dry collection sites. The data were compared with other published studies, showing that aspen heritability (H2) estimates and coefficients of genetic variation (CVG) were comparable or higher than other Populus species and hybrid F1 Populus genotypes, indicating a large amount of quantitative-genetic variation in aspen.


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