scholarly journals A simple genetic architecture and low constraint allows rapid floral evolution in a diverse and recently radiating plant genus

2019 ◽  
Author(s):  
Jamie L. Kostyun ◽  
Matthew J.S. Gibson ◽  
Christian M. King ◽  
Leonie C. Moyle

SummaryGenetic correlations among different components of phenotypes, especially resulting from pleiotropy, can constrain or facilitate trait evolution. These factors could especially influence the evolution of traits that are functionally integrated, such as those comprising the flower. Indeed, pleiotropy is proposed as a main driver of repeated convergent trait transitions, including the evolution of phenotypically-similar pollinator syndromes.We assessed the role of pleiotropy in the differentiation of floral and other reproductive traits between two species —Jaltomata sinuosa and J. umbellata (Solanaceae)—that have divergent suites of floral traits consistent with bee- and hummingbird-pollination, respectively. To do so, we generated a hybrid population and examined the genetic architecture (trait segregation and QTL distribution) underlying 25 floral and fertility traits.We found that most floral traits had a relatively simple genetic basis (few, predominantly additive, QTL of moderate to large effect), as well as little evidence of antagonistic pleiotropy (few trait correlations and QTL co-localization, particularly between traits of different classes). However, we did detect a potential case of adaptive pleiotropy among floral size and nectar traits.These mechanisms may have facilitated the rapid floral trait evolution observed within Jaltomata, and may be a common component of rapid phenotypic change more broadly.

2021 ◽  
Author(s):  
Molly B. Edwards ◽  
Gary P. T. Choi ◽  
Nathan J. Derieg ◽  
Ya Min ◽  
Angie C. Diana ◽  
...  

Interactions with animal pollinators have helped shape the stunning diversity of flower morphologies across the angiosperms. A common evolutionary consequence of these interactions is that some flowers have converged on suites of traits, or pollination syndromes, that attract and reward specific pollinator groups. Determining the genetic basis of these floral pollination syndromes can help us understand the processes that contributed to the diversification of the angiosperms. Here, we characterize the genetic architecture of a bee-to-hummingbird pollination shift in Aquilegia (columbine) using QTL mapping of 17 floral traits encompassing color, nectar composition, and organ morphology. In this system, we find that the genetic architectures underlying differences in floral color are quite complex, and we identify several likely candidate genes involved in anthocyanin and carotenoid floral pigmentation. Most morphological and nectar traits also have complex genetic underpinnings; however, one of the key floral morphological phenotypes, nectar spur curvature, is shaped by a single locus of large effect.


Botany ◽  
2017 ◽  
Vol 95 (2) ◽  
pp. 121-138 ◽  
Author(s):  
Åsa Lankinen ◽  
Josefin A. Madjidian ◽  
Stefan Andersson

Relatively few studies have investigated how geography, environmental factors, and genetics affect floral trait variation. We used mixed-mating Collinsia heterophylla Buist to explore variation in a suite of floral traits related to mating system in populations representing four geographic regions of California, USA, and relate this variation to geography, climatic factors, and local site characteristics. We evaluated the environmental vs. genetic trait variability in the greenhouse. Stage of anther–stigma contact correlated positively with temperature, stage of stigma receptivity was negatively associated with vegetation cover, and flower size differed among populations without any clear relation to environmental factors. Greenhouse data indicated heritability for stage of anther–stigma contact, flower size, and time to flowering, and positive correlations between field and greenhouse for stage of stigma receptivity and flower size; however, stage of anther–stigma contact showed a high degree of environmental influence. Stage of anther–stigma contact covaried positively with stage of stigma receptivity and flower size across maternal families, indicating genetic correlations between traits. In conclusion, phenotypic floral variation within mixed-mating C. heterophylla is mostly determined by a genetic component. Geography, environment, and genetics affect traits differently, suggesting that ecological and evolutionary processes contribute to shaping variability in mating system-related traits.


2020 ◽  
Author(s):  
Juannan Zhou ◽  
Charles B. Fenste ◽  
Richard J. Reynolds

AbstractThe amount of genetic variation of floral traits and the degree to which they are genetically correlated are important parameters for the study of plant evolution. Estimates of these parameters can reveal the effect of historical selection relative to neutral processes such as mutation and drift, and allow us to predict the short-term evolutionary trajectory of a population under various selective regimes. Here, we assess the heritability and genetic correlation of the floral design of a native N. American tetraploid plant, Silene stellata (Caryophyllaceae), in a natural population. Specifically, we use a linear mixed model to estimate the genetic parameters based on a genealogy reconstructed from highly variable molecular markers. Overall, we found significant heritabilities in five out of nine studied traits. The level of heritability was intermediate (0.027 – 0.441). Interestingly, the floral trait showing the highest level of genetic variation was previously shown to be under strong sexually conflicting selection, which may serve as a mechanism for maintaining the observed genetic variation. Additionally, we also found prevalent positive genetic correlations between floral traits. Our results suggest that S. stellata is capable of responding to phenotypic selection on its floral design, while the abundant positive genetic correlations could also constrain the evolutionary trajectories to certain directions. Furthermore, this study demonstrates the utility and feasibility of marker-based approaches for estimating genetic parameters in natural populations.


2020 ◽  
Author(s):  
Daiki Takahashi ◽  
Yu Feng ◽  
Shota Sakaguchi ◽  
Yuji Isagi ◽  
Ying-Xiong Qiu ◽  
...  

AbstractThe Sino-Japanese Floristic Region is highly diverse with respect to temperate plants. However, the reasons for this diversity are poorly understood because most studies have only considered geographic isolation caused by climatic oscillations. Heterotropa (genus Asarum; Aristolochiaceae) diverges here and shows high species diversity in insular systems (63 species) compared to continental areas (25 species). Heterotropa shows low dispersal ability with small distribution ranges, implying diversification by geographic events, and high floral diversity, implying pollinator-mediated diversification. To reveal how abiotic and biotic factors have shaped the diversity anomaly of Heterotropa, we conducted phylogenetic analysis using ddRAD-seq and chloroplast genome datasets including 79 species, estimation of floral trait evolution, and comparison of isolation factors within clades based on distribution range and floral trait analysis. Phylogenetic analysis indicates that Heterotropa originated in mainland China and expanded to the Japanese Archipelago in the Miocene, and the major clades almost correspond to geographic distributions. Floral traits evolved repeatedly in the tip nodes within the clades. Although the major clades include a high proportion of species pairs showing isolation by floral traits, there are no conditional relationships between two isolation factors, indicating that most species pairs with floral trait isolation are distributed allopatrically. The repeated exposure and submergence of land-bridges caused by climatic oscillations would have led to significant population fragmentation in insular systems. Thus, the diversity anomaly of Heterotropa would have resulted from geographic and climatic events during the Miocene, while subsequent repeated floral trait evolution would have followed geographic isolation during the Pleistocene.


2014 ◽  
Vol 369 (1648) ◽  
pp. 20130349 ◽  
Author(s):  
Carolyn A. Wessinger ◽  
Lena C. Hileman ◽  
Mark D. Rausher

Distinct floral pollination syndromes have emerged multiple times during the diversification of flowering plants. For example, in western North America, a hummingbird pollination syndrome has evolved more than 100 times, generally from within insect-pollinated lineages. The hummingbird syndrome is characterized by a suite of floral traits that attracts and facilitates pollen movement by hummingbirds, while at the same time discourages bee visitation. These floral traits generally include large nectar volume, red flower colour, elongated and narrow corolla tubes and reproductive organs that are exerted from the corolla. A handful of studies have examined the genetic architecture of hummingbird pollination syndrome evolution. These studies find that mutations of relatively large effect often explain increased nectar volume and transition to red flower colour. In addition, they suggest that adaptive suites of floral traits may often exhibit a high degree of genetic linkage, which could facilitate their fixation during pollination syndrome evolution. Here, we explore these emerging generalities by investigating the genetic basis of floral pollination syndrome divergence between two related Penstemon species with different pollination syndromes—bee-pollinated P. neomexicanus and closely related hummingbird-pollinated P. barbatus . In an F 2 mapping population derived from a cross between these two species, we characterized the effect size of genetic loci underlying floral trait divergence associated with the transition to bird pollination, as well as correlation structure of floral trait variation. We find the effect sizes of quantitative trait loci for adaptive floral traits are in line with patterns observed in previous studies, and find strong evidence that suites of floral traits are genetically linked. This linkage may be due to genetic proximity or pleiotropic effects of single causative loci. Interestingly, our data suggest that the evolution of floral traits critical for hummingbird pollination was not constrained by negative pleiotropy at loci that show co-localization for multiple traits.


2001 ◽  
Vol 17 (5) ◽  
pp. 719-728 ◽  
Author(s):  
HIROSHI KUDOH ◽  
TAKASHI SUGAWARA ◽  
SUGONG WU ◽  
JIN MURATA

Floral trait correlations were compared between the two flower morphs of a distylous Ophiorrhiza napoensis population in a subtropical evergreen forest at the Defu Natural Animal Preserve, Guangxi, China. Common principal component analyses indicated that overall patterns in correlations among floral traits were morph specific in the study population. Strong positive correlations (r > 0.9) between anther height and corolla-tube length were found in both morphs. Stigma height correlated positively with corolla-tube length in the long-styled morph (r = 0.843), but not in the short-styled morph (r = −0.018). Flower-morph-specific correlation suggests that natural selection by pollinators has moulded trait covariance among floral traits. Because morph-specific correlations are expressed as the patterns of within-morph variation among multiple traits, putative genes responsible for the stigma-corolla tube correlation should not link to the supergene for sex-organ reciprocity between the morphs, but their expression is limited in the long-styled morph.


Genetics ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
Juntao Hu ◽  
Sara J S Wuitchik ◽  
Tegan N Barry ◽  
Heather A Jamniczky ◽  
Sean M Rogers ◽  
...  

Abstract Epigenetic mechanisms underlying phenotypic change are hypothesized to contribute to population persistence and adaptation in the face of environmental change. To date, few studies have explored the heritability of intergenerationally stable methylation levels in natural populations, and little is known about the relative contribution of cis- and trans-regulatory changes to methylation variation. Here, we explore the heritability of DNA methylation, and conduct methylation quantitative trait loci (meQTLs) analysis to investigate the genetic architecture underlying methylation variation between marine and freshwater ecotypes of threespine stickleback (Gasterosteus aculeatus). We quantitatively measured genome-wide DNA methylation in fin tissue using reduced representation bisulfite sequencing of F1 and F2 crosses, and their marine and freshwater source populations. We identified cytosines (CpG sites) that exhibited stable methylation levels across generations. We found that additive genetic variance explained an average of 24–35% of the methylation variance, with a number of CpG sites possibly autonomous from genetic control. We also detected both cis- and trans-meQTLs, with only trans-meQTLs overlapping with previously identified genomic regions of high differentiation between marine and freshwater ecotypes. Finally, we identified the genetic architecture underlying two key CpG sites that were differentially methylated between ecotypes. These findings demonstrate a potential role for DNA methylation in facilitating adaptation to divergent environments and improve our understanding of the heritable basis of population epigenomic variation.


Botany ◽  
2018 ◽  
Vol 96 (7) ◽  
pp. 425-435 ◽  
Author(s):  
Devin E. Gamble ◽  
Megan Bontrager ◽  
Amy L. Angert

The benefits of self-fertilization can vary across environments, leading to selection for different reproductive strategies and influencing the evolution of floral traits. Although stressful conditions have been suggested to favour self-pollination, the role of climate as a driver of mating-system variation is generally not well understood. Here, we investigate the contributions of local climate to intraspecific differences in mating-system traits in Clarkia pulchella Pursh in a common-garden growth chamber experiment. We also tested for plastic responses to soil moisture with watering treatments. Herkogamy (anther–stigma spacing) correlated positively with dichogamy (timing of anther–stigma receptivity) and date of first flower, and northern populations had smaller petals and flowered earlier in response to experimental drought. Watering treatment alone had little effect on traits, and dichogamy unexpectedly decreased with annual precipitation. Populations also differed in phenological response to watering treatment, based on precipitation and winter temperature of their origin, indicating that populations from cool and dry sites have greater plasticity under different levels of moisture stress. While some variation in floral traits is attributable to climate, further investigation into variation in pollinator communities and the indirect effects of climate on mating system can improve our understanding of the evolution of plant mating.


Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 704
Author(s):  
Jill M. Ekar ◽  
Kevin J. Betts ◽  
Adam C. Herman ◽  
Robert M. Stupar ◽  
Donald L. Wyse ◽  
...  

This study chronicles the ongoing process to domesticate an interspecific trigenomic tetraploid hybrid sunflower derived from a series of interspecific crosses between Helianthus annuus and Helianthus tuberosus. The goal of this process is to develop a perennial oilseed crop that can produce both high value vegetable oil and continuous ground-cover. Selection has focused on developing an ideotype with the domesticated morphology of H. annuus and the below-ground perennial features of H. tuberosus. The overarching challenge in the process of breeding and domesticating this interspecific perennial sunflower is overcoming obstacles associated with interploid meiosis in order to resolve a chromosomally stable hybrid population. As selection progresses through generations of intermating, there are improvements toward the desired ideotype, but selection efficiency is slowed by apparent antagonisms between annual- and perennial morphological targets and irregular meiosis which is especially problematic in a trigenomic tetraploid. This shows that keys toward perennial crop development through interspecific hybridization will be to capitalize on the abundant phenotypic variation within our population, achieve meiotic stability in order to maximize selection efficiency, and to break genetic correlations between annual and perennial traits.


2010 ◽  
Vol 92 (1) ◽  
pp. 1-11 ◽  
Author(s):  
HARRI VEHVILÄINEN ◽  
ANTTI KAUSE ◽  
HEIKKI KOSKINEN ◽  
TUIJA PAANANEN

SummarySurvival from birth to a reproductive adult is a challenge that only robust individuals resistant to a variety of mortality factors will overcome. To assess whether survival traits share genetic architecture throughout the life cycle, we estimated genetic correlations for survival within fingerling stage, and across egg, fingerling and grow-out stages in farmed rainbow trout. Genetic parameters of survival at three life cycle stages were estimated for 249 166 individuals originating from ten year classes of a pedigreed population. Despite being an important fitness component, survival traits harboured significant but modest amount of genetic variation (h2=0·07–0·27). Weak associations between survival during egg-fry and fingerling periods, between early and late fingerling periods (rG=0·30) and generally low genetic correlations between fingerling and grow-out survival (mean rG=0·06) suggested that life-stage specific survival traits are best regarded as separate traits. However, in the sub-set of data with detailed time of death records, positive genetic correlations between early and late fingerling survival (rG=0·89) showed that during certain years the best genotypes in the early period were also among the best in the late period. That survival across fingerling period can be genetically the same, trait was indicated also by only slightly higher heritability (h2=0·15) estimated with the survival analysis of time to death during fingerling period compared to the analysis treating fingerling survival as a binary character (h2=0·11). The results imply that (1) inherited resistance against unknown mortality factors exists, but (2) ranking of genotypes changes across life stages.


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