scholarly journals Evolution of C4 photosynthesis predicted by constraint-based modelling

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Mary-Ann Blätke ◽  
Andrea Bräutigam
Keyword(s):  
Ground State ◽  
C4 Photosynthesis ◽  
Selective Pressure ◽  
Light Availability ◽  
Resource Limitation ◽  
Optimal Solutions ◽  
Leaf Architecture ◽  
Selective Pressures ◽  
C3 Photosynthesis ◽  
Evolutionary Trajectories

Constraint-based modelling (CBM) is a powerful tool for the analysis of evolutionary trajectories. Evolution, especially evolution in the distant past, is not easily accessible to laboratory experimentation. Modelling can provide a window into evolutionary processes by allowing the examination of selective pressures which lead to particular optimal solutions in the model. To study the evolution of C4 photosynthesis from a ground state of C3 photosynthesis, we initially construct a C3 model. After duplication into two cells to reflect typical C4 leaf architecture, we allow the model to predict the optimal metabolic solution under various conditions. The model thus identifies resource limitation in conjunction with high photorespiratory flux as a selective pressure relevant to the evolution of C4. It also predicts that light availability and distribution play a role in guiding the evolutionary choice of possible decarboxylation enzymes. The data shows evolutionary CBM in eukaryotes predicts molecular evolution with precision.

scholarly journals Evolution of C4 photosynthesis predicted by constraint-based modelling

2019 ◽  
Author(s):  
Mary-Ann Blätke ◽  
Andrea Bräutigam
Keyword(s):  
Ground State ◽  
C4 Photosynthesis ◽  
Selective Pressure ◽  
Light Availability ◽  
Resource Limitation ◽  
Optimal Solutions ◽  
Leaf Architecture ◽  
Selective Pressures ◽  
C3 Photosynthesis ◽  
Evolutionary Trajectories

AbstractConstraint-based modelling (CBM) is a powerful tool for the analysis of evolutionary trajectories. Evolution, especially evolution in the distant past, is not easily accessible to laboratory experimentation. Modelling can provide a window into evolutionary processes by allowing the examination of selective pressures which lead to particular optimal solutions in the model. To study the evolution of C4 photosynthesis from a ground state of C3 photosynthesis, we initially construct a C3 model. After duplication into two cells to reflect typical C4 leaf architecture, we allow the model to predict the optimal metabolic solution under various conditions. The model thus identifies resource limitation in conjunction with high photorespiratory flux as a selective pressure relevant to the evolution of C4. It also predicts that light availability and distribution play a role in guiding the evolutionary choice of possible decarboxylation enzymes. The data shows evolutionary CBM in eukaryotes predicts molecular evolution with precision.

scholarly journals Specific phenotypic, genomic, and fitness evolutionary trajectories toward streptomycin resistance induced by pesticide co-stressors in Escherichia coli

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yue Xing ◽  
Xiaoxi Kang ◽  
Siwei Zhang ◽  
Yujie Men
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Selective Pressure ◽  
Fold Increase ◽  
Streptomycin Resistance ◽  
Evolutionary Stage ◽  
Fitness Costs ◽  
Evolutionary Trajectories ◽  
K 12 ◽  
Late Stages

AbstractTo explore how co-occurring non-antibiotic environmental stressors affect evolutionary trajectories toward antibiotic resistance, we exposed susceptible Escherichia coli K-12 populations to environmentally relevant levels of pesticides and streptomycin for 500 generations. The coexposure substantially changed the phenotypic, genotypic, and fitness evolutionary trajectories, resulting in much stronger streptomycin resistance (>15-fold increase) of the populations. Antibiotic target modification mutations in rpsL and rsmG, which emerged and dominated at late stages of evolution, conferred the strong resistance even with less than 1% abundance, while the off-target mutations in nuoG, nuoL, glnE, and yaiW dominated at early stages only led to mild resistance (2.5–6-fold increase). Moreover, the strongly resistant mutants exhibited lower fitness costs even without the selective pressure and had lower minimal selection concentrations than the mildly resistant ones. Removal of the selective pressure did not reverse the strong resistance of coexposed populations at a later evolutionary stage. The findings suggest higher risks of the selection and propagation of strong antibiotic resistance in environments potentially impacted by antibiotics and pesticides.

Antibiotic selective pressure for the maintenance of antibiotic resistant genes in coliform bacteria isolated from the aquatic environment

2003 ◽  
Vol 47 (3) ◽  
pp. 249-253 ◽  
Author(s):  
J.C. Park ◽  
J.C. Lee ◽  
J.Y. Oh ◽  
Y.W. Jeong ◽  
J.W. Cho ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Selective Pressure ◽  
Functional Class ◽  
Coliform Bacteria ◽  
Antibiotic Resistant ◽  
Gene Cassettes ◽  
Class 1 Integrons ◽  
Selective Pressures ◽  
Class 1 ◽  
Inti1 Gene

Coliform bacteria isolated from the aquatic environment were investigated for antibiotic susceptibility and detailed structures of class 1 integrons. A high proportion of isolates were found to be resistant to sulfamethoxazole, aminoglycosides, and β-lactams. The 750 (53.6%) isolates were resistant to one or more of the antibiotics tested out of 1,400 coliform bacteria. Based on the MIC of antibiotics and antibiogram, 150 isolates were selected and further studied for class 1 integrons. The intI1 gene was found in 36 (24.0%) of the 150 isolates. Twelve isolates carried the gene cassettes responsible for antibiotic resistance, while no gene cassettes were found in 24 isolates. Seven different genes, dfrA5, dfrA7, dfrA12, dfrA17, aaA2, aaA5, and aad(3’), were detected in gene cassettes. The dfrA and aad genes located on class 1 integrons were responsible for resistance to trimethoprim and aminoglycosides. The remaining 24 coliform bacteria had the incomplete or non-functional class 1 integrons. These results indicated that antibiotic selective pressures may play an important role to maintain gene cassettes of class 1 integrons and in the absence of sustained antibiotic pressures, such as the aquatic environment, coliform bacteria may carry empty or non-functional class 1 integrons.

scholarly journals The diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C4 photosynthesis

2021 ◽  
Author(s):  
William J Davis ◽  
Jo Anne Crouch
Keyword(s):  
Secondary Metabolites ◽  
Host Plant ◽  
Downy Mildew ◽  
Host Plants ◽  
C4 Photosynthesis ◽  
Plant Secondary Metabolites ◽  
Free Carbon ◽  
Photosynthetic Pathway ◽  
Mycorrhizal Associations ◽  
C3 Photosynthesis

There are approximately 700 obligate biotrophic species grouped into 20 genera (Oomycota, Peronosporaceae) that cause downy mildew diseases. Dick hypothesized in 2001 that diversification of downy mildew species was driven, in part, by host plant secondary metabolites. Dick further speculated that this was driven by the transition of host plants away from mycorrhizal associations or the evolution of C4 photosynthesis. Specifically, loss of mycorrhizal associations or the use of C4 photosynthesis would result in more free carbon that the plants could then use to produce more secondary metabolites. If true, then there should be more downy mildew species that infect hosts from plant lineages that lack mycorrhizal associations or use C4 photosynthesis. However, analysis of 677 downy mildew species for host plant mycorrhizal associations and host plant photosynthetic pathway type show that this is not what occurred. Seventy percent of downy mildew species parasitize hosts that form mycorrhizal associations and 94% of downy mildew species parasitize hosts that use C3 photosynthesis. From this, it is concluded that the diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C4 photosynthesis. However, 85% of downy mildew species that parasitize Poaceae (grasses) parasitize C4 hosts. Thus, it is possible that C4 photosynthesis plays a role in the diversification of these genera.

scholarly journals Balanced polymorphisms and their divergence in a Heliconius butterfly

2021 ◽  
Author(s):  
James Ogilvie ◽  
Steven Van Belleghem ◽  
Mathieu Chouteau ◽  
Ryan Range ◽  
Riccardo Papa ◽  
...  
Keyword(s):  
South America ◽  
Selective Pressure ◽  
Interspecific Variation ◽  
Color Patterns ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Selection Regime ◽  
Selective Pressures ◽  
Heliconius Butterflies ◽  
Positive Frequency

The evolution of mimicry in similarly defended prey is well described by Müllerian mimicry theory, which predicts the convergence of warning patterns in order to gain the most protection from predators. However, despite this prediction, we can find great diversity of color patterns amongst Müllerian mimics such as Heliconius butterflies in the neotropics. Furthermore, some species have evolved the ability to maintain multiple distinct warning patterns in single populations, a phenomenon known as polymorphic mimicry. The adaptive benefit of these polymorphisms is questionable since variation from the most common warning patterns is expected to be disadvantageous as novel signals are punished by predators naive to them. In this study, we use artificial butterfly models throughout Central and South America to characterize the selective pressures maintaining polymorphic mimicry in Heliconius doris. Our results highlight the complexity of positive frequency-dependent selection, the principal selective pressure driving convergence amongst Müllerian mimics, and its impacts on interspecific variation of mimetic warning colouration. We further show how this selection regime can both limit and facilitate the diversification of mimetic traits.

Grasslands of the World

2018 ◽  
Author(s):  
Brian J. Wilsey
Keyword(s):  
Human Impact ◽  
Soil Type ◽  
C4 Photosynthesis ◽  
Homo Sapiens ◽  
C4 Grasses ◽  
Before Present ◽  
African Savanna ◽  
The World ◽  
C3 Photosynthesis ◽  
Trees And Shrubs

Grasslands are herbaceous dominated areas with very low abundance of trees and shrubs. They are found in areas with intermediate precipitation amounts (250–1000 mm) characterized by occasional droughts and are usually the most extensive in the interior of continents. Grasslands began to form 11–24 million years ago (MYA) when grasses invaded woodlands. Grasses initially all had C3 photosynthesis and were found in shaded conditions. However, grasses with C4 photosynthesis require full sun, and they increased in abundance during this time to achieve between 20–40 percent of the local vegetation. By around 6–8 MYA before present, C4 grasses were widespread on most continents that now have extensive grasslands. Grasslands can be classified by soil type or based on gradients of humidity-aridity and human impact (wild grasslands to improved pastures). African savanna grasslands are important because it is where Homo sapiens (humans) speciated and eventually spread to other continents.

scholarly journals Host heterogeneity mitigates virulence evolution

2020 ◽  
Vol 16 (1) ◽  
pp. 20190744 ◽  
Author(s):  
P. Signe White ◽  
Angela Choi ◽  
Rishika Pandey ◽  
Arthur Menezes ◽  
McKenna Penley ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Parasite Prevalence ◽  
Mixed Genotype ◽  
Selective Pressures ◽  
Virulence Evolution ◽  
Specific Host ◽  
Trade Offs ◽  
Evolutionary Trajectories ◽  
Parasite Populations ◽  
Host Heterogeneity

Parasites often infect genetically diverse host populations, and the evolutionary trajectories of parasite populations may be shaped by levels of host heterogeneity. Mixed genotype host populations, compared to homogeneous host populations, can reduce parasite prevalence and potentially reduce rates of parasite adaptation due to trade-offs associated with adapting to specific host genotypes. Here, we used experimental evolution to select for increased virulence in populations of the bacterial parasite Serratia marcescens exposed to either heterogeneous or homogeneous populations of Caenorhabditis elegans . We found that parasites exposed to heterogeneous host populations evolved significantly less virulence than parasites exposed to homogeneous host populations over several hundred bacterial generations. Thus, host heterogeneity impeded parasite adaptation to host populations. While we detected trade-offs in virulence evolution, parasite adaptation to two specific host genotypes also resulted in modestly increased virulence against the reciprocal host genotypes. These results suggest that parasite adaptation to heterogeneous host populations may be impeded by both trade-offs and a reduction in the efficacy of selection as different host genotypes exert different selective pressures on a parasite population.

On the Relationships between the Genetic Code Coevolution Hypothesis and the Physicochemical Hypothesis

1991 ◽  
Vol 46 (3-4) ◽  
pp. 305-312 ◽  
Author(s):  
Massimo Di Giulio
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Comparative Study ◽  
Genetic Code ◽  
Selective Pressure ◽  
Active Role ◽  
Selective Pressures ◽  
Evolutionary Hypothesis

This paper analyzes the relationships between the genetic code coevolution hypothesis and the physicochemical hypothesis by means of a comparative study of the precursor-product amino acid pairs on which the former hypothesis is based. Even if the coevolution between the biosynthetic relationships of amino acids and the organization of the genetic code is not questioned in this paper, the results and the arguments used lead us to believe that the selective pressures considered essential by the physicochemical postulates, played a more active role than that of the precursor-product relationships in defining the allocation of these amino acids in the genetic code. It is furthermore pointed out that the two evolutionary hypothesis might be aspects of the same selective pressure, and thus difficult to differentiate.

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