scholarly journals Ecological Specialization in a Spatially Structured Population of the Thermophilic Cyanobacterium Mastigocladus laminosus

2008 ◽  
Vol 75 (3) ◽  
pp. 729-734 ◽  
Author(s):  
Scott R. Miller ◽  
Carin Williams ◽  
Aaron L. Strong ◽  
Darla Carvey
Keyword(s):  
Population Sample ◽  
Natural Populations ◽  
Niche Differentiation ◽  
Laboratory Culture ◽  
Microbial Populations ◽  
Ecological Specialization ◽  
Selection Gradient ◽  
Mastigocladus Laminosus ◽  
Ecological Selection ◽  
Evolutionary Innovation

ABSTRACT Laboratory evolution experiments suggest the potential for microbial populations to contribute significant ecological variation to ecosystems, yet the functional importance of genetic diversity within natural populations of microorganisms is largely unknown. Here, we investigated the distribution of genetic and phenotypic variation for a population of the cyanobacterium Mastigocladus laminosus distributed along the temperature gradient of White Creek, Yellowstone NP. A total of 153 laboratory strains were directly isolated from five sites with mean annual temperatures ranging between 39 and 54�C. Genetic characterization at four nitrogen metabolism genes identified 15 closely related lineages in the population sample. These lineages were distributed nonrandomly along White Creek, but the observed geographic structure could not be explained by limited dispersal capabilities. Temperature performance experiments with six M. laminosus lineages that maximized their respective relative abundances at different positions along the gradient provided evidence for niche differentiation within the population. Niche differentiation included a tradeoff in performance at high and low temperatures, respectively. The physiological variation of these lineages in laboratory culture was generally well matched to the prevailing temperature conditions experienced by these organisms in situ. These results suggest that sympatric diversification along an ecological selection gradient can be a potent source of evolutionary innovation in microbial populations.

scholarly journals Patterns of ecological specialization among microbial populations in the Red Sea and diverse oligotrophic marine environments

2013 ◽  
Vol 3 (6) ◽  
pp. 1780-1797 ◽  
Author(s):  
Luke R. Thompson ◽  
Chris Field ◽  
Tamara Romanuk ◽  
David Kamanda Ngugi ◽  
Rania Siam ◽  
...  
Keyword(s):  
Red Sea ◽  
Microbial Populations ◽  
Marine Environments ◽  
Ecological Specialization

scholarly journals Micro-geographic variation of inversions in natural populations of Drosophila pseudoobscura

Genetika ◽  
2006 ◽  
Vol 38 (2) ◽  
pp. 97-105 ◽  
Author(s):  
Víctor Salceda ◽  
José Espinoza-Velazquez
Keyword(s):  
Geographic Variation ◽  
Population Sample ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
Drosophila Pseudoobscura ◽  
Natural Habitats ◽  
San Luis ◽  
San Luis Potosi ◽  
San Luis Potosí

Chromosomal polymorphism for the third chromosome in Drosophila pseudoobscura has been widely studied for genetic variation in different environments or locations far apart. However, there is less information regarding sites geographically near one another. Targeting on possible micro-geographic variation in the species, a serial study was done on 12 Mexican populations grouped in four regions, including locations in Durango (DU), the border area of Guanajuato-San Luis Potosi states (GP), Chiapas (CH) and Saldilo (SA). Flies were trapped in their natural habitats using fermenting bananas as bait. They were individually cultivated in the laboratory for larvae production. In a given population sample several flies were cultivated together but only one larva per culture provided salivary tissue to observe polytene chromosomes. Gene arrangements or inversions were identified and frequencies were calculated. A total of 767 third chromosomes were studied and 11 different inversions detected. The type and relative frequencies of the arrangements varied among regions. From the 11 inversions observed, 10 were found in Durango, five in Guanajuato-San Luis Potosi and Chiapas, and eight in Saltillo. The inversion frequencies in the Durango locations varied in four cases, but only one in Chiapas, three cases in Guanajuato-San Luis Potosi, and five in Saltillo. It was also observed that there were geographical gradients for inversions within regions as follows: four arrangements in Saltillo and Durango, three in Guanajuato-San Luis Potos? and one in Chiapas. Moreover, all four regions studied showed evidences for micro-geographical variation. Nevertheless, more studies are needed to elucidate the relevance of the inversion frequencies changes in neighboring populations and also any seasonal-annual frequencies observed in the locations studied here.

scholarly journals Testing Host-Plant Driven Speciation in Phytophagous Insects: A Phylogenetic Perspective

2019 ◽  
Author(s):  
Emmanuelle Jousselin ◽  
Marianne Elias
Keyword(s):  
Host Plant ◽  
Evolutionary Biology ◽  
Phylogenetic Analyses ◽  
Evolutionary Process ◽  
Niche Differentiation ◽  
Ecological Speciation ◽  
Model Systems ◽  
Phytophagous Insects ◽  
Ecological Specialization ◽  
Recent Developments

During the last two decades, ecological speciation has been a major research theme in evolutionary biology. Ecological speciation occurs when reproductive isolation between populations evolves as a result of niche differentiation. Phytophagous insects represent model systems for the study of this evolutionary process. The host-plants on which these insects feed and often spend parts of their life cycle constitute ideal agents of divergent selection for these organisms. Adaptation to feeding on different host-plant species can potentially lead to ecological specialization of populations and subsequent speciation. This process is thought to have given birth to the astonishing diversity of phytophagous insects and is often put forward in macroevolutionary scenarios of insect diversification. Consequently, numerous phylogenetic studies on phytophagous insects have aimed at testing whether speciation driven by host-plant adaptation is the main pathway for the diversification of the groups under investigation. The increasing availability of comprehensive and well-resolved phylogenies and the recent developments in phylogenetic comparative methods are offering an unprecedented opportunity to test hypotheses on insect diversification at a macroevolutionary scale, in a robust phylogenetic framework. Our purpose here is to review the contribution of phylogenetic analyses to investigate the importance of plant-mediated speciation in the diversification of phytophagous insects and to present suggestions for future developments in this field.

scholarly journals The ‘algebra of evolution’: the Robertson–Price identity and viability selection for body mass in a wild bird population

2020 ◽  
Vol 375 (1797) ◽  
pp. 20190359 ◽  
Author(s):  
G. K. Hajduk ◽  
C. A. Walling ◽  
A. Cockburn ◽  
L. E. B. Kruuk
Keyword(s):  
Phenotypic Diversity ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Phenotypic Selection ◽  
Relative Fitness ◽  
Price Equation ◽  
Genetic Covariance ◽  
Selection Gradient ◽  
Viability Selection ◽  
Temporal Correlations

By the Robertson–Price identity, the change in a quantitative trait owing to selection, is equal to the trait's covariance with relative fitness. In this study, we applied the identity to long-term data on superb fairy-wrens Malurus cyaneus , to estimate phenotypic and genetic change owing to juvenile viability selection. Mortality in the four-week period between fledging and independence was 40%, and heavier nestlings were more likely to survive, but why? There was additive genetic variance for both nestling mass and survival, and a positive phenotypic covariance between the traits, but no evidence of additive genetic covariance. Comparing standardized gradients, the phenotypic selection gradient was positive, β P = 0.108 (0.036, 0.187 95% CI), whereas the genetic gradient was not different from zero, β A = −0.025 (−0.19, 0.107 95% CI). This suggests that factors other than nestling mass were the cause of variation in survival. In particular, there were temporal correlations between mass and survival both within and between years. We suggest that use of the Price equation to describe cross-generational change in the wild may be challenging, but a more modest aim of estimating its first term, the Robertson–Price identity, to assess within-generation change can provide valuable insights into the processes shaping phenotypic diversity in natural populations. This article is part of the theme issue ‘Fifty years of the Price equation’.

scholarly journals The Bacterial Flora Associated with the Polyphagous Aphid Aphis gossypii Glover (Hemiptera: Aphididae) Is Strongly Affected by Host Plants

2019 ◽  
Vol 79 (4) ◽  
pp. 971-984 ◽  
Author(s):  
Shifen Xu ◽  
Liyun Jiang ◽  
Gexia Qiao ◽  
Jing Chen
Keyword(s):  
Host Plant ◽  
Host Plants ◽  
Statistical Tests ◽  
Bacterial Flora ◽  
Aphis Gossypii ◽  
Natural Populations ◽  
Aphid Species ◽  
Ecological Specialization ◽  
Cotton Aphid ◽  
Symbiotic Associations

AbstractAphids live in symbiosis with a variety of bacteria, including the obligate symbiont Buchnera aphidicola and diverse facultative symbionts. The symbiotic associations for one aphid species, especially for polyphagous species, often differ across populations. In the present study, by using high-throughput 16S rRNA sequencing, we surveyed in detail the microbiota in natural populations of the cotton aphid Aphis gossypii in China and assessed differences in bacterial diversity with respect to host plant and geography. The microbial community of A. gossypii was dominated by a few heritable symbionts. Arsenophonus was the most dominant secondary symbiont, and Spiroplasma was detected for the first time. Statistical tests and ordination analyses showed that host plants rather than geography seemed to have shaped the associated symbiont composition. Special symbiont communities inhabited the Cucurbitaceae-feeding populations, which supported the ecological specialization of A. gossypii on cucurbits from the viewpoint of symbiotic bacteria. Correlation analysis suggested antagonistic interactions between Buchnera and coexisting secondary symbionts and more complicated interactions between different secondary symbionts. Our findings lend further support to an important role of the host plant in structuring symbiont communities of polyphagous aphids and will improve our understanding of the interactions among phytophagous insects, symbionts, and environments.

scholarly journals Phenotypic plasticity and diversity in insects

2010 ◽  
Vol 365 (1540) ◽  
pp. 593-603 ◽  
Author(s):  
Armin P. Moczek
Keyword(s):  
Gene Expression ◽  
Phenotypic Plasticity ◽  
Natural Populations ◽  
Evolutionary Developmental Biology ◽  
Life Cycles ◽  
Biological Organization ◽  
Trade Off ◽  
Evolutionary Innovation ◽  
Trade Offs ◽  
Evolutionary Trajectories

Phenotypic plasticity in general and polyphenic development in particular are thought to play important roles in organismal diversification and evolutionary innovation. Focusing on the evolutionary developmental biology of insects, and specifically that of horned beetles, I explore the avenues by which phenotypic plasticity and polyphenic development have mediated the origins of novelty and diversity. Specifically, I argue that phenotypic plasticity generates novel targets for evolutionary processes to act on, as well as brings about trade-offs during development and evolution, thereby diversifying evolutionary trajectories available to natural populations. Lastly, I examine the notion that in those cases in which phenotypic plasticity is underlain by modularity in gene expression, it results in a fundamental trade-off between degree of plasticity and mutation accumulation. On one hand, this trade-off limits the extent of plasticity that can be accommodated by modularity of gene expression. On the other hand, it causes genes whose expression is specific to rare environments to accumulate greater variation within species, providing the opportunity for faster divergence and diversification between species, compared with genes expressed across environments. Phenotypic plasticity therefore contributes to organismal diversification on a variety of levels of biological organization, thereby facilitating the evolution of novel traits, new species and complex life cycles.

scholarly journals New Methods for Analysis of Spatial Distribution and Coaggregation of Microbial Populations in Complex Biofilms

2013 ◽  
Vol 79 (19) ◽  
pp. 5978-5987 ◽  
Author(s):  
Robert Almstrand ◽  
Holger Daims ◽  
Frank Persson ◽  
Fred Sörensson ◽  
Malte Hermansson
Keyword(s):  
Quantitative Methods ◽  
Niche Differentiation ◽  
Biofilm Reactor ◽  
Microbial Populations ◽  
Distribution Analysis ◽  
Content Type ◽  
New Methods ◽  
Nitrosomonas Oligotropha ◽  
Automated Tools ◽  
Sequential Fish

ABSTRACTIn biofilms, microbial activities form gradients of substrates and electron acceptors, creating a complex landscape of microhabitats, often resulting in structured localization of the microbial populations present. To understand the dynamic interplay between and within these populations, quantitative measurements and statistical analysis of their localization patterns within the biofilms are necessary, and adequate automated tools for such analyses are needed. We have designed and applied new methods for fluorescencein situhybridization (FISH) and digital image analysis of directionally dependent (anisotropic) multispecies biofilms. A sequential-FISH approach allowed multiple populations to be detected in a biofilm sample. This was combined with an automated tool for vertical-distribution analysis by generatingin silicobiofilm slices and the recently developed Inflate algorithm for coaggregation analysis of microbial populations in anisotropic biofilms. As a proof of principle, we show distinct stratification patterns of the ammonia oxidizersNitrosomonas oligotrophasubclusters I and II and the nitrite oxidizerNitrospirasublineage I in three different types of wastewater biofilms, suggesting niche differentiation between theN. oligotrophasubclusters, which could explain their coexistence in the same biofilms. Coaggregation analysis showed thatN. oligotrophasubcluster II aggregated closer toNitrospirathan didN. oligotrophasubcluster I in a pilot plant nitrifying trickling filter (NTF) and a moving-bed biofilm reactor (MBBR), but not in a full-scale NTF, indicating important ecophysiological differences between these phylogenetically closely related subclusters. By using high-resolution quantitative methods applicable to any multispecies biofilm in general, the ecological interactions of these complex ecosystems can be understood in more detail.

Procedure for mass collection of mermithid postparasites (Nematoda: Mermithidae) from larval blackflies (Diptera: Simuliidae)

1974 ◽  
Vol 52 (5) ◽  
pp. 660-661 ◽  
Author(s):  
C. H. Bailey ◽  
R. Gordon ◽  
J. Mokry
Keyword(s):  
Natural Populations ◽  
Laboratory Culture ◽  
Mass Collection

Larval blackflies, Prosimulium mixtum/fuscum Syme and Davies and Simulium venustum Say, were collected from natural populations and maintained in the laboratory for emergence of their mermithid parasites, Neomesomermis flumenalis (Welch, 1962) Nickle, 1972. Between April and July 1973, 4378 postparasitic N. flumenalis were obtained from about 250 000 blackflies for laboratory culture experiments.

Genetic and morphological variability in cestodes of the genus Proteocephalus: geographical variation in Proteocephalus percae populations

1999 ◽  
Vol 77 (9) ◽  
pp. 1450-1458 ◽  
Author(s):  
Vladimíra Hanzelová ◽  
Viliam Šnábel ◽  
Ivica Král'ová ◽  
Tomáš Scholz ◽  
Stefano D'Amelio
Keyword(s):  
Random Amplified Polymorphic Dna ◽  
Morphological Variability ◽  
Population Sample ◽  
Natural Populations ◽  
Water Reservoir ◽  
Perca Fluviatilis ◽  
Morphological Characters ◽  
Rapd Profile ◽  
Perch Perca Fluviatilis ◽  
Apical Sucker

Genetic and morphological variability was studied in the tapeworm Proteocephalus percae (Müller, 1780) (Cestoda: Proteocephalidae), a parasite of perch (Perca fluviatilis L.). Geographic variation in isoenzyme patterns, random amplified polymorphic DNA (RAPD) profiles, and morphological characters were found within six natural populations of P. percae from Slovakia and Switzerland. All approaches used showed that similarity was substantially higher among Swiss populations than among Slovak populations. Proteocephalus percae specimens from the Dobšiná water reservoir (Slovakia) differed significantly from all other population sample sets in that they exclusively expressed the genotype Acp92/Acp92 and possessed a specific RAPD profile after amplification with the primer p78 and distinct measurements of the scolex (scolex width and apical sucker). The unique position of the P. percae population from Dobšiná could be related to the contamination of this locality with heavy metals (cadmium), through the possible impact of these metals on the alterations observed. The taxonomic relevance and stability of the morphological characters related to the scolex in the Proteocephalus tapeworm group is confirmed.

scholarly journals Developmental expression of the 412 retrotransposon in natural populations of D. melanogaster and D. simulans

2000 ◽  
Vol 76 (3) ◽  
pp. 217-226 ◽  
Author(s):  
N. BORIE ◽  
C. LOEVENBRUCK ◽  
C. BIEMONT
Keyword(s):  
Expression Pattern ◽  
Copy Number ◽  
Developmental Stages ◽  
Population Sample ◽  
Natural Populations ◽  
Developmental Expression ◽  
Regulatory Sequences ◽  
Copy Numbers ◽  
Species Specific ◽  
Very High

We analysed the pattern of expression of retrotransposon 412 through developmental stages in various populations of Drosophila simulans and D. melanogaster differing in 412 copy number. We found that the 412 expression pattern varied greatly between populations of both species, indicating that such patterns were not entirely species-specific. In D. simulans, total transcripts increased with number of 412 copies in the chromosomes when this number was low, and then decreased for high copy numbers. D. melanogaster, which has a higher 412 copy number than D. simulans, had overall a lower global 412 expression, but again showed variation in 412 expression pattern between populations. These results suggest that in populations of D. simulans with low 412 copy number, the expression pattern of this element depends not only on copy number but also on host cellular regulatory sequences near which the elements were inserted. In D. simulans populations with high copy number overall transcription was on the contrary globally repressed, as observed in D. melanogaster. A population from Canberra (Australia) which had a very high 412 copy number was found to be associated with very high expression of 412 over all developmental stages, suggesting that the above 412 expression regulation processes are overcome in this population sample. The analysis of hybrids between geographically distinct populations of D. simulans showed that 412 expression was trans-regulated differently according to developmental stages, implying complex interactions between the 412 element and stage-specific host genes.

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