Santos et al 2013 J Gen
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This study examined genetic differentiation in laboratory populations of Drosophila subobscura derived from six wild populations collected from different locations and years. The researchers found striking genetic differentiation between the laboratory populations within the first two generations of being established, despite all founders being similar. This early divergence was likely due to strong genetic drift and changes in demography resulting from a significant drop in effective population size during the colonization process. The results demonstrate that rapid and significant evolutionary changes can occur during the initial generations of a founding event in a new environment due to powerful genetic sampling effects.
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![c Indian Academy of Sciences
RESEARCH ARTICLE
Fast evolutionary genetic differentiation during experimental
colonizations
JOSIANE SANTOS1∗
, MARTA PASCUAL2
, PEDRO SIMÕES1
, INÊS FRAGATA1
, MICHAEL R. ROSE3
and MARGARIDA MATOS1
1
Faculdade de Ciências da Universidade de Lisboa, Centro de Biologia Ambiental, Departamento de Biologia Animal,
Campo Grande, 1749-016 Lisboa, Portugal
2
Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, España
3
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA
Abstract
Founder effects during colonization of a novel environment are expected to change the genetic composition of populations,
leading to differentiation between the colonizer population and its source population. Another expected outcome is differenti-
ation among populations derived from repeated independent colonizations starting from the same source. We have previously
detected significant founder effects affecting rate of laboratory adaptation among Drosophila subobscura laboratory popula-
tions derived from the wild. We also showed that during the first generations in the laboratory, considerable genetic differenti-
ation occurs between foundations. The present study deepens that analysis, taking into account the natural sampling hierarchy
of six foundations, derived from different locations, different years and from two samples in one of the years. We show that
striking stochastic effects occur in the first two generations of laboratory culture, effects that produce immediate differentia-
tion between foundations, independent of the source of origin and despite similarity among all founders. This divergence is
probably due to powerful genetic sampling effects during the first few generations of culture in the novel laboratory environ-
ment, as a result of a significant drop in Ne. Changes in demography as well as high variance in reproductive success in the
novel environment may contribute to the low values of Ne. This study shows that estimates of genetic differentiation between
natural populations may be accurate when based on the initial samples collected in the wild, though considerable genetic
differentiation may occur in the very first generations of evolution in a new, confined environment. Rapid and significant evo-
lutionary changes can thus occur during the early generations of a founding event, both in the wild and under domestication,
effects of interest for both scientific and conservation purposes.
[Santos J., Pascual M., Simões P., Fragata I., Rose M. R. and Matos M. 2013 Fast evolutionary genetic differentiation during experimental
colonizations. J. Genet. 92, 183–194]
Introduction
Population size plays a key role in determining the rela-
tive importance of natural selection and genetic drift, with
small isolated populations more exposed to stochastic loss
of genetic variability, potentially reducing their subsequent
response to selection (Robertson 1960). During a coloniza-
tion event, a population may experience a considerable
reduction in size. The effect of a census population-size
bottleneck on effective population size (Ne) is expected to
be strong even when a population expands quickly after
the initial colonization event (Wade and McCauley 1988;
∗For correspondence. E-mail: jmssantos@fc.ul.pt.
Charlesworth 2009). Genetic drift arising from a founder-
generation bottleneck is thus expected to lead to divergence
between the source population and newly founded popula-
tions. In a classic paper, Carson and Templeton (1984) pro-
posed that ‘under some circumstances the founder event may
set the stage for speciation by altering genetic conditions
in the gene pool’, due to genetic changes such as gametic
disequilibrium. Moreover, quantitative genetic models show
that a strong bottleneck may increase the evolutionary poten-
tial of a population, due to conversion of nonadditive into
additive component of genetic variance (Goodnight 1988).
This may also lead to divergence from the ancestral pop-
ulation. Empirical evidence of such increases in evolution-
ary potential after a bottleneck comes from several species
and traits (see Bryant et al. 1986; Regan et al. 2003). Such
Keywords. founding event; genetic drift; colonization; captive populations; genetic differentiation; Drosophila subobscura.
Journal of Genetics, Vol. 92, No. 2, August 2013 183](https://image.slidesharecdn.com/089fbec9-5430-4a8f-b48f-d3dbd2b2d766-160408090845/85/Santos-et-al-2013-J-Gen-1-320.jpg)
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Genetic drift is the random change in allele frequencies between generations in a small population due to chance. It can cause loss of genetic variation and lead to homozygosity. The bottleneck effect occurs when a population is drastically reduced in size, such as by a natural disaster, leaving a small surviving population with less genetic diversity than the original. The founder effect is similar, occurring when a new population is established by a small number of colonists from a larger population, resulting in allele frequencies that may not represent the original population. Both effects can increase the prevalence of genetic disorders in the new populations.
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Santos et al 2010 Chr Res
This document summarizes a study that mapped 72 dinucleotide microsatellite loci from Drosophila subobscura onto its polytene chromosomes using fluorescent in situ hybridization (FISH). The distribution of microsatellites was not uniform across chromosomes, with higher density in the sex chromosome than autosomes. Homologous regions were identified in D. pseudoobscura and D. melanogaster genomes, supporting conservation of chromosomal elements among Drosophila species but also intrachromosomal rearrangements within lineages. The lack of microsatellite repeats in homologous D. melanogaster sequences suggests convergent evolution for high density in the X chromosome distal region.
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Challenges opportunities and way forward in making indian cities and citizens...
This was presented by me during Panel Discussions on Captioned Topic during IoT India Congress – 2016 Bangalore, on 8th September 2016.
http://theiet.in/The_IET_announces_Indias_largest_conclave_on_the_Internet_of_Things%E2%80%93IoT_India_Congress_2016
It was a coincidence that during panel discussions I came across team from Deloitte and C44, instrumental in preparation of NTK's winning Smart City Proposal. For me it was one of the happiest moment for being in the same panel with current mentors, as I was involved with the NTK project from pre-takeoff to maturity stage.
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I have also highlighted the fact that what we have done in (terms of TND design) more than 1.5 decades back in the year 2000-01, is being replicated now as a Brownfeild Retrofit by Global Smart City Barcelona through creation of SMART SUPER BLOCKS ( we were ahead of time).
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https://www.linkedin.com/pulse/greenfield-urban-retrofit-inspired-traditional-design-choudhury?trk=pulse_spock-articles
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Systemische Professionalität - Dilemma, Sinn und komplexe Wirklichkeiten
Systemische Professionalität - Dilemma, Sinn und komplexe Wirklichkeitenisb GmbH Systemische Professionalität
Kernsapekte:
- Dilemma: Eingebaute Unlösbarkeit
- Innerhalb Dilemmalogik keine oder nur unbefriedigende Lösungen
- Dilemmagleichungen: Bedeutungsgebungen konstituieren Unlösbarkeit
- Dilemmainszenierungen: Verschiedene Inszenierungen auf der selben Bühne; Inszenierungen nach unterverträglichen, konkurrierenden Gesichtspunkten, Mehrfachzugriff auf die selben Ressourcen;
- Dilemmazirkel: Strampeln (Aktivität ohne Zuversicht); Erschöpft abschalten (Pause ohne Neubelebung); Verzweifeln; Vermeiden/ Leugnen
- Chancenreiche Haltungen:
- Verzweifeln als Professionelle Kompetenz: Bei Zeiten loslassen können
Hyperlinks zu youtube*:
Link Slide #1: http://www.youtube.com/watch?v=84JVEw0a6r4&t=0m
Link Slide #2: http://www.youtube.com/watch?v=84JVEw0a6r4&t=16m20s
Link Slide #3: http://www.youtube.com/watch?v=84JVEw0a6r4&t=20m10s
*Slideshare verhindert Hyperlinks auf den ersten drei Folien.Systemische Professionalität - Verantwortung und Macht
Kernaspekte:
- Verantwortung:
- Dimensionen von Verantwortung (Qualifikation, Wertorientierung, Zuständigkeit, Autorisierung)
- Komplementäre Verantwortung (Verantwortung "für"/ Verantwortung "in Bezug auf")
- Störungen im Verantwortungssystem
Hyperlinks zu youtube*:
Link Slide #1: http://www.youtube.com/watch?v=G9s5SUHkBv8&t=24m40s
Link Slide #2: http://www.youtube.com/watch?v=G9s5SUHkBv8&t=26m
Link Slide #3: http://www.youtube.com/watch?v=G9s5SUHkBv8&t=28m30s
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Behavioral signature of intraspecific competition anddensity.docx
This document summarizes a study that analyzed the movement patterns and foraging behavior of gray seals from a large breeding colony on Sable Island, Nova Scotia using satellite tracking data. The study found evidence that young-of-year juvenile seals were being displaced from foraging areas near the colony by adult female seals, especially in summer. This displacement was likely due to the juveniles' lesser diving abilities and intraspecific competition for resources with adults. Combined with data showing declining juvenile survival rates, this provides evidence that density-dependent population regulation is occurring in the form of compensatory competition between age classes.
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FROM THE CLASSROOM TO AN OPINION NOTE: COMPLEMENTARY ANALYSIS OF THE GENETIC ...International Educational Applied Scientific Research Journal (IEASRJ)
Here, we describe a learning strategy that results an excellent choice for a first approach of students to produce scientific knowledge that can be confronted in the scientific field as well as recognize in this knowledge the transferability to the natural resources management. Nowadays, the availability of several Population Genetics software together with public molecular database represents a valuable tool of great assistance for teachers of this discipline. In this way, we implemented a
lecture where the students worked with empirical data set from a recent published article. The students joined theoretical concepts learned, computational software free available and empirical data set. The development of the activity comprised four steps: i) estimate population genetics parameters using software recommended by teachers, ii) understand results in a biological sense, iii) read the original manuscript from dataset authors and iv) compare both results in a comprehensive way. The students assumed the challenge under a reflective look and they kept a very fruitful discussion playing a role of population geneticists. Their exchange of ideas allowed them arrive to the conclusion that Manilkara zapota populations keep high levels of genetic diversity, although Ancient Maya left traces in the genetic makeup of these non-native populations with different management histories.3902 wileyonlinelibrary.comjournalmec Molecular Ecology.docx
3902 | wileyonlinelibrary.com/journal/mec Molecular Ecology. 2019;28:3902–3914.© 2019 John Wiley & Sons Ltd
1 | I N T R O D U C T I O N
Maynard‐Smith and Haig (1974) recognized the influence of selection
on linked neutral sites, proposing that strong positive selection could
reduce genetic diversity at nearby sites. This process is now referred
to as a ‘selective sweep’. Much later, Charlesworth, Morgan, and
Charlesworth (1993) proposed that deleterious mutations could also
affect genetic diversity at nearby sites, because some haplotypes
would be removed from the population as selection acts against
linked deleterious alleles. They named this process background se‐
lection (BGS). Both selective sweeps and background selection af‐
fect genetic diversity; they both reduce the effective population size
and distort the site frequency spectrum (SFS) of linked loci. Empirical
evidence of a positive correlation between genetic diversity and
recombination rate has been reported in several species (Cutter &
Payseur, 2013), including Drosophila melanogaster (Begun & Aquadro,
1992; Elyashiv et al., 2016), humans (Spencer et al., 2006), collared
flycatchers, hooded crows and Darwin's finches (Dutoit et al., 2017;
see also Vijay et al., 2017).
BGS is also expected to affect FST (Charlesworth, Nordborg, &
Charlesworth, 1997; Cruickshank & Hahn, 2014; Cutter & Payseur,
2013; Hoban et al., 2016). The negative relationship between effec‐
tive population size Ne and FST is captured in Wright's classical in‐
finite island result; FST =
1
1+4Ne(m+�)
(Wright, 1943), where m is the
migration rate and µ is the mutation rate. One might therefore ex‐
pect that loci under stronger BGS would show higher FST.
Many authors have also argued that, because BGS reduces the
within‐population diversity, it should lead to high FST (Cruickshank
Received: 20 May 2018 | Revised: 19 June 2019 | Accepted: 3 July 2019
DOI: 10.1111/mec.15197
O R I G I N A L A R T I C L E
Background selection and FST: Consequences for detecting
local adaptation
Remi Matthey‐Doret | Michael C. Whitlock
Department of Zoology and Biodiversity
Research Centre, University of British
Columbia, Vancouver, BC, Canada
Correspondence
Remi Matthey‐Doret, Department of
Zoology and Biodiversity Research Centre,
University of British Columbia, Vancouver,
BC V6T 1Z4, Canada.
Email: [email protected]
Funding information
The work was funded by NSERC
Discovery Grant RGPIN‐2016‐03779 to
MCW and by the Swiss National Science
Foundation via the fellowship Doc.Mobility
P1SKP3_168393 to RMD.
Abstract
Background selection is a process whereby recurrent deleterious mutations cause a
decrease in the effective population size and genetic diversity at linked loci. Several
authors have suggested that variation in the intensity of background selection could
cause variation in FST across the genome, which could confound signals of local ad‐
aptation in genome scans. ...
Santos et al 2016 JEB
This document summarizes a study that tracked changes in chromosomal arrangements and genetic content over 30 generations of laboratory evolution in three replicated populations of Drosophila subobscura. The researchers found evidence that chromosomal polymorphisms and life history traits adapted to the new environment. Selection was detected for seven of 23 chromosomal arrangements, supporting a role for inversions in adaptation. Linkage disequilibrium evolved between some microsatellites and chromosomes, suggesting adaptive changes in arrangements involved changes in genetic content. Several microsatellite alleles increased in frequency within targeted inversions in all populations more than expected by drift alone. Overall, the selection detected on the genetic content of inversions provides evidence that genetic changes within inversions play an important role in adaptation.
Genetic diversity enhances the resistance of aseagrass ecosy
Genetic diversity enhances the resistance of a
seagrass ecosystem to disturbance
A. Randall Hughes* and John J. Stachowicz
Section of Evolution and Ecology, One Shields Avenue, University of California, Davis, CA 95616
Edited by G. David Tilman, University of Minnesota, St. Paul, MN, and approved May 4, 2004 (received for review April 14, 2004)
Motivated by recent global reductions in biodiversity, empirical
and theoretical research suggests that more species-rich systems
exhibit enhanced productivity, nutrient cycling, or resistance to
disturbance or invasion relative to systems with fewer species. In
contrast, few data are available to assess the potential ecosystem-
level importance of genetic diversity within species known to play
a major functional role. Using a manipulative field experiment, we
show that increasing genotypic diversity in a habitat-forming
species (the seagrass Zostera marina) enhances community resis-
tance to disturbance by grazing geese. The time required for
recovery to near predisturbance densities also decreases with
increasing eelgrass genotypic diversity. However, there is no effect
of diversity on resilience, measured as the rate of shoot recovery
after the disturbance, suggesting that more rapid recovery in
diverse plots is due solely to differences in disturbance resistance.
Genotypic diversity did not affect ecosystem processes in the
absence of disturbance. Thus, our results suggest that genetic
diversity, like species diversity, may be most important for enhanc-
ing the consistency and reliability of ecosystems by providing
biological insurance against environmental change.
There is growing recognition that humans are highly depen-dent on natural ecosystems for a variety of goods and
services (1). Maintaining the provision of these goods and
services in the face of natural and anthropogenic disturbances is
critical to achieving both conservation and economic goals.
Motivated by accelerating rates of worldwide decline in biodi-
versity (2), considerable research has focused on the conse
quences of local species loss for goods and services provided by
ecosystems (2– 8). Much of this work focuses on the effects of
declining species richness on short-term processes such as pro-
duction, community respiration, and nutrient cycling (2). Al-
though the results are far from unequivocal and subject to
varying interpretation (e.g., ref. 9), it does appear that, in some
systems, reductions in local species diversity contribute to a
decline in ecosystem properties such as productivity and resis-
tance to disturbance (see review in ref. 2).
Nevertheless, many important ecosystems, such as kelp forests,
cattail marshes, and fir forests, are dominated by, and dependent
on, one or a few key plant species (10). Furthermore, individual
predator and herbivore species often play a disproportionate role in
determining ecosystem processes, overwhelming any effect of spe-
cies diversity (11). Dominant, numerically abundant s ...
Genotype-By-Environment Interaction (VG X E) wth Examples
Introduction
Phenotypic variation can be caused by the combination of genotypes and environments in a population. Genotypes are all equally sensitive to their environments, meaning that a change of environment would impact the phenotype of all genotypes to the same extent. In fact, genotypes very often have different degrees of sensitivity to environmental conditions. This cause of phenotypic variance is called genotype by- environment interaction and is symbolized by VG x E. This adds another term to the expression for the independent causes of total phenotypic variation in a population
Ve = VG + VE + VG xE
Some of our most basic questions about the history of life concern w.pdf
Some of our most basic questions about the history of life concern when major events occurred.
Some evolutionary events can be dated from the fossil record But what options are available
when fossil data are missing? In at least some instances, it should be possible to address
questions about timing by analyzing molecular traits that change at a steady rate. This
hypothesis, called the molecular clock, @ originated with Emile Zuckerkandl and Linus Pauling
(1962). There are reasons to expect that some types of DNA sequences change in a clocklike
fashion. Many mutations change an individual's DNA but not its phenotype In most cases,
mutations like these are not exposed to natural selection. Instead, these neutral @ changes evolve
by a random process called genetic drift As we will discuss elsewhere, the neutral theory of
molecular evolution predicts that neutral changes in DNA should accumulate in populations at a
rate equal to the mutation rate If the mutation rate stays reasonably constant, and if generation
times remain similar, then the number of neutral molecular differences between two taxa should
be proportional to the age of their most recent common ancestor By counting distinct neutral
mutations observed in two species and multiplying by a calibration rate representing how
frequently neutral changes occur per million years, researchers can estimate when the species
diverged. Although the possibility of dating events from estimates of genetic divergence is
tantalizing, there are several important caveats. For example, it is critical to realize that the
mutation rate to neutral alleles will vary from gene to gene and lineage to lineage, and even from
base to base. For reasons explained in another chapter, silent site changes in the third positions of
codons are more likely to be neutral with respect to fitness, and thus to accumulate at a clocklike
rate, than replacement changes that occur at the first and second positions in codons. And if
allele frequencies change rapidly due to strong selection at a particular gene, it is unlikely that
the mutations involved are accumulating in a clocklike fashion. Finally rates of change calibrated
for a particular gene and lineage are unlikely to work for other groups, which may have different
generation times and selection histories (Martin et al. 1992; Martin and Palumbi 1993; Hillis et
al. 1996). Even if clocklike change occurs in a particular gene and lineage, how can the rate be
determined? Investigators have to rely on the fossil or geological records. The idea is to measure
the genetic distance between two taxa whose divergence date is known from fossil or geological
data and then to use this calibration to date the divergence times of groups that have no fossil
record. As an example of how researchers use molecular clocks to date events, consider work by
Ralf Kittler and colleagues (2003, 2004) on the origin of human body lice Body lice (Pediculus
humanus corporis) are similar to head lice (.
Speciation in fungi by RATHOD PARSHURAM
Speciation in plant pathogens can occur through geographical isolation, environmental factors, or hybridization. Geographical isolation leads to genetic divergence as populations accumulate differences separated by physical barriers. Environmental factors like host or temperature can also drive reproductive isolation over time. Rarely, hybridization between species can result in hybrids reproductively isolated from parents. Studying speciation in plant pathogens provides insights into their evolution and emergence, helping predict new pathogens. Combining classical and genomic approaches reveals how speciation occurs in fungi and oomycetes.
niche_construction_evolution2005_3449025
The document summarizes a study that investigated how genetically variable germination timing in Arabidopsis thaliana influences the evolution of plant life histories. The researchers grew recombinant inbred lines of A. thaliana under different photoperiod and geographic conditions to manipulate germination timing. They found that adult life history traits exhibited strong plasticity depending on season of germination. The season of germination also significantly altered the strength, mode, and direction of natural selection on life history traits. However, the average plastic responses to season were not adaptive. Genetic variation in germination timing increased genetic variation in adult traits but did not increase heritability due to also increasing environmental variation. Under some conditions, plasticity in response to genetically variable germination
Speciation Contents History Key Components of the Concept of Speciation Modes...
Speciation Contents History Key Components of the Concept of Speciation Modes of Speciation Speciation-Gradual and additive mechanism Speciation Types@ Allopatric Pperipatric Parapatric and Sympatric with examples
Complex adaptation in Zea
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- Studies find evidence of both hard and partial sweeps during selection for traits like increased branching, with convergent evolution occurring through both multiple mutations and standing variation at gt1.
- Research also examines the adaptation of maize as it spread from Mexico to the highlands and South America, finding evidence of introgression between wild and domesticated populations that aided this adaptation.
c⃝ Indian Academy of SciencesRESEARCHARTICLESexual con.docx
1) The study used experimental evolution to investigate the interaction between intralocus sexual conflict, sexual dimorphism, and adaptation to environmental variation in Drosophila melanogaster populations selected for desiccation resistance over 46 generations.
2) The desiccation-selected populations showed increased survival time under arid conditions and body weight compared to control populations, but this adaptation came at a cost of reduced preadult viability and female fecundity.
3) The sexes showed differing patterns of desiccation resistance and resource acquisition in response to selection, with a trend toward increasingly female-biased sexual size dimorphism, suggesting divergent selection pressures on males and females from the same environmental stress.
Understanding the basic principles of population genetics and its application
This document discusses key concepts in population genetics, including:
- Gene pool, gene frequency, genetic equilibrium, genetic drift, natural selection, isolation
- Hardy-Weinberg principle, which states that gene frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences
- How Hardy and Weinberg used Punnett squares and equations to mathematically prove the principle based on observations of dominant and recessive alleles in a population
- An example application of using the Hardy-Weinberg equation to determine the number of heterozygotes and homozygous individuals for a dominant trait in a population
Evolution by natural selection
This document discusses evolution by natural selection. It notes that members of a population vary in traits, traits are inherited from parents to offspring, and all species can produce offspring. However, if the environment lacks survival resources like food, some offspring will not survive. This leads to the conclusions that individuals with inherited traits better suited to the environment will have a higher probability of surviving and reproducing, passing on these favorable traits over generations. The document then defines natural selection as increasing adaptation over time by differential survival and reproduction of individuals with heritable traits. It also discusses speciation, or the origin of new species, and the mechanisms that can lead to reproductive isolation between populations.
Tracking evolutionary paths
This document summarizes a thesis on tracking evolutionary paths during colonization events in Drosophila subobscura populations. The author studied: 1) founder effects on genetic differentiation between populations, finding early genetic drift impacts adaptation, 2) associations between genetic variability and adaptive responses, showing variability predicts evolutionary potential, and 3) the role of chromosomal inversions in adaptation, providing evidence for local adaptation within inversions. The research improves understanding of how selection and drift interact during colonization to impact genetic composition and adaptive trajectories.
03 concept of gene pools
This document discusses the concept of a gene pool. It begins by defining the gene pool as the set of all genes in a population, usually of a particular species. It then provides a brief history of the term and how it was formulated by geneticists in the 1920s. The document goes on to explain the rational behind the gene pool concept, including how genetic diversity within a population allows for greater adaptability. It then discusses how the gene pool concept is applied to crop breeding, dividing plant materials into primary, secondary, and tertiary gene pools based on their genetic relationship and the ease of gene transfer. Key aspects of each gene pool type are outlined. The document concludes by discussing gene pool centers and the importance of studying the gene
Genotyping an invasive vine
The climbing vine kudzu, a member of the leguminous
pea family (Fabaceae), was introduced into the USA
from its native Asia in the 1800s. It was initially lauded
for efficacy in erosion control along highways and as a
high-quality grazing crop for livestock. P. montana var.
lobata has since become a truculent invasive, spreading
via vegetative runners and seed dispersal. Seven
million acres of the American southeast are now
plagued by this vine.
1-s2.0-S0923250811001872-main
This study analyzed the occurrence and diversity of integrons in bacteria isolated from an urban wastewater treatment plant. A total of 697 isolates of Enterobacteriaceae and Aeromonas were screened for integrons. Three new gene cassettes were identified, including a novel aadA variant and genes involved in cell signaling and unknown functions. Thirteen different gene cassette arrays were detected, with four representing novel integrons. Approximately 80% of isolates were resistant to at least 3 antibiotic classes. The presence of novel integron structures in treated effluent suggests wastewater treatment plants may facilitate the formation and spread of antibiotic resistance genes.
the others our biased perspective
Understanding the origin and evolution of the eukaryotic cell and the full diversity of eukaryotes is relevant to many biological disciplines.
However, our current understanding of eukaryotic genomes is extremely biased, leading to a skewed view of eukaryotic biology.
We argue that a phylogeny-driven initiative to cover the full eukaryotic diversity is needed to overcome this bias.
•
◦There is an important bias in eukaryotic knowledge, affecting cultures and genomes.
Eukaryotic genomics are biased towards multicellular organisms and their parasites.
◦A phylogeny-driven initiative is needed to overcome the eukaryotic genomic bias.
◦We propose to sequence neglected cultures and increase culturing efforts.
◦Single-cell genomics should be embraced as a tool to explore eukaryotic diversity
Recent theories on community structure and functioning
Presentation at ABIOMED workshop - Greece, 25.10.2022.
In this presentation I give an overview of recent mathematical models for population dynamics both for terrestrial and marine ecosystem, and I show how emergent patterns can be used to infer ecosystems' health.
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Recent theories on community structure and functioning
Recent theories on community structure and functioning
Santos et al 2013 J Gen
- 1. c Indian Academy of Sciences RESEARCH ARTICLE Fast evolutionary genetic differentiation during experimental colonizations JOSIANE SANTOS1∗ , MARTA PASCUAL2 , PEDRO SIMÕES1 , INÊS FRAGATA1 , MICHAEL R. ROSE3 and MARGARIDA MATOS1 1 Faculdade de Ciências da Universidade de Lisboa, Centro de Biologia Ambiental, Departamento de Biologia Animal, Campo Grande, 1749-016 Lisboa, Portugal 2 Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, España 3 Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA Abstract Founder effects during colonization of a novel environment are expected to change the genetic composition of populations, leading to differentiation between the colonizer population and its source population. Another expected outcome is differenti- ation among populations derived from repeated independent colonizations starting from the same source. We have previously detected significant founder effects affecting rate of laboratory adaptation among Drosophila subobscura laboratory popula- tions derived from the wild. We also showed that during the first generations in the laboratory, considerable genetic differenti- ation occurs between foundations. The present study deepens that analysis, taking into account the natural sampling hierarchy of six foundations, derived from different locations, different years and from two samples in one of the years. We show that striking stochastic effects occur in the first two generations of laboratory culture, effects that produce immediate differentia- tion between foundations, independent of the source of origin and despite similarity among all founders. This divergence is probably due to powerful genetic sampling effects during the first few generations of culture in the novel laboratory environ- ment, as a result of a significant drop in Ne. Changes in demography as well as high variance in reproductive success in the novel environment may contribute to the low values of Ne. This study shows that estimates of genetic differentiation between natural populations may be accurate when based on the initial samples collected in the wild, though considerable genetic differentiation may occur in the very first generations of evolution in a new, confined environment. Rapid and significant evo- lutionary changes can thus occur during the early generations of a founding event, both in the wild and under domestication, effects of interest for both scientific and conservation purposes. [Santos J., Pascual M., Simões P., Fragata I., Rose M. R. and Matos M. 2013 Fast evolutionary genetic differentiation during experimental colonizations. J. Genet. 92, 183–194] Introduction Population size plays a key role in determining the rela- tive importance of natural selection and genetic drift, with small isolated populations more exposed to stochastic loss of genetic variability, potentially reducing their subsequent response to selection (Robertson 1960). During a coloniza- tion event, a population may experience a considerable reduction in size. The effect of a census population-size bottleneck on effective population size (Ne) is expected to be strong even when a population expands quickly after the initial colonization event (Wade and McCauley 1988; ∗For correspondence. E-mail: jmssantos@fc.ul.pt. Charlesworth 2009). Genetic drift arising from a founder- generation bottleneck is thus expected to lead to divergence between the source population and newly founded popula- tions. In a classic paper, Carson and Templeton (1984) pro- posed that ‘under some circumstances the founder event may set the stage for speciation by altering genetic conditions in the gene pool’, due to genetic changes such as gametic disequilibrium. Moreover, quantitative genetic models show that a strong bottleneck may increase the evolutionary poten- tial of a population, due to conversion of nonadditive into additive component of genetic variance (Goodnight 1988). This may also lead to divergence from the ancestral pop- ulation. Empirical evidence of such increases in evolution- ary potential after a bottleneck comes from several species and traits (see Bryant et al. 1986; Regan et al. 2003). Such Keywords. founding event; genetic drift; colonization; captive populations; genetic differentiation; Drosophila subobscura. Journal of Genetics, Vol. 92, No. 2, August 2013 183