Selection pressure refers to factors in an organism's environment that give certain variations an advantage, pushing evolution in a direction. Random mutations occur during reproduction, and favorable mutations that increase survival and reproduction will become more common through natural selection over generations. A selection pressure can be anything consistent that impacts survival and reproduction rates, like availability of resources, presence of predators, or competition. Selection operates at the individual level, favoring traits that increase individual fitness even if they harm the species as a whole.
types of orientation- primary and secondary, different types of kinesis - orthokinesis and klinokinesis and taxis - tropotaxis, klinotaxis, menotaxis, transverse orientation, dosal light reaction and ventral light reaction
types of orientation- primary and secondary, different types of kinesis - orthokinesis and klinokinesis and taxis - tropotaxis, klinotaxis, menotaxis, transverse orientation, dosal light reaction and ventral light reaction
Cooperative behavior among members of the same species that includes cooperative nesting, generational overlap, and reproductive division of labor. The termites, the ants, and some of the exceptionally well-organized bees and wasps are among the truly social insects that exhibit eusocial behavior. Multiple effectors such as ecological contributions, kin selection, delayed benefits and multi-level selection drive primitive eusociality towards advanced sociality through a point of "no return". These factors are not mutually exclusive - each may play a different role in the evolution of eusociality in different groups.
When a perfectly harmless animal resembles in its colour and shape, with a well protected species, the phenomenon is called mimicry.
The concept of mimicry was first given by H. W. Bates in 1862.
Mimicry is an important feature of organism which protect the animals against enemies. Mimicry often used as self defense which increases the survival value of organisms.
Speciation is the evolutionary process by which reproductively isolated biological populations evolve to become distinct species.There are few mechanisms through which this process can be well understood.
Cooperative behavior among members of the same species that includes cooperative nesting, generational overlap, and reproductive division of labor. The termites, the ants, and some of the exceptionally well-organized bees and wasps are among the truly social insects that exhibit eusocial behavior. Multiple effectors such as ecological contributions, kin selection, delayed benefits and multi-level selection drive primitive eusociality towards advanced sociality through a point of "no return". These factors are not mutually exclusive - each may play a different role in the evolution of eusociality in different groups.
When a perfectly harmless animal resembles in its colour and shape, with a well protected species, the phenomenon is called mimicry.
The concept of mimicry was first given by H. W. Bates in 1862.
Mimicry is an important feature of organism which protect the animals against enemies. Mimicry often used as self defense which increases the survival value of organisms.
Speciation is the evolutionary process by which reproductively isolated biological populations evolve to become distinct species.There are few mechanisms through which this process can be well understood.
About natural selectionOne subtle but important point is that alth.pdfarjuncorner565
About natural selection
One subtle but important point is that although natural selection occurs through interactions
between individua lorganisms and
their environment, individuals do not evolve. Rather, it is the population that evolves over time.
A second key point is that
natural selection can amplify or diminish only those heritable traits that differ among the
individuals in a population. Thus, even if
a trait is heritable, if all the individuals in a population are genetically identical for that trait,
evolution by natural selection cannot occur.
Third, remember that environmental factors vary from place to place and over time. A trait that is
favorable in one place or time may be useless—or even detrimental—in other
places or times. Natural selection is always operating, but which traits are favored depends on
the context in which a species lives and mates.
someone can explain what that means? with easy example..bio is too hard....
Solution
Natural selection occurs through interactions between individual organisms and their
environment, individuals do not evolve. Rather, it is the population that evolves over time.
The statement is very simple and easily understood. By natural selection we understand that it is
the forces of the nature including both biotic and abiotic factors that influence the growth ,
development and perpetuation of an organism .Which means according to Darwin\'s theory the
survival of the fittest is operative. Only organisms that can adapt and change will survive and are
established in population.
For ex In Asian lady bird beetles there is a variation in the spot pattern and color if one of the
color is favored in nature by helping the organism to survive the predators will establish itself
among the population and if successfully reproduces over a period of time it establishes itself as
successful variant.
This can alos be understood with another example : Darwin\'s finches are a type of finches native
to galapagos island . Much study is done regarding the evolution of the birds beak.This bird are
medium in size and feeds on nuts when birds of bigger size entered the island and competed with
the native birds for the nuts the larger bids drove the smaller native birds and ate all the large
nuts to withstand the competetion the smaller birds evolved smaller beaks to enable them to feed
on smaller nuts and this evolution has happened over a period of time and in the population of
native finches and established itself as a new trait.
Natural selection can amplify or diminish only those heritable traits that differ among the
individuals in a population. Thus, even ifa trait is heritable, if all the individuals in a population
are genetically identical for that trait, evolution by natural selection cannot occur.
This means that in any group of organisms having similar traits the chances of evolution is less
however if the same species migrates to a different environment in order to establish itself in that
environment .
Community
all the organisms that live together in a place
Community Ecology
study of interactions among all -populations in a common environment
In what ways do populations interact?
Community – all the organisms that live together in one place
Community ecology – study of interactions among all populations in a common environment.
Interspecific interactions – among individuals of the different species.
Intraspecific interactions – among individuals of the same species.
Species Interaction…
-A traditional approach to population interactions has been to consider the direct pair-wise interactions.
Community Ecology is the study of interactions among all populations in a common environment.
Species Interaction is a traditional approach to population interactions has been to consider the direct pair wise interactions.
Two populations may or may not affect each other; if they do, the influence may be beneficial or adverse
Types of Population Relationships:
Interspecific interactions:
Competition and Coexistence
Predation
Mutualism
Commensalism
Intraspecific Interactions
Grasshoppers provide an animal example. Individual grasshoppers deprive their fellow conspecifics of food (exploitation competition).
It is probably a major factor involved in the evolution of plumage patterns in birds.
during intraspecific competition, animals will use whatever weapons are available to them and this makes it likely that the nature of the weapons determines the nature and location of patterns.
Environmental Science Table of Contents 37 L.docxYASHU40
Environmental Science Table of Contents
37
Lab 3
Biodiversity
Biodiversity
Concepts to Explore
• Biodiversity
• Species diversity
• Ecosystem diversity
• Genetic diversity
• Natural selection
• Extinction
Introduction
Biodiversity, short for biological diversity, includes the genetic variation between all organisms, species, and
populations, and all of their complex communities and ecosystems. It also reflects to the interrelatedness of
genes, species, and ecosystems and their interactions with the environment. Biodiversity is not evenly distrib-
uted across the globe; rather, it varies greatly and even varies within regions. It is partially ruled by climate,
whereas tropical regions can support more species than a polar climate. In whole, biodiversity represents
variation within three levels:
• Species diversity
• Ecosystem diversity
• Genetic diversity
It should be noted that diversity at one of these levels may
not correspond with diversity within other levels. The degree
of biodiversity, and thus the health of an ecosystem, is im-
pacted when any part of that ecosystem becomes endan-
gered or extinct.
The term species refers to a group of similar organisms that
reproduce among themselves. Species diversity refers to
the variation within and between populations of species, as
well as between different species. Sexual reproduction criti-
cally contributes to the variation within species. For exam-
ple, a pea plant that is cross-fertilized with another pea plant
can produce offspring with four different looks! This genetic
mixing creates the diversity seen today.
Figure 1: There are more than 32,000 species of
fish – more than any other vertebrate!
39
Biodiversity
Ecosystem diversity examines the different habitats, biological communities, and ecological processes in
the biosphere, as well as variation within an individual ecosystem. The differences in rainforests and deserts
represent the variation between ecosystems. The physical characteristics that determine ecosystem diversity
are complex, and include biotic and abiotic factors.
? Did You Know...
A present day example of natural
selection can be seen in the cray-
fish population. The British crayfish
are crustaceans that live in rivers in
England. The American crayfish
was introduced to the same bodies
of water that were already populat-
ed by the British crayfish. The
American crayfish are larger, more
aggressive and carry an infection
that kills British crayfish but to
which they are immune. As a re-
sult, the British crayfish are de-
creasing in number and are ex-
pected to become extinct in Britain
within the next 50 years. Thus, the
American crayfish have a genetic
variation that gives them an ad-
vantage over the British crayfish to
survive and reproduce.
The variation of genes within individual ...
This presentation elaborates the economic crisis in Sri Lanka. It explains the causes of economic instability in Sri Lanka and the factors worsening it. Such miserable economic situation is presenting valuable lessons for other sister asian countries to counter their economic instability. Pakistan, a sister country of Sri Lanka is facing severe political and economic instability these days. Pakistan is learning from the Sri Lankan economic situation and tending to improve its economy but the extreme political instability is hurdling and exacerbating the economic crisis. However, policies are underway to counter the economic crisis and more probably Pakistan will escape the Sri Lankan experience.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
In silico drugs analogue design: novobiocin analogues.pptx
Selection pressure
1. Selection pressure
Selection pressure can be regarded as a force that causes a particular organism to evolve in a certain
direction. It is not a physical force, but an interaction between natural variation in a species and factors in its
environment that cause a certain form to have an advantage over the others. This can be thought of as a
“pressure” that pushes the evolution of that organism toward a greater prevalence of this variation.
Evolution and Natural Selection
When organisms reproduce, random mutations can occur, which cause the offspring to vary in some way
from their parents. These changes may be damaging, but they may sometimes give an advantage. For
example, a change that allows an animal to run slightly faster may increase its ability to catch prey or to
escape predators.
A favorable mutation may increase an individual’s chances of surviving long enough to reproduce and pass
this new trait on to its offspring, and so it will become more common. Eventually, all members of the
species may have this characteristic. Unfavorable mutations quickly disappear, as they are less likely to be
passed on to the next generation.
These changes in the populations of different forms of a species are known as natural selection: the form of
a species that is best adapted to its environment is the one that survives. This is sometimes referred to as
“survival of the fittest.” The term “fittest,” in this context, does not mean the strongest or fastest, but the
variant that is the best fit for its environment. Strength and speed may play a role, but other factors, such as
intelligence or coloration may be more important, depending on the circumstances. Natural selection is the
outcome of selection pressures and drives evolution: as favorable mutations accumulate, organisms evolve
into new species.
How Selection Pressures Operate
A selection pressure can derive from practically anything, as long as it acts in a relatively consistent fashion
over reasonably long timeframes, and actually impacts the reproductive or survival rates of a species.
Potential pressures may include availability of prey, presence of predators, environmental stresses,
competition with other species — including humans — and competition between members of a species. In
the eyes of evolution, the likelihood of reproduction is all that matters: if, for example, a certain predator
only consumes old animals that are already incapable of reproducing, the predator will have no impact on
the evolution of the prey species.
An organism’s color may affect its survival chances. For example, insects with colors that blend in to their
surroundings are less likely to be seen by predators such as birds. A mutation that produces coloration
similar to an insect’s usual background, for example, a green color in a species that spends most of its time
eating the leaves of plants, will increase its chances of successful reproduction, and over a number of
generations, this will become the normal form. Mutations that produce a different color will quickly
disappear from the population.
It is important to note that selection pressure has no intelligence, foresight, rhyme, or reason. Selection
operates at individual, not species, level. A new adaptation does not appear "for the good of the species": it
only becomes fixed in a population if it is good for each individual that has it, even if it collectively makes
life worse for the species.
New adaptations can be partially self-destructive, as long as their net effect promotes the fitness of the
organism. For example, Komodo Dragons bite down into their own gums with their sharp teeth when they
feed, apparently increasing their likelihood of lethal infection. This, however also gives an advantage
because the blood-saliva mix is an ideal environment for bacteria that infect their prey when they bite; the
lizard can track a wounded animal until it dies from the infection, or is too weak to escape.
2. Selection pressure can operate more quickly than one might think, and this is especially true under
conditions of selective breeding, when the pressure is intelligently applied by humans. One of the most
striking examples is seen in a series of experiments by scientist Dmitri Belyaev that took place in the Soviet
Union. The object was to domesticate the silver form of the red fox, and it was achieved in just 10
generations of selective breeding. These foxes lost their distinct musky smell, wagged their tails like
domestic dogs, and showed no fear of humans, even licking their hands to show affection. Related
experiments also produced a group of highly aggressive foxes that would leap at their cage walls ferociously
when humans walked by.
Examples of Selection Pressure
A classic example of selection pressure in action is the case of the peppered moth. Until the middle of the
19th century, almost all specimens of this insect were light colored. It spent a lot of its time resting on tree
trunks, and blended in well with the light colored lichens that grew there. In urban areas, however, industrial
pollution began to kill off the lichens, and darken the tree trunks with soot. A dark form of the moth that was
better camouflaged rapidly became more common, until almost all specimens collected in urban areas were
dark.
Attempts by humans to control undesirable organisms can sometimes result in a selection pressure that leads
to new forms that are resistant to the methods used. For example, insect pests that are resistant to
insecticides, and weeds that are unaffected by herbicides have been seen to emerge. Some other examples of
man’s influence are more worrying. The widespread use of antibiotics has resulted in some disease-causing
bacteria to evolve into strains that are resistant to many of these compounds.