This document discusses different types of selection and their effects on populations. It describes three main types of selection:
1. Natural selection, which is based on survival of the fittest in a given environment. Only the most adapted individuals survive to reproduce.
2. Artificial selection, which is selection done by breeders to achieve specific objectives. Breeders choose which individuals get to reproduce.
3. Three patterns of selection are described - directional selection which changes the population mean over generations, disruptive selection which favors two extreme types, and stabilizing selection which favors intermediate types close to the population mean.
Selection is a very important procedure in animal genetics and breeding. it is the method of choosing high genetic merit parents and produce superior progenies. Selection changes gene frequencies.
Selection is a very important procedure in animal genetics and breeding. it is the method of choosing high genetic merit parents and produce superior progenies. Selection changes gene frequencies.
Dr. Sushil Neupane's notes on "Introductory Genetics and Animal Breeding" for the 2nd year, 1st semester of the Diploma in Animal Science (latest syllabus of CTEVT) provide a comprehensive overview of key concepts and principles related to genetics and animal breeding. The notes cover fundamental topics in genetics and their practical applications in livestock production and breeding programs.
in natural selection, explain what is a sexual selection, neutral va.pdfjaronkyleigh59760
in natural selection, explain what is a sexual selection, neutral variation and balancing selection
Solution
The concept of natural selection explains that how a species can have breeding populations
adapted to local conditions. Based on the principle of natural selection the selection of genotypes
occurs and that would result in offspring with better reproductive capabilities. Natural selection
always results in better survival of an organism, so the genetic changes driven by the natural
selection make the species to adapt to the local conditions so that they can survive. These species
may exhibit high genetic variation may be because out breeding, but gradually due to the
inbreeding in these adapted species, the genetic variation will be minimized and they evolve as a
separate species.
The sexual selection refers that a species which exhibit dominant sexual characters to the
opposite partner has the ability to mate with female and expand its gene pool.
Natural variation: In variation selection, the traits within the organisms undergo mutations to
allow the organism to best adapt to the environment by means of natural selection (Darwinian
evolution), these mutations are inherited by the nest generation offspring. In case of
transformational selection or Lamarck’s theory, the individual organisms change by inheriting
the transformations within a generation.
The three types of selection that we observe in speciation are disruptive selection, stabilizing
selection and directional selection. Disruptive selection occurs due to the selection for the
extreme values of traits instead of intermediate values. This divides the population into two
different groups. Disruptive selection is one of the main driving forces of sympatric speciation,
which occurs when there are no physical barriers that prevent species to mate together. The
occurrence of speciation may be depending on the availability of different food sources and
existence of different shelters. When comes to the balanced selection the allele frequencies
remain contestant throughout the evolution..
Basis of selection in animal genetics and breeding Dr. Jayesh Vyas
The sources of information based on which the breeding value of the individual is estimated are called as the basis of selection or aids to selection or criteria of selection which are the basis of estimating the breeding value.
The breeding value so obtained is known as estimating breeding value(EBV)or probable breeding value(PBV).
The different selection criteria to estimates the B.V. of an individuals for single trait
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How to Add Chatter in the odoo 17 ERP ModuleCeline George
In Odoo, the chatter is like a chat tool that helps you work together on records. You can leave notes and track things, making it easier to talk with your team and partners. Inside chatter, all communication history, activity, and changes will be displayed.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
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Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
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Normal Labour/ Stages of Labour/ Mechanism of LabourWasim Ak
Normal labor is also termed spontaneous labor, defined as the natural physiological process through which the fetus, placenta, and membranes are expelled from the uterus through the birth canal at term (37 to 42 weeks
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
A Survey of Techniques for Maximizing LLM Performance.pptx
Selection, type of selection, patterns of selection and their effect on population
1. SELECTION, TYPE OF SELECTION, PATTERNS OF
SELECTION AND THEIR EFFECT ON POPULATION
Submitted to :
Dr. P. C. Patel
Assistant Professor
Dept. Of Genetics And Plant Breeding
C. P. College of Agriculture
SDAU
Submitted by :
Kalpeshkumar M. Damor
Reg.no.04-AGRMA-01983-2019
C. P. College of Agriculture
SDAU
2. SELECTION :
The selection is the differential propagation of
genetic material to the next generation.
Process of differential survival and reproduction of
individuals is known as selection.
4. 1. NATURAL SELECTION
The first type of selection is the natural selection whose
principle is the "survival of fittest" in a given
environment.
The individual which are not fit/adapted to survive and
to produce their progeny died of their genetic death
without any offspring. This is known as natural selection.
The survival of the fittest is determined measured by the
survivability and the reproductive success of the
individual.
There fore, survivability and the reproductive status are
known as the fitness or adaptive characters.
5. The natural selection is based on the theory that certain
genotypes in a population have advantage over others in
survival and reproduction.
Natural selection is a term used to indicate that some
genotypes leave more offspring than others.
The natural selection (has no purpose except that it) is a
consequence of the differences between individuals for
their capacity to produce progeny.
Large population have all the time a great store of
potential genetic variability know as the plasticity of a
population.
6. Stages of life cycle of natural selection
Gametic stage:
• Segregation of homologous chromosomes at meiosis for gamete formation
(Segregation distortion).
• Gametic competition in the way of differential penetration or elimination of
male gamete and compatibility of ova and sperm before fertilization.
Zygotic stage:
• Embryonic growth and development .
• Maturity rate (Early or late puberty).
• Fecundity, age-specific fertility, gamete production, care and protection of
young.
• Mating ability
• Total progeny produced .
• Survival at different ages viz embryonic stage, birth to maturity and
adulthood.
7. The factors affect survival are
• Resistance to disease, outbreak of disease.
• Protection from danger wild animals (predation) and
natural calamities.
• Accident, hunger.
• Competitive ability to use resources.
• Differential ability to cope with climate and other
environmental conditions.
• Differential survival of certain genotypes.
• Lethal genes.
8. 2. ARTIFICIAL SELECTION
The second type of selection is man made which depends
upon the will or choice of the breeder to allow the animals to
produce the next generation. This is called as artificial
selection.
It is under the control of breeder who decides that to which
animals he wants to retain and to allow to become parents of
next generation.
The choice the breeder is objective specific and hence the
artificial selection bas purpose.
Some genotypes are either more attractive, productive or more
efficient functionally and hence preferred by the breeder.
The artificial selection is under the control of certain rules to
govern the probability that an individual reproduces .
9. PATTERNS OF SELECTION
Three pattern of selection
1. Directional selection
2. Stabilizing selection
3. Disruptive selection
10. 1. DIRECTIONAL SELECTION
This is also called as one way upward selection or linear
selection.
It is done to change the mean by selecting the individuals
with extreme phenotypic value (greatest or least) and not
allowing to reproduce the individuals whose phenotypic
value is intermediate for the trait under selection.
This results a change in the mean value of the offspring
generation in the direction of the favored phenotype
compared with parent population.
11. The individual selected are genetically superior with
higher frequencies of favorable alleles for that trait and
thus these individuals contribute these favorable alleles
to the next generation.
On the other hand, the individuals which have less
favorable alleles arc not allowed to contribute (the less
favorable alleles) to the next generation.
Thus, the frequency of alleles in the next generation is
changed, increasing the frequencies of more favorable
alleles and it results in an improvement in the average
phenotype of next generation.
12. BASIS OF DIRECTIONAL SELECTION
The individuals to become parents of the next generation
are selected on the basis of their breeding value for the
trail under selection.
The breeding value is estimated on the basis of
individual's own performance or on the basis of the
information on the performance of their relatives.
1. Individual selection
2. Selection based on relatives performance
13. I. INDIVIDUAL SELECTION
When the individual are selected based on their higher rank
for phenotypic/breeding values is called the "individual
selection" or "mass selection".
The variant of this system of selection is the “truncation
selection”.
when all the individuals above a specific value are selected
and individuals below the value are rejected.
The individuals may he selected for improvement either in
one trait or for more traits simultaneously.
The selection for more than one trait simultaneously is known
as multi trait selection or methods of selection.
Therefore, the methods of selection come under the individual
selection.
14. II. SELECTION BASED ON RELATIVES
PERFORMANCE
The other method of ranking the individuals to be selected
is to rank them on the basis of the performance of their
relatives.
The relatives on the basis of whose performance the
individuals are selected may be either parents (called as
pedigree selection) progeny (called as progeny selection or
progeny testing) or their collateral relatives (called as
family selection). The families may he of full sibs or of half
sibs.
There are three forms of family selection
1. Sib selection
2. Family selection
3. Within family selection
15. 1. Sib selection:- The sib selection is when the individuals
selected are not measured to estimate family mean and
selection of individuals is based on the values of their
sibs.
2. Family selection:- The selected individual are also
measured and included in the family mean. However,
the selection is based on family mean which implies
deviation of individuals' family mean from population
mean (pf)
3. Within family selection:- In which is a procedure when
the better individual within each family are selected
based on the deviation of each individual from the
mean value of their family (pw) and the individuals
with the maximum deviation are selected.
16. 2. DISRUPTIVE SELECTION
This is also called as two way selection or bidirectional
selection or diversifying or centrifugal.
The individuals are selected with extreme phenotypes
from both sides (maximum and minimum) and those
having their phenotypes near the average the population
there are selected for reproduce.
selection favor's two diverse types at a time and
eliminating the individuals with intermediate phenotypic
values.
17. Thus individuals of intermediate phenotypes
(heterozygotes) are at a selective disadvantage relative to
those of both extremes.
Disruptive selection is the selection for the tails of a bell-
shaped statistical distribution and once it is started in the
population it then becomes directional selection of
opposite side in the two resulting populations.
This type of selection result in little change in the
phenotypic/breeding values or gene frequencies in the
next generation.
18. 3. STABILIZING SELECTION
This is also called as centripetal selection on balanced
selection.
This is third type of selection when the individuals with
intermediate phenotypes (having their phenotype values
near the population mean) are selected the parents of
progeny generation and those having extreme
phenotypes on either side are not allowed to reproduce.
This does not change the mean of the progeny generation
and to some extent reduces the variance.
19. The phenotype breeding value and the gene frequency of
progeny generation under this type of selection are near
the average because the parents selected were also near
the average There is no decrease in phenotypic variance
when the selection of replacements is entirely random,
The effect of birth weight on infant mortality is an
example of stabilizing selection.
This selection operates contrary to directional selection.
This selection favours heterozygotes.