Genotype – environment –microenvironment and macro-environment – classification of environmental variation – genotype × environment interaction – adaptation – types of adaptation – adaptability – stability – models for stability analysis.

1. GENOTYPE,
ENVIRONMENT
AND
THEIR INTERACTION
PREPARED BY:
MONALISA SAHU
ADM. NO. 43C/14
3RDYEAR, B.SC.AG

2. GENOTYPE
 The genotype is the part (DNA sequence) of the
genetic makeup of a cell, and therefore of an
organism or individual, which determines a
specific characteristic (phenotype) of that
cell/organism/individual. Genotype is one of three
factors that determine phenotype, the other two
being inherited epigenetic factors, and non-
inherited environmental factors. DNA mutations
which are acquired rather than inherited, such as
cancer mutations, are not part of the individual's
genotype; hence, scientists and physicians
sometimes talk for example about the genotype of
a particular cancer, that is the genotype of the
disease as distinct from the diseased.

3. ENVIRONMENT
 Environment is what is around something. It can
be living or non-living things. It includes
physical, chemical and other natural forces.
Living things live in their environment. They
constantly interact with it and change in response
to conditions in their environment. In the
environment there are interactions between
animals, plants, soil, water, and other living and
non-living things.
 Types of environment
(a)Micro environment
(b)Macro environment

4. MICRO ENVIRONMENT
 Microenvironment known as a microhabitat, a very small,
specific area in a habitat, distinguished from its immediate
surroundings by factors such as the amount of incident
light, the degree of moisture, and the range of
temperatures.
 The environment of a single plant or organism as opposed
to that of another growing at the same time in almost the
same place is known as micro environment.
 Each member of a population is subjected to a specific
environment of its own.
 The individual itself contributes to its environment by way
of maintaining a certain level of temperature and humidity
around it.
 This micro environ differ from one individual to another
in a pop. And includes solar radiation, disease and pest
incidence and soil factors and weather fluctuations.

5. MACRO ENVIRONMENT
 The environment associated with variables
having large and easily recognizable effect
is termed as macro-environment and may
include differences over years, locations
(latitude / altitude) fertilizer levers, planting
dates, irrigation schedules etc.
 A macro environment can be reviewed as a
collection of micro environments whose
individuals effects on organism are quite
small.

6. CLASSIFICATION OF ENVIRONMENTAL VARIATION
 Allard and Bradshaw (1964) : classified the
environmental variation into two types:
1. Predictable
2. Unpredictable variations.
Predictable component variations : Predictable component
variations include all the permanent attributes features of the
environment, such as climate, edaphic factors (soil types),
day length (photo period), agronomic practices such as
planting dates, plant density, water management, fertilization
etc.
Unpredictable variations / component : All the uncontrollable
actors i.e. it include fluctuations, mild or violent, in weather /
season / year with respect to annual precipitation (rainfall),
te- mperature, relative humidity, etc. coupled with variant
agronomic practices.

7. GENOTYPE-ENVIRONMENT
INTERACTION
 Gene–environment interaction (or genotype–
environment interaction or G×E) is when two
different genotypes respond to environmental
variation in different ways. A norm of reaction is
a graph that shows the relationship between genes
and environmental factors when phenotypic
differences are continuous. They can help
illustrate GxE interactions. When the norm of
reaction is not parallel, as shown in the figure
below, there is a gene by environment interaction.
This indicates that each genotype responds to
environmental variation in a different way.
 PHENOTYPE=GENOTYPE x ENVIRONMENT

8. This norm of reaction shows lines that are not
parallel indicating a gene by environment
interaction. Each genotype is responding to
environmental variation in a different way.

9.  Gene–environment interactions are studied to gain
a better understanding of various phenomena. In
genetic epidemiology, gene-environment
interactions are useful for understanding some
diseases. Sometimes, sensitivity to environmental
risk factors for a disease are inherited rather than
the disease itself being inherited. Individuals with
different genotypes are affected differently by
exposure to the same environmental factors, and
thus gene-environment interactions can result in
different disease phenotypes. For example,
sunlight exposure has a stronger influence on skin
cancer risk in fair-skinned humans than in
individuals with darker skin.

10. VARIATION IN RELATIVE PERFORMANCE OF GENOTYPES IN DIFFERENT
EVVIRONMENTS

11.  There are two different conceptions of gene–environment interaction.
Tabery has labeled them biometric and developmental interaction, while
Sesardic uses the terms statistical and commonsense interaction.
 The biometric (or statistical) conception has its origins in research
programs that seek to measure the relative proportions of genetic and
environmental contributions to phenotypic variation within populations.
Biometric gene–environment interaction has particular currency in
population genetics and behavioral genetics. Any interaction results in the
breakdown of the additivity of the main effects of heredity and
environment, but whether such interaction is present in particular settings
is an empirical question. Biometric interaction is relevant in the context of
research on individual differences rather than in the context of the
development of a particular organism.
 Developmental gene–environment interaction is a concept more
commonly used by developmental geneticists and developmental psycho
biologists. Developmental interaction is not seen merely as a statistical
phenomenon. Whether statistical interaction is present or not,
developmental interaction is in any case manifested in the causal
interaction of genes and environments in producing an individual's
phenotype.

12. Examples:- Mean Bristle Number by °C
1. In Drosophila: A classic example of gene–environment
interaction was performed on drosophila by Gupta and
Lewontin in 1981. In their experiment they demonstrated that
the mean bristle number on drosophila could vary with
changing temperatures. As seen in the graph to the right,
different genotypes reacted differently to the changing
environment. Each line represents a given genotype, and the
slope of the line reflects the changing phenotype (bristle
number) with changing temperature. Some individuals had an
increase in bristle number with increasing temperature while
others had a sharp decrease in bristle number with increasing
temperature. This showed that the norms of reaction were not
parallel for these flies, proving that gene-environment

13. 2. In plants: Seven genetically distinct yarrow
plants were collected and three cuttings taken
from each plant. One cutting of each genotype
was planted at low, medium, and high elevations,
respectively. When the plants matured, no one
genotype grew best at all altitudes, and at each
altitude the seven genotypes fared differently. For
example, one genotype grew the tallest at the
medium elevation but attained only middling
height at the other two elevations. The best
growers at low and high elevation grew poorly at
medium elevation. The medium altitude produced
the worst overall results, but still yielded one tall
and two medium-tall samples. Altitude had an
effect on each genotype, but not to the same

14. ADAPTATION
 In biology, adaptation has three related meanings.
Firstly it is the dynamic evolutionary process that
fits a population of organisms to their
environment, enhancing their evolutionary fitness.
Secondly, it is a state reached by the population
during that process. Thirdly, it is a phenotypic or
adaptive trait, with a functional role in each
individual organism, that is maintained and has
been evolved by natural selection.
 It is the capacity of genotypes to adjust
themselves in a specific or particular
environmental condition, so as to reach a certain
level of phenotypic expression.

15. TYPES OF ADAPTATION
1. Morphological adaptation :
Growth habit, stalk strength, radial symmetry of
rhizome etc.
2. Physiological adaptation :
Resistance to parasites, greater ability to
compete for nutrients or to stand desiccation.

16. ADAPTABILITY
 Organisms face a succession of environmental
challenges as they grow, and show adaptive
plasticity as traits develop in response to the
imposed conditions. This gives them resilience
to varying environments.
 It is the ability of a genotype to produce a
relatively narrow range of phenotypes in
different environments. It is the result of
genetic homeostasis, refers to the buffering
capacity of a genotype to environmental
fluctuations.

17. STABILITY
 It refers to its performance with respective changing
environmental factors overtime within a given location.
This means that a stable variety is less sensitive to the
temporal environmental changes that may take place.
 Depending on the goal and on the character under
consideration, two different concepts of stability exist,
which are termed as the static concept of stability and as the
dynamic concept of stability (LEON 1985). Both concepts
of stability are valuable but their application depends on the
trait considered.

18.  With regard to the static concept a stable genotype's
possesses an unchanged performance regardless of any
variation of the environmental conditions. This stable
genotype shows no deviation from the expected character
level, that means its variance among environments is zero.
 Unlike this static concept, where a stable genotype has a
constant performance level, the dynamic concept permits a
predictable response to environments and a stable genotype
according to the dynamic concept has no deviation from this
response to environments. For each environment the
performance of a stable genotype corresponds completely to
the estimated level or the prediction. In the dynamic concept
of stability, it is not required that the genotypic response to
environmental conditions should be equal for all genotypes.
What is important, however, is the agreement of the
estimated or predicted level with the level of performance
actually measured when defining stability'. BECKER
(1981a) termed this type of stability the agronomic concept
and distinguished it from the biological concept of stability,
which is equivalent to the static concept.

19. MODELS FOR STABILITY
ANALYSIS
 1. Finlay and Wilkinson Model (1963)
 2. Eberhart and Russell Model (1966)
 3. Perkins and Jinks Model (1968)
 4. Freeman and Perkins Model (1971)

20.  STRINGHELD and SALTER (1934) were
probably the first to calculate a linear
regression coefficient to characterize the
specific response of genotypes to varying
climatic factors. This regression technique has
been described and elaborated by Y,ATES and
COCHRAN (1938), FINLAY and
WILKINSON (1963), EBERHART and
RUSSELL (1966) and PERKINS and JINKS
(1968).

21.  In addition to the coefficient of regression, the deviation
mean squares (S²di) describe the contribution of genotype
i to GE-interactions (EBERHART and RUSSEEE) 1966.
 FREEMAN (1973) recommends that the significance test
of regression coefficients should be based on individual
error terms rather than on pooled deviations because of
possible heterogeneity of deviation mean squares. In an
analysis of variance the GE interactions Can be
subdivided into a part due to heterogeneity of bi and a
remainder due to pooled deviations from regression
(FINLAY and WILKINSON 1963, PERKINS and JINKS
1968). Heterogeneity of bi does not reach significance, the
usefulness of the regression approach for interpretation of
the data is doubtful. For further significance tests see e.g.
EBERHART and RUSSEEE (1966), FREEMAN and
PERKINS (1971).

22. THANK YOU