The gene pool refers to the total collection of genes and genetic variants within an interbreeding population. It can change over time through mechanisms like mutation, natural selection, and genetic drift in response to environmental pressures. Larger, more diverse gene pools may help populations better adapt to changing conditions, while smaller pools with less variation could hinder adaptation. Genetic variation within a population is measured by the number and frequencies of different gene alleles present.

1.  Populations are made up of members of the
same species that interbreed.
 Variation naturally occurs among the genes
within a population.
 The collection of all the genes and the various
alternate or allelic forms of those genes
within a population is called its gene pool.

2. The gene pool is the set of all genes, or genetic
information, in any population
It is the sum of a population’s genetic material
at a given time
includes all genes and combinations of genes
(sum of the alleles in the population)
The combination of all of the versions of all of
the genes in a species is called the gene pool of
the species.

3.  The composition of gene pool can change
over time through evolution
 can occur by a variety of mechanisms,
a. mutations,
b. natural selection,
c. genetic drift
 The results is a gene pool altered according
to the needs of the population’s specific
environment.

4.  The ability of a population to adapt and
evolve is thought to be influenced in part by
the size of its gene pool.
 A large and diverse gene pool, may improve a
population’s chances for future adaptation to
changing environmental conditions.
 populations with smaller, narrower gene
pools, on the other hand, may be less
successful when confronted with swift
environmental change.

5.  Genetic variation within a population is
measured according to the number of
different alleles of all genes and the
frequency with which they appear.
 Variation is high when there are many
different allelic forms of all genes and when
there are many different combinations of
those alleles.

6.  However, genetic variation is constantly
changing. Different allelic forms of a single
gene can appear and disappear from time to
time within a single group of organisms.
 This means that the gene pool of a
population is dynamic and can change at any
moment for a variety of reasons. In addition,
the rate of change within a gene pool can
vary at different points in time.

7.  Scientists, however, cannot always determine
which alleles are present in a population
based on phenotypes of the organisms that
comprise it
 Some phenotypes associated with certain
alleles are masked or deemphasized when
other alleles are present

8.  Hence, a gene pool is a collective set of
alleles whose phenotype may or may not be
observable.

9.  Genetic variation within three
butterfly species. Three different
butterfly species (top row) show
distinct wing colors and patterns.
When individuals from the same
three species are born in a different
season, they each show different
wing color and pattern phenotypes
(bottom row). This is a reflection of
the variation that exists in the gene
pool.

10.  The differences in wing colors and patterns
reflect the underlying genetic variability
 The gene pool of each species, therefore,
contains a collection of many different alleles
whose phenotype may or may not be
observable.

11.  Over time, a population's gene pool may
change. The factors accounting these
changes include
a) migration of new individuals into the
population
b) death of a large number of individuals
within the population
c) or environmental factors that favour certain
traits over others.

12.  Over time, the size of a gene pool changes.
The gene pool increases when a mutation
changes a gene and the mutation survives
 The gene pool decreases when an allele dies
out.

13.  There is a population of 1,000 fruit flies in a
jar
 At locus 1 on chr1, we might identify 20
different alleles
 Those 20 alleles are the gene pool for that
locus.
 The set of all alleles at all loci is the full gene
pool for the species.

14.  Suppose we selected 5 of them
 These 5 may possess only 3 alleles at locus 1.
 Then let them breed to 1,000,
 the gene pool is now 3 instead of 20

15.  small gene pool is bad for a species because
it reduces variation.
 Suppose there are 20 alleles at locus 1
 1 of those alleles causes a disease in
homozygous
 The probability of a fly getting two copies of
that harmful allele is relatively small.

16.  If bad allele survives when the gene pool
shrinks to 3 alleles
 the probability of flies getting the disease
from that allele becomes much larger
 A large gene pool provides a good buffer
against diseases like
a) Infertelity
b) Deformaties
c) Genetic diseases

17.  This is exactly what happens when a species
faces extinction.
 The total population dwindles down to the
point where there might be just 100 or 1,000
surviving members of the species.
 In the process, the number of alleles at each
locus shrinks, and the gene pool of the
species contracts significantly.

18.  the mating of organisms that are closely
related through common ancestry
 is useful in the retention of desirable
characteristics
 or the elimination of undesirable ones
 the combined effect of harmful genes that
were recessive in both parents.

19.  Useful in live stock breeding and plant
breeding through Selective breeding
a) Self fertilization
b) Back cross
c) Self crosses

20.  results in homozygosity leading
to recessive or
 decreased biological fitness of
a population (inbreeding depression)
 Reduced biological fitness

21.  Autosomal recessive disordrs
 Mostly disease alleles are recessive
 Recessive alleles are rare
 2 recessive partners, 25% chances of
homozygous off spring
 Natural selection
 Spontaneous abortions
 Birth defects
 Mental defects

22. Isolated populations don’t randomly mate
e.g Island communities
High inbred populations may lead to a new
race or even speciation

23.  which is the mating of unrelated organism