Trends in evolution by faunafondness

TOPIC :- TRENDS IN EVOLUTION
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SYNOPSIS
1. INTRODUCTION
( DEFINITION OF EVOLUTION)
2.TRENDS IN EVOLUTION
3. DEFINITION OF MOLECULAR EVOLUTION
4.GENE EVOLUTION
*Mutation
*Horizontal gene transfer
*Sexual reproduction
5.EVOLUTION OF GENE FAMILIES
(Kind of gene families)

* Gene duplication
*Gene conversion
6. ASSESMENT OF MOLECULAR EVOLUTION
*Natural selection
* gene flow
* Genetic drift
7. CONCLUSION
8. REFERENCES

EVOLUTION
Evolution in change over time
Or we can say
Evolution is a process by which modern organism have descended
from ancient organism.
or
Development of organism from earlier forms.

TRENDS IN EVOLUTION
An evolutionary trend can be either directional change within a single
lineage or parallel change across lineages, in other words, several
lineages undergoing the same sort of change. However, not just any
change counts as a trend. After all, if the weather gets warmer one
day, you wouldn't call it a warming trend; warming would have to go
on for some length of time before you'd call it a trend. Biologists think
about evolutionary trends in the same way — there has to be
something about the change that suggests that it's not just a random
fluctuation before it counts as a "trend."

•For example, titanotheres (a cool, extinct clade
related to modern horses and rhinos) exhibit an
evolutionary trend. Titanotheres had bony
protuberances extending from their noses. The
sequence of fossil skulls from these animals shows
that evolutionary changes in the size of these
"horns" were not random; instead, changes were
biased in the direction of increasing horn size. And in
fact, several different titanothere lineages
experienced the same sort of change in horn size.

EVOLUTIONARY TRENDS IN GIRAFFE NECK

MOLECULAR EVOLUTION
• Molecular evolution is the process of change in the sequence
composition of cellular molecules such as DNA, RNA, and proteins across
generations.

Gene evolution
• A gene is the basic physical and functional unit of heredity.
GENE EVOLUTION :
• Genome evolution is the process by which a genome changes in
structure (sequence) or size over time. The study of genome evolution
involves multiple fields such as structural analysis of the genome, the
study of genomic parasites, gene and ancient genome
duplications, polyploidy, and comparative genomics. Genome evolution
is a constantly changing and evolving field due to the steadily growing
number of sequenced genomes, both prokaryotic and eukaryotic,
available to the scientific community and the public at large.

GENE EVOLUTION
1. MUTATION
2. HORIZONTAL GENE TRANSFER
3. SEXUAL REPRODUCTION

MUTATION
• Mutation is a change in DNA, the hereditary material of life. An
organism's DNA affects how it looks, how it behaves, and its
physiology — all aspects of its life. So a change in an organism's DNA
can cause changes in all aspects of its life.
• Mutations are random
Mutations can be beneficial, neutral, or harmful for the organism, but
mutations do not "try" to supply what the organism "needs." In this
respect, mutations are random — whether a particular mutation
happens or not is unrelated to how useful that mutation would be.
• Not all mutations matter to evolution
Since all cells in our body contain DNA, there are lots of places for
mutations to occur; however, not all mutations matter for
evolution. Somatic mutations occur in non-reproductive cells and
won't be passed onto offspring

2. HORIZONTAL GENE TRANSFER
• The movement of genetic material between two organisms. Once
incorporated it is then ‘vertically’ inherited.
• Also called Lateral Gene Transfer.
• HGT and LGT for short.

• Process in which an organism incorporates genetic material from
another organism without being its offspring Common in bacteria
and Achaea, rare in eukaryotic cells Genetic information transferred
via conjugation, transduction, and translation.

• Transformation, the genetic alteration of a cell resulting from the
introduction, uptake and expression of foreign genetic material
(DNA or RNA). This process is relatively common in bacteria, but less so
in eukaryotes. Transformation is often used in laboratories to insert
novel genes into bacteria for experiments or for industrial or medical
applications. See also molecular biology and biotechnology.
• Transduction, the process in which bacterial DNA is moved from one
bacterium to another by a virus (a bacteriophage, or phage).
• Bacterial conjugation, a process that involves the transfer of DNA via a
plasmid from a donor cell to a recombinant recipient cell during cell-to-
cell contact.
• Gene transfer agents, virus-like elements encoded by the host that are
found in the alphaproteobacteria order Rhodobacterales

3. SEXUAL REPRODUCTION
Sexual reproduction is a form of reproduction where two different type
of specialized reproductive cell called gamete fuse together.
It has been described powerful evolutionary that does not exist in
asexual population.

EVOLUTION OF GENE FAMILIES
• A gene family is a group of genes that share important characteristics
• In many cases genes in a family share a similar sequence of DNA
building blocks.
• These gene provide instruction for making product that have similar
structure and function.
• All the genes which are originated from same ancestor .

Formation of gene family
• Gene duplication
• Gene conversion
Gene duplication
Gene duplication (or chromosomal duplication or gene amplification)
is a major mechanism through which new genetic material is
generated during molecular evolution. It can be defined as
any duplication of a region of DNA that contains a gene.

What is the role of gene duplication in evolution?
• Gene duplication is an important mechanism for acquiring
new genes and creating genetic novelty in organisms. ... Gene
duplication can provide new genetic material for mutation, drift and
selection to act upon, the result of which is specialized or new gene
functions.

Gene conversion
• Gene conversion is the process by which one DNA sequence replaces
a homologous sequence such that the sequences become identical
after the conversion event. Gene conversion can be either allelic,
meaning that one allele of the same gene replaces another allele,
or ectopic, meaning that one paralogous DNA sequence converts
another.

ASSESMENT OF MOLECULAR VARIATION.
• Molecular markers have ability to detect genetic variation and
provide a reliable method to ensure the integrity of cultivars genetic
constitution.
• Heritable variation within and between population of organism.
• Encoded in the sequence of four base pair that makes up DNA

Evolutionary process
• 1. NATURAL SELECTION
• 2. GENE FLOW
• 3.GENETIC DRIFT

NATURAL SELECTION
• The process whereby organisms better adapted to their environment
tend to survive and produce more offspring. The theory of its action
was first fully expounded by Charles Darwin, and it is now regarded
as be the main process that brings about evolution.

GENE FLOW
In population genetics, gene flow (also known as gene migration or allele flow)
is the transfer of genetic variation from one population to another. If the rate
of gene flow is high enough, then two populations are considered to have
equivalent genetic diversity and therefore effectively be a single population.

GENETIC DRIFT
• variation in the relative frequency of different genotypes in a small
population, owing to the chance disappearance of particular genes as
individuals die or do not reproduce.

CONCLUSION
• Evolution is change in the heritable characteristics of biological
population over successive generation.
• Molecular evolution is change in the sequence of molecule of cell.
• Evolutionary genetics is study where how change in genes leads to
change.
• Molecular markers have ability to detect genetic variation.

REFERENCE
• VEER BALA RASTOGI – BOOK OF EVOLUTIONARY BIOLOGY
• P.S VERMA AGARWAL – CELL BIOLOGY

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