The document discusses evolution and how it occurs through various processes. Fossil records provide evidence of evolution by showing how organisms have changed over time as new species developed. Darwin's theory of evolution by natural selection explains how organisms compete for resources and favorable variations are more likely to be passed on, leading to the emergence of new species over generations. The document also discusses different types of evolution like microevolution within species and macroevolution between species or higher taxa.
This presentation is uploaded by Mahar Tanvir ul Hassan Tibbi Tarhana Samandry Faisalabad Pakistan. I am enrolled in University of Sargodha in MSc Zoology.
This presentation is uploaded by Mahar Tanvir ul Hassan Tibbi Tarhana Samandry Faisalabad Pakistan. I am enrolled in University of Sargodha in MSc Zoology.
Moving gradually but with the brute force of a tsunami, the natural movement is flowing through every aisle in every store near you, churning up tough questions for every growth-minded consumer-facing business and its innovation efforts.
In our newest white paper, we examine this movement and how we believe it will impact businesses globally.
Is macroevolution simply “microevolution over very long periods of t.pdfarishmarketing21
Is macroevolution simply “microevolution over very long periods of time?” What processes or
events become very important at the macroevolutionary scale, where the fossil record gives
evidence of different species, genera, families, and higher taxa replacing others?
Solution
It is not macroevolution simply “microevolution over very long periods of time but
microevolution is leading to macroevolution and speciation over very long periods of time.
\"Gradualism and the primacy of natural selection followed by Speciation and genome
reorganization due to genetic drift\" are the processes or events that become very important at the
macroevolutionary scale, where the fossil record gives evidence of different species, genera,
families, and higher taxa replacing others. For example, micro-evolutionary changes that
accumulate within two organisms of opposite sex may cause macro-evolutionary changes in the
offspring produced by their mating. The offspring greatly varies genetically from their parents
and is special enough to result in speciation; this is called “macroevolution.”
In Darwin\'s theory, the microevolutionary changes observed in the phenotypic features of the
“finches”, beaks, tortoises and coral reefs that are observable during a scientist’s lifetime provide
support for Darwin’s view that all life is connected in a branching pattern of phylogenetic tree.
According to Darwin, natural selection including genetic variations is leading to “branching
pattern” in the origin of species. He concluded in his lifetime microevolutionay observation base
on gradualism of species evolution with “branching interrelationships” among all living beings
by meticulous “metaphor of branching pattern” as described below.
Darwin’s theory of gradualism and evolution:
Darwin uses Gradualsim and he proposed that the gradual changes associated with variations of a
species through evolution to get adapted to the present ecosystem with no much transitional
forms. Human evolution based on the gradualism and their adaptations are extremely complex.
Initially in the gradualism, natural selection operates to obtain specific traits according to biome,
ecosystem because of large-scale events followed by formation of rivers, water availability and
habitat formation. Humans did not evolve from primates until just 7 million years ago; while life
appeared on earth 3.5 billion years ago. Humans are well adapted for the environment and
developed their adaptation features as per interspecific and intraspecific genetic variations. If the
evolution time-line compressed to a calendar year, the first organism would appear around
March and Humans would not appear until December 31.
Darwin has developed a meticulous scientific theory about the exact biological evolution of a
species and he explained the evolution of modern species over a long period from a common
ancestor base on morphological convergent & divergent features as explained below.
Descent with modification from a common ance.
The history of life is very ancient, that is, millions of years. During such a long period of time, innumerable species continued to occur. How come there is so much variety in it? Where did it come from? Some of what is produced is destroyed, and some that is (and still is!) Grows from one type of organism to another. The similarities between the two are sometimes significant and some are not. If the speed of some transitions is too slow to breathe The rush to change for just a few days! Some live in a certain area and some are so widespread everywhere! How did this gigantic mountain range of biodiversity come to be? Why produce diversity? When and how fast? What are the pressures in nature for such changes to take place? What is the nature of these pressures? What is their strength? Answers to such questions are not always found in descriptive and categorical systems.
1. Evolution is define as the process by which
new types of organisms develop from other
existing organisms, for example amphibians
evolved from fish.
2. Main sources of evolution are the following
Fossil records
Structural similarities
Development of embryo
Biochemical similarities
3. Plants and animals that lived million years
ago are no longer exist today. These plants
and animals are extinct, fossils of this plant
and animals are recorded, fossils are
preserved remaining's of living organisms
found in rocks.
Fossils can also tell us about ancient climate
and environment, for example if
paleontogist-scientists who study fossils-find
fossil of animals such as fish and amphibians
that live in or near water, they know that
that area was covered with water
4. Fossils are formed in sedimentary rocks,
these rocks form as a result layers of sands
and clay pilling up on the seabed or the
bottoms of inland lakes and seas, sediments
builds over the dead plants and animals.
All fossils forms when dead plants and
animals become covered with a substance
that exclude oxygen. The particles of
minerals in the bones or shell move into the
surrounding rock, and the particles of silica
in the rocks move into the bones, causing the
bones to change into crystalline substance.
5. Sometimes if the layers of sediments are
deposited over the dead organism very
quickly, you can sea the outline of the
organism that was formed before its tissue
decompose away. Most plant fossils form in
this way, an example of fossil is shown on the
picture below.
6. According to calculations of scientists the
earth is about 4 500 million years old. From
fossil evidence it seems that the first life on
earth is 3 800 million years ago and the first
living things were very small and simple.
8. Fossilrecords also show us how living
organisms have changed and developed over
time. When scientists study the fossil record
they look for similarities and differences in
the type, origin and functions of body
structures. This is one way in which they get
clues as to relationships that exist between
extinct fossil species and living species.
Some body structures are analogous
structures, which means same function in
different species but developed
independently.
9. Lamarck’s theory of evolution
• According to Lamarck, evolution occurs when the
characteristics an organism acquire during its
lifetime are passed on its offspring. In this way
organisms were able to change from generation
to generation. Lamarck believe that if certain
organs were used more often they would become
more developed and if organs were not used
more often they would eventually disappear.
Lamarck’s best known example is giraffe’s neck.
He argued that giraffes have long neck because,
for many generations, they stretched their necks
to reach leaves on high branches of tree, its
neck would get longer.
10. Lamarck then suggest that if giraffes repedeately
stretched its neck to reach leaves high up on a tree,
its neck would get longer and giraffes will pass on
this acquired characteristics to its offspring
therefore giraffes will develop long necks.
Figure 1.3
Lamarck theory of evolution about giraffes
11. Darwin’s theory of evolution
According to Charles Darwin organisms are
competing for resources, any variation in an
organism faivour survival in a particular
environment, this will increase a chances of
reproducing and leaving fertile offspring,
organisms with less favourable variation are less
likely to and leave offspring. This means more
favourable variations are transferred to future
generation and as time goes, variation within
individual species increase, it result to a new
species. The theory of natural selection is
referred to as survival of the fittest.
12. Biological evolution is the evolution which
result in a change in frequency of some
alleles in a population over time, allele is
two or more different forms of a gene. New
allele can be formed by means of mutation.
The proportion of a particular allele in a
population is called the allelic frequency,
and it is a measure of genetic diversity.
13. Evolutionis divided into two types which is
microevolution and macroevolution. The
difference between the two is that
microevolution involve evolutionary change
within individual members of the same
species, while macroevolution involve change
on a large scale, such as within families or
organisms.
14. Small changes in populations of organisms lead
to the development of new species. For example
two wild flower populations that grow on two
separate side of the mountain. Population will
be different, it can be on pollination.
The formation of new species is called
speciation, there are two types of speciation
which is allopatric speciation-occurs when a new
species forms when the populations are
physically or geographical separated from one
another. Sympatric speciation occurs when a new
species forms when populations are not
physically or geographically separated from one
another.