continental drift and theory of tolerance

It have all the information related to two concept of ecology ie continental drift theory and theory of tolerance

1. PPT by- Yajush Mishra
Roll no- 2234151
Continental Drift and Theory of Tolerance
Submitted to- Dr. Archana Singh and Dr. Ram
Babu Shrivastava

2. Introduction to Continental
Drift
Abraham Ortelius, a Barbantian cartographer also known
as the creator of modern altlas was the first to underline
the geometrical similarity between the coasts of America
and Europe-Africa and proposed Continental drift as an
explanation.
The Continental Drift theory refers to the movement of the
Earth's continents relative to each other, appearing to
'drift' across the ocean bed.
This theory is published in the book, ''Origin of Continents
and Oceans'' by Alfred Wegener.

3. Wegener's Theory of Continental Drift
German meteorologist Alfred Wegener proposed the continental
drift theory in 1912.
Wegener proposed that all continents were once part of a
supercontinent called Pangaea, which began breaking apart
about 200 million years ago. Pangaea eventually split into two
large landmasses, Laurasia in the north and Gondwanaland in the
south, which then further fragmented into the continents we see
today.
Wegener noted the jigsaw-like fit of the continents' coastlines,
particularly the matching between South America and Africa.
Despite facing skepticism from the scientific community at the
time, Wegener's ideas laid the groundwork for modern theories of
plate tectonics.

5. Evidences for Continental Drift
1-Fossil evidence-
Fossils of identical plant and animal species have
been found on continents that are now separated
by oceans, suggesting that these landmasses
were once connected.
Before Pangea broke apart, similar layers of rocks
were formed in Anatarctica, Australia, South
America, Africa and India. Glossopteris fossils
were found in the rocks on each continent.
2- Rock formation -
Rock formations on different continents often
match up when the continents are pieced
together like a puzzle. For example the
Appalachian mountains in the US are similar to
Greenland and Scotland.

6. Evidences for Continental Drift
3- Paleoclimatic evidences-
Paleoclimatic evidence refers to geological
evidence that provides insights into past climate
conditions on Earth.
It was siad that the earth`s climate has not
changed instead the positions of the continents
have changed.
Glacial deposits, such as moraines, till, and glacial
striations, are found in regions that are now far
from modern glaciers, indicating that these areas
were once covered by ice sheets.

7. Lack of Mechanism: One of the main reasons for the rejection of
Wegener's theory was the lack of a plausible mechanism to explain how
continents could move across the Earth's surface or what forces moves
the continents. Wegener suggested that continents plowed through the
oceanic crust, but he couldn't provide a satisfactory explanation for the
mechanism driving this movement.
Limited Geological Evidence: Although Wegener presented compelling
geological evidence to support his theory, including matching rock
formations and fossil distributions across continents, some scientists
argued that the evidence was not conclusive
Disciplinary Boundaries: Wegener's background in meteorology and lack
of formal training in geology may have contributed to the skepticism
surrounding his theory. Many geologists viewed Wegener as an outsider
to their field and were reluctant to accept ideas from someone outside
the discipline.
Wegener's theory laid the groundwork for modern Plate Tectonics
Theory.
Rejection of Continental Drift theory

8. Introduction to Theory of Tolerance

9. Theory of Tolerance
Shelford's law of tolerance is a principle developed
by American zoologist Victor Ernest Shelford in 1911.
Shelford's law of tolerance states that an organism’s
success is based on a complex set of conditions and
that each organism has a certain minimum,
maximum, and optimum environmental factor or
combination of factors that determine success.
According to the law of tolerance, populations have
optimal survival conditions within critical minimal
and maximal thresholds.
•As population is exposed to the extremes of a
particular limiting factor, the rates of survival begin
to drop.

10. Components of Law of Tolerance
Shelford's Law of Tolerance consists of two main components:
1-Law of Minimum: The single factor in least supply relative to demand will be the
limiting factor for an organism's growth and reproduction. This concept highlights the
importance of identifying the most limiting environmental factor in a given ecosystem.
2-Law of the Maximum: Too much of an environmental factor can limit an organism's
ability to survive and reproduce. This principle underscores the idea that excess of
environmental factors can be detrimental to organisms.
Examples of Shelford's Law of Tolerance can be found in various ecosystems and for
different organisms like Aquatic organisms have specific temperature tolerance
limits, beyond which they may experience physiological stress or mortality.
Soil microorganisms have pH tolerance limits, with some species thriving in acidic
soils while others prefer alkaline conditions.

11. Graph for Law of Tolerance
The distribution of a species in response to a limiting
factor can be represented as a bell-shaped curve with
three distinct regions:
1. Optimal zone: Central portion of curve which has
conditions that favour maximal reproductive success
and survivability.
2. Zones of stress: Regions flanking the optimal zone,
where organisms can survive but with reduced
reproductive success.
3. Zones of intolerance: Outermost regions in which
organisms cannot survive (represents extremes of the
limiting factor.

12. References
https://www.researchgate.net/figure/Graphical-representation-of-
Shelfords-Law-of-Tolerance_fig4_287972756
https://www.oxfordreference.com/display/10.1093/acref/97801917931
58.001.0001/acref-9780191793158
Textbook of ecology by N.V Subrahmanyam.
https://www.sciencedirect.com/topics/social-sciences/continental-
drift
https://www.britannica.com/science/continental-drift-geology