PCZO100 — FOUNDATIONS OF ZOOLOGY (LECTURE)
MODULE 4 — Concepts of Evolution
LESSON 1 — HISTORY OF EVOLUTION
•
Organic evolution – defined by Charles Darwin as “descent with
modification” (the idea that species change over time, give rise to
new species, and share a common ancestor).
PRE-DARWINIAN THEORIES OF CHANGE
•
•
•
•
Empedocles and Aristotle
— Living organisms undergo changes through time
Georges-Louis Buffon
— Specific organs of related animals have structural variations
— Change in organisms is brought about by actions of the
environment
— There is a special creation of species, so change is degenerate
(e.g., apes as degenerate humans)
Erasmus Darwin
— All organisms share a common ancestor
Jean Baptiste Lamarck (1744–1829)
— French naturalist who offered the first scientific explanation of
evolution
— He based his theory on the widely accepted theory of
inheritance during his time wherein need is the driving force to
develop new organs or modify existing organs, otherwise
disuse leads to the degeneration of organs (evolution proceeds
by inheritance of acquired characteristics)
— He concluded that species could not become extinct but that
they simply evolve into different species
— However, his theory has been rejected and replaced by neoDarwinian theories
SOURCES OF EVIDENCE FOR MACROEVOLUTION
(1)
Biogeography
the study of the geographic distribution of plants and animals
evolutionary histories are unique to particular life-forms
geological events such as volcanic eruptions, continental drift,
climate change, and mountain building can create and remove
barriers to the movement of plants and animals
the world is divided into six major biogeographic regions:
1) Palearctic region
2) Nearctic region
3) Ethiopian region
4) Oriental region
5) Neotropical region
6) Australian region
(2)
Paleontology
the study of ancient life
focuses on the fossil record
fossils are evidence of past plants and animals that became
part of the Earth’s crust
the fossil record presents the sequences of appearances and
disappearances of organisms
LESSON 2 – DARWIN’S THEORY OF EVOLUTION
THEORY OF EVOLUTION BY NATURAL SELECTION
(Modern Version of Darwin’s Theory)
1.
2.
3.
4.
Greater reproductive potential is an attribute of all organisms
There is an occurrence of inherited variations
o
Inherited variations result from mutation, genetic recombination,
and random fertilization
o
Genetic variations can either be helpful, harmful, or neutral to
the individual and eventually passed on to offspring
Survival is a constant struggle due to inadequate resources
In succeeding generations, adaptive traits are commonly observed
o
Adaptive traits encourage successful reproduction while
maladaptive traits are less likely to reproduce, so in the
population, it has decreased recurrence
LESSON 3 – EVIDENCE OF EVOLUTION
•
•
Microevolution – alleles' rate of recurrence changes through time
which eventually leads to large-scale changes
Macroevolution – large-scale changes whose consequence is
extinction and formation of new species
Page 1
PCZO100 — FOUNDATIONS OF ZOOLOGY (LECTURE)
MODULE 4 — Concepts of Evolution
(3)
•
•
•
(4)
Analogy and homology
Analogous structures
brought about by convergent evolution
similar structures in organisms that are not related
example: wings (with flat and gliding surfaces) of birds and
insects
Homologous structures
similar structures and processes in two kinds of organisms with
a shared ancestry
example: wings of bats and arms of primates
Comparative anatomy
emphasizes the structure of living and fossilized animals and
their homologues
example: common arrangement of bones in vertebrate
appendages
(5)
Molecular biology
the study of the molecular basis of biological activity
genetic change and evolution leads to changes in anatomical
structures and physiological processes
Transes by Cyfert B. Francisco (BSMT1G)
Bachelor of Science in Medical Technology | Centro Escolar University
First Year | First Semester—Learning Term 1
Developmental patterns
common features are kept in the developmental stages of
related animals
example: similar early embryonic stages of vertebrates
Page 2