Evidence and Pattern of Evolution Flashcards
are the useless remnants of structures or organs which were prominent and functional in ancestors.
These are often undersized, degenerated and nonfunctional. Man alone possesses nearly 100 vestigial structures.
Vestigial or rudimentay organs
in man is the remnant of caecum which is
large and functional in herbivorous mammals. It contains bacteria that produce the enzyme cellulase for the digestion of cellulose.
Vermiform appendix
are used in many mammals
for collecting sound waves from the surroundings. A complete set of muscles for their movements is present in the external ear of man but these muscles are nonfunctional.
Auricular muscles of external ear
What are the Vestigial Organs in Man
Vermiform appendix
Auricular muscles of external ear
Nictitating membrane or Plica semilunaris
Vestigial Tail Vertebrae
Lobe of the external ear
Wisdom teeth
Canines
Mammary glands in males
Body hair
is the third eyelid in the inner angle of each eye in man and many mammals. It corresponds to the nictitating membrane but it is completely unstretchable and nonfunctional.
Nictitating membrane or Plica semilunaris
Early embryo of man possesses an external tail but it is shed off much before the adulthood is attained. Rarely, a child may be born with a short visible tail. In adults the tail is represented by a string of caudal vertebrae, which constitute the coccyx (tail bone).
Vestigial Tail Vertebrae
is of no practical benefit to man ,
although serve d the purpose of sound gathering in the ancestors
of man.
Lobe of the External ear
are the third pair of molars. They are vestigial.
These are last to erupt or even fail to erupt.
Wisdom Teeth
in man are reduced due to taking soft food and noncarnivorous habit.
Canines
in humans are of no use and are vestigial remains.
Body hair
Vestigial Organs in Other Animals
Vestigial of Hindlimbs and Pelvic
Vestigial wings
Splint bones
Eyes in deep, dark habitats
is the reappearance of ancestral
characteristics in an organism or in the organisms of a group, which do not occur normally or which represent the reminiscent of normal structures possessed by the individuals of other groups
Atavism or reversion
the neck may possess an additional opening through which the throat or nasal cavity communicates with the exterior. This represents the opening of an additional pharyngeal pouch to the
exterior and is known as
Cervical Fistula in Man
It is devoid of vertebrae and is
removed by surgery with no trouble.
Tail
The same condition is noted in all the primates but in pigs, these occur in two rows one along either side of the chest and abdomen. Sometimes, extra-mammary glands or nipples appear in man.
Mammary glands
Man is characterized by scanty hair on the body and no hair on face but in the relatives of man (apes) hair are present profusely. A man was born in Russia with profuse development of hair on the face and body (Irish dogman).
Hair on the Body and Face in Irish Dogman
Types of Atavism
Family Atavism
Race Atavism
Atavism or Teratology
It includes sudden reappearance of a character or characters in the offspring after remaining latent in the family for several generations. This phenomenon is controlled at gene
level and can be explained by simple Mendelian laws of inheritance.
Family Atavism
It includes those cases of reversal where one or more characters of one race appear in the individuals of another race.
Race Atavism
This includes the appearance in a race of such abnormal characters which were normal in other supposedly ancestral races. The appearance of cervical fistula in man,
which actually corresponds to the gill-slit, or the appearance of external hindlimbs in a humpback
whale or the homodont dentition in piscivorous cetaceans are examples of teratology.
Atavism of Teratology
had noticed remarkable similarity
among vertebrate embryos, whose adults are markedly different
Von Baer
was impressed by the generalized pattern of
development and the general resemblances between the embryos of different groups of animals
Ernst Haeckel (1834-1919)
is the life history of an individual starting from ovum and phylogeny is the evolutionary history of the group
Ontogeny
which says “Ontogeny recapitulates phylogeny”.
Recapitulation Theory or Biogenetic Law
All start their life from a fertilized egg called
Zygote
It undergoes repeated cleavages and develops into
morula, blastula, and gastrula
Three germinal layers
ectoderm, mesoderm, and endoderm
refers to the degenerative changes wherein an active larva transforms into a sedentary adult. Adults of certain animals have degenerated features and do not show any resemblance with other animals of their group or any other group. But, their larval forms have helped in establishing their phylogenetic relationship
Retrogressive metamorphosis
It develops gonads, attains sexual maturity and starts reproduction. This is called
Neoteny or paedogenesis
The Recapitulation Theory was first proposed
by
Von Baer (1828)
every organism during its development recapitulates in an
abbreviated form the evolutionary history of its race. In
other terms, an organism repeats its ancestral history
during its development.
Recapitulation theory
is the study of fossil remains of plants and animals that
lived in the past.
Palaeontology
What is the Latin of “something to dug out”
Jossilum
are actual remains, traces or impressions left by the organisms that lived in the past and got preserved in sedimentary rocks. These include bones, teeth, shells and other hard parts of animals or impressions of plants pressed into shale or insects trapped in tree resin.
Fossils
called the ‘Father of Palaeontology’
Leonardo Da Vinci (1452-1519)
‘Founding Father of Modern Palaeontology’.
Cuvier (1800)
the process by which organic matter exposed to minerals over a long period is turned into a stony substance
Petrifaction
Types of Fossils
Unaltered remains of entire organisms
Petrified fossils (altered fossils)
Molds and Casts
Prints or Impressions
Coprolites
Under exceptionally
favourable conditions, the entire
animal body gets preserved in ice,
petroleum spring, asphalt, resin,
amber and oil-soaked ground.
Unaltered remains of entire organisms
are formed by the
replacement of organic parts of dead
and decaying organisms molecule by
molecule by minerals
Petrified fossils (Altered fossils)
Their bodies disintegrate leaving
hollow cavities, called
Molds
They get filled with natural deposits of minerals
which harden to form exact _______ of the original organism.
Cast
The footprints of animals or impressions of leaves,
stems, skin and wings, etc., left in soft
mud are preserved when it changes into
a rock.
Prints or Impressions
____________ of moving animals
left in the soft mud are preserved
when the soft mud hardens into
rocks, preserving the prints.
Footprints or tracks and trails
These are fossils of fecal
matter or droppings. These are found in
association with the animal fossils. Their
study may provide information
pertaining to their food habits.
Coprolites
is the study of distribution of animals and plants on Earth in
space and time .
Biogeogrpaphy
The study of geographical distribution of animals is called
Zoogeography
He divided the Earth surface into six biogeographical regions or life zones called realms based on the distribution of birds.
Philip Lutley Sclater (1858)
regions or life zones called
realms
e reorganized these biogeographical realms on the basis of the distribution of terrestrial and freshwater vertebrates
Wallace
Six biogeographical regions or life zones
Neartic
Palaearctic
Neotropical
Oriental
Ethiopian
Australian
Asia (south of the Himalayas including India, Sri Lanka, Malaya peninsula), Sumatra.
Borneo, Java, Celebes and Philippines.
Oriental
can be found in Protopterus in Africa
▫ Neoceratodus in Australia
▫ Lepidosiren in South America
Lungfishes
are found in Africa and India but not in places with identical
climate in Brazil.
Elephant
_______ or egg laying mammals occur only in Australian Island while marsupials, the pouched mammals are exclusively found in Australia, New Zealand and
South America.
Monotremes
is one which never had any connection
with the mainland. It is formed from submerged volcanic mountains which are pushed up above the surface of sea. On being exposed, the mountain peaks cool down providing a suitable surface for animals and plants that reached there.
Oceanic Island
The prominent inhabitants in Galapagos Island
Iguana
Giant Land Tortoise
Darwin’s Finches
While classifying animals, scientists come across certain animals or small animal groups which exhibit characteristics of more than one group. Such animals or animal groups are called
Connecting links
are a connecting link between nonliving and living
because they characteristics of both groups.
Viruses
a protozoan that has chlorophyll and chloroplasts like plants. It is
holophytic or autotrophic and synthesizes food by photosynthesis
Euglena
a colonial protozoan whose cells are similar to choanocytes or
collared cells of phylum Porifera.
Proterospongia
a connecting link between Annelida and Arthropoda because it exhibits characteristics of both phyla.
Peripatus
: belonging to class Monoplacophora of Phylum Mollusca. Its first living specimens were dredged from a depth of 3500 meters off the Pacific Coast of Costa Rica (Mexico)
Neopilina
The science of naming, describing and classifying organisms is known
Taxonomy
allowed the study of blood proteins that helped in
tracing phylogenetic relationships
Precipitation method
A method introduced by __________ called the
Precipitation Method allowed the study of blood proteins that helped in tracing phylogenetic relationships.
Dr. George H.F. Nuttal
When such molecular changes accumulate at a constant rate, the
phenomenon was called
Molecular clock
When such molecular changes accumulate at a constant rate, the
phenomenon was called molecular clock by
Zuckerandl and Pauling (1965)
The pattern of substitutions in the nucleotide sequences in
globin genes during the entire course of evolution can be laid down in the form of a phylogenetic tree. It represents the evolutionary history of the gene and it closely resembles to the evolutionary relationships predicted by anatomical studies
Phylogenetic trees
The essential component of nucleus in every living cell is the chromatin material or hereditary material that organizes into chromosomes during cell division.
Chromatin
As they are inherited from generation after generation, genes may
undergo changes producing
mutations and variation
assembled data from recent surveys conducted
in 32 European countries, the United States, and
Japan. All the polls had included this question:
True or False? Human beings, as we know them,
developed from earlier species of animals.
Jon D. Miller et al., 2006
Two models of the history of life on earth
Theory of Special Creation and Theory of Descent with Modification
species are immutable—unchanged since their origin—and
variation among individuals is limited.
▪ All species were created separately and are thus genealogically
unrelated to each other.
Special Creation
the first scientist to give a biological definition of species,
“One species never springs from the seed of another.”
John Ray (1686)
first published in 1859, convinced the scientific community that it
was true—that Earth’s species are the products of descent with modification from a common ancestor (Mayr 1964)
On the Origin by means of natural selection
The evidence—some of it presented by
Darwin, much of it accumulated since—has convinced
virtually all scientists who study life that Darwin was
right. Darwin called the pattern he saw
Descent with modification
Each generation, the experimenter
examines the population and chooses as breeders only
those individuals with the most desirable characteristics.
Selective breeding or artificial selection
Why microevolution matters?
Microevolution is important in human affairs because it alters
the nature of the many organisms we interact with. These include
domestic plants and animals, wild organisms we eat, microbes that cause disease, parasites, pests, and commensal organisms such as the bacteria that inhabit our guts and help us digest our food. In addition, our interactions with other organisms sometimes cause our own populations to evolve, leading to genetic differences among individuals who live in different places and have divergent lifestyles.
are populations, or groups of populations, within and among
which individuals actually or potentially interbreed and outside of
which they do not interbreed.
Species
If individuals from different populations have the opportunity to mate but are disinclined to do so, or if such individuals mate but fail to produce healthy, fertile offspring, then the individuals belong to
Different species
A lesson from experiments like Dodd’s is that speciation is typically not a sudden event, but a
gradual process
Why Speciation Matter?
Essay
is any trace of an organism that lived
in the past
Fossil
The worldwide collection of fossils is called
Fossil record
He published a list of 23 species known only from fossils. His point was to challenge the hypothesis that unusual forms in the fossil record would eventually be found alive, once European scientists had visited all parts of the globe
Georges Cuvier
was the first to publish a related observation that was
later confirmed and elaborated by Darwin
William Clift
The general pattern of
correspondence between fossil and
living forms from the same locale came
to be known as the
Law of Succession
What makes the amphibious blenny Praealticus a transitional form?
It is derived from, and thus represents, a lineage that
had evolved some, but not all, of the novel traits that transform
an aquatic blenny into a terrestrial one. It shows that an
intermediate species, with only some of these traits, is viable.
And it indicates that coordinated hopping evolved before tail
twisting.
give us a way to test specific
hypotheses about macroevolution by making predictions
that we can confirm or refute by digging for fossils.
Transitional forms
argued, from detailed anatomical analyses, that the dinosaurs from which birds are most likely derived were theropods—a group of bipedal carnivores that includes
Compsognathus, Velociraptor, and Tyrannosaurus rex
John Ostrom (1973)
noted that if Ostrom is correct, then “feathers may have
been widespread in bird-like theropods.” The undiscovered fossil record, in other words, should
hold theropod dinosaurs with feathers in various stages of evolution. At the time, no such animals
were known.
Robert Bakker and Peter Galton (1974)
reported the discovery, in China’s Liaoning Province, of a
theropod called Sinosauropteryx. The fossils were the most exquisitely preserved dinosaur
remains found to that date. Sinosauropteryx, about the size of a chicken, bore bristly structures on
its neck, back, flanks, and tail. Many paleontologists took these bristles to be simple feathers
(though this was controversial).
Pei-ji Chen et al., 1998
a group that includes mammals, reptiles, and birds
amniotes
—a group of bipedal carnivores that includes
Compsognathus, Velociraptor, and Tyrannosaurus rex.
Theropods
Why macroevolution matters
Macroevolution matters in our everyday lives
because our own bodies are its products. As we will
see in the next section, our deep ancestry traces back
to fish and beyond. Otherwise puzzling aspects of our
anatomy and physiology begin to make sense when
viewed in an evolutionary context.
The crucial evidence for universal
common ancestry is
homology
Britain’s leading anatomist, defined
homology as “the same organ in different animals under every
variety of form and function.”
Richard Owen
as similarity due to the inheritance of
traits from a common ancestor.
homology
Why common ancestry matters
Common ancestry is the conceptual foundation upon
which all of modern biology, including biomedical science, is
built. Because we are descended from the same ancestral
lineage as monkeys, mice, baker’s yeast, and even bacteria,
we share with these organisms numerous homologies in the
internal machinery of our cells. This is why studies of other
organisms can teach us about ourselves.
m is the claim that geological processes
taking place now worked similarly in the past. It was a direct challenge to catastrophism, the hypothesis that today’s geological formations resulted from catastrophic events in the past on a scale never observed now.
Uniformitarianism
Why Earth’s Age matters?
The extreme age of Earth and of life matter,
because descent with modification is a slow
process. New evidence and discoveries in various
fields including biology and geology only make
sense in the view that the Earth and life on it are at
least a few billion years old.
