1. The Dodo (Raphus cucullatus) is an extinct flightless bird that was endemic to the island of Mauritius, east of
Madagascar in the Indian Ocean. Subfossil remains show the Dodo was about 1 metre (3.3 feet) tall and may
have weighed 10–18 kg (22–40 lb) in the wild. The Dodo's appearance in life is evidenced only by drawings,
paintings and written accounts from the 17th century. Because these vary considerably, and because only some
illustrations are known to have been drawn from live specimens, its exact appearance in life remains unresolved.
Similarly, little is known with certainty about its habitat and behaviour. It has been depicted with brownish-grey
plumage, yellow feet, a tuft of tail feathers, a grey, naked head, and a black, yellow, and green beak. It used
gizzard stones to help digest its food, which is thought to have included fruits, and its main habitat is believed to
have been the woods in the drier coastal areas of Mauritius. One account states its clutch consisted of a single
egg. It is presumed that the Dodo became flightless because of the ready availability of abundant food sources
and a relative absence of predators on Mauritius.
''Blue parrots are very numerous there, as well as other birds; among which are a kind, conspicuous for their size,
larger than our swans, with huge heads only half covered with skin as if clothed with a hood. These birds lack
wings, in the place of which 3 or 4 blackish feathers protrude. The tail consists of a few soft incurved feathers,
which are ash coloured. These we used to call 'Walghvogel', for the reason that the longer and oftener they were
cooked, the less soft and more insipid eating they became. Nevertheless their belly and breast were of a pleasant
flavour and easily masticated.'' One of the earliest accounts, from van Warwijck's 1598 journal, describes the bird
thus.
Dodo skeleton cast and model based on
modern research, at Oxford University
Museum of Natural History
Adriaen van de Venne's 1626
depiction of a Dodo Previously unpublished 17th-
century illustration of a Dodo

2. Endemism is the ecological state of a species being unique to a defined geographic location,
such as an island, nation, country or other defined zone, or habitat type; organisms that are
indigenous to a place are not endemic to it if they are also found elsewhere. The extreme
opposite of endemism is cosmopolitan distribution. Another term for a species that is endemic, is
precinctive - which applies to species (and subspecific categories) that are restricted to a
defined geographical area.
There are two subcategories of endemism – paleoendemism and neoendemism.
Paleoendemism refers to a species that was formerly widespread but is now restricted to a
smaller area. Neoendemism refers to a species that has recently arisen such as a species that
has diverged and become reproductively isolated, or one that has formed following hybridization
and is now classified as a separate species. This is a common process in plants, especially
those that exhibit polyploidy.
Endemics can easily become endangered or extinct if their restricted habitat changes,
particularly but not only due to human actions, including the introduction of new organisms.
"Hot spots" of high
endemism.

3. Darwin's theory of evolution is based on key facts and the
inferences drawn from them, which biologist Ernst Mayr
summarised as follows:
Every species is fertile enough that if all offspring survived to
reproduce the population would grow (fact).
•Despite periodic fluctuations, populations remain roughly the
same size (fact).
•Resources such as food are limited and are relatively stable over
time (fact).
•A struggle for survival ensues (inference).
•Individuals in a population vary significantly from one another
(fact).
•Much of this variation is inheritable (fact).
•Individuals less suited to the environment are less likely to survive
and less likely to reproduce; individuals more suited to the
environment are more likely to survive and more likely to
reproduce and leave their inheritable traits to future generations,
which produces the process of natural selection (inference).
•This slowly effected process results in populations changing to
adapt to their environments, and ultimately, these variations
accumulate over time to form new species (inference).
Here is Darwin's own summary of the idea, which can be found in the fourth chapter of the Origin:
If during the long course of ages and under varying conditions of life, organic beings vary at all in the several parts of their
organisation, and I think this cannot be disputed; if there be, owing to the high geometrical powers of increase of each species,
at some age, season, or year, a severe struggle for life, and this certainly cannot be disputed; then, considering the infinite
complexity of the relations of all organic beings to each other and to their conditions of existence, causing an infinite diversity in
structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever
had occurred useful to each being's own welfare, in the same way as so many variations have occurred useful to man. But, if
variations useful to any organic being do occur, assuredly individuals thus characterised will have the best chance of being
preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly
characterised. This principle of preservation, I have called, for the sake of brevity, Natural Selection.
charles darwin

4. Natural selection
Natural selection is the gradual process by which biological traits become either more or less common in a population as
a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their
environment. It is a key mechanism of evolution. The term "natural selection" was popularized by Charles Darwin who
intended it to be compared with artificial selection, now more commonly referred to as selective breeding.
Variation exists within all populations of organisms. This occurs partly because random mutations occur in the genome
of an individual organism, and these mutations can be passed to offspring. Throughout the individuals’ lives, their
genomes interact with their environments to cause variations in traits. (The environment of a genome includes the
molecular biology in the cell, other cells, other individuals, populations, species, as well as the abiotic environment.)
Individuals with certain variants of the trait may survive and reproduce more than individuals with other variants.
Therefore the population evolves. Factors that affect reproductive success are also important, an issue that Charles
Darwin developed in his ideas on sexual selection, for example. Natural selection acts on the phenotype, or the
observable characteristics of an organism, but the genetic (heritable) basis of any phenotype that gives a reproductive
advantage may become more common in a population (see allele frequency). Over time, this process can result in
populations that specialize for particular ecological niches and may eventually result in the emergence of new species.
In other words, natural selection is an important process (though not the only process) by which evolution takes place
within a population of organisms. Natural selection can be contrasted with artificial selection, in which humans
intentionally choose specific traits (although they may not always get what they want). In natural selection there is no
intentional choice. In other words, artificial selection is teleological and natural selection is not teleological.
By the definition of fitness, individuals with greater fitness are more likely to contribute offspring to the next generation,
while individuals with lesser fitness are more likely to die early or fail to reproduce. As a result, alleles that on average
result in greater fitness become more abundant in the next generation, while alleles that in general reduce fitness
become rarer. If the selection forces remain the same for many generations, beneficial alleles become more and more
abundant, until they dominate the population, while alleles with a lesser fitness disappear. In every generation, new
mutations and re-combinations arise spontaneously, producing a new spectrum of phenotypes. Therefore, each new
generation will be enriched by the increasing abundance of alleles that contribute to those traits that were favored by
selection, enhancing these traits over successive generations.

5. Resistance to
antibiotics is
increased though
the survival of
individuals that
are immune to the
effects of the
antibiotic, whose
offspring then
inherit the
resistance,
creating a new
population of
resistant bacteria.
The life cycle of a sexually reproducing
organism. Various components of natural
selection are indicated for each life stage
Diagrammatic
representatio
n of the
divergence of
modern
taxonomic
groups from
their common
ancestor.
Natural selection occurs at every life stage of an individual. An
individual organism must survive until adulthood before it can
reproduce, and selection of those that reach this stage is called
viability selection. In many species, adults must compete with
each other for mates via sexual selection, and success in this
competition determines who will parent the next generation.
When individuals can reproduce more than once, a longer
survival in the reproductive phase increases the number of
offspring, called survival selection.

6. Biodiversity is the degree of variation of life.This can
refer to genetic variation, species variation, or
ecosystem variation within an area, biome, or planet.
Terrestrial biodiversity tends to be highest at low
latitudes near the equator, which seems to be the
result of the warm climate and high primary
productivity. Marine biodiversity tends to be highest
along coasts in the Western Pacific, where sea
surface temperature is highest and in mid-latitudinal
band in all oceans. Biodiversity generally tends to
cluster in hotspots, and has been increasing through
time but will be likely to slow in the future.
Rapid environmental changes typically cause mass
extinctions. One estimate is that <1%–3% of the
species that have existed on Earth are extant.
Biodiversity is not evenly distributed, rather it varies
greatly across the globe as well as within regions.
Among other factors, the diversity of all living things
(biota) depends on temperature, precipitation,
altitude, soils, geography and the presence of other
species. The study of the spatial distribution of
organisms, species, and ecosystems, is the science
of biogeography.
Diversity consistently measures higher in the tropics
and in other localized regions such as the Cape
Floristic Region and lower in polar regions generally.
Rain forests that have had wet climates for a long
time, such as Yasuni National Park in Ecuador, have
particularly high biodiversity.
Biodiversity
Conceptual diagram showing how
increasing diversity can stabilize
ecosystem functioning

7. In evolutionary biology, a group of organisms share common descent if they have a
common ancestor. There is strong evidence that all living organisms on Earth are
descended from a common ancestor, called the last universal ancestor or LUA (or last
universal common ancestor, LUCA).
Common ancestry between organisms of different species arises during speciation, in
which new species are established from a single ancestral population. Organisms which
share a more recent common ancestor are more closely related. The most recent common
ancestor of all currently living organisms is the last universal ancestor, which lived about
3.9 billion years ago. The earliest evidences for life on Earth are graphite found to be
biogenic in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland[5]
and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western
Australia. All currently living organisms on Earth share a common genetic heritage
(universal common descent), with each being the descendant from a single original
species, though the suggestion of substantial horizontal gene transfer during early
evolution has led to questions about monophyly of life.
common descent

8. The realization that the non-avian dinosaurs are closely related to birds raised the possibility of feathered dinosaurs. Fossils of
Archaeopteryx include well-preserved feathers, but it was not until the mid-1990s that clearly non-avialan dinosaur fossils were
discovered with preserved feathers. Since then, more than twenty genera of dinosaurs, mostly theropods, have been
discovered to have been feathered. Most fossils are from the Yixian formation in China. The fossil feathers of one specimen,
Shuvuuia deserti, have tested positive for beta-keratin, the main protein in bird feathers, in immunological tests.
Shortly after the 1859 publication of Charles Darwin's On the Origin of Species, British biologist Thomas Henry Huxley proposed
that birds were descendants of dinosaurs. He compared the skeletal structure of Compsognathus, a small theropod dinosaur,
and the 'first bird' Archaeopteryx lithographica (both of which were found in the Upper Jurassic Bavarian limestone of
Solnhofen). He showed that, apart from its hands and feathers, Archaeopteryx was quite similar to Compsognathus. In 1868 he
published On the Animals which are most nearly intermediate between Birds and Reptiles, making the case. The leading
dinosaur expert of the time, Richard Owen, disagreed, claiming Archaeopteryx as the first bird outside dinosaur lineage. For the
next century, claims that birds were dinosaur descendants faded, with more popular bird-ancestry hypotheses including
'crocodylomorph' and 'thecodont' ancestors, rather than dinosaurs or other archosaurs.
After a century of hypotheses without conclusive evidence, well-preserved fossils of feathered dinosaurs were discovered
during the 1990s, and more continue to be found. The fossils were preserved in a Lagerstätte — a sedimentary deposit
exhibiting remarkable richness and completeness in its fossils — in Liaoning, China. The area had repeatedly been smothered
in volcanic ash produced by eruptions in Inner Mongolia 124 million years ago, during the Early Cretaceous epoch. The fine-
grained ash preserved the living organisms that it buried in fine detail. The area was teeming with life, with millions of leaves,
angiosperms (the oldest known), insects, fish, frogs, salamanders, mammals, turtles, and lizards discovered to date.
The most important discoveries at Liaoning have been a host of feathered dinosaur fossils, with a steady stream of new finds
filling in the picture of the dinosaur–bird connection and adding more to theories of the evolutionary development of feathers
and flight. Turner et al. (2007) reported quill knobs from an ulna of Velociraptor mongoliensis, and these are strongly correlated
with large and well-developed secondary feathers.[5]
A nesting Citipati osmolskae specimen, at the AMNH.
Behavioural evidence, in the form of an oviraptorosaur on its nest, showed another link with birds. Its forearms were folded, like
those of a bird.[6] Although no feathers were preserved, it is likely that these would have been present to insulate eggs and
juveniles
feathered dinosaurs

9. The Berlin Archaeopteryx
Fossil cast of a
Sinornithosaurus millenii
Cast of a Caudipteryx fossil with feather
impressions and stomach content
Fossil of Microraptor gui impressions of
feathered wings