Evidence For Evolution Flashcards
What is evolution
The cumulative change in the heritable characteristics of a population
What are factors that provide evidence for evolution
Fossil record Homologous structures Analogous structures Vestigial structures Direct observation Comparative DNA Selective breeding Natural selection
How does fossil record provide evidence for evolution
Fossils document the existence of now-extinct species, which in turn helps us find the relation and similarities between past and present day species. It also physically helps us see how species evolved. They show a chronological sequence in which characteristics appear and develop in complexity in organisms.
What are homologous structures
Homologous structures are parts of an organism’s body that are similar in structure to other species’ comparative parts. It is evidence of divergent evolution and shows an evolutionary relationship between organism that is a common ancestor.
Five-fingered pendactyl limb in vertebrates (humerus, ulna, radius, carpals, metacarpals, phalanges) these organisms in different forms of organisms have adapted to different modes of locomotion
What are analogous structures
Structures of organisms that have the same function but do not have the same structural similarity. They do not have the same evolutionary path and do not show common ancestry. They are evidence of convergent evolution as different species have evolved to have similar features due to adaptation and environments.
Eg. Whale flipper and fish fin
Vestigial structures?
An anatomical feature that no longer seems to have a purpose in the current form of an organism of the given species. It is an evidence of evolutionary relationship
Eg. Pelvic bone of whales are reduced and functionless but are evidence of their evolutionary relationship
The vestigial versions of a structure can be compared to the original version of the structure in other species in order to determine the homology of the structure
how does direction observation support evidence for evolution
We can directly observe small scale evolution in organisms with a short life span, in turn providing evidence for evolution.
Eg. Antibiotic resistance where bacteria threat have grown resistant to antibiotics cannot be killed, the genes for resistances are passed on this increasing the population of resistant bacteria
How is Comparative DNA evidence ??
DNA and the genetic code reflect the shared ancestry of life. DNA comparison can show how related species are
What is the difference between a fact and a theory
A theory is a set of statements or principles that explains several phenomena at once. Most theories that are accepted by scientists have been repeatedly tested by experiments and can be used to make predictions about natural phenomena. A fact is any observation that has been repeatedly confirmed and accepted as true and has not yet been refuted.
How does a hypothesis become a theory
Tests are made after a hypothesis is generated. From there, results can be corroborated or uncorroborated. Corroborated results goes on to be corroborated unquestionably thus a theory can be formed. Uncorroborated results are retested once a new hypothesis is formulated
What is convergent and divergent evolution
Convergent evolution occurs when species with different ancestral origins evolve to develop similar features and adaptions
Divergent evolution occurs when species from a common ancestor evolve differently eg. Darwins finches as they had to adapt to different environments and different food sources
What is a fossil and fossil record
Fossils are preserved remains, impressions or trace of an organism found usually in sediments, hardened as rocks from the remote past
Fossil record is the sum of all discovered and undiscovered fossils and their relative placement in rocks. It provides the dimension of time to the study of evolution as the fossils found can be dated.
Types of fossils
Direct and indirect
Direct fossils are body fossils such as bones, teeth, shells and leaves
Indirect fossils are trace fossils such as footprints, tooth marks, tracks, feces, burrows
Organism can be fossilised by being trapped in a substance that protects it from destruction eg. Ice, amber, tar
What are gaps in the fossil record due to
Special circumstances are required for fossilisation to occur eg. An organism who is buried quickly has better changes of being fossilised
Only hard parts of an organism are preserved
Fossils can be damaged so that only fragments remain to be discovered
What are transitional fossils
And what type of rock is most likely to contain fossils
Transitional fossils all show the links between groups or species by exhibiting traits common to both ancestors and derived descendants
Sedimentary rock most likely contains fossils
