Unit 4: Evolution Flashcards
Immutable
Unchanging over time. Species are not immutible, they change a lot.
Decent with modification
One of Dawin’s two big ideas. It says that creatures are constantly changing based on their environments, and that organisms alie today have changed constantly to survive. These changes are acquired gradually over many generations from ancient ancestors.
Natural selection
One of Darwin’s two big ideas. It says that change is driven by an organism’s struggle for survival (limited resources push competition and therefore adaption), natural variation among members of a species (Variation is heritable and can be benificial), and the role of the environment (The environment pressures species into survival and determines ackquired characteristics).
Mutation
The only source of additional genetic variation. Larger populations experience more muations, and mutations in gametes are the only mutations that effect evolution (they are passed onto later generations)
There are 3 types
Neutral: very common, have no effect
Harmful: not common, Ex Progeria
Beneficial: extremely uncommon, Ex. 32 base pair deletion in humans resulting in HIV resistance in homozygotes and delayed AIDS onset in heterozygotes, teenage mutant ninja turtles (debated)
Adaptation
The ability of a species to change its traits in response to the environment it lives in. This will increase its fitness.
Fitness
This is the ability to survive and reproduce in an environment.. An individual who is better adapted to its environment has better fitness. That individual is more likely to survive and produce viable, fertile offspring.
Survival of the fittest
An individual who is better adapted to its environment has better fitness. That individual is more likely to survive and produce viable, fertile offspring. This is called survival of the fittest.
Catastrophism
From time to time earth experiences global catastrophic events in which groups of creatures are wiped out and replaced with new sets. Created by George Cuvier.
Convergent
Organisms that inhabit similar environments tend to have similar adaptations that make them better suited to survive in their environments
Uniformitarianism
Geological change is slow and gradual rather than sudden and catastrophic. Natural laws and processes are constant and eternal, and they operated with the same kind of intensity in the past as they do in the present. Earth’s shifts were uniform and steady. Created by Sir Charles Lyell.
Divergent Evolution
Differences occur due to competition for resources such as food and shelter. By developing traits that allow for better use of one or more aspects of the environment, the chance of survival increases.
Biogeography
Contenents seperated geographically have similar species with similar traits, and when geographically isolated, a species will splinter off into similar but distinct species. The study can explain how species evolved and from what species they evolved from based on location.
Fossil record
Fossils are commonly formed when the bodies of organisms become trapped in sediments, which become compressed into strata, or layers and eventually harden into sedimentary rock.
The fossil record is able to provide evidence of extinction such as with the dinosaurs. It is also able to link ancestral species to modern day ones to show evolutionary links.
There are limits to using the fossil record since species that do not possess hard tissues rarely become fossilized. There are gaps in the fossil record that makes it difficult to establish the evolutionary history of some species.
Homologous structures
Structures that share a common origin but have developed into different structures through evolution and natural selection. Structures that originally functioned one way in ancestral species, become modified as they take on new functions. (Divergent evolution).
Example: The forelimbs of human, whale, bat, bird, horse are each adapted to carry out very different functions, yet they all possess very similar bone structure.
Analogous structures
Structures that originated from different sources but became similar due to the environments that they are in. They are anatomically different but share the same function. (convergent evolution)
Example: Insects and birds are very distantly related. The wings of each have the same function but do not share any common structures.
Vestigial structures
Structures that had an important role in ancestral related species but are useless in the modern species.
Example: The existence of hipbones in whales is compelling evidence that these mammals evolved from ancestors that possessed hind legs. The hipbones are used to transfer body weight to the hind legs.
Artificial selection
The intentional breeding and mixing of plants and animals by humans to produce certian traits. Not random and reduces genetic variability greatly.
Variation
Members of the same species are different, and variation is heritable. This is what causes different alleles and drives evolution and microevolution.
Theory
In science, a theory is synonymous with the term fact even if it can’t be ‘proved’ in the way a mathematical theorem can be proved. i.e. cell theory, kinetic theory, germ theory of disease, molecular orbital theory, Big Bang theory, atomic theory
They are testable and they further scientific knowledge.
Observation
Actual tests and notes on a subject observed by humans. Objectively true, but sometimes do not tell the whole story so can be flawed or misleading. Can also be wrond due to extrenuating factors (faulty study, tech mishap, etc.)
Inferences
the reasoning involved in drawing a conclusion or making a logical judgment on the basis of circumstantial evidence and prior conclusions rather than on the basis of direct observation
the process of drawing a conclusion by applying clues (of logic, statistics, etc.) to observations or hypotheses; or by interpolating the next logical step in an intuited pattern.
Directional selection
Selection that favours an increase or decrease in the value of a trait different from population average. Example: If the hummingbird population moves to a new habitat with longer flowers, individuals with bills that were best adapted to medium-length flowers will no longer be ideal.
Stabilizing selection
Selection against individuals that differ from the population average, reinforcing the average. Example: According to the theory of Natural Selection, babies born at weights that offer the best chance of surviving birth should be more numerous, and research shows that far more human babies are born weighing just over 3 kg than any other weight. Babies with significantly lower weights are often developmentally premature and less likely to survive, while heavier babies often experience birth-related complications that threaten the life of both baby and mother.
Disruptive selection
Selection that favours two or more traits that differ from population average. Example: The African Blackbellied Seedcracker Finch (Pyrenestes ostrinus) depends on the seeds of two different types of sedge, one that produces a soft seed and the other a much harder seed. Finches with small bills are efficient at feeding on soft seeds, while birds with larger bills are able to crack the hard seeds.
