Evolution Unit Test Flashcards
What is a theory?
A hypothesis or series of hypotheses that have been supported by repeated tests. It is a valid explanation of a phenomenon.
What must a theory be?
Explanatory, Predictable (guess what will occur accurately), Testable
What are the types of mutations?
Harmful- more common than beneficial; selected against and have no influence on populations
Beneficial- relatively rare; favored by natural selection; tend to accumulate in populations over time (opposable thumbs)
Neutral- provide no benefit or harm; will not be selected upon if neither beneficial or harmful (eye color)
What is selective breeding?
Directive breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation (aka artificial breeding)
What is the age of the earth?
4.5 billion years old
What is absolute dating?
Determining a specific age of an object or event; a scientific method
What is relative dating?
The science of determining events relative to each other; used for materials w/o radioisotopes
What is radiometric dating?
Uses radioisotopes to determine the age of fossils
Radioisotopes - an atom w/ an unstable nucleus capable of undergoing decay
What is the fossil record?
Fossils- ancient remains, impressions or traces of an organism that have been preserved in rocks or other mineral deposits
Fossils allow us a snapshot of early species; helps us understand where new variations have arisen; suggest transitions between species
What is the plate tectonics theory?
Theory that describes large scale movements and features or earths crust; earths crust is made of plates that move around very slowly
What would the plate tectonics theory explain?
Species would have lived together where all three continents connected at some point in history (Pangea)
What is biogeography?
The scientific study of the geographic distribution of organisms based on both living species and fossils (where they were and where they are)
Fossil evidence suggests Pangea was real
What are homologous features?
A structure with a common evolutionary origin that may serve different functions in modern species
Ex: forearms
What are analogous features?
A structure that performs the same function as another but is not similar in origin or anatomical structure
Ex: dolphin and shark fins, birds and bats flying
What are vestigial features?
A non-functioning, or only marginally functioning, structure that is homologous to a full functioning structure in closely related species
Ex: whales have tiny hip bones and leg bones
What is Charles Darwin’s theory?
When traveling to South America, specifically Argentina, Darwin found new species that looked like many of the species found in South America; also found fossils resembling species in the same area; found his finches (13 species of finches)
Created the theory of evolution (the origin of species)
What is modern evolutionary synthesis?
Modern theory of evolution; takes into account all branches of biology (includes genetics and plate tectonic theory)
How are evolution and genes related?
Genes code for different raids and evolution acts on genes
What is gene duplication?
Gene mutation can often be harmful; if there’s an extra copy of a gene that mutates, the healthy copy makes sure the cell functions properly; often neutral
What are homologous genes?
Homologous genes share a common ancestor but have mutated over time
The more closely related 2 species are, the more similar their homologous genes will be
What are pseudogenes?
Vestigial genes undergone mutations and no longer serves a purpose
What is natural selection?
The way in which nature favors the reproductive success of some individuals within a population over others (some individuals are more likely to pass their genes along than others)
What does reproduction have to do with natural selection?
Organisms have features that make them better suited to an environment and are more likely to reproduce and these features are more likely to persist in a population
What are three ways a species can be successful?
- Better suited at gathering resources in a population
- Better able to avoid predators
- Ability to adapt to a unique environment
What is adaptation?
A characteristic or feature of a species that makes it well suited for survival or reproductive success in its environment
What is directional selection?
Favors an increase or decrease in the value of a trait from the current population average (if white butterfly is more likely to be eaten, number of white butterflies decreases)
What is stabilizing selection?
Selection against individuals exhibiting traits that deviate from the current population (keeping the population)
What is disruptive selection?
Favors two or more variations of a trait that differs from the current population average (changing the population)
What is sexual selection?
The favoring of any trait that specifically enhances the mating success; leads to features that don’t aid in survival but enhances mating success
What is intrasexual selection?
Selection based on “male to male competition”; the winner is seen as more worthy as the stronger of the two
What is intersexual selection?
Selection based on “female choice”; prettier= healthier and stronger
(for example peacocks choose the male with the prettiest feathers)
How can hinder some traits evolve?
Even if a trait is harmful or useless to a species’ survival, if it aids in sexual reproduction, it will survive and evolve as it increases mating success
What is genetic drift?
The random shifting of the genetic makeup between generations
Population size has a major effect on the drift
Smaller populations are more likely to have a trait that becomes very common or to disappear
What is the bottleneck effect?
Dramatic reduction in population size, usually resulting in significant genetic drift, due to catastrophe
Can happen due to overhunting, habitat loss, or natural disaster
Ones that survive only pass on those genes which makes them vulnerable to disease and low reproductive success
What is the founders effect?
A small number of individuals separate from their original population and establish a new population
The new population can have more or less variation depending on how many go over with the variation
What is the Hardy-Weinberg Principle?
States that in larger populations where only random chance is at work, alleles should stay constant between generations
What is microevolution?
Changes in allele frequencies and physical traits within a population and species
What is a species?
All members of a population with a common gene pool; able to interbreed under normal conditions and produce fertile offspring
What are prezygotic mechanisms?
A reproductive isolating mechanism that prevents fertilization and zygote formation (sperm and egg can’t fuse) so different species can’t breed and start new species
What are the kinds of prezygotic mechanism?
- Behavioral isolation (courtship rituals to find a mate. ex birds of paradise)
- Temporal isolation (different species breed at different times)
- Ecological isolation (similar species may inhabit different habitats within a region)
- Mechanical isolation (differences in physical features that make two species unable to mate)
- Gamete isolation (male gametes unable to recognize and fertilize egg cells of another species)
What are postzygotic mechanism?
An isolating mechanism that prevents maturation and reproduction in the offspring of interspecies reproduction
What are the kinds of postzygotic mechanisms?
- Zygotic morality (mating and fertilization possible but zygote is unable to develop)
- Hybrid inviability (hybrid develops but cannot survive to maturity; may die before birth may die before reaching maturity)
- Hybrid infertility (hybrid remains healthy and viable but are sterile therefor unable to make more of the hybrid ex mules)
What is allopatric speciation?
The formation of a new species as the result of evolutionary changes after a period of geographic isolation (no longer exchange genetic info therefor become different species)
What is sympatric isolation?
The formation of new species within the same geographic area
Can occur through human action (humans introduce apples to Hawthorne flies causing some to eat apples and some Hawthornes, making two different species)
What is polyploidy?
Cells should have 2n chromosomes; some have more (non-disjunction)
Polyploids: organisms with more chromosomes than normal
Can only breed with other polyploids
What is adaptive radiation?
Relatively fast evolution of one species into a number of distinct but related species (each fills a previously empty ecological niche)
What is divergent evolution?
The large scale evolution of a group into many different species
Ex: red squirrels live during the day
Flying squirrels fill similar niche but at night
What is convergent evolution?
Occurs when 2 different species evolve to fill similar ecological niches (cause of analogous features)
What is co-evolution?
Process in which a species evolves in response to the evolution of another species
(ex: plants evolve hard shells to protect against animals, causing herbivores to develop more powerful jaws)
An evolutionary arms race
How does competition influence evolution?
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What is macroevolution?
Large-scale evolutionary changes including the formation of new species and taxa
What is abiogenesis?
The formation of life from non-organic material
Non-organic= not carbon based
What is the Cambrian explosion?
A period of time in which the evolution of most major animal phyla occurred over 40 million years
What is mass extinction and what is their effect on species and evolution?
An event in which a large amount of life is wiped out
Gene pools shift, shrink and get altered
Lead to genetic drift on massive scale
What is phylogeny?
The evolutionary relationships of different groups of species or organisms
What are cladistics?
A method of showing evolutionary relationships based on the presence of recently evolved, or derived, traits
What are cladograms?
Used to show the evolutionary relationships between groups of organisms
What are synapomorphies?
Derived traits shared by two or more species or groups (basically a homologous structure)
What is the theory of gradualism?
As new species evolve, they appear very similar to the original species and only gradually become more distinctive
What is the theory of punctuated equilibrium?
Suggests that most evolutionary changes occur in relatively rapid spurts, followed by long periods of little or no change
What are transitional forms and missing links?
A fossil or species intermediate between two other species in a direct line of descent
Missing links are species between two similar fossils that can’t be found but would link the two together
