bio 212 exam 1 Flashcards
What is Evolution?
A change in allele frequencies of a population over time across generations.
This includes changes in inherited traits from one generation to the next, often referred to as ‘descent with modification.’
Who evolves, individuals or populations?
Populations (species) evolve, not individuals.
This means evolutionary changes are observed at the population level rather than within single organisms.
Over what time frame does evolution occur?
Over time, between generations.
Evolutionary changes are not instantaneous but occur gradually.
What type of traits evolve?
Only traits that can be inherited (i.e., are genetically based) evolve.
This highlights the importance of genetic inheritance in the process of evolution.
True or False: Evolution always results in adaptation.
False.
Changes can occur that are not driven by natural selection and may not lead to increased competitive ability or better survival and reproduction.
Fill in the blank: Evolution is often described as _______.
‘descent with modification’.
This phrase emphasizes the gradual changes in traits over generations.
Who is considered the father of modern evolutionary biology
Charles Darwin (1809-1882).
What did Charles Darwin observe that sparked his studies?
The diversity of species and patterns in their variations.
What did Darwin expect about species over time?
He expected that species changed over time.
Who had previously noted that species might change over time?
Lamarck and others.
What was Darwin lacking in his early theories of evolution?
A plausible mechanism for how evolution occurred.
What was Darwin’s role on the HMS Beagle from 1831-1836?
He served as the naturalist during its voyage around the world.
What did Darwin do with the specimens he collected on the HMS Beagle?
He analyzed the collections when he returned.
What key observation did Darwin make during the HMS Beagle voyage?
He observed species diversity but did not know how species could change over time.
What influential book did Darwin read during his voyage on the HMS Beagle?
Lyell’s Principles of Geology.
Who sent a letter to Darwin proposing similar evolutionary ideas?
Alfred Russel Wallace.
What key concepts did both Darwin and Wallace propose?
Universal common ancestry and natural selection.
When and where were the letters from Darwin and Wallace presented?
At the Linnaean Society in 1858.
How are Darwin and Wallace viewed in the history of evolutionary theory?
They are considered co-discoverers of evolution by natural selection.
What is the title of Darwin’s book published in 1859?
On the Origin of Species by Means of Natural Selection.
What did Darwin’s book explain?
The diversity of life in general and odd patterns in nature in particular.
How did Darwin describe evolution in his book?
As descent with modification, predicting universal common descent.
What qualities of On the Origin of Species made it influential?
It was richly detailed, clearly reasoned, and exhaustively researched.
Why is Darwin credited for proposing evolution by natural selection?
Because of the strength of the arguments and evidence in his book.
What question did Darwin address with natural selection?
How patterns in biology could be explained by evolution.
What are examples of homologies Darwin observed?
Human, seal, and bat limbs have homologous bones.
What did Lamarck claim about the history of life?
It followed a trend toward ‘higher’ forms.
What did German biologists in the early 1800s argue about evolution?
Life evolved from simple to complex forms.
Who proposed natural selection as a driver of evolution?
Darwin and Wallace.
What are two characteristics of natural selection?
It is a natural and observable process.
What is the definition of natural selection?
The process by which individuals better adapted to their environment preferentially survive and reproduce, passing their genes to future generations.
Why is the term ‘Darwinism’ no longer considered appropriate?
Because we now know more about how natural selection works and have discovered additional evolutionary mechanisms.
What is genetic drift?
The change in frequency of genetically based traits due to chance events.
What is horizontal gene transfer?
The movement of genes from one organism to another without reproduction.
What is epigenetics?
The inheritance of variation in gene expression without changes to the underlying DNA sequence.
What did Darwin get wrong about inheritance?
Inheritance is not ‘blending’ and is not based on ‘gemmules.’
What is incorrect about the idea that evolution is always uniform over time?
Evolution is not always constant or gradual; it can vary in pace.
How has evolutionary biology expanded beyond Darwin’s initial ideas?
It includes new developments like genetics, epigenetics, and horizontal gene transfer, and it corrects initial errors.
What is the hierarchical organization of life from the broadest to the most specific level?
Domain (e.g., Eukarya)
Kingdom
Phylum
Class
Order
Family
Genus
Species
What does faunal succession refer to in fossil evidence?
The succession of different types of animals through geological layers, and the occurrence of extinctions.
What are the two types of dating used in fossil evidence?
Relative dating and absolute dating.
What might complicate the interpretation of fossil layers?
Layers may have been overturned, requiring multiple lines of evidence to be assembled.
What are transitional forms in the fossil record?
Fossils that exhibit a mix of traits found in both modern and ancient species.
Why don’t scientists use the term ‘missing link’?
Because transitional forms are not single links but show a gradual transition of traits.
What are homologies in evolutionary biology?
Similarities in phenotype or genotype resulting from descent from a common ancestor.
What does it mean when different structures are made up of modified versions of the same parts?
It means that species may have different physical features, but those features are derived from the same basic parts inherited from a common ancestor.
What is an example of homology in limb structures?
Humans, seals, and bats have very different limb structures, but all share similar bone structures.
What are vestiges in evolutionary biology?
An inherited feature that is now less elaborate and functional than in the ancestor.
How do vestigial structures typically form?
They form when a lineage faces a different set of selective pressures than its ancestors, and the selection to maintain the feature’s elaboration or function ends or is greatly reduced.
What is an example of a vestigial structure?
Dew claws, which are reduced, nonfunctional digits that typically do not touch the ground.
What are atavisms in evolutionary biology?
A modification of a biological structure where an ancestral genetically-based trait reappears after being previously lost through evolution.
What is an example of an atavism in humans?
The human caudal appendage, or tail, which is normally resorbed during fetal development but may rarely be retained at birth.
When do human fetuses typically lose their tail during development?
Around Week 8 of fetal development.
What is done if a human retains a tail at birth?
Surgery is typically performed to remove the tail.
Is evolution controversial among biologists?
No, evolution is not controversial among biologists.
What types of evidence support the theory of evolution?
Evidence includes the hierarchical organization of life, fossils, comparative anatomy, genetics, biogeography, and developmental evidence.
What is natural selection?
Natural selection is a mechanism by which evolution occurs.
How do phenotypes affect survival and reproduction in natural selection?
Individuals have varied, heritable phenotypes that differentially affect their survival and reproduction based on the environment in which they live.
How was life primarily during the first ~2.5 billion years?
Life was mainly microscopic.
What are the three main groups, or Domains, in the Tree of Life based on DNA?
Eukarya, Bacteria, and Archaea.
What defines the Domain Eukarya?
Eukarya includes unicellular and multicellular organisms, has membrane-bound organelles, and includes plants, animals, fungi, and protists. It likely evolved from a lineage of Archaea.
What is unique about Bacteria?
Bacteria have a unique membrane molecule.
What is unique about Archaea?
Archaea have no photosynthetic species and use unique proteins to transcribe DNA to RNA.
What is the definition of taxonomy?
Taxonomy is the science of describing, naming, and classifying organisms.
What is the definition of taxa?
Taxa refers to any level within the taxonomic hierarchy.
What is the definition of phylogenetics?
Phylogenetics is the study of the evolutionary relationships between organisms.
What is the definition of a phylogenetic tree (or phylogeny)?
A phylogenetic tree is a representation of the branching pattern of evolutionary history, showing the ancestor-descendant relationships of a group of organisms.
What is the definition of the Most Recent Common Ancestor (MRCA)?
The MRCA is the last ancestor shared by a pair of species.
What is the definition of the Closest Living Relative?
The Closest Living Relative is the living species that shares the most recent common ancestor with another species.
