Lecture 16 - Macroevolution: BIO 1

These flashcards cover the key concepts of macroevolution including species definitions, speciation mechanisms, biotic changes, and phylogenetic classification based on the BIO 1 course transcript.

According to the biological species concept, how are species defined?

Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.

What is reproductive isolation?

The inability of individuals from two populations to mate with each other, making gene exchange between the populations impossible.

Approximately what percentage of all species that have ever existed are now extinct?

$$99\%$$

What are the three general steps for how new species arise?

1. Geographic separation of a population. 2. Shift in allele frequencies of separate populations (e.g., genetic drift, natural selection). 3. Changes in allelic frequencies result in differences that prevent interbreeding.

Define allopatric speciation.

Speciation that results from the geographic isolation of populations by a barrier that prevents interbreeding.

What is the difference between vicariance and dispersal?

Vicariance is the splitting of an organism's native range due to a geological barrier to gene flow, while dispersal is the movement of organisms to locations outside of their native range.

What is an Ensatina ring species?

A population that started in the north, split to the east and west of the Central Valley in California, and when they met again in Southern California, they could no longer interbreed or produced infertile hybrid offspring.

What is adaptive radiation?

A process in which organisms rapidly speciate, especially when exposed to a new environment with different challenges, new resources, and available niches.

What is biotic interchange?

A phenomenon that occurs when the barrier between previously separated biotas breaks down, resulting in drastic changes to biodiversity.

During the Great American Biotic Interchange, which animal families headed south across the Isthmus of Panama?

Bear, Cat, Camel, Horse, Elephant, Dog, and Pig families.

During the Great American Biotic Interchange, which animal families headed north across the Isthmus of Panama?

Anteater, Porcupine, Armadillo, Sloth, and Possum families.

Define sympatric speciation.

Speciation that occurs without geographic separation.

What is polyploidy and in which group of organisms is it most common?

Polyploidy refers to organisms containing more than two paired sets of chromosomes; it is most common in plants.

What is exaptation?

Structures that evolved for one function but become adapted or used for another function, such as feathers in birds or inner ear bones in mammals.

What are the levels of taxonomic classification from Domain down to Species?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Contrast ancestral traits and derived traits.

An ancestral trait existed in an ancestor, while a derived trait is a characteristic that is a modified form of an ancestral trait.

What is a synapomorphy?

A shared, derived characteristic used to support evolutionary relationships on a phylogenetic tree.

What is Maximum Parsimony in the context of phylogenetics?

Adopting the simplest explanation consistent with the facts, which means selecting the tree that requires the fewest evolutionary events or number of times a derived trait appears.