Bio Ch. 26

Paraphyletic

A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants

Polyphyletic

A polyphyletic grouping consists of various species that lack a common ancestor.

Monophyletic

A taxon is equivalent to a clade only if it is monophyletic - consisting of an ancestral species and all its descendants.

Homoplasies

Analogous structures or molecular sequences that evolved independently are also called homoplasies (from the Greek - to mold in the same way).

Systematics

Biologists utilize systematics - an analytical approach to understanding the diversity and relationships of organisms both extant and extinct.

What is a clade? a cladogram? Be able to distinguish among the different types of clades.

Clade - another word for phylogenetic tree which includes an ancestral species and ALL OF ITS DESCENDENTS clades can be nested in larger clades, but not all groupings or organisms qualify as clades cladogram - shows relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants or how much they have changed

Convergent Evolution

Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages. Analogous structures or molecular sequences that evolved independently are also called homoplasies (from the Greek - to mold in the same way).

How are phylogenies determined? What types of information are used in establishing phylogenetic relationships?

Phylogenies are determined by utilizing systematics (looking at fossils, molecules, genes to explain diversity and relationships of organisms bot extant and extinct) Types of info used is morphological (appearance of the organism itself), biochemical, and molecular (RNA/DNA sequences)

Phylogeny

Phylogeny is the evolutionary history of a species or group of related species.

Taxonomy

Taxonomy is the ordered division of organisms into categories based on characteristics used to assess similarities and differences.

What is the two-part scientific name of a species called? How is it constructed?

binomial it is constructed by 1. first part of name is the genus 2. second part, called the specific epithet, is unique for each species within the genus the first letter of the genus is capitalized and the entire binomial is ITALICIZED Both parts together name the species (NOT THE SPECIFIC EPITHET ALONE)

What is the principle of maximum parsimony? maximum likelihood?

maximum parsimony - (simplist) assumes that the tree requires the FEWEST EVOLUTIONARY EVENTS (appearance of shared derived characters) is the most likely maximum likelihood - states that, given CERTAIN RULES ABOUT HOW DNA CHANGES OVER TIME, A TREE CAN BE FOUND THAT REFLECTS THE MOST LIKELY SEQUENCE OF EVOLUTIONARY EVENTS

What is an out-group? an in-group?

outgroup -is a species or group of species from an evolutionary lineage that diverged earlier than the species we are studying ingroup - the species or group we are studying at the time. they are alive

What is the difference between a shared primitive character and a shared derived character? Which one is more important for constructing a cladogram?

shared primitive character - is a character that is shared beyond the taxon we are trying to define (shared characteristics outside of the clade) shared derived character - is an evolutionary novelty unique to a particular clade (unique to the group we are looking at) ONLY FOUND IN ONE CLADE shared derived characters are what separate that organism from its ancestors and other organisms the most imporant would be the shared primtive charcters becuase they show relations amound oransims

Understand how a phylogenetic tree is constructed.

sister taxa are the two organisms that share the most common ancestor in the tree 1. the sequence of branching does not necessarily indicate the actual (absolute) ages of the particular species 2. we cannot assume that a taxon on a phylogenetic tree evolved from the taxon next to it (just bc two species are located near each other does not mean the are more clostly related)

Memorize the system of classification developed by Linnaeus.

species, genus, family, order, class, phylum, kingdom, domain

Remember that a phylogenetic tree is a hypothesis; it fits the most data.

the most data is regarding 1. morphological 2. molecular 3. fossil