BY 124 Chapter 26

mastering biology chapter 26: phylogeny and the Tree of Life

systematics

a scientific discipline focused on classifying organisms and determining their evolutionary relationships

shared ancestral characteristics

A character that originated in an ancestor of the taxon

maximum parsimony

the principle that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.

classes

in Linnaean classification, the taxonomic category above the level of order

phylogeny

The evolutionary history of a species or group of related species

sister taxa

groups of organisms that share an immediate common ancestor that is not shared by any other group

clade

a group of species that includes an ancestral species and all of its descendants. Only monophyletic groups.

phylogenetic tree

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms

Orthologous genes

homologous genes that are found in different species because of speciation

shared derived charater

An evolutionary novelty that is unique to a particular clade

branch point

the representation on a phylogenetic tree of the common ancestor of the attached groups

Analogy

similarity between 2 species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.

genus

A taxonomic category above the species level, designated by the first word of a species’ 2-part scientific name.

binomial

Acommon term for the 2-part, latinized format for naming a species. It consists of a genus and a binomen

binomen

a specific epithet that is the second word of a species 2-part scientific name

polyphyletic

a group of species that includes distantly related species but doesn’t include their most recent common ancestor

evolutionary lineage

The sequence of ancestral organisms leading to a particular descendant taxon

taxon

A named taxonomic unit at any given level of classification that is represented by a branch (line) in a phylogenetic tree.

Outgroup

A species or group of species closely related to, but not part of, the group of species being studied. It’s typically a group that has diverged before the ingroup

orders

In Linnaean classification, the taxonomic category above the level of family.

paralogous genes

homologous gene that are found in the same genome as a result of gene duplication

horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, and viral activity

rooted

describing a phylogenetic tree that contains a branch point representing the most recent common ancestor of all taxa in the tree

Ingroup

A species or group of species that is being compared to an outgroup to differentiate between shared derived and shared ancestral characters

basal taxon

in a specified group of organisms, a taxon whose evolutionary lineage diverged early in the history of the group.

monophyletic

A group of taxa that consists of a common ancestor and all of its descendants, and it is equal to a clade.

family

the taxonomic category above genus.

kingdoms

A taxonomic category, the second broadest after domain.

phyla

In Linnaean classification, the taxonomic category above class.

Cladistics

An approach to systematics in which organisms are placed into groups called clades based primarily by common ancestry

maximum likelihood

A principle that states that when considering multiple phylogenetic hypotheses, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.

molecular clock

a method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes evolve at constant rates.

paraphyletic

a group of species that consists of an ancestral species and some, but not all, of the descendants

hatch mark

represents a character shared by the groups to the right of the mark.

What is the correct way to write the scientific name for humans?

Homo sapiens

Which of the taxonomic categories includes the fewest number of species

Panthera

homologies

phenotypic and genetic similarities due to shared ancestry

homology

similarity due to shared ancestry

convergent evolution

Organisms evolve into similar body forms due to similar environmental conditions or lifestyles, not from a common ancestor

Animals thar possess homologous structures probably

evolved from the same ancestor

When describing a group of animals. you speak about an ancestral species and some but not all of its descendants. This is an example of a:

paraphyletic group

What would make the most suitable outgroup species for a cladogram relative to all the other species?

tuna

taxonomy

the scientific discipline concerned with classifying and naming organismsc

classification

The division of organisms into increasingly broad taxonomic categories based on similarities and differences in a set of characteristics