Phylogeny And Systematics

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phylogeny

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

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systematics

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classifies organisms and determines their evolutionary relationship

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systematists use what to infer evolutionary relationships?

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fossil, molecular, and genetic data

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evolutionary relationships can be depicted in

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branching phylogentic trees

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much protist diversity has origins in

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endosymbiosis

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plastids evolved by endosymbiosis of an ______

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aerobic prokaryote

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plastid bearing lineage of protists evolved into ____ and ____

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red algae and green algae

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red and green algae underwent ____ in which they were ingested by a heterotrophic eukaryote

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secondary endosymbiosis

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horizontal gene transfer

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is the movement of genes from one genome to another

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early evolutionary relationships might be depicted by a ____ instead of a tree of life

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a ring (bc some researchers suggested that eukaryotes arose from an endosymbiosis between a bacterium and archaen)

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eukaryotes are divided into how many groups?

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5

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Archaeplastida

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is a supergroup used by some scientists and includes red algae, green algae, and land plants

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over a billion yrs ago, a heterotrophic protist acquired a cyanobacterial endosymbiont

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the photosynthetic descendants of this ancient protist evolved into red algae and green algae

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systematists proposed the ___ which recognizes only groups that include a common ancestor and all its descendants

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PhyloCode

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each branch point represents

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the divergence of two species

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sister taxa

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are groups that share an immediate common ancestor

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a rooted tree

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includes a branch to represent the last common ancestor of all taxa in the tree

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a polytomy

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is a branch from which more than two groups emerge

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to infer phylogenies, systematists gather info about __ __ __

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morphologies, genes, and biochemistry of living organisms

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homology

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is similarity due to shared ancestry

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analogy

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is similarity due to convergent evolution

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____________ occurs when similar environmental pressures and natural selection produce similar(analogous) adaptations in organisms from different evolutionary lineages

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convergent evolution

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bat and bird wings are ____ as forelimbs but analogous as functional wings

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homologous

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how can homology be distinguished from analogy?

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by comparing fossil evidence and degree of complexity

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the more complex two similar structures are, the more likely it is ____

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homologous

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systematists

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use comp programs and mathematical tools when analyzing comparable DNA segments from different organisms

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cladistics

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group organisms by common descent

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a clade

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is a group of species that includes an ancestral species and all its descendants

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monophyletic

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signifies that it consists of ancestor species and all its descendants

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a paraphyletic grouping

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consists of an ancestral species and some but not all descendants. not a clade.

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a polyphyletic grouping

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consists of various species that lack a common ancestor

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a shared ancestral character

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is a character that originated in an ancestor of the taxon

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a shared derived character

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is an evolutionary novelty unique to a particular clade

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a character can be both ___ and ___

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ancestral and derived, depending on the context

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outgroup

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is a species or group of species that is closely related to the ingroup( the various species being studied)

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systematists compare each ingroup species w/ outgroup to differentiate between

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shared derived and shared ancestral characteristics

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Homologies shared by the outgroup and ingroup are

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ancestral characters that predate the divergence of both groups from a common ancestor

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Gene number and the complexity of an organism

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are not strongly linked

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Orthologous genes

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are widespread and extend across many widely varied species

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Genes in complex organisms

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appear to be very versatile and each gene can perform many functions

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molecular clock

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uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change

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paralogous genes

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nucleotide substitutions are proportional to the time since the genes became duplicated

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neutral theory

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states that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian selection

states that rate of molecular change in these genes and proteins should be regular like a clock

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problem with molecular clock is that

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it does not run smoothly as neutral theory predicts

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irregularities result from

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natural selection in which some DNA changes are favored over others

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phylogentic analysis showed that HIV descended

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from viruses that infected chimpanzees and other primates

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comparison of HIV samples through-out epidemic shows that virus evolved in a very ___ way

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clocklike way

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application of a molecular clock to one strain of HIV suggest that strain spread to humans during

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the 1930s