BZ 220 Final part 1

Morphospecies Concept

-Distinct morphological differences -subset of phylogenetic species concept

Postmating Barriers

-Gametic Mortality -Zygotic Mortality -Hybrid Inviability -Hybrid Sterility

What types of characters are used to recognize monophyletic, paraphyletic, polyphyletic groups?

-Monophyletic are identified by synapomorphies -Paraphyletic groups are identified by synapomorphies and Symplesiomorphies (or reversals) -Polyphyletic groups are identified by convergences

Premating Barriers

-Seasonal and habitat Isolation -Ethological Isolation (behavioral)

How is a preferred phylogeny identified using parsimony with multiple characters?

-The most parsimonious pattern of character-state change is noted for each character separately, for each tree -The number of changes is summed across characters for each tree -The preferred tree is the one that implies the fewest overall character-state changes, minimizing ad hoc hypotheses (i.e., convergences, reversals)

Phylogenetic Species Concept

-diagnosable by a unique combination of character states -smallest aggregation of sexual populations or asexual lineages diagnosable by a fixed, unique combination of character states in comparable individuals -Examples of Character States →Single DNA substitution →Major Morphological Change →Behavioral Difference

What are characters states that the phylogenetic species concept can use to identify distinct species?

-fixed, unique conbination of character states in comparable individuals -Single DNA substitution -Major morphological change -Behavioral difference

Allopatric Speciation

-geographic isolation of populations →Dispersal-individual(s) cross barriers →Vicariance- new barrier separated pre-existing populations

Convergence

-morphological similarities -occurs when natural selection favors similar structures as solutions to problems posed by similar environments -If convergent evolution has occurred, then similar traits are not homologous and do not qualify as synapomorphies

Biological Species Concept

-reproductive isolation -a group of interbreeding organisms that are reproductively isolated from all other such groups -"interbreeding"=successfully producing fertile offspring -legal definition of species for Endangered Species Act

Sympatric Speciation

-speciation without geographical isolation →food source →host specificity →timing of reproduction

How ware phylogenies used to test hypotheses of adaptation and the order of evolutionary changes?

-used to establish order of events in which changes took place -can optimize and "character" onto a tree, regardless of whether it is heritable or not

Parsimony Informative

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Parsimony Uninformative

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What is an independent evolutionary lineage?

An independent evolutionary lineage is a species.

How do each of the three species concepts differ from each other? (consider all 3)

Unlike the others the Biological Species Concept only refers to sexual species and reproductive isolation. The Phylogenetics Species Concept refers to asexual and sexual species and focusses on a unique combination of character states. The Morphospecies Concept focusses on distinct morphological differences

What are the character states that the morphospecies concept can use to identify distinct species?

distinct morphological differences

How can you use phylogenetic trees to infer how viruses have spread?

establish order of events and similarities

Phylogeny

evolutionary history of a group or species

Phylogenetic Tree

graphical summary of the evolutionary history of a group or species

Polyphyletic Group

group that does NOT contain the most recent common ancestor

Monophyletic Group

include all descendants of common ancestor -group that contains the most recent common ancestor plus all and only all of its descendants

Paraphyletic Group

include some but not all descendants of a common ancestor -group that contains the most recent common ancestor, but NOT all of its descendants

Polyploidy

increase in chromosome number relative to ancestors

Genetic Distance

infers relationships among taxa based on genetic similarity

How would you test for coevolution from two phylogenies (for two different groups of species)?

make a phylogenetic tree

Cladistics

naming schemes that are based on evolutionary relationships

Vicariance

new barrier separated pre-existing populations -allopatric speciation

Tokogeny

relationships among individuals of the same species

How is the branch support for clades on the most parsimonious tree determined using bootstrap?

resample characters with replacement to estimate support for each branch in inferred phylogenetic tree

Symplesiomorphy

shared, primitive character state

Independent Evolutionary Lineage (Convergent Evolution)

similarity between species that is caused by a similar, but evolutionary independent, response to a common environmental problem.

Homology

similarity due to common ancestor -all synapomorphies are homologous -symplesiomorphies can be homologous

Analogy

similarity not due to common ancestry -reversal -convergence

What types of groups are species concepts trying to recognize?

species

Interbreeding

successfully producing fertile offspring

What does "interbreeding" mean in the context of the biological species concept?

successfully producing fertile offspring. It means theres one species if they are able to interbreed.

Why do the phylogenetic species concept and the morphospecies concept focus on differentiating between comparable individuals rather than differentiating between all individuals?

there are too many differences between all individuals than there are in comparable individuals

Autapomorphy

unique derived character state

Coevolution

when natural selection occurs and produces adaptations in both species involved

Reversal

-"back mutations" -DNA changes back to an ancestral form -If a reversal has occurred, then similar traits are not homologous and do not qualify as synapomorphies

Maximum Likelihood

In addition to evaluating the best trees implied by a parsimony analysis, most researchers analyze their data sets with a phylogenetic method that computes a probability or likelihood that alternative trees are supported by the data

Dispersal

Individual(s) cross barrier -allopatric speciation

From a phylogenetic perspective, which kinds of groups should be named in our taxonomic classification system: monophyletic, paraphyletic, or polyphyletic? Why?

Monophyletic groups should be named because they include all the descendants of a common ancestor

Which of the three species concepts can be applied to asexual linages?

Morphospecies Concept and Phylogenetics Species Concept

Which of the three species concepts can be applied to sexual lineages?

Morphospecies Concept, Phylogenetics Species concept and Biological Species Concept

What kinds of characters can be used for phylogenetic analysis? What are some requirements for characters used in phylogenetic analysis?

Possible Sources of Characters are; Morphological Structures, DNA sequences, Chromosome numbers, behavior, and chemical compounds -Requirements for characters are; they must be Independent, Heritable, and Variable

Why might the three different species concepts provide different answers on the number of species in a given lineage?

They take different factors into account

Bootstrap Support

a computer creates a new data set from the existing one by repeated sampling

Synapomorphy

a homologous trait that is shared among certain species and is similar because it was modified in a common ancestor -shared, derived traits

Parsimony

a logical way to distinguish homology from homoplasy and identify synapomorphies