Ch. 24 & 26 Flashcards
Define anagenesis
Anagenesis is the transformation of one species into another
Define cladogenesis
When a gene pool splits and is exposed to different selection pressures which creates one or more new species
What are differences between cladogenesis and anagenesis
Anagenesis: new specie is born out of TRANSFORMATION , does not branch
Cladogenesis: new specie is born out of CREATION (from selection pressures) , does branch out
What is the Biological Species Concept
Organisms are reproductively compatible with members of their own species and can reproduce with each other, but they CANNOT INTERBREED with other populations
Who is Ernst Mayr?
Scientist who created the biological species concept
Define biological species
Must be fertile and able to interbreed
List the 5 prezygotic barriers
Habitat, temporal, behavioral, mechanical, and gametic isolation
List the 3 postzygotic barriers
Reduced hybrid viability (inviability), reduced hybrid fertility, and hybrid breakdown
What is meant when barriers are postzygotic or prezygotic
Postzygotic barriers are barriers that are meant to stop inter-species breeding AFTER zygote has been fertilized
Prezygotic barriers are barriers that are meant to stop inter-species BEFORE the zygote can be fertilized
Explain hybrid breakdown**
In hybrid breakdown, the first generation of inter-species breeding may be fertile but the next generations will be feeble or sterile
What are the limits of the biological concept
The concept does NOT apply to: asexual organisms, fossils, organisms that have little information known about their reproduction
Define the ecological species concept
This concept defines species by their ecological niche (aka, how they adapted to a particular set of resources in an environment)
Define paleontological species concept
Concept used to define species known only from the fossil record (morphologically discrete)
Define the phylogenetic species concept
Concept used to define species as a set of organisms with unique genetic history
Define the morphological species concept
Concept that defines a species by their structural features
What is allopatric speciation
Where a new species is developed as a result of being geographically isolated from the parent population
Define sympatric speciation
Where a new species is formed from the same ancestral population without any geographical separation
List and describe some mechanisms that may lead to a divergence of isolated gene pools
For gene pool isolation to occur, a species must be divided and adapted to their new/differing surroundings. This can be done through:
- allopatric speciation (geographic isolation)
- sympatric speciation (reproductive barrier isolation)
- adaptive radiation (species of common ancestor rapidly diversifies when exposed to many new environments)
Define phylogeny
The evolutionary history of a species or group of related species
Define systematics
Understanding the diversity and relationships of organisms (present-day and extinct) and evolutionary relationships.
Uses morphological, biochemical, and molecular comparisons.
Distinguish between systematics and phylogeny
Phylogeny: the actual history of the species
Systematics: the understanding of the relationships and diversity the specie has
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What are homoplasies
Independently evolved molecular sequences or analogous structures
What is taxonomy
The ordered division of organisms into categories based on characteristics - used to assess similarities and differences
What is binomial nomenclature
The two-part scientific name of a species, consists of the genus + the specific ephitet. Both parts must be said to refer to the specific organism.
What is a specific ephitet
The second part of a species’ binomial nomenclature that is specific to each species under a genus.
ex: “felis” genus covers cats, “felis margarita” covers a specific species of cat
What is hierarchical classification
The grouping of species in increasingly broad or increasingly narrow categories
What are the 8 major taxons
- DOmain
- Kingdom
- PHylus
- Class
- Order
- Family
- Genus
- Species
What is the most inclusive taxon
domain
What is the least inclusive taxon
species
Distinguish between homology and analogy
Homologous similarities come from a common ancestor, analogous similarities come from convergent evolution
What is convergent evolution
When similar environmental / selection pressures produce similar (analogous) adaptations in organisms from different evolutionary lineages
Why are bird and bat wings analogous but have wing bones that are considered homologous
The bird and bat wings evolved independently - making their similarity in form/function analogous, but their wing bones were inherited from a common ancestor - making their similarity in structure homologous
What is molecular systematics
A method that uses nucleic acids or other molecules to infer evolutionary relationships between different species
What is a clade
A grouping of species on a cladogram that includes an ancestral species and all its descendants.
Can be nested in larger clades.
What is a cladogram
A cladogram depicts patterns of shared characteristics among taxa
What is a monophyletic clade
To be monophyletic signifies that it consists of the ancestor species and all its descendants
What is a paraphyletic grouping
A grouping that consists of an ancestral species and some, but not all, of the descendants
What is a polyphyletic grouping
A grouping that consists of various species that lack a common ancestor
Distinguish between a monophyletic clade, paraphyletic grouping, and polyphyletic grouping
monophyletic: has ancestor species and ALL descendants
paraphyletic: has ancestor species and SOME, not all, descendants
polyphyletic: various species with NO common ancestor species listed
What are shared primitive characters
A homologous structure that is older than (shared beyond) the defined taxon
What are shared derived characters
An evolutionary characteristic unique to the defined clade
How are shared derived characters can be used to construct a phylogenic diagram
Because they are unique to particular clades, making it possible to match the shared derived characteristic to the clade and use it to infer
What is an outgroup
A species that is closely related to but not in the ingroup
What is an ingroup
The group of various species that are being studied
Why are phylogenetic diagrams technically hypotheses about evolutionary relationships among organisms
Because one cannot go back to confirm the proposed relationships
What does outgroup comparison tell us
That homologies shared by the outgroup and ingroup must be primitive characters that predate the divergence of both groups from a common ancestor
Describe the evidence that suggests the existence of a universal tree of life
By studying ribosomal RNA sequences, scientists discovered that all life on earth can be placed in one of the three major categories, pointing to the existence of a common ancestor that all life came from
What are the 3 categories that all life can fit into at least one of
Archaea, Bacteria, and Eukarya
