Week 9 Flashcards
Describe binomial nomenclature
Each species has two names:
1-Indicates the genus at which it belongs
2-Indicates the species
Describe Biological Species Concept
“Species are group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups”
What are the four problem of the Biological Species Concept?
- It cannot be applied to asexual species
- It cannot be applied to allopatric species
- It cannot be applied to organisms separated by geological time
- It doesn’t consider the level of reproductive isolation
Describe evolutionary (or lineage) species concept:
Species are seen as branches of the tree of Life
Describe the morphological species concept:
Species consist of individuals with the same morphology
Describe Phylogentic Species Concept:
Is based on two assumption:
1-Group taxa using the criterion of monophily (shared common ancestor)
2-Ranks group by the criterion of having the smallest diagnosable monophyletic group possible
What’s Phylogeny?
Is the evolutionary history of relations among organisms and their genes
What’s a node on the Phylogenetic tree?
A point at which two lineages diverged in the past
What’s the root of the Phylogenetic tree?
It rappresent the common ancestor of one or two lineages
What’s a clade?
Any taxon that consists of all the evolutionary descendants of a common ancestor
What are sister species?
Two species that are each other closest relatives
What are sister clades?
Two clades that are each other closest relatives
What’s systematics?
Is the study and classification of biodiversity
What’s a taxon?
Any group of species that we designate with a name
What’s cladistic?
Is the study of clades
What’s a lineage?
A series of organisms that is connected by a continuos line of descent from a common ancestor
What are homologous features?
Features shared by two or more species that were inherited from a common ancestor
What is a Plesiomorphy?
A trait that was also present in the ancestor of a group (It’s also called the ancestral state of a trait)
What’s a Synapomorphy?
A trait found in the descendant that differ from its ancestral state (It’s also called derived trait)
What’s an homoplasy?
A character shared between a set of species that wasn’t present in their common ancestor
What are the two reasons of origin of homoplasies?
1-Convergent Evolution
2-Evolutionary reversal
Describe the effect of convergent evolution on a trait:
Independently evolved traits subjected to similar selective pressure may become similar superficially
Describe evolutionary reversal:
A character reverts from its derived state back to the ancestral state.
What’s the parsimony principle?
The simplest explanation (the one with the fewest number of homoplasies) is the preferred one.
What are the five sources of data used to construc phylogenetic trees?
Morphology Development Paleontology Behavior Molecular Data
Describe how morphology is used to build a phylogenetic tree:
We observe the presence, size and shaped of body parts
Describe how Development is used to build a phylogenetic tree:
We observe the similarities in the developmental pattern
Describe how Paleontology is used to build a phylogenetic tree:
Fossil record provide important references that can help us distinguis between ancestral and derived traits
Describe how Behavior is used to build a phylogenetic tree:
Some behavioral traits are culturally transmitted but others are inherited
Describe how Molecular Data is used to build a phylogenetic tree:
We use DNA for phylogenetic analyses
What are the three main uses of Phylogenetic Trees for biologists?
- They help them recostructing the past
- Compare and contrast living organisms
- Ancestral state of traits can be reconstructed
What are the three different type of taxa?
- Monophiletic
- Polyphiletic
- Paraphiletic
Describe monophiletic taxa:
Taxa that contain the ancestor and all the descendants
Describe polyphiletic taxa:
Taxa that contain only the descendants and exclude the common ancestor
Describe paraphiletic taxa:
Taxa that don’t include all the descendants from a common ancestor.
