Exam 1 Chapter 1: introduction Flashcards
(23 cards)
What is a vertebrate?
- Has body plan including segmented vertebral column, paired appendages dorsal hollow nervous system, and ventral digestive system
- Animal possessing a backbone/spinal column, includes mammals, reptiles, amphibians, fish
Name 2 types of biological similarity
homology and homoplasy
Homology
o a character shared between species that was also present in their common ancestor
Homoplasy
o A character shared by a set of species but not present in their common ancestor
- different kinds of homoplasy include Analogy, Convergent Evolution, and Parallel Evolution
Analogy
homoplasy, similar function
Covergent Evolution
homoplasy, – set of characteristics due to adaptations to a particular environment; bodies superficially similar (example: sharks and dolphins, similar since aquatic environment)
Parallel Evolution
homoplasy, when the similar features are caused by an equivalent developmental mechanism
Symmetry
A balanced distribution of duplicate body parts or shapes within the body of an organism
-How an animal’s body meets the environment
Two types of symmetry
radial and bilateral
Which symmetry characterizes vertberates?
bilateral symmetry
Radial symmetry
- organism divided into sections that rotate and match
bilateral symmetry
body divided into two equal halves, with halves mirroring each other
Segmentation
o The serial repetition of similar organs, tissues, cell types or body cavities along the anterior- posterior (A-P) axis of bilaterally symmetric animals
o Seen in annelida, arthorpoda(most diverse), chordata
Preadaptation
o A trait that has evolved for one particular function may come to serve another function
Why is preadaptation important to vertebrate evolution?
o It has important role in development of birds
o Feathers on dinosaurs were originally for warmth, but now serve for the purpose of flight in bird species
- Changing/remodeling what exists
- Rarely adding wholly novel structures
- Selection only acts on what’s there
What does phylogenetics study?
the study of evolutionary relationships among biological entities –species, individuals or genes (which may be referred to as taxa)
What is a phylogeny?
o A visual representation (a hypothesis) of the evolutionary history of populations, genes, or species
Describe and understand the set up of a phylogeny
o The tips of the tree represent groups of descendent taxa (often species)
o The root of the tree represents the ancestral lineage
o The nodes represent the common ancestors of those descendants
o When a lineage splits (speciation), it is represented as a branch
What is a clade?
groups that include a common ancestor and all the descendants (living and extinct) of that ancestor
What are synapomorphies?
o Shared derived characters
o Different from ancestor and shared by 2 or more lineages
Monophyletic group
a single common ancestor and all descendants
Paraphyletic group
a common ancestor and some but not all descendants
Polyphyletic group
based on non-homologous characters
