evolution
changes in the genetic makeup of populations of animals through time - change in
genetics eventually leads to changes in phenotype
recapitulation
similarities in embryonic developmental stages of different species is evidence that the
embryos are repeating the developmental stages of the ancestors
mosaic evolution
parts of the body can change independent of others
homology
similarity in organs from different organisms as a result of inheritance from COMMON
ancestors
analogy
functional similarity among non homologous organs (like butterfly and bird wings)
Darwin's reasoning behind natural selection
-animals have high reproductive potential and if unchecked will deplete resources
-heritable variation between organisms
-competition for resources allows the most fit attributes to be passed on with survivors
monophyletic group
a group with the ancestor and all of its descendants
character states
various forms of individual attributes
derived characters
evolutionarily changed and used to delineate relationships
transformation series
change in character states through time within a clade (ex transition to land)
outgroup analysis
used to assess patterns of change by establishing polarity (direction of change)
outgroup taxa
closely related lineages to the one of interest
polarity
patterns of change or stasis
vestigiality
organs that are no longer being used for their original function
atavism
throw back structures - present in ancestors but rare in most individuals today
Fossil Biases
-they are always morphologically based and not molecular
-include only skeletal elements (like teeth since its so hard)
-mainly found in fluvial or arid environments
-large animals are more commonly found
heterochrony
, evolutionary change to developmental timing or rates
anatomical position
the standard position an animal should be in before we embark on explaining direction
and movement
bilateral symmetry
body is divided by a mid-sagittal plane forming two mirror images
Lateral
away from midline (farther from the middle)
medial
closer to the midline
proximal
closer to the top of the appendage
distal
closer to the tip of the appendage (farther from the start)
frontal plane
divides an animal into dorsal and ventral
dorsal
above the frontal plane (top when laying down)
ventral
under the frontal plane (belly)
transverse plane
plane dividing the front and back
cranial (anterior)
towards the head
caudal (posterior)
towards the tail