Introduction Flashcards
What is functional morphology?
the relationship between the form (structure) and the function of tissues, organs, or organ systems within organisms (in an adaptive and evolutionary context)
What are primitive structures?
the original condition of that trait in a common ancestor
What are derived structures
indicates a notable change from the original condition (a modification of the primitve trait)
What are homologous structures?
A homologous structure is found in 2 or more organisms that is derived from a common ancestry. structure has a similar anatomical position but may not serve the same function or look similarly.
homologous structures can be used to investigate phylogenetic relationships and construct trees.
e.x. middle ear ossicles of more derived vertebrates are homologous with the jaw elements of more primitive vertebrates
What are analogous structures?
analogous structures are found in 2 or more organisms that look similar and are used for the same function but have evolved independently of one another. Produced for convergent evolution
What is Exaptation (preadaptation)?
a pre-existing structure that is inherited from an ancestor but is used for an unrelated function
What is descent with modification?
Evolutionary change that involves continuous modification of ancestral structures?
What is Phylogeny?
The study of evolutionary relatedness among past and present taxonomic groups (i.e., relationships among living things through time)
Can be visualized as evolutionary trees
What is Cladistics?
a system of biological classification in which organisms are categorized based on shared derived characteristics (synapomorphies) that can be traced to a group’s most recent common ancestor
What is Synapomorphy (and apomorphy)?
A shared derived trait found in 2 or more taxa that are used to infer a phylogenetic relationship
What is Symplesiomorphy?
a shared primitive trait that is relatively unchanged from the ancestral form (not informative and tells nothing about relatedness)
What is autapomorphy?
a derived trait that is unique to only one group (not informative, tells nothing about relatedness)
What is Homoplasy?
a shared derived trait found in 2 or more taxa that did not arise from a common ancestor
cladogram
a branching diagram showing the evolutionary relationship between taxa
clade
a natural evolutionary lineage that includes the most recent common ancestor and all and only its descendants (forms a monophyly)
monophyly
a complete clade that consists of the most recent common ancestor and ALL of its descendants
Paraphyly
an incomplete clade that includes the most recent common ancestor but NOT all of its descendants
Polyphyly
an artificial clade composed of unrelated organisms descended from more than one ancestor (containing misleading convergent or homoplastic traits)
sister taxa
groups of organisms that share an immediate common ancestor and hence are each others closest relatives
Crown group
includes the most recent common ancestor of all living taxa of a particular group (plus any extinct descendants)
stem group
includes extinct taxa related to but not part of the crown group. i.e., extinct lineages that diverged below the most recent common ancestor of the crown group.
total group
composed of both the crown and stem groups
Isometric growth
all structures of an organism have the same rate of growth so that its shape is consistent throughout ontogeny
allometric growth
certain structures of an organism have a differential rate of growth in an individual throughout ontogeny
what is the size range of vertebrates?
7.7 mm to 33 m
What happens to volume and surface area as an organism increases in size?
volume, which is proportional to mass, and surface area do not increase at the same rate. Volume/ mass increases faster than the surface area with an increase in overall size, thus supportive bones must become more robust
heterochrony
evolutionary change in the timing or rate of developmental events in the descendant species when compared to the ancestral condition (i.e., ontogenetic change with phylogenetic consequences leads to changes in size and shape.
Paedomorphosis
juvenile characteristics of ancestors appear in the adults of their descendants (includes progenesis and neoteny)
progenesis
acceleration of reproductive development relative to somatic development when compared to the ancestral condition (maturation of the reproductive organs is accelerated relative to the non-reproductive body parts)
Give an example of progenesis
Bolitoglossa occidentalis sexual maturity (relative to somatic development) occurs earlier than in closely related species. retaining small size and webbed hands and feet which are adaptations for arboreal lifestyle
neoteny
slowing down of somatic development relative to reproductive development when compared to the ancestral condition (i.e., delayed development or resorption of non-reproductive body parts relative to the maturation of reproductive organs
Give an example of neoteny
axolotls retain external gills, even after becoming reproductively mature
Peramorphosis
adult somatic characters of descendants are exaggerated in shape (undergoes an extended period(s) of growth) when compared to that of ancestors (includes acceleration and hypermorphosis)
acceleration
rate of development of a somatic structure is increased compared to the ancestral condition
hypermorphosis
offset in the developing somatic structure is delayed compared to the ancestral condition
