Ichthyology

Poikilothermic

body temperature at or near identical to surrounding water

taxonomy

describing biodiversity and arragning it into classes

systematics

relationships that may exist among classisfied taxa, trends in trait modifications and when they appear

Meristic characters

countable structures that are clearly definable, and stable over a wide range of body sizes, easily compared statistically

Morphometric characters

measurable structures that are continuous and can be assessed at different levels of precision

allometry

defines how size of various morphometric features change relative to overall body size

isometric trait

trait grows at same rate as the best of the body

hyperallometric

trait grows faster than the rest of the body

hypoallometric

trait grows slower than the rest of the body

Molecular markers

assumes more closely related taxa are genetically related, markers used to estimate degree of difference and if rate of DNA changes are unknown, the timing of divergence among take

international barcode for life (iBOL)

genetic characterisation ofall species using genetics

systematics and classification approaches

cladistics, phenetics, evolutionary systematics

cladistics

uses characters/traits to classify groups and infer relatedness

two types of cladistics

apomorphy and plesiomorphy

apomorphy

recently evolved, derived or advanced traits/characters

plesiomorphy

ancestral, primitive or generalised trait/characteristic

phylogenetic systematics

fundamental approach to observe and identify traits

synapomorphy

shared derived characteristics that isolate monophyletic clades/clusters

autapomorphy

specialized character only in one single focal taxon

sympleslomorphies

shared ancestral characters, not useful in constructing relationships

outgroup

closely related group outside of taxa of study

monophyletic

all taxa descend from common ancestor and not the ancestor of any other group

paraphyletic

cluster doesn’t contain all taxa descendants from most recent common ancestor

polyphyletic

taxa in focal group are descendants from several ancestors that are also ancestors of taxa classified in other group

Parsimony

select relationships explaining most data using fewest number of steps

Numerical taxomony (phenetics)

begins by considering operational taxonomic units

evolutionary systematics

takes amount of time and accumulates differences into account when developing relationships among taxa