Ichthyology Flashcards
Why study fish
food source,conservation,fun/interest,ecosystem/links
Fish characteristics (6)
• live in aquatic habitats
• Poikilothermic
• Chordates
• Have fins as Appendages
• Use Gills as respiratory organs
• Body generally covered with scales
Poikilothermic
body temperature at or near identical to surrounding water
What does loss of features/unfish like characteristics tell us?
tells us about the function of these traits in other species
clarify how the missing or new traits might be useful
What is a species?
groups of actually or potentially interbreeding individuals which are reproductively isolated from other such groups
Biological species concept works for fish, but is flawed; some species reproduce asexually, but for fish this def works
Taxonomy vs systematics
Taxonomy: arranging biodiversity it into classes,Devising identification keys to recognize and group individuals into those classes
Systematics: how traits they change among groups, relationships that may exist between taxa
Taxonomic characters
used to differentiate taxa
Meristic Characters: Countable structures
Morphometric Characters: Measurable structures
Allometry (allometric growth) defines how the size of various morphological features change relative to overall body size
colour/patterns
genetic markers
Types of Allometry
Isometric = trait grows at the same
rate, slope = 1
Hyperallometric = trait grows faster, slope > 1
hypoallometric= trait grows slower, slope<1
Taxonomic characters (Molecular markers)
Use genetics to compare taxa/ specieation, etc
iBOL
Molecular marker
Works because intraspecific sequences more similar to each other than to interspecific sequences – Barcoding gap
• Useful in:
- identifying new species (biodiversity), - identifying cryptic species,
- verify fish bought at grocery store, restaurant, or landed during fisheries
Cladistics (phylogenetic systematics)
Uses characters/traits to classify groups and infer relatedness
Divides useful characters into 2 types
Apomorphy: Recently evolved, derived or advanced traits/character
Plesiomorphy: Ancestral, primitive or generalized trait/character
Observe traits and identify synapomorphies
synapomorphies
shared derived characters that isolate monophyletic clade/cluster
Symplesiomorphies
shared ancestral characters (not useful in constructing relationships)
Outgroup
closely related group outside the taxa of study
ie can use hagfish as outgroup (base) to help classify and identify other species but determining what is considered ancestral or not
Types of clades (3)
Monophyletic (aka clade): all taxa descendant from common ancestor and not the ancestor of any other group (every taxa descendant from ancestor included)
Paraphyletic: cluster does not contain all taxa descendant 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
