What are the subgroups of the linnaean classification system?
Kingdom Phylum Class Order Family Genus Species
What is the highest level of classification?
Domain (3 domains of life)
What is a rank/group called?
Taxon (plural: taxa)
What is the latin binomial and how must it be written?
The genus and species put together respectively. This binomial must be always italicized or underlined. Abbreviation can be used for genus (eg C. familiaris)
What is classification based on?
What is the graphic representation of evolutionary relationships?
What are sister taxa?
Taxa within branch points that are more closely related to each other than other species
How accurate are evolutionary trees?
They are hypotheses
What are traits?
Informative characters such as: Gene sequence Comparative body architecture and morphology Development
What are the types of evidence that are used to construct a phylogeny?
Fossil record informative characters
Which characters are used in constructing phylogenies?
What is a share-derived character (synapomorphy)?
character shared by all descendents of the ancestor in which it arose due to common descent (homologous not analogous characters)
What is the difference between homologous and analogous structures?
Homologous characters are similar because they are the same structure inherited from a common ancestor but have been modified for different functions. Analogous structures are similar in function but are not structurally and evolutionary similar.
How are genetic sequences compared?
What are some other types of evidence for constructing phylogenies?
Levels of organisation in complexity (unicellular, tissue level, organ level, etc) Body symmetry Number of embryonic tissue layers (have one, others have 2, others have 3) Body cavities of triploblastic animals between gut and outer body wall (coelomate or not)
What is cephalisation and which types of animals have this?
Bilaterally symmetrical animals often have a head with concentrated nerve tissues and sense organs
What are the types of organisation of body cavity?
Pseudocoelomate (body lined by mesodermally derived tissue on outer side only) Acoelomate (no body cavity) Coelomate (body cavity lined by mesodermally derived tissue on outer and inner sides)
What are protostomes?
Blastopore becomes the mouth
What are deutrostomes?
Blastopore becomes anus
What are synapomorphies?
shared derived characters
What is the problem with using several traits to create phylogenies?
Molecular phylogenies often disagree with morphological phylogenies
What is a monophyletic group?
Includes all descendants of the most reent common ancestor (excluding the ancestor) Also known as a clade
What is a paraphyletic group?
A group that does not include all descendants of the most recent common ancestor. A paraphyletic group typically includes the ancestor
What is a polyphyletic group?
A group that is neither monophyletic nor paraphyletic. This kind of grouping typically groups together taxa that resemble each other due to convergent evolution.
Which groupings are most effective at displaying relationships between animals?
What is an example of paraphyletic grouping being problematic?
The reptile class separates reptiles from birds. Birds and reptiles are derived from the same common ancestor. This paraphyletic grouping is changed to monophyletic grouping by including birds in class reptilia.
How are lophotrochozoan and Ecdysozoan phyla related?
They are sister taxa
Is the vertebrate phylum monophyletic?
Is the invertebrate group of animals monophyletic?
No (it doesn't include vertebrates, hence that entire lineage is missed)
What are the features of metazoans?
Multicellular Eukaryotic Possess true tissues with intercellular junctions and communication
What are the features of protozoans?
Unicellular Eukaryotic Most possess flagella or cilia Limited communication among animals
What group do sponges belong do?
Metazoans (barely) and most have no true tissues
What are the 3 domains of organisms?
Bacteria: Prokaryotic Archaea: Prokaryotic Eukarya: Eukaryotic
What organisms are metazoa?
How are choanoflagellate protozoa related to animals?
They are a sister taxon to animals (metazoa)
What kind of creatures are formed from choanoflagellates?
The first animals
What are the characteristics of choanoflagellates?
Cell-cell communication in choanoflagellates. Loose association of protozoan cells Filter feeding by beating flagellae to drive current of water through filtering microfibril collar. First animals are believed to have arised from choanoflagellates
How do choanoflagellates divide?
What are the key features of phylum porifera?
Among the simplest metazoans Some degree of differentiation, cooperation, and communication. Most have no true tissues such as epithelia (no intercellular junctions, no basal membrane) Some totipotent cells Entirely aquatic Sessile (immobile) No body symmetry Porous Pump water through body Filter feed with choanocytes
How do sponges feed?
Choanocytes are located within sponges and they contain flagella which direct water outward forcing new water inwards through pores formed by porocytes. Choanocytes filter this water and feed through this mechanism. All digestion is done intracellularly.
What cells form the outer layer of sponges?
pinacocytes form a layer called the pinacoderm
What is the function of spicules?
Give the body rigidity and form gametes.
What are spicules made of?
Can be made of calcium carbonate or silica
What is spongin?
A structural material composed of collagen.
Which cells produce spicules?
archaeocytes in the mesohyl
What is the asconoid body type for sponges?
Simplest form where water enters through pores (ostium) and exits through the opening at the top (known as osculum). The cavity within the sponge is known as the spongocoel.
Why are asconoid body types very small?
Due to decrease in SA:V ratio
What is the second type of sponge architecture?
Asconoid Syconoid Leuconoid
What is the difference between asconoid and syconoid body types for sponges?
Syconoid architecture contains a larger surface area due to a more folded body structure. Water has to travel through canals in the folds known as incurrent canals prior to entering the ostia.
What is the difference between leuconoid body architecture and other sponges?
No spongocoele and instead water flows through many incurrent canals and ostia as well as several oscula. These sponges are able to become the largest size.
What is the density of chambers in typical leuconoid sponges?
10000 chambers/cubic cm
How do sponges reproduce?
Asexually via breakage and regeneration or via cysts called gemmules. Sexually by shedding sperm and retaining eggs and capturing sperm via choanocytes which transforms into archaeocyte and transports sperm to egg (good example of totipotency).
What does monoecious mean?
each individual produces both eggs and sperm.
What does diecious mean?
What cells produce gametes?
What is the larval stage of a sponge called?
Do sponges undergo blastulation?
Yes and they form blastocoeles
Do sponges undergo gastrulation? What does it say about gastrulation as a trait?
No, this indicates that gastrulation is a synapomorphism
What are the classes of sponges?
Calcarea: calcium carbonate spicules. All are marine Hexactinellida: siliceous spicules with 6 rays, "glass sponges". Deep sea Demospongiae: siliceous spicules, spongin fibers, or both. All are leuconoid and contains 80% of sponge species. Freshwater and Marine Homoscleromorpha: No skeleton or siliceous spicules. Contain true tissue (pinacoderm). all are marine
What distinguishes the classes of sponges?
Where are hexactinellida located?
In the deep sea
What is the problem with porifera classification these days?
It is paraphyletic and includes homoscleromorpha which are distant in ancestry.
How are sponges used by humans?
Harvesting bath sponges for chemicals that have pharmaceutical benefits.
What is the exception to sponge filter feeding mechanism?
Carnivorous sponge (Asbestopluma) contains long spicules which capture animals and archaeocytes surround and engulfe tissue of shrimp
What is the first true metazoan phylum?