Taxonomy Flashcards
(20 cards)
What is the core idea of the theory of evolution?
Species are not immutable; they change through natural selection.
What is phylogeny?
The evolutionary history of a species or group.
What is systematics?
The study of organisms in an evolutionary context.
What is cladistics?
A method to determine evolutionary relationships using shared characteristics to draw cladograms.
What drives genetic evolution?
Mutations, DNA sequencing, developmental biology (e.g. Hox genes)
Why is cytochrome c important in evolution?
It’s a highly conserved mitochondrial gene used in phylogenetics.
What is the likely ancestor of animals?
Choanoflagellates — protists with choanocytes.
What distinguishes animals from choanoflagellates?
True multicellularity, germ cells, collagen, and cellular differentiation.
What are Parazoa?
Animals without true tissues, e.g. sponges (Porifera) and Placozoa.
What are Eumetazoa?
Animals with true tissues
What is Radiata?
Animals with radial symmetry and 2 germ layers (diploblastic), e.g. cnidarians and ctenophores.
What is Bilateria?
Animals with bilateral symmetry and 3 germ layers (triploblastic).
What does the mesoderm form in triploblasts?
Connective tissue, muscles, notochord, kidneys, blood cells.
What distinguishes protostomes from deuterostomes?
In protostomes, the blastopore becomes the mouth (e.g., molluscs, annelids, arthropods); in deuterostomes, it becomes the anus (e.g., echinoderms, vertebrates).
What defines Lophotrochozoa?
Includes molluscs and annelids; some possess a feeding structure called a lophophore or trochophore larvae.
What defines Ecdysozoa?
Animals that undergo ecdysis (moulting), e.g. arthropods and nematodes; have a cuticle
What are the key features of Placozoa?
Simplest non-parasitic metazoans; flat body; Trichoplax adhaerens is the only species described but likely many exist.
What are the key features of Porifera (sponges)?
- Asymmetrical, no true tissues or organs
- Filter feeders with choanocytes
- Layers: pinacoderm (outer), mesohyl (middle), choanocyte layer (inner)
- Contain amoebocytes and spicules
- Skeleton made of spongin, silica, or calcium carbonate
- 3 body plans:
- Asconoid – simple, tubular
- Syconoid – folded walls
- Leuconoid – highly folded with chambers
- 4 classes based on skeleton type
What are the three types of body cavities?
- Acoelomate: No body cavity (e.g., flatworms)
- Pseudocoelomate: Cavity not fully lined by mesoderm (e.g., nematodes)
- Coelomate: Body cavity fully lined with mesoderm (e.g., annelids)
What terms describe body axes in bilateral animals?
Dorsal (top), ventral (bottom), anterior (head), posterior (tail), left, right; cephalisation is the development of a head.
