Lecture 1 Flashcards
What is the definition of monophyly?
Single evolutionary origin.
What is the definition of polyphyly?
Multiple origins.
What is apomorphy?
A characteristic shared by groups of individuals that are not present in the ancestral form. Derived.
What is plesiomorphy?
A characteristic shared by groups of individuals that are also found in their common ancestor. Ancestral.
What is synapomorphy?
Shared derived character.
What is symplesiomorphy?
Shared ancestral character.
Briefly summarize the gastrulation of an embryo
The blastopore forms, followed by the in-pocketing of the endoderm and then the enterocoelic pouches.
What does the ectoderm give rise to?
Different tissues and the epidermis.
What does the endoderm give rise to?
Internal things like organs, the gut lining and glands.
What does the mesoderm give rise to?
Muscles, blood, bone and connective tissue.
What are the key characteristics of chordates?
Notochord, dorso-hollow nerve cord, pharynx with pouches or slits, post-anal tail and an endostyle.
What fold does the dorso hollow nerve cord come from?
Tthe ectodermal neural fold. It also closes over.
What becomes enclosed in the vertebrae in vertebrates?
The notochord and nerve cord.
What does the pharynx with pouches/slits give rise to?
Lungs, gills, skeleton & jaw musculature, endocrine glands, middle ear cavity (tetrapods) and initial foetal immune system (humans).
Describe the function of the pharyngeal/branchial basket in gill-less primitive chordates.
The many slits on the the walls increase the surface area exposed to water. Respiration.
