Comparative Anatomy Test 1

• The study of the functional morphology of the vertebrates 
• Compares body form & functionof various strucutres 
• Compares the similarities & differences in morphology among organism 
• Interprets similarities & differences in form within the contexts of ancestry, function, & evolution

An organism adapt to its environment with limitations from its ancestors.

• Changes in gene frequency of a population through time 
• Change in the character states of organisms through time 
• Requires genetic variability - difference in the ability to survive and reproduce being linked to differences in heritable genetic variation

• Differential reproduction & survival of organisms with certain character states or genotypes. 
• It is NOT survival of the fittest as the term "fittest" is typically thought of.

• More offspring are produced than can survive each generation. 
• Population size exceeds the environment's carrying capacity 
• A critcial resource becomes limiting. 
• Competition occurs 
• Additive genetic variation in competitive ability exists 
• Best competitors survive & reproduce 
• Results in an increase in the frequency of the traits that increased fitness in the next question 
• If the frequency of a given chracter state changes: It's natural selection in the current generation and evolution in the next generation.

• Adaptation is a process of population becoming adjusted to a particular environment over many generations. 
• An adaptive trait is a structure, a physiological mechanism, behavior that increases the probability that an organism will survive to reproduce.

• Natural selection - Differential survival of certain genotypes or phenotypes 
• Artificial selection - Differential breeding of organisms with certain desirable traits by humans 
• Sexual selection - Differential mating success

• Directional selection - Selects for an extreme phenotype at one end of the distribution; Mean, Median, & Mode all change; Standard deviation may increase, decrease, or remain the same. 
• Stabilizing selection - Tends to eliminate individuals at each end of the distribution; Mean, Median & Mode are stationary; Standard deviation decreases 
• Disruptive selection - Eliminates individuals with the mean character state, and selects for the two extreme forms; Mean may remain the same; Bimodal; Standard deviation increases; Gives rise to speciation

• Artificial selection 
• Embryology 
• Molecular similarities 
• Fossil record 
• Biogeography 
• Comparative anatomy

A group of interbreeding or potentially interbreeding organisms that are reproductively isolated from other similar organisms

• Generating new species in different geographic locations 
• Barriers arise that separate gene pools 
• No gene flow between gene pools 
• Differential selection, genetic dirft, & mutation within the different populations 
• Barriers removed 
• Two populations come in secondary contact 
• Reproductive isolation

When organisms of the same species are not separated by a physical barrier, but sexual selection basically causes speciation.

• Dorsal Notochord 
• Dorsal tubular nerve cord 
• Pharyngeal gill slits
• Ventral Heart or Aorta 
• Tend to have some degree of cephalization & a post-anal tail

• Have a head with a brain & paired light sensitive organs "eyes" 
• Large persistent notochord 
• Two semicircular canals in each ear 
• Soft skin no scales 
• Two chambered heart (1 atrium, 1 ventricle) 
• External fertilization

• 200 slime glands - slime is used for protection; slime absorbs water and covers the gills of predators 
• Degenerate eyes 
• Large tentacles around terminal nasal opening and mouth
• Marine only 
• No larval stage 
• 5-15 of pouched gills 
• Poorly-developed cartilaginous skeleton 
• Multiple contractile vessels 
• Live in soft mud bottoms 25-600 m in depth, found up to 1000 m 
• Burrow in the mud 
• Live in cold water 
• Eat a variety of foods 
• Lay 20-30 yolky eggs 
• Size is 20-70 mm 
• Six genera & over 60 species

• 5 genera & 41 species 
• Eel-like 
• Lateral eyes 
• Ventral mouth with horny teeth 
• Poorly developed cartilaginous skeleton but has well developed skull and branchial region 
• Vertebrae lack centra but have rudimentary neural arches 
• Dorsal and caudal fins are present by not pectoral and pelvic fins 
• Lack a lateral septum so the are no epaxial or hypaxial muscles 
• Gills open into a respiratory tube that ends at the 7th arch 
• May be more closely related to bony fish than hagfish or sharks 
• Long larval stage, 5 years 
• Filter feed as larvae 
• Two feeding types as adult - parasitic and nonparasitic