Comparative Anatomy Test 1
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What is comparative vertebrate anatomy?
- 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
What is the adaption paradigm?
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.
How does natural selection occur?
- 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.
What is adaptation?
- 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.
What are the kinds/types of selection?
- 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
What are the forms of selection?
- 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
What is the evidence for evolution?
- Artificial selection
- Molecular similarities
- Fossil record
- Comparative anatomy
What is a species?
A group of interbreeding or potentially interbreeding organisms that are reproductively isolated from other similar organisms
What is allopatric speciation?
- 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
What is parapatric speciation?
When organisms of the same species are not separated by a physical barrier, but sexual selection basically causes speciation.
What is some characteristics of the phylum Chordata?
- Dorsal Notochord
- Dorsal tubular nerve cord
- Pharyngeal gill slits
- Ventral Heart or Aorta
- Tend to have some degree of cephalization & a post-anal tail
What are some characteristics of the superclass Agnatha?
- 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
What are some characteristics of the class Myxini, or the hagfishes?
- 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
What are some characteristics of the class Cephalaspidomorhl or lamprey?
- 5 genera & 41 species
- 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
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