Natural Selection
what is directional selection? give an ex?
most common; allele frequencies shift in
one consistent direction only
- ex: antibiotic resistance
what is the fossil record?
includes many types of fossil evidence
what are photoautotrophs?
cyanobacteria
- oldest known fossils (3.5 billion yrs.)
- 5% of all photosynthesis (marine and freshwater)
what are characteristics of echinoderms? give an ex.
Radial symmetry, but evolutionarily advanced (closest relative to chordates)
- ex: starfish, sea stars, urchins
what are of gastropods?
- snails
- sea slugs
what is stabilizing selection? give ex.
intermediate forms are favored,
extremes are selected against
- ex: goldenrod galls
what is biogeography?
geographic distribution of organisms
what are beneficial heterotrophs?
bacteria in GI tract and on skin surfaces
• protect against harmful bacteria and viruses
• help nutrient absorption
what are characteristics of chordates? give ex.
Features (at some point in life)
♦ dorsal, hollow nerve cord
♦ notochord to support body (becomes disks between
vertebrae in humans)
♦ pharyngeal (gill) slits
♦ tail
- fishes, amphibians, reptiles, birds
what are bivalves?
clams, scallops, mussels, oysters (filter
feeders)
what is sexual selection? give an example.
avors traits that do not help
survival, but are preferred by mates
ex: flashy feather color in birds, antlers in deer, male song
what is comparative anatomy?
study of similarities and
differences between major groups
what are pathogenic heterotrophs? give an ex.
- some have cell wall (important for antibiotics)
- others have sticky capsule to adhere to surfaces
- ex: strep throat, food poisoning
what are cnidarians? give ex.
- radial symmetry, all predators
♦ have stinging tentacles w/ cnidocytes (cells with
barbed threads, sometimes toxic)
♦ medusa and polyp stages – some have both
- ex: jellyfish, hydra, sea anemone
what are cephalopods?
- octopus
- squid
- nautilus
what are bottlenecks? give ex.
population reduced to very small
number in short time frame
- ex: cheetahs
what are examples of comparative anatomy?
- ex: homologous structures – similar b/c of shared ancestry
- ex: convergent – similar b/c of shared environmental
pressures
- ex: vestigial structures:remnants of features that no longer have function
what are halophiles? what are thermophiles? what the difference? give ex.
- thermophiles: anaerobic; volcanoes or hot springs
- halophiles: aerobic, can be be photosynthetic; dead sea or great salt lake
types of worms?
- Nematodes (roundworms) – very abundant (billions
in 1 acre of topsoil)
- ex: parasites
- Segmented worms (annelids) – more evolutionarily advanced
- ex: earthworms, leeches
what are characteristics of arthropods?
- highly developed segmentation
- specialized jointed appendages
- cephalization – distinct head region
- exoskeleton of chitin and protein sometimes calcium carbonate
what is the founder effect? give an ex.
start new population with only a few
individuals
- ex: higher frequency of genetic disorders in some isolated religious communities
what is moelcular biology?
use of DNA analysis to determine
evolutionary relationships
what are viruses? are they alive?
Non-cellular agents that infect virtually all organisms
- no metabolism of their own
- can reproduce, but host cell does all the work
what are characteristics of mollusks?
Soft fleshy body, muscular ‘foot’, most have shell made by tissue layer called mantle
name types of arthropods + characteristics. give ex for each.
1. chelicerates: 4 pairs of legs; horseshoe crabs and arachnids (spiders)
2. myriapods: many similar segments; millipedes
3. crustaceans: have calcium carbonate shells; lobster
4. hexapods: 3 pairs of legs; winged invertebrates; mostly insects (fly)