lecture 2 Flashcards
microevolution
change through time. species are not fixed.
artificial selection
dogs are the first domesticated species. earliest records 15,000 years ago. most breeds < 200 years old. share a common ancestor (wolves).
selective breeding
patience required, 24 generations of mice, variation in activity on wheels, “high runner” lines who used the wheel a lot, controls lines (random), nearly 3x the activity.
- observed changes: genotypes, physiology, morphology, neurology
- high runners resembled human ADHD: ritalin treatment reduced the amount they ran.
cane toad expansion
introduced to Australia in 1935 to control insect pests in cane fields.
- then: 10 km per year
- now: 60 km per year. evolving longer legs, travel greater distances, front of the invasion change through time.
speciation
general lineage concept of species; species are separately evolving population lineages.
evidence for separate lineages (species criteria):
reproductive isolation, morphology, ecology, behavior, genetics, phylogenetics
vestigial structures
traits that are homologous with structures in other organisms that are more fully functioning. evidence of a past history where the trait was more useful. attributed to change in the environment or change in the behavior or ecology of the organism. for ex:
- dolphin embryo (5 weeks) with limb buds, but the genetic mechanism even though it is still there, typically shuts off.
atavistic limbs
the developmental genetic mechanisms fail to shut off, resulting in a partial structure.
law of succession
fossil and living organisms in the same geographic region resemble each other, but are distinct from organisms found in other areas.
snakes evolved from
lizards. a snake-like body has evolved independently in lizards about 25 times.
living terrestrial forms
terrestrial fish, pacific leaping blenny.
homology
similarity in structure despite different function.
- evidence for common ancestry.
- similarity due to the inheritance of traits from a common ancestor.
