Chapter 1: Adaptation by Natural Selection Flashcards
what is a theory?
an explanation supported by evidence and tests
what are adaptations?
anatomical/behavioural features that help an organism survive and reproduce
evolution/natural selection - which is the theory, which is the phenomenon?
the theory is natural selection, the natural phenomenon is evolution
what are the four qualities of science?
- cumulative
- self-correcting
- iterative (builds upon itself)
- evidence based
define evolution
the change in gene pool (genetics/allele frequency) of a population from generation to generation that occurs over time
what evolves, individuals or populations?
populations, individuals do NOT evolve
what is lamarckism?
the idea that organisms pass physical characteristics acquired through use/disuse to offspring
what is catastrophism?
the idea that organisms are completely replaced over time due to catastrophic events
what was the consensus BEFORE darwin?
it was known there was variation among species AND that animals existed that no longer do (unsure why/how)
what are darwin’s postulates?
- there is a “struggle for existence” or competition
- there is variation in features that are related to survival/reproduction
- variation is passed from generation to generation
e.g.
1. during draught, finch population declined
2. variation in beak depth influenced survival
3. beak depth was passed to offspring
what does natural selection act on, phenotype or genotype?
phenotype
what does “evolution is not uni-directional” mean?
it means that there are costs and benefits to all variations, and that not all variations will be selected for in different environments
what is stabilizing selection?
when genetic diversity decreases as the population stabilizes on a more average trait value (extremes chosen against)
what is directional selection?
when one phenotype is favoured an allele frequency shifts in one direction
what is disruptive selection?
when two extreme traits are favoured over intermediate traits
