Evolution - Cliff Notes Flashcards
evolution
- changes in population, species, groups of species
- process by which the frequency of heritable traits in a population changes from one generation to the next
Jean-Baptiste Lamarck
- one of earliest advocates for evolution
- use and disuse idea
- inheritance of acquired characteristics
use and disuse
body parts of organisms can develop w/ increased usage; unused parts weaken
-correct
inheritance of acquired characteristics
body features acquired during lifetime of an organism could be passed onto offspring
-incorrect
Charles Darwin
- Origin of Species
- natural selection
paleotology
provides fossils that reveal prehistoric existence of extinct species
- fossils found in sediment layers
- age of fossils found w/ C-14 dating
5 pieces of evidence for evolution
paleontology (track changes), biogeography (distrib of species), embryology (stages in development), comparative anatomy, molecular biology
biogeography
uses geography to describe distrib of species; unrelated species in diff regions of world look alike when found in similar enviro (eg. rabbits and wallaby; placental vs marsupial), comparative anatomy (similar structures)
embryology
similar stages in development (ontogeny) among related species; similarities establish evolutionary relationships (phylogeny)
comparative anatomy
2 kinds of structures that contribute to identification of evolutionary relationships among species (homologous, analogous)
homologous structures (homologies)
body parts that resemble one another in diff species b/c they have evolved fr common ancestor; will resemble one another in pattern (how put together)
vestigial
homologous structures that no longer serve any function (eg. limbs in snakes)
analogous structures (analogies)
body parts that resemble one another in diff species, not b/c evolved fr common ancestor, but b/c evolved independently as adaptations to environments (eg fins and body shapes of sharks, penguins, porpoises_
molecular biology
nucleotide and amino acid sequences of DNA and proteins fr diff species; closely related species share higher percentages of sequences than species distantly related
-all living things share same genetic code and w/ minor variations, the same basic biochem pathways (incl for replication, protein synth, respiration, photosynth)
natural selection
differences in survival and reproduction among individuals in a population as a result of their interaction w/ the environment
-some individuals possess alleles/genotypes that generate traits/phenotypes that enable them to cope more successfully in their enviro
“survival of the fittest”, driving force of evolution
-acts on individual phenotypes already present in population
-does NOT cause mutations/create new phenotypes; only “selects”
adaptations
superior inherited traits, increase fitness
fitness
relative ability to survive and produce offspring
Darwin’s arguments for theory of evolution
- populations possess enormous reproductive potential
- population size remains stable
- resources are limited
- individuals compete for survival
- there is variation among individuals in a population
- much variation is heritable (not b/c enviro influence, eg. radiation)
- only the most fit individuals survive
- evolution occurs as favorable traits accumulate in the population
4 types of selection
stabilizing selection (eg. human height variation), directional selection (light/dark moths b/c industrialization), disruptive selection (eg. height variation in weeds of lawns and in wind); sexual selection (eg. weight variation in elephant seals)
stabilizing selection
eliminates individuals that have extreme/unusual traits; most common form of a trait = best adapted
-maintains existing population frequencies
directional selection
favors traits that are at one extreme of range of traits; traits at opposite extreme selected against (eg. Darwin finches and beak size)
insecticide resisitance
- direction selection
- chooses insects resistant to pesticide
peppered moth
- directional selection
- w/ soot, dark form of moth became better camouflaged
industrial memlanism
changes in enviro conditions promote evolution
selection of dark-colored varieties in various species of moths as a result of industrial pollution
season creep
shortening of inters and earlier arrivals of spring due to global climate change
-selection fro plants that germinate and flower earlier; invasive plant species favored
disruptive/diversifying selection
enviro favors extreme unusual traits, while selecting against common traits
-in wild, tall weeds favored, but in lawns, short forms exist)
sexyak sekectuib
- mating of males/females in a population
- females usually make greater energy investment in producing offspring, can increase fitness by increasing quality of offspring by choosing superior males
- males increase fitness by maximizing quantity of offspring produced
male competition
contests of strength that award mating opportunities to strongest males
female choice
leads to traits/behaviors in males that are attractive to females
sexual dimorphism
differences in appearance of males and females
-disruptive selection
artificial selection
directional selection
-carried out by humans when so when sow seeds/breed animals w/ desirable traits (eg. dogs, brussel sprouts, broccoli, etc)
