Biology - Evolution

adaptation

the evolutionary process in which organisms become better fit for their environment, leading to increased survival and reproduction

• is a heritable trait

modification by means of natural selection

the organisms who have traits better suited to the environment thus have a greater chance of survival and reproduction. as a result, the animals with the better traits become the dominant adaptation/species

• species change over time as a result of the competition in the environment

• species gradually diversify from their ancestor overtime

decent by modification

genetic variation occurs from generation to generation (parents to offspring) and so the traits passed down are changed overtime

mutation

a change in the dna sequance of an organism

• increases genetic diversity

gene flow

the movement of genetic information (alleles) in/out of a population as a result of the migration of alleles

• bring new alleles or take certain alleles out

genetic drift

the change in allele frequencies within a population over time due to chance

• reduces population size

• two types

founder effect

organisms from a previous location migrate to another and reproduce

• do not reflect their original biodiversity

• brings alleles

bottle neck effect

resulting from a chance event, certain organisms survive and are able to pass their alleles along

• do not reflect the diversity of the original population

• due to chance which alleles survive and are able to populate (not change in fitness)

sexual selection

non random mating

• as in birds choosing the more attractive partner due to their coloring

  • amplifies certain traits

• decreases genetic diversity

biogeography

the geographical distribution of living organisms

• hints to pangea —> animals far away share traits

• shows how species change over time

darwin

came up with the theory of evolution

• studied finches, tortoises, embryos, fossils in the galapagos archipelagos

wallace

co discovers evolution but doesn’t really get credit

• worked independent —> helped solidify it

lamarck

living organisms evolved through use or disuse —> upward direction

• so a giraffe using its neck more would pass on the traits of a longer neck to its child

• wrong since adaptations occur before the need —> random

lyell

saw that earth was made today based on continuous developments over time

• earth is longer than when god created it

• earth “evolves”

• slow steady constant changes

cuvier

worked with fossils

• argued that species were wiped out and then repopulated

  • didnt evolve to get the changes

• the fossils of animals no longer living = extinct rather than ancestors

evidences of evolution

1. fossils —> giant sloth

2. embryology —> gills on human

3. biogeography —> animals with no seeming connection have same traits

4. observation —> finches

5. morphology+vestigial structures —> tailbone, snake legs

6. DNA similarities (most used today)

homologous structure

share very similar structural traits but serve different functions

analogous structures

have very different structures but serve the same function

embryology

branch of bio dealing with embryos

• some animals have similarities in early development but grow to have very different traits

adaptive radiation

• looking at the radiation dating of certain fossils to determine their age

  • helps look at the process of evolution (timeline)

microevolution

within one population

• change in frequency of alleles

macroevolution

relationships across species

• such as deer to whales, or wolves to dog

divergent evolution

how one species evolves into several different

• two similar species grow increasingly dissimilar over time due to difference in environment forces

convergent evolution

the process where unrelated species grow increasingly similar traits due to similar environmental pressure

• like bats and birds?

role of isolation in evolution

an isolated species will eventually diverge to prevent inbreeding

• prevents gene flow between different populations

archipelago is a chain of islands

three patterns of natural selection

1. directional

   1. one side is favored for survival over both (the most extreme trait)

2. stabilizing

   1. individuals with average traits are the most successful

   2. middle increases and sides decrease

3. disruptive

   1. both extreme traits are favored while the average is not

   2. two poles increase while middle decreases

evolution =

∆%alleles in gene pool/T