Flashcards in Evolution Deck (18):
How does adaptation happen (use moths as example)
-starts with mutation in DNA
-this leads to variation
-if variation helps survival it has greater chance of being passed on to future generations
-If trees are light most moths will be light, if trees are dark most moths will be dark
What is the difference between natural and artificial selection?
-is situational. Whatever helps survival
-controlled by humans
-may not be beneficial
What is selective pressure?
Environmental conditions that select for certain characteristics of individuals against other characteristics
What is fitness?
The relative contribution an individual makes to the next generation by producing offspring that will survive long enough to reproduce
What were different scientists' contribution to the theory of evolution?
John Ray: Classification of plants and animals
Charles Linnaeus: Father of taxonomy
1. George-Louis Leclerc, Comte de Buffon
-published 44 volume "Histoire naturelle"
-suggested species change over time
-suggested earth is older than 600 years
2. Mary Anning
-expert fossil collector and paleontologist
-found first plesiousar fossil (aquatic reptiles)
3. George Cuvier
-suggested catastrophism (periodic catastrophes allowed areas to be repopulated)
4. Charles Lyell
-proposed uniformitarianism (geological process occur at the same speeds as in the past
5. Jean Baptiste Lamarak
-suggested inheritance of aquired characteristics
(passed on to offspring)
-influenced Charles Darwin
6. Alfred Russel Wallace
-reached similar conclusion to Darwin, influenced him
7. Thomas Matthus
-suggested more offspring were born than could be supported, creating survival of the fittest
8. Charles Darwin:
-made observations on the coast of south america
-combined observations and theories into theory of evolution by natural selection
-originally not termed evolution, which would imply progress, but descent with modification
What is it and who coined the term "survival of the fittest"
The idea that the organisms that are the fittest leave the most offspring, so those organisms win the struggle for survival. Coined by John Spencer
What is some of the evidence for evolution?
1. Fossil record
-older layers have simpler species
-appear in chronological order
-not all appear at the same time
2. Transitional fossils
-vestigial structures, a reduced version of something functional in ancestors
-close environments have more closely related species
-animals on islands resemble those on the main continent
-fossils of the same species can be found on neighboring continents
-closely related species are almost never found in exactly the same location
-homologous structures have similar structure but different function
-analogous structures have similar function but no common origin
-most are similar as embryos
-many are similar
What are factors that affect allele frequencies?
Mutation: Randomly introduce new alleles
Gene flow: Occurs between two different interbreeding populations that have different allele frequencies
Non-random mating: Individuals in a population select mates on the basis of phenotypes. Includes inbreeding or self pollination. Increases the presence of homozygous individuals
Genetic drift: Random changes due to chance
Natural selection: Environment selects for certain traits that make it easier to survive
What are kinds of genetic drift?
-only some will reproduce causing some alleles to be drifted out
The founder effect: A limited gene pool that results when just a few individuals start a population
The bottleneck effect: Changes in gene distribution due to dramatic reduction in population size
What are kinds of natural selection?
Stabilizing selection: Both extremes get chopped off
Directional selection: One extreme becomes more common
Disruptive selection: Both extremes become more common
What are some pre-zygotic isolating mechanisms?
Prevention of mating:
-Behavioral isolating (different songs, different ranges)
-Habitat isolation (same area, diff habitat, don't encounter)
-temporal isolation (timing, overlap between flowing times)
Prevention of fertilization
-mechanical isolation (anatomically incompatible)
-gametic isolation (different species will rarely form zygote. Won't fuse)
What are some post-zygotic isolating mechanisms?
-Hybrid inviability (they die)
-Hybrid breakdown (after a generation or two cannot produce viable offspring)
What is sympatric speciation?
Populations within the same areas diverge and become reproductively isolated. If a genetic change results in reproductive barrier a new species can be generated in a single generation. Example, errors in meiosis resulting in polyploidy
What is allopatric speciation?
A population is split into two or more isolated groups by a geographical barrier. Once removed if they cannot reproduce a new species is formed (Ex. Darwins finches)
What is adaptive radiation?
The diversification of common ancestral species into a variety of differently adapted species ( a form of allopatric speciation)
What is divergent and convergent evolution?
Di: Species that were once similar become distinctly different
Con: Similar traits arise in different species because of independent adaption to similar environments
What are the possible speeds of evolutionary change
Gradualism: Slow and steady before and after divergence
Punctuated equalibrium: Evolutionary history consists of long periods of stasis interrupted by periods of divergence