AP Bio Unit 1

mutation

mutation

change in DNA. primary source of genetic variation. Change in genotype —> change in phenotype (Increases GV)

Sexual selection

form of natural selection. When one sex of a species prefers certain characteristics in individuals of the other sex (Decrease GV)

Genetic Drift

Caused when allele (gene) frequencies change in a population randomly

Bottleneck Effect

a phenomenon in which a population decreases in size due to natural disaster(s) (Decrease in GV)

Founder Effect

When a population is descended from a small number of colonizing ancestors (Decrease GV)

Gene flow

the transfer of alleles (genes) into or out of a population due to the movement of individuals - migration (Decrease GV)

evolution

how a population of organisms has changed over time.

Isolation

A new species arises as populations become geographically & reproductively separated and each population evolves independently due to differences in environmental pressures

Allopatric speciation

isolation due to geographic barriers.

Sympatric speciation

the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region. same environment, diff. habitats. different selection pressures cause diff. genotypes in each group ex: one big lake, diff parts of it species evolve differently

Prezygotic barriers

impede mating between species or hinder fertilization. stop mating

• Habitat (snakes; water/terrestrial)

• Behavioral (fireflies; mate signaling)

• Temporal (salmon; seasonal mating)

• Mechanical (flowers; pollination anatomy)

• Gametic (frogs; egg coat receptors)

Postzygotic barriers

fertilization occurs, but the hybrid zygote does not develop into a viable, fertile adult. stop hybrids

• Reduced hybrid viability (frogs; zygotes fail to develop or reach sexual maturity)

• Reduced hybrid fertility (mule; horse x donkey; cannot backbreed)

Fitness

how good an individual with a particular trait/phenotype is at leaving offspring in the next generation relative to other individuals with different traits/phenotypes.

Phylogeny

represents the evolutionary relationships among a set of organisms or groups of organisms, evolutionary tree

outgroup

last related organism

5 parts to Hardy-Weinberg Equilibrium

1.huge population size

2. no migration

3. no mutation (no genetic change)

4. random mating (no sexual selection)

5. no natural selection (everyone is equally fit)

Stabilizing Selection

The middle phenotype is selected for the extreme phenotypes are selected against

Directional Selection

One phenotype is selected for, over the other phenotypes

Disruptive selection

Both extreme phenotypes are selected for, over the middle

Origin of Life on Earth

H20, volcanoes, methane, NH3, CO2, Sulfur, PO4, hot

Miller-Urey Experiment

Created monomers (building blocks) of the organic compounds- amino acids, fatty acids (lipids), nucleotides

Stages of life

monomers—> polymers (DNA, proteins, lipids, carbs) —> membrane —> cells

RNA world hypothesis

genetic info, the first cells most have had RNA as the genetic material

can act like an enzyme and make protein it codes for

Endosymbiotic Theory

the mitochondria and chloroplast in eukaryotic cells were once free living prokaryotes that weren’t digested (DNA and ribosomes) and eventually were by a larger prokaryote (Endocytosis-double membrane)

Steps to natural selection

1. Genetic variation in pop.

2. Selection pressure- environmental change

3. Those w/ an advantageous trait survive and reprod.

4. over time pop. will change, having more advanced traits

Lamarck

Inheritance of acquired traits. If organism changes during life to adapt, those changes are passed onto offspring ex: giraffes developed their long neck and passed it on

Punctuated equilibrium

population changes quickly because environments change quickly- Reality of Darwin’s gradualism

sexual reproduction

combining 2 different genomes (maintaining g.v.)

diploid

2 chromosomes for every trait- never know what will pass on (maintaining g.v.)

polymorphism

more than one phenotype is equally successful, selected for, in a population

gradualism

changes in genotypes accumulate slowly over time. traits remain unchanged for millions of years (Darwin)

Fossils

The remains or traces of once-living organisms. Provide important evidence for evolution and the adaptation of plants and animals to their environments. Can determine WHEN they existed and WHAT they looked like/body structures (morphology) found

Embryological comparisons

Different species that appear vastly different as adults, often have very similar early embryonic stages, indicating a shared common ancestor from which they evolved over time.

Homologous structures

Have similar structure and similar/not exact  functions.—> share common ancestor

analagous structures

 have very different structures, but similar functions.  —> similar environments

vestigial structures

have no direct function in modern species but had a major function in ancestral species. show HOW species changed over time

Molecular (DNA and Protein) Comparisons

compare the DNA and/or proteins of different organisms to determine evolutionary relatedness. more similar dna or protein sequence is, more related they are.

divergent evolution

when a population is split into two groups because of isolation (geographic and reproductive separated so each pop. evolves independently because of environmental pressures)

convergent evolution

two different species living in the same habitat develop similar traits (analogous structures)

parallel/coevolution

2 species have a relationship, symbiotic (2 species relationship share a common habitat), predator/prey