Bio 20C Week Two

Front 1

Locus

Back 1

Physical location of a gene on a chromosome

Front 2

Allele

Back 2

Version of a specific Gene. Different forms of a specific gene

Front 3

Hardy-Weinberg Equation

Back 3

Measures allele changes.
P^2 + 1/2(pq)
If the population is not evolving..
p^2 + 1/2(2pq)

Front 4

Hardy-Weinberg Equation assumptions

Back 4

No Natural Selection
No Genetic Drift
No Gene Flow
No Mutation
Random Mating

Front 5

Directional Selection

Back 5

Alleles change in one direction. Favors one extreme of a trait. Reduces genetic diversity

Front 6

Stabilizing Selection

Back 6

Alleles associated with the average trait values are favored. No change in average. It reduces trait variability and genetic variability. Example, optimal birth weight

Front 7

Disruptive Selection

Back 7

Alleles associated with both extremes of a trait are favored. Increases genetic diversity. Can often result in 2 separate species

Front 8

Sexual Selection

Back 8

Sexual Selection acts more strongly on males. Sexual Dimorphism is when males and females look differently

Front 9

Female Choice

Back 9

Females respond to some aspect of the male phenotype.

Front 10

Male-Male Competiton

Back 10

Males compete with each other for females

Front 11

Balancing polymorphism

Back 11

Maintains less fit alleles in a population. Two types-Heterozygote Advantage, and Negative Frequency Dependent Selection

Front 12

Heterozygous Advantage

Back 12

Heterozygous, Aa, has a higher fitness. Even though A is dominant over a. Aa is more fit to fight malaria.

Front 13

Negative Frequency Selection

Back 13

Rare individuals have higher fitness. Example, scale eating fish and non-rewarding orchids

Front 14

Genetic Drift

Back 14

Changes in genetic frequency from generation to generation as a result of random chance. It's random with respect to fitness. Most pronounced in small populations. Over time it can lead to lost of fixed alleles.

Front 15

Founder Effect

Back 15

When a small set of individuals starts a new population. May not reflect the allele frequencies of the sources population. One of the causes of genetic drift

Front 16

Genetic Bottleneck

Back 16

Results from a drastic and random reduction in a population size. One of the causes of genetic drift

Front 17

Gene Flow

Back 17

Movement of alleles from one population to another. Immigration and poppagules(seed spreading). Gene flow homogenizes the population.

Front 18

Mutation

Back 18

Production of a new allele. Increases genetic diversity. Most mutations lower fitness. Natural selection acts upon the phenotype of the mutation.Once new alleles arise, meiosis and sexual reproduction combine different alleles in new ways to increase genetic variation. This is why we are unique.

Front 19

Inbreeding

Back 19

Increases homozygosity in genotypes. Alters genotype frequencies.

Front 20

Neutral Evolution

Back 20

Much of genetic variation is neutral. Neutral mutations don't affect phenotype.

Front 21

Speciation

Back 21

Formation of new species. Genetic isolation and divergence. Species are distinguished by common characteristics.

Front 22

Species arise as a consequence of?

Back 22

Lack of gene flow with other populations, genetic divergence, functionally different characteristics

Front 23

Biological Species

Back 23

Reproductively isolated, members of a species cannot interbred and produce a viable offspring. Advantages: Strong foundation with darwin. Disadvantage: Cannot apply to fossils or asexual orgs. Cannot apply to geologically isolated populations.

Front 24

Morphological Species

Back 24

Based on differences in morphology. Advantages: Widely applicable to fossils and asexual orgs. Disadvantages: Subjective criteria, intraspecies morphology is often greater than interspecies variation

Front 25

Phylogenetic Species

Back 25

Based on ancestral analysis (phylogeny). Smallest identifiable group assigned species status. Advantages: Strong foundation with darwin and is widely applicable. Disadvantages: There are few thorough enough phylogenies.

Front 26

Ecological Species

Back 26

Based on environmental context. Each species occupies a unique niche. Adavantages: avoids problems with morphologically similar species and aseuxal orgs. Disadvantages: It's difficult to characterize niches in sufficient details.

Front 27

Reproductive Isolation in respect to hybrid formation

Back 27

Prezygotic and postzygotic isolation prevents a zygote from forming or a viable zygote to produce offspring.

Front 28

Prezygotic Isolation

Back 28

Causes: Disruptions of temportal (timing) spatial (location) and behavioral. Or a gamete cannot physically form in the womb.

Front 29

Post Zygotic Isolation

Back 29

Causes: Hybrid's ability to survive is questionable or is sterile.

Front 30

Anagenesis

Back 30

One species gradually transforms into another species (no branching) Gradual Natural Selection

Front 31

Cladogenesis

Back 31

One species gives rise to two or more species (branching). Disruptive selection

Front 32

Allopatrick Speciation (Other Country)

Back 32

Occurs between geographically isolated populations. Gene flow stops and genetic divergence occurs by natural selection, genetic drift, and mutation

Front 33

Vicariance

Back 33

The separation of a group of organisms by a geographic barrier, resulting in differentiation of the original group into a new one.

Front 34

Sympatrick (Same Country)

Back 34

Speciation without geographic isolation. Natural selection overwhelms gene flow. Can occur with spatial, temporal, and behavioral isolation.

Front 35

Polyploidy

Back 35

More than 2 homologous chromosomes. Mutations can create an extra chromosome copy.

Front 36

Autoploidy

Back 36

Mutation doubles chromosome number, and the resulting individual can be infertile or can only self fertilize. mostly plants

Front 37

Alloploidy

Back 37

Two different species mate. Mutation in the zygote doubles the chromosome number and can produce offspring. Horizontal evolution

Front 38

Gene

Back 38

A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins.