BIO 150: Exam 1

**Biodiversity**

range of variation found among microorganisms, plants, fungi, and animals

* Richness of species of living organisms
* three levels: genetic, species, ecosystem
* variety of life in the world, or in a particular habitat or ecosystem

ecosystem diversity

measure of the variety of biotic components in a region along with abiotic components

Genetic diversity

total genetic information contained within all individuals of a species, population, or community 

species diversity

diversity of species present in a community 

community

populations of organisms of different species that interact with one another 

**Ecosystem**

any geographic area with all of the living organisms present and the nonliving parts of their physical environment 

* Involves the movement and storage of energy and matter through living things and activities

gene

unit of inherited material

organism

individual living thing

population

group of individuals belonging to one species living in an area

species

group of populations of similar organisms that reproduce among themselves, but do not naturally reproduce with any other kinds of organisms 

Ecologists

conduct research to better understand biodiversity, quantify its loss, and develop strategies for conserving and using it 

**Ecosystem services**

all direct and indirect benefits that humans derive from organisms and ecosystem

* provisioning
* regulating
* cultural
* supporting

provisioning services

provide raw materials 

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Ex. food, fuel, fiber and other materials, medicines, genetic resources 

regulating services

part of Earth’s life-support system 

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Ex. climate moderation, soil formation, erosion control, O2 and CO2 regulation, water capture, water purification, air cleaning, flood control, storm mitigation, waste decomposition, bioremediation

cultural services

enrich quality of life 

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Ex. aesthetics, recreation, education, spiritual value, human mental and physical health 

supporting services

enable all the other ecosystem services 

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Ex. primary productivity, nutrient cycling, pollination, biological control 

existence value

economic value of a system and our willingness to mitigate biodiversity loss 

threats to biodiversity

* Habitat loss/alteration
* Invasive species
* Pollution
* Population (human): human population is growing exponentially at the same time there is a exponential decline in other animal populations 
* Overharvesting 
* Climate change

**Natural selection**

results in allele frequencies changing from generation to generation according to the allele’s impact on the survival and reproduction of individuals 

* Brings about adaptations
* Increases the frequency of advantageous mutations and decreases the frequency of deleterious (harmful) mutations

positive selection

increases the frequency of an advantageous allele 

negative selection

decreases the frequency of a deleterious allele

balancing selection

acts to maintain two or more allele in a population

heterozygote advantage

when the heterozygote’s fitness is higher than that of either homozygotes, resulting in selection that ensures both alleles remain in the population at intermediate frequencies

stabilizing selection

intermediate phenotypes have a higher fitness than the extreme varieties, normal bell-shaped curve 

* Ex. from normal curve → normal curve (potentially increase in intermediate values 
* Ex. birth weight and child mortality 

directional selection

individuals with __**one**__ of the extreme phenotypes has a higher fitness than intermediate varieties 

* Ex. from normal curve → skewed distribution
* Ex. peppered moths, from white spotted to black due to industrial revolution 
* sexual selection

disruptive (divergent) selection

__**both**__ extreme phenotypes are favored at the expense of intermediate varieties, can facilitate speciation 

* Ex. from normal curve → bimodal shaped curve 
* Ex. stickleback fish, both large fish and small fish favored 

sexual selection

promotes traits that increase an individual’s access to reproductive opportunities

intrasexual selection

focuses on interactions between individuals of one sex, as when members of one sex compete with one another for access to the other sex

intersexual selection

focuses on interactions between males and females, as when females choose from males

allele

alternate versions of genes

viruses

* Very, very small (

bacteria

* Small, but bigger (200-1000 nm), microbe


* Single cell - DNA and other contents enclosed by cell membrane and wall
* Reproduce independently
* Contain ribosomes and generate ATP

beta-lactams

kill bacteria surrounded by a cell wall (by blocking how molecules in the cell-wall are linked together)

* Penicillin and cephalosporin

macrolides

affect bacterial ribosomes and prevent protein synthesis

* erythromycin

quinolines

breakdown bacterial DNA and prevent repair

* ciprofloxacin and levofloxacin

antibiotic resistance

general means by which bacteria resist antibiotics

* intrinsic resistance
* acquired resistance

intrinsic resistance

resistance naturally coded and expressed by a bacterial species to a particular antibiotic, certain types of antibiotics work on certain types of antibiotics

gram staining

***Gram positive bacteria-*** looks purple (adhering more of the dye), thick cell wall

***Gram negative bacteria-*** looks pink, thin cell wall, antibiotic will not work for this bacteria

acquired resistance

genetic changes that lead to bacteria becoming resistant to an antibiotic

* Germs develop new cell processes that avoid using the antibiotic’s target 
* Germs change or destroy the antibiotics with enzymes, proteins that break down the drug 
* Germs restrict access by changing the entryways or limiting the number of entryways 
* Germs change the antibiotic’s target so the drug can no longer fit and do its job
* Germs get rid of antibiotic using pumps

evolution

change in the genetic composition (inherited traits) of a population from one generation to the next (modification)

* Theory that all organisms on Earth are related by common ancestry and that they have changed over time (common descent)
* when living organisms reproduce, they pass on to their progeny a collection of traits
* pattern v. process

pattern

observed evolutionary change

process

mechanisms that produce observed patterns change

microevolution

small changes in the gene pool of a population over successive generations

gene pool

all the genes in a population at a given time 

mechanisms leading to evolutionary change

\*all impacted by genetic variation

* selection
* genetic drift
* gene flow

selection

differential success in reproduction of organisms carrying variations of a trait (non-random)

artificial selection

form of directional selection where given traits are selected for by humans

genetic variation

differences among individuals in their composition of genes and other DNA sequences due to mutation and gene transfer / sexual reproduction 

adaptation

inherited trait that enhances the fitness of an individual in a given environment 

Types: structural, physiological, and behavioral 

biological fitness

relative survival and reproduction of one variant compared to others in the same population, contribute the most to the gene pool 

biological benefits

* system stability
* ecosystem productivity

system stability

diverse systems are more

* resilient (speed of recovery after disturbances)
* resistant (ability to absorb disturbances while retaining function)

ecosystem productivity

diverse systems have higher net primary productivity

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Ex. more chemical energy, form of potential energy, in a system

plato

typological thinking

* organisms were created in a perfect way, unchanging, and not related

aristotle

typological thinking and scale of nature

* lower and higher organisms

lamarck

change through time and scale of nature

* organisms will gradually change through time depending on their environment \`

darwin and wallace

change through time and common ancestry

* organisms are related

Charles Darwin (1809-1882)

curiosity in studying the natural world

* voyage of the HMS Beagle (1831-1836): traveled to Galapagos islands with different ocean currents resulting in different landscapes / environments

darwin observations

* different species are often similar, with slight variations in theme
* Could figure out which island you were on based on the tortoises there, the tortoises were similar to the ones found in south africa 
* Marine iguanas only exist in the Galapagos islands 
* Even though he saw the patterns, he didn’t see the process of how change came about 
* Used pigeons to see how breeding different types resulted in variations 
* **Selection leads to biological change**

acclimation

short term response to an environmental change

phenotypic plasticity

ability of individuals to alter its physiology, morphology, and/or behavior in response to a change in the environmental conditions 

natural selection limitations

1. Selection is limited by historical and genetic constraints 
2. No organisms is “perfectly” adapted 


1. Favored traits are dependent on the environmental and temporal context 
3. Adaptations are compromises 
4. Not all traits are adaptive (i.e. just a by-product, result of history, an outdated adaptation)
5. Natural selection (evolution) does not have a goal

trait

characteristic of an individual

blending inheritance

traits in the offspring resemble the average of those in the parents

X-linked genes

genes in the X chromosome 

crisscross inheritance

pattern in which an X chromosome present in a male in one generation is transmitted to a female in the next generation, and in the generation after it can be transmitted back to a male

wild type

most common allele, genotype, or phenotype present in a population; non mutant

nondisjunction

failure of a pair of chromosomes to separate normally during anaphase of cell division

hemophilia

trait characterized by excessive bleeding that results from a recessive mutation in a gene encoding a protein necessary for blood clotting

linked

describes genes that are sufficiently close together in the same chromosome that they do not assort independently 

non recombinant

descendant in which the alleles are present in the same combination as that present in a parent 

recombinant

offspring with a different combination of alleles from that of either parent, resulting from one or more crossovers in prophase I of meiosis 

genetic map

diagram showing the relative positions of genes along a chromosome

map unit

one unit of distance, distance between genes resulting in 1% recombination 

somatic mutations

mutation that occurs in somatic cells 

germ-line mutations

mutation that occurs in eggs, sperm, or the cells that give rise to these reproductive cells and therefore is passed onto the next generation 

neutral mutations

genetic changes that have no effect or negligible effects on the organism, or whose effects are not associated with differences in survival or reproduction 

deleterious mutations

genetic changes that are harmful to an organism 

advantageous mutations

genetic changes that improve their carriers’ chances of survival or reproduction 

allele frequencies

proportion of a specified allele among all the alleles of a gene in a population

fixed population

in genetics, describes the situation in which all individuals in a population are homozygous for the same allele of a particular gene 

genotype frequency

proportion of a specified genotype among all the genotypes for a particular gene or set of genes in a population 

genetic drift

change in allele frequency due to chance, large effect in small populations 

* increases genetic variation

population bottleneck

an extreme, usually temporary, reduction in population size that may result in marked loss of genetic diversity and, in the process, genetic drift 

founder event

type of genetic drift that occurs when only a few individuals establish a new population 

migration

movement of organisms from one place to another, including the movement of individuals from one population to another 

* Can result in gene flow

gene flow

movement of alleles from one population to another through interbreeding between members of each population 

molecular evolution

evolution at the level of DNA, which in time results in the genetic divergence of populations 

molecular clock

rate of consistency in molecular evolution, extent of genetic divergence at a gene in two taxa is thus a reflection of the time since the taxa last shared a common ancestor 

* Fast molecular clock is associated with a pseudogene 

pseudogene

gene that is no longer functional

sources of genetic variation

* altering gene number or position
* formation of new alleles (mutation)
* gene transfer / sexual reproduction (most common)

increasing genetic variation through sexual reproduction

* mixing of genetic information from two games
* independent assortment
* random fertilization
* crossing over in meiosis

human trait activity

based on the premise of discrete autosomal single gene traits and differences within the population 

discrete traits

you either possess the trait or you do not

autosomal traits

not on a sex chromosome

discrete autosomal traits

yes or no trait found on a chromosome that is not the sex chromosome 

trait limitations

* Traits are not the product of a single gene 
* There can be more than two possible variations of a gene 
* Genes are not the sole determinants of traits 
* Different groups do not have different traits (genes), by race or familial history 

single gene pattern

single gene is associated with a  given outcome

autosomal with a dominant allele (Mendelian)

discrete traits shown through crosses to appear in the ratios that are consistent with single gene inheritance

incomplete dominance

heterozygous condition produces an intermediate trait, mixing of two parental phenotypes

* White sheep and black sheep mate producing gray offspring 
* Orange bird hatchlings whose parents are red and yellow