BIS2B Final - UC Davis

mycorrhizal fungi

symbiotic relationships between fungi and plants, the fungi colonizes the root system of a host plant, providing increased water and nutrition absorption while the plant provides fungus with carbohydrates formed from photosynthesis

For soils with high nutrient and water availability, mycorrhizal fungi are PARASITIC on plants.

ecological succession

process of change in the species structure of an ecological community over time

logistic growth

takes place when a populations per capita growth rate decreases as population size approaches a maximum imposed by limited resources, the carrying capacity (k)

inhibition

negative effect of one species on another preventing it from establishing as quickly (or at all) during succesion

keystone species

A species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the ecosystem

competition/exploitation

interactions between organisms or species in which both of the organisms or species are harmed

facilitative/amenlism

encounters between organisms that benefit at least one of the participants and cause harm to neither

facultative

one or both are benefitted

realized niche

where the species actually lives

fundamental niche

an organism can take advantage of all the biotic and abiotic factors in an ecosystem without competition from other species or pressure from predators

fragmentation

the form of asexual reproduction wherein a parent organism breaks into fragments each capable of growing independently into a new organism

r-selected traits

rapid development, high production rate, small body size, short life span

k-selected traits

slow development, low reproductive rate, large body size

The Keeling curve

a graph of the accumulation of carbon dioxide in the earth's atmosphere based on continuous measurements

primary productivity

describe the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem

character displacement

species co-occur and causes changes based off each other

competitive release

occurs when one of two species competing for the same resource disappears, thereby allowing the remaining competitor to utilize the resource more fully than it could in the presence of the first species

disruptive selection

changes in population genetics in which extreme values for a trait are favored over intermediate values

stabilizing selection

when the average is most favorable

directional selection

a mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction

competitive exclusion principle

states that two species that compete for the exact same resources cannot stably coexist

inbreeding

selects a mating partner that resembles itself geno/phenotypes

outbreeding

preference for diff genotype/phenotype

heterozygote advantage

Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools (inbreeding).

allopatric speciation

speciation that happens when two populations of the same species become isolated from each other due to geographic change

Hybrid inviability

a post-zygotic barrier, which reduces a hybrid's capacity to mature into a healthy, fit adult. The relatively low health of these hybrids relative to pure-breed individuals prevents gene flow between species.

founder effects

the reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors

Behavioral isolation

Mating rituals within species. Prezygotic mechanism that has been favored by selection for reinforcement of reproductive isolation. Example: mating dance by birds.

hybrid infertility

A postzygotic barrier in which hybrid zygotes (gamete cells) fail to develop or to reach sexual maturity

habitat isolation

Species occur in the same area, but they occupy different habitats and rarely encounter each other. Example: prezygotic mechanism that prevents hybrid mating between benthic and limnetic forms within lakes in the wild

local radiation

an event in which a lineage rapidly diversifies with the newly formed lineages evolving different adaptations

key innovation

a novel phenotype trait that allows subsequent radiation and success of a taxonomic group

ecological speciation

the process which ecologically based divergent selection between different environments leads to creation of reproductive barriers between populations

Demographic stochasticity refers to __________.

random year-to-year variations in a population's birth and death rates

theory of island biography

a theory that demonstrates the dual importance of habitat size and distance in determining species richness (larger island=greater number of species because lower extinction rates and lower in reserves geography closer to other reserves due to higher colonization rates)

Cambrian explosion

A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago.

Carboniferous Period

354 to 290 mya. refers to the rich coal deposits found in rocks of this age.cooler period, much of the land covered by forest swamps. Very large plants and trees became prevalent. amniotic egg, which prevents dessication of the embryo inside.

negative frequency dependent selection

Phenotypes favored only when rare. Example is left-handed fighting ability

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species (Darwins finches had very different phenotypes but all came from the same generation)

founder event

A type of bottleneck that occurs when only a few individuals establish a new population.

Vicarience

speciation due to isolation by geographic separation-blocks mating

Bottleneck

process in which a large population declines in number, then rebounds

reproductive barriers

serve to isolate the gene pools of species and prevent interbreeding

key innovation

an adaptation which enhances the diversification rate of a lineage (sympatric speciation, autopolyploid, allopolyploid)

divergent selection

evolution in which species that were once similar to an ancestral species diverge; occurs when populations change as they adapt to different environmental conditions; eventually resulting in a new species

autopolyploid speciation

an individual or strain whose chromosome consists of more than two complete copies of the genome of a single ancestor species

duplication - > post zygotic - > sterile

allopolyploid speciation

genetic makeup of two different species (HYBRID)

helpful hint: ALLOsin "donkeeey"

gamete incompatibility

proteins on egg that allow sperm binding do not bind with sperm from another species

commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

positive frequency dependent selection

Phenotypes are favored only when common. Example is warning coloration

obligate

at least one species could not grow and reproduce without the other

Epistasis

A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited. (fur color, height, skin color)

Fragmentation

A means of asexual reproduction whereby a single parent breaks into parts that regenerate into whole new individuals. (small parts)

intermediate disturbance

Moderate levels of disturbance can create conditions that foster greater species diversity.

intermediate predation hypothesis

diversity is maximized at intermediate levels of predation

exponential growth

Growth pattern in which the individuals in a population reproduce at a constant rate

A symbiotic relationship in which both species benefit is

mutualistic relationship

a symbiotic relationship in which one benefits and has no effect on the other

commensalism

parasitic relationship

only the infecting organism benefits from the relationship

allopatric

geographic isolation

Dobzhansky-Muller incompatibility

breakup of "coadapted gene complexes" by independent mutations in isolated populations (creates low fitness)

Reproductive isolation mechanisms

Post zygotic (after fertilization)- hybrid inviability- zygote is formed but because of genetic incompatibilities it will not develop

Hybrid sterility- develop into adults but the offspring will not have viable gametes

Hybrid breakdown- fertile hybrids form but they have low reproductive success

Gametic incompatibility

gametes are incompatible and will not form a zygote

evolutionary radiation

rapid proliferation of many species from a common ancestor

Inhibition

early colonist makes environment less suitable for subsequent colonization

Indirect effect

a change in the abundance of one species resulting from its interaction with another species which is affected by a third species

Trophic Cascade

powerful indirect interactions that can control entire ecosystems, occurring when trophic level in a food web is suppressed

Niche Partitioning

Natural Selection drives competing species into different patterns of resource use

Maintenance of Diversity

Intermediate disturbance , predation, and productivity hypotheses > local species diversity is maximized when ecological disturbance is neither too rare nor too frequent

Maintenance of Diversity explained

Niche Partitioning

Intermediate disturbance, predation, and productivity

Competitive intrasitivities

Fluctuations in environmental conditions

Intermediate disturbance hypothesis

Species richness is greatest on medium sized boulders > supports the intermediate disturbance

hypothesis

Intermediate Productivity Hypothesis

Diversity is maximized @ intermediate levels of productivity and predation

Keystone species

species that have major effects on a community structure and an effect disproportionate to their abundance

Foundation species

species that have a major effect on a community structure by virtue of their high biomass and habitat forming characteristics

Cyclical Succession

a pattern of change in community composition (succession) due to recurring events or changing interactions with plants and animals

prezygotic isolation (prevents fertilization)

Prezygotic isolation (prevents fertilization)

Geographic (allopatry) - little opportunity for gene flow or mating, species with low dispersal can be isolated by short distances

Ecological- If two sympatric species use different habitats, they will rarely encounter one another

Because the 2 species never encounter one another, they never actually mate so they are reproductively isolated

Sympatric speciation must satisfy

Sister Species

Currently sympatric

Genetically based reproductive isolation

No historic phase of geographic isolation

phylogenetic diversity

A measure of biodiversity using the pattern of the relationships of lineages to one another over time.

periodic disturbances

Catastrophic disturbances, including fires, hurricanes, tornadoes, and volcanic eruptions, can devastate biological communities. After the disturbance, (1) the area is recolonized by organisms or repopulated by survivors, but (2) the structure of the community undergoes a succession of changes during the rebound. Several communities actually depend on periodic fire to maintain them.

microbial succession

The initial microbes change the environment so that other microorganisms can thrive

cyclic succession

succession may increase chances of disturbance, buildup of understory leads to intense fire

infection duration

the amount of time it takes for a virus to go away

optimal foraging theory

compromise between benefits of nutrition and costs of obtaining food.

aerobic metabolism

Metabolism that can proceed only in the presence of oxygen.

Eukaryotic cells

Contain a nucleus and other organelles that are bound by membranes.

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

examples of genetic drift

bottleneck effect, founder effect, gene flow, mutations

Example of allopolyploid speciation***

Formation of a fertile new salt marsh grass species from a sterile hybrid between two other species

independent assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes

hair gene has no effect on eye gene

Pleiotropy

A single gene having multiple effects on an individuals phenotype

The species richness of an forest fragment in a deforested landscape is predicted to be_______________

in small fragments compared with large fragments, and ______________ in

isolated fragments compared with fragments closer to undisturbed forest.

lower; lower

intristic growth rate

the maximum potential for growth of a population under ideal conditions with unlimited resources

Breeder's equation

R=h^2S

R=response to selection

S=selection differential

Equation from previous examples:-5/-10= 0.5

carbon dioxide in northern hemisphere

They are highest in the winter, because winter photosynthesis rates are lower than winter respiration rates.

algal bloom

The rapid growth of a population of algae

Acclimation

the process or result of becoming accustomed to a new climate or new conditions

CAN BE REVERSIBLE

what events depend upon the concentration of atmospheric oxygen?

- origin of aerobic metabolism

- giant flying insects

- origin of eukaryotic cells

- origin of multicellular animals

what events DID NOT depend upon the concentration of atmospheric oxygen?

- origin of photosynthesis

Cenozoic

rapid adaptive radiation of mammals, angiosperms, etc. Rise of symbiotic nitrogen fixation; spread of grasslands; Pleistocene ice ages; holocene warming; recent climate change and its causes; anthropocene

what caused spread of grasslands

A lineage of angiosperms evolves symbiosis with N-

fixing bacteria housed in root nodules, increasing

rates of biological N-fixaton in ecosystems