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.

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

foundation species

referred to a species that has a strong role in structuring a community

facilitative encounters

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

antagonistic interactions

interactions between organisms so that one organism benefits at the expense of another

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

invasion resistance

resistance to invasion from predators

fragmentation

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

climax species

also known as late-successional k-selected or equilibrium species are plant species that will remain essentially unchanged in terms of species composition as long as it remains undisturbed

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

primary producers

plants and other photosynthetic organisms produce organic compounds in an ecosystem

character displacement

the phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur, but are minimized or lost where the species' distributions do not overlap.

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 extreme phenotypes on both ends of the spectrum are unfavorable

directional selection

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

inbreeding

when an organism selects a mating partner that resembles itself (homozygotes match)

outbreeding

Dissimilar phenotypes mate preferentially.

Favors heterozygosity

genotype x environment interaction

Phenotypic variation arising from the difference in the effect of the environment on the expression of different genotypes.

heterozygote advantage

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

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 inviability

A postzygotic barrier in which hybrid zygotes fail to develop or to reach sexual maturity

Activities that have altered ecosystems

Fossil fuel emissions (global warming, rise in sea level, greenhouse gasses, loss of coral reefs, ocean acidification)

Industrial agriculture (increases biological availability)

More: deforestation, habitat destruction, species extinction

ecological 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

inbreeding depression

when individuals with similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to survive and reproduce (lowers fitness)

adaptive radiation of certain lineages

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

key innovations

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

lineage

temporal series of organisms, populations, cells, or genes

sexual selection

natural selection arising through preference by one sex for certain characteristics in individuals of the other sex

ecological speciation

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

vacant ecological niches

the possibility that in ecosystems or habitats more species can exist that are present in a particular time, because many are not being used by potentially existing species

series of events in chronological order

origin of photo synthesis

origin of aerobic metabolism

origin of eukaryotes

Cambrian explosion

colonization of land

carboniferous coal formation

end - cretaceous astroid impact

spread of grassland

angiosperms

flowering plants

pleistocene

ice age

Chronological order of events

origin of photosynthesis, origin of aerobic metabolism, origin of eukaryotes, Cambrian explosion, colonization of land, carboniferous coal formation, end-cretaceous astroid impact, spread of grassland.

negative frequency dependent selection

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

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

ecological specialization

the concentration of homogeneous groups and activities into different sections or urban areas-divergent selection in different environments lead to creation of reproductive barriers between populations.

Late Cenozoic Ice Age

The last great ice age that ended 10,000 years ago, lasting for the past 2 million years. (cooling climate)

Important global events during the Cenozoic era

adaptive radiation of MAMMALS, diversification and dominance of angiosperms, Pleistocene glacial cycles.

Human sister lineage

chimpanzees

vicariance

the geographical separation of a population, typically by a physical barrier such as a mountain range or river, resulting in a pair of closely related species

temporal isolation

when species that could interbreed do not because the different species breed at different times

prezygotic isolating mechanism

occurring before breeding; produces a fertilized egg, or zygote

gamete incompatibility

proteins on egg 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)

random mating

no selective mating in which animals chose mate depending on phenotype

Exploitation

one benefits, other is harmed

competitive interaction

both harmed

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

Facilitation

one or both species are benefitted but neither are harmed

exponential growth

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

mychorrhizae

specialized mutualistic associations between roots and fungi

both species benefit is

mutualistic relationship

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

commensalism

parasitic relationship (exploitation)

only the infecting organism benefits from the relationship

allopatric

geographically isolated

Gametic incompatibility

gametes are incompatible and will not form a zygote

Indirect effect

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

Maintenance of Diversity

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

Competitively transitive

Whenever species A excludes species B and species B excludes species C

Maintenance of Diversity explained

Niche Partitioning

Intermediate disturbance, predation, and productivity

Competitive intrasitivities

Fluctuations in environmental conditions

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

Phylogeny

evolution of development and the diversification of species

Stress amelioration

stress that makes something better (improvement)

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water (think post zygotic barrier)

primary succession

succession that occurs in an area in which no trace of a previous community is present (analyzing microbial in an infant gut)

secondary succession

type of succession that occurs in an area that was only partially destroyed by disturbances

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

transmission probability

how rapidly a disease can spread between hosts

Virgulent

(of a disease or poison) extremely severe or harmful in its effect

Northern Hemisphere

the hemisphere north of the equator

optimal foraging theory

Views foraging behavior as a compromise between benefits of nutrition and costs of obtaining food.

contact rate

frequency of contact between susceptible and infected individuals

virulent

extremely poisonous

acclimation vs adaptation

acclimation

-reversible changes in organisms PHENOTYPE (morphology, physiology)

-allows organisms to respond to its ENVIRONMENT to improve performance

OFTEN REVERSIBLE

Adaptation

-long term GENETIC response of population that improves performance