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.

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

intermediate productivity hypothesis

diversity is maximized at intermediate levels of productivity

intermediate disturbance hypothesis

states that moderate levels of disturbance can create conditions that foster greater species diversity than low or high levels of disturbance

ecosystem regulating service

changing the quality of something instead of directly providing it

colonize

relates to a plant or an animal establishing itself in an area

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)

competitive interactions

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

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

scaling law

scaling laws are linear on loglog scales and means that something observable is something measured

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

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

Incipient speciation

when two groups are beginning to diverge, but there is not yet complete reproductive isolation between them

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

competitive exclusion principle

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

assortative mating

the type of mating that occurs when an organism selects a mating partner that resembles itself (homozygotes match)

disassortative mating

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

late Cenozoic

Ice age in Northern Hemisphere
mammoths, first humans, modern organisms

deleterious alleles

alleles that lower fitness

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)

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.

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

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

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

prezygotic isolating mechanism

occurring before breeding; produces a fertilized egg, or zygote

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

symbiosis

A close relationship between two species that benefits at least one of the species.

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

Scaling Laws

linear on log-log scale.
something measurable is equal to something observable

Fragmentation

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

antagonistic interaction

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

Tolerance

lack of species on others

Facilitation

An interaction in which one species has a positive effect on the survival and reproduction of another species without the intimate association of a symbiosis

exponential growth

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

mychorrhizae

specialized mutualistic associations between roots and fungi

symbiotic relationship

close interaction between species in which one species lives in or on the other

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

active protection

Some organisms (crustaceans) are given food and shelter in exchange for protection

vigilance behavior

scanning the environment for predators

allopatric

geographic isolation

Dobzhansky-Muller incompatibility

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