APES- Topic 2: The Living World: Biodiversity

Biodiversity

has the components of genetic diversity, species diversity, & habitat/ecosystem diversity

Genetic Diversity

# of genetic characteristics in a population or differences in DNA composition among individuals in a population; provides raw material for adaptation to local conditions & opportunity for mutations & evolution

Gene Diversity

average % of gene loci that are heterozygous in a population

Species Diversity

# of different species (species richness) and relative abundance (species evenness)

• high species diversity= large # of different species & even balance

• low species diversity= few species & uneven population

Shannon Index of Biodiversity

quantifies biodiversity at a given time & place

Speciation & Extinction Effects on Species Diversity

speciation makes more species; extinction reduces the # of species

Immigration & Emigration Effects on Species Diversity

immigration adds species; emigration reduces species

Habitat/Ecosystem Diversity

# of different habitats provided by a particular landscape

• some organisms use different habitats in different seasons or periods of life

• some organisms spend their entire life in one habitat

Landscapes

patches of habitat; the more landscape, the more habitat diversity there is

Ecotone

transition from one patch to another & is important in conservation as they contain characteristics of both habitats

Ecosystem Stability

the ability of ecosystems to maintain a state of equilibrium and consistent biodiversity

Resistance

a landscape’s ability to resist disturbances

Resilience

a landscape’s ability to recover from disturbances

Latitudinal Gradient

species richness increases with decreasing latitude (toward equator)

but living things are not evenly distributed on earth

Ecosystem Services

services that arise from the normal functioning of healthy, natural systems; 1) provisioning, 2) regulating, 3) supporting, 4) cultural

Provisioning Services

material benefits & natural resources (ex. food, diversity of materials, water, effective medicine)

Regulating Services

benefits obtained from the regulation of ecosystem processes (ex. erosion prevention, pollination, biological control of pests, regulation of water, carbon storage, ocean climate, air quality, moderation of weather, waste water treatment)

Supporting Services

necessary for the production of all other ecosystem services (ex. habitat for species, maintenance of genetic diversity, photosynthesis, cellular respiration)

Cultural Services

non-material benefits people gain from ecosystems (ex. recreation, mental & physical health, aesthetic appreciation, inspiration for culture, art, & design, spiritual experience, sense of place)

Island Ecosystem

small, vulnerable to disturbances and species loss, & have hotspots of biodiversity with endemic species

Endemic Species

island species that are found nowhere else and are specialists (small niche)

What is the #1 cause of Biodiversity loss?

Habitat Loss & Fragmentation → creates “islands of habitats”, isolating species on suitable land, surrounded by a “sea” of unsuitable land

Island Biogeography Theory

can predict biodiversity of island ecosystems & isolated habitats depending on varying sizes and distances from source populations

How does species richness affect niches?

• low species richness → broad niches & less likely to overlap

• high species richness → overlapping niches & competition

Area Effect

larger islands have more species because they have more habitats; have lower extinction rates because more space allows for more population, greater genetic diversity; have higher immigration

Distance Effect

Closer islands have higher immigration rates because they are easier to reach & not all species have dispersal mechanisms to go far

Corridors

narrow strip of protected land that allow animals to travel between islands of suitable habitat, get more habitat diversity, & enable gene flow

Evolution

change in inheritable traits of populations over generations in response to selective pressures caused by disturbances in their environment → natural selection acts on mutations

Meiosis

two parent gene sets are shuffled together & divided into separate gametes & new combinations are made through crossing over & independent assortment

Random Fertilization

pairs one randomly selected gamete to another, resulting in unique combinations of genes

Mutations

mistakes in the replication of nucleotide sequences

Natural Selection

populations produce more offspring than can survive, leading to a struggle to survive and reproduce

Directional Selection

drivers a feature in one direction & favors an extreme trait

Stabilizing Selection

favors moderate version of a trait & reduces diversity

Diversifying Selection

favors both extremes & increases diversity

Genetic Drift

random change in the gene pool of a population

Bottleneck Effect

a large population is drastically reduced & those who survive, survive by chance

Founder Effect

isolated populations have some genes overrepresented and underrepresented

Divergent Evolution

related species with different environments experience different pressures & adapt differently

Convergent Evolution

unrelated species may acquire similar traits because they live in similar environments

Speciation

processing of generating new species from a single species

Allopatric Speciation

species formation due to physical isolation from one another

Sympatric Speciation

mutation & nondisjunction events create genetically isolated, self—fertilizing populations (common in plants)

Law of Ecological Tolerance

for each abiotic factor, a species, population, or individual organism has a tolerance range within which it can survive, grow, & reproduce (ex. specific nutrients, light, temp, salinity range)

• may vary at different life stages & individuals

• greater range of tolerance → more genetic diversity & resistance

Optimal Range

range where the larges population lives & will survive in

Zone of Physiological Stress

range where organisms survive but experience stress (ex. decreased activity, stunted growth, infertility) → smaller population

Zone of Intolerance

causes organism death or migration to areas with more favorable conditions

Periodic Changes

occur with regular frequency (ex. seasons & tides) & are predictable allowing organisms to adapt

• Earth’s orbit & tilt alters climate, sea levels, & CO2 → CO2 levels rise & fall as result of temp change (ocean absorption of CO2, permafrost, greenhouse effect) → changes in climate increase/decrease exposed land mass & land bridges

Episodic Changes

occasional events with irregular frequency & are somewhat predictable (ex. hurricanes, droughts, fires)

Random Changes

no regular frequency or means of prediction (ex. volcanic eruptions earthquakes, meteor strikes)

What are responses to Disturbances?

migrating, adapting, extinction

Disturbance Regime

pattern of disturbances in a community

Succession

predictable series of changes in a community following a disturbance

Primary Succession

occurs after disturbances (ex. glaciation, volcanic eruptions, paves roads) remove all vegetation and soil → weathering of rocks + chemical secretiation of lichen & moss + decomposition of dead organisms →forms new soil

Secondary Succession

process of recovery from a disturbance (ex. fired, hurricanes, farming, logging) but does not destroy the soil or seed banks → allow plants to regrow immediately

Pioneer Species

the first species to arrive after a disturbance & disperse seeds, soil, & sunlight (ex. mosses, lichen, grasses, wildflowers, raspberries)

Mid-Successional Species

help develop deeper soils through death & decomposition; have a broad range of tolerance & moderate growth rates (ex. shrubs & small trees)

Late-Successional Species

community that developed remain in place with view changes; narrower range of tolerance & niche (ex. larger slower-growing trees, ex. maple & oaks)

Resistant Communities

communities with large amounts of energy & matter stored in biomes, that are well suited to resisting many potential disasters

Resilient Communities

communities with low intensity disturbances that are not resistance, but recover quickly