test 3 environmental

some groups have more species than others

species are not evenly distributed among taxonomic groups. insects are the most abundant organism species

edward o. wilson

developed theory of island biography

first to use “biodiversity” in a scientific paper

champion of conservation

entomologist specialized in ants

theory of island biography

big islands close to mainland: high pops., lower rate of extinction

small island close to mainland: lower immigration rate, high extinction rate

big islands far from mainland: high pop., higher extinction rate, low immigration rates

small islands far from mainland: smaller pop., high extinction rate, low immigration rates

biodiversity is unevenly distributed

abundance increases towards the poles

species richness increases towards the poles

natural selection

1. variation: genetic mutations arise in populations of species

2. adaptation: some individuals’ mutations mean they are better suited to their environment than others. this leads to differential reproductive success

how do new species evolve?

speciation: one species splits into two or more species

geographic isolation: happens first, physical isolation of a species for a long period

reproductive isolation: mutations and natural selection in geographically isolated populations lead to inability to produce viable offspring when members when members of two difference populations meet

extinction

extirpation: local extinction (other populations of said species exist elsewhere)

mass extinction: 5 over 500 million years; earth has had 5 major extinctions in the past 440 mill years (humans causing 6th)

bg extinction: typically low

today’s extinction rate is 100-1000 times higher than bg rate and its rising

vulnerable species to extinction

vulnerable: endemic species, large species, specialists, apex predators, large range required, small/isolated populations

niche

the summary of everything an organism does

• use of resources, functional role in a community

specialists vs. generalists

s: specific habitat, range, food

g: edge species, omnivorous, don’t need specific food/habitats

population density

the number of individuals in a population per unit area

high density advantages: easier to find mate (add more)

high density disadvantages: increased competition and vulnerability to predation, increased transmission of disease, sometimes organisms leave bc its too dense

population distribution

spacial arrangement of organisms

limiting factors

physical, chemical, and biological attributes of the environment that restrain population growth

carrying capacity

the maximum population size of a species that its environment can sustain

• s shapes logistics curve

density dependent factors

limiting factors whose influence is affected by population density

• risk of predation, disease, and competition

density-independant factors

limiting factors whose influence is not affected by population density

• events such as landslides, fires, and floods

• biotic potential (an organisms capacity to produce offspring)

k - selected species

species with long gestation periods, few offspring, and strong parental care, low biotic potential, stabilize at or near carrying capacity (good competitors)

r - selected species

species that reproduce quickly and offer little or no care for offspring, have high biotic potential, populations fluctuate greatly

species interact in 5 key ways

predation:

parasitism:

mutualism: black rhinos and ox-peckers

commensalism: one organism benefits off another without harming it, bromeliads in a tree

competition:

resource partitioning

process by which species use different resources or shared resources in different ways

ex) birds all eat insects, but they all catch them on different parts of the tree

primary succession

no soil in a terrestrial system, no bottom sediment in an aquatic system, takes hundreds to thousands of years, need to build up soils/sediments to provide necessary nutrients

secondary succession

some soil remains in a terrestrial system, some bottom sediments remain in an aquatic system, ecosystems have been disturbed, removed, destroyed

how do fragmented forests effect ecosystems?

edge species prevail (white tail dear, crows, opossums, raccoons), and forest interior species suffer (oven birds)

metapopulations

a network of separated subpopulations, each occupying a patch of a mosaic (fragmented complex ecosystem)

how can we join subpopulations?

habitat corridors (link “patches” together)

how does energy (sun) interact with ecosystems?

order energy is converted to biomass

primary production: conversion of solar energy to chemical energy in glucose by autotrophs

secondary production: biomass generated by heterotrophs from consuming autotrophs

gross primary production: total amount of energy captured by autotrophs

net primary production: energy remaining after respiration—used to generate biomass

high net primary productivity

ecosystems whose plants rapidly convert solar energy to biomass

ex) rainforests, corral reefs

macronutrients and nutrients

macronutrients: nutrients required in larger amounts (phosphorous, nitrogen, carbon)

nutrients: elements & compounds required for survival that are consumed by organisms

how do nutrients circulate through ecosystems?

sink: a pool that mostly accepts nutrients

source: a pool that mostly releases nutrients

how does the water cycle affect all other cycles?

it is essential for biochemical reactions, involved in nearly every environment system

hydrologic cycle: summarizes how liquids, gasses, and solid water flow through the environment (oceans are the main resirvoir)

evaporation: process by which water moves from aquatic and land systems into the atmosphere

transpiration: release of water vapor by plants

precipitation: run-off and surface water where water returns to the earth as rain, snow, and flows into oceans/lakes etc.

ground water & aquifers

ground water: water found underground beneath layers of soil

aquifers: underground reservoir of ground water found in sponge like regions of rock and soil (refills from water seeping through rock). this water may be ancient and can take years to refill

water table

the upper limit of ground water in aquifers; ground water becomes exposed to air where the water table reaches the surface (exposed water runs off to the ocean or evaporates)

human impacts on the water cycle

removing forests/vegetation increases erosion, decreases transpiration, and decreases filtration of water

• daming rivers slows water movement to the sea & increases evaporation

• irrigating crop fields depletes rivers and lakes, & lowers water table