Ecosystem Ecology Flashcards
Evolution
the change in the characteristics of a species over several generations and relies on the process of natural selection.
Natural Selection
process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Mutation
when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene.
population
a group of individuals of the same species living and interbreeding within a given area.
Population Density
a number of organisms/area
birth rate
The ratio of live births in an area to the population of that area
expressed per 1000 population per year
Death rate
The ratio of deaths in an area to the population of that area; expressed per 1000 per year
Growth rate
The rate, or speed, at which the number of organisms in a population increases.
Immigration
when new organisms join a population, changing allele frequencies.
Emigration
Emigration is when members of a population leave, taking with them their genes.
Biotic Potential
the maximum reproductive capacity of an organism under optimum environmental conditions
Exponential Growth
Exponential growth requires specific ideal conditions.
A population can grow exponentially when it has access to unlimited resources and no competition.
begins at a slow rate then speeds up when the population rises
Logistic Growth
population increase - growth rate starts slowly, as there are few individuals, then increases in speed as numbers increase, but then
competition increases and resources become increasingly scarce, populations reach the carrying capacity (K) of their environment, causing their growth rate to slow nearly to zero
Carrying Capacity
the number of people, other living organisms, or crops that a region can support without environmental degradation.
Limiting Factor
anything that constrains a population’s size and slows or stops it from growing
can be biotic - food
or abiotic - logging
Density Dependent Factors
regulating factor - any force that affects the size of a population of living things in response to the density of the population (the number of individuals per unit area). usually biotic forces
disease
food access
Density Independent Factors
a limiting factor that affects the size of a population of living things regardless of the density of the population
flooding - wildfire - disasters
Boom and Bust Cycle
long periods of almost exponential growth (boom) and a subsequent population crash due to competition (bust)
boom-bust dynamics, can allow for the evolution of much larger amounts of diversity than would be expected with stable equilibrium dynamics.
R strategist
production of numerous small offspring followed by exponential population growth. They require short gestation periods, mature quickly (and thus require little or no parental care), and possess short life spans
reproduce at a relatively young age; however, many offspring die before they reach reproductive age.
initially opportunistic - flourish in temporary environments and unpredicatble events - roaches - rats -weeds then replaced by competition over time
K strategist
stable populations and tend to produce relatively low numbers of large offspring
long gestation periods lasting several months
slow maturation (and thus extended parental care), and long life spans
inhabit relatively stable biological communities
elephants
humans
survivorship Type 1, 11, 111
type I - high probability to survive early and middles life but rapid decline in late life
type II - roughly constant mortality rate
type III greatest mortality is early in life
Metapopulation
“population of populations” distributed in discrete habitat patches
meta-population approach tracks the occupancy of habitat patches through time
useful when discussing species in disturbed habitats
Source habitat
high quality habitats that produce and export population
considered better than sink habitat, but when natural disaster destroys source habitat, sometimes sink habitat is last place for a species.
sink habitats
habitats in which populations cannot survive when they are isolated from other populations
(sometimes are last place of species when source habitat is destroyed)
Climate
atmospheric conditions in an area, such as temperature and rainfall
Biome
a large naturally occurring community of flora and fauna occupying a major habitat
tundra
treeless regions found in the Arctic and on the tops of mountains
Tundra is the coldest and driest of all the biomes. Tundra comes from the Finnish word tunturia, meaning treeless plain
Permafrost
permanently frozen layer below Earth’s surface
consists of soil, gravel, and sand, usually bound together by ice
earth remains frozen for at least two consecutive years
Boreal Forest/Conifer
northern boreal forest, is found in 50° to 60°N latitudes.
evergreen—they bear needles all year long. These adaptations help conifers survive in areas that are very cold or dry.
Boreal Forest/Taiga
russian word = forest
Snow forest - subarctic region variety of trees species. coldest forest
coniferous species - cone shape helps snow fall off branches - canopy
deciduous trees- white birch, trembling aspen and balsam poplar.
thin layer of soil - short growing season - dry - russia siberia - finland
Temperate Rain Forest
coniferous or broadleaf forests
mild climates or temperatures
two seasons.
(winter) is quite long and wet
(summer) is short, dry and foggy.
tall trees, mosses ferns, broad sarray of wildlife
from alaska to california - mild weather conditions are maintained by moisture-laden air blown in off the Pacific Ocean and hemmed in by the coastal mountains
Tropical Rain Forest
wet warm hot humid climate consistent all year round
thin soil shallow roots
ground layer
shrub
undercanopy
main canopy
emergents
Temperate Deciduous
eastern part of the United States and Canada, most of Europe and parts of China and Japan.
biome that is changing.
four distinct seasons: winter, spring, summer and fall.
Winters are cold and summers are warm.
Grasslands: Temperate
having short grasses as the dominant vegetation. plants with long, extensive roots that dig deep into soft, nutrient-rich soil.
Precipitation in the temperate grasslands usually occurs in the late spring and early summer
inland
massive root structure creates a dense net that develops a sod layer anchor - reduces erosion retains water
taken over in 1800s for crops - mismanaged
north america
eurasian steppe
Grasslands: Savanna
grassland with scattered individual trees
half the surface of Africa
found in warm or hot climates
dry and a rainy season
rainfall is concentrated in six or eight months of the year, followed by a long period of drought
Annual fires then maintain the area as a savanna.
Grasslands: Chaparral
Spanish word “chaparro” which means scrub oak
coastal regions, varied vegetation, (not the same as desert scrub which is a transitional zone between deserts and grasslands.)
cool, moist air from the ocean hits dry, warm land masses, typically along the west coast, forming this semi-arid mediterranean climate. The chaparral covers somewhere between 2-5% of terrestrial earth and is found on multiple continents
climate here is considered semi-arid and summer and winter are quite distinct
mild year round, there is a drastic change between daytime and nighttime temperatures
only 5% of planet but 20% of vascular plants - poor soil - easily eroded rocky
precipitation is generally unpredictable, but always very low in summer
Desert
20% of the Earth. less than 50cm of rainfall per year
- little rainfall (less than 50 centimeters per year)
- temperatures vary greatly between day and night
- high evaporation rates
- coarse-textured soils
- drought-resistant vegetation
4 types:
hot and dry - hot, dry deserts that occur at low latitudes
semiarid - long, dry summers and cool winters
coastal - western edges of continents
cold - low temperatures and long winters
