unit 2 Flashcards
natural selection
- developed by darwin, published first in book “Origin of species” (1859)
- there is physical/behavioral variations in living organisms, even within the species level (genetic)
- higher fitness= more likely to reproduce
The range of different inherited traits within a species
genetic diversity
**The more genetic diversity a species has, the more RESILIENTit is; it has more “options” for response/adaptation to occur if the environment changes
the number of different species present in an ecosystem and relative abundance of each of those species (takes into account species richness and species evenness)
Species Diversity
**The more species diversity there is; the more resilient that ecosystem is to changes
the range of habitats where different species live (habitat→the natural home or environment of an animal, plant, or other organism)
habitat diversity
**When habitats are lost, specialist species are lost followed by generalist species and then species that require a lot of territory (space) are lost
number of different species
species richness
describes distribution of abundance (total number) across the species; it is high when all species have a similar number
species eveness
- broad niche
- very adaptable
- uses a variety of resources/different food
- can be found around the world
- high tolerance
generalist species
- narrow niche
- limited diet
- found in specific habitats
- low tolerance
- not adaptable
specialist species
-alternative forms of a gene found at the same place on a chromosome; arise due to mutations
alleles
*-Different alleles⇒variation of traits
A change in allele frequencies in a population from generation to generation
occurs due to chance events
can result in the loss of some alleles (even beneficial ones) and the fixation (rise to 100%) of others
Happens in populations of all size; effects are stronger in smaller populations
genetic drift (2 major processes are founder’s and bottleneck effect)
-Occurs when a population is sharply reduced in size by a natural disaster (ex: earthquakes, floods, fires)
bottleneck effect
-A small group splits off from the main population to found a colony (ex: islands, habitats cut off due to urbanization)
founder’s effect
. Over time, a natural selection will ensure that certain characteristics appear more and more often as they are passed through generations. Entire species can change over time in this way.
Genes for new traits have to ALREADY BE PRESENT in a population’s gene pool through random mutation.
Our generation times are too long to keep up with rapidly changing conditions
*specifically for humans, human evolution takes thousands of years
why can’t organisms evolve immediately to adapt to current changes
“Fitness” means strongest, fastest, or biggest.
Organisms develop new traits in order to help them in their environment.
Evolution is a constant progression towards some perfect ideal.
myths about evolution
- locations of continents influence climate and habitats
- movement of continent allow for DISPERSAL, SPECIATION, AND EXTINCTION
geological processes affecting population
- ex. earthquakes can isolate populations, leading to speciation
- volcanoes can destroy habitat and can extinction
- asteroid impact can cause widespread extinction and climate change
- ice ages/warming periods can cause migration, extinction, new niches
geological and climate change impact on evolution
Islands that are larger and closer to the mainland have HIGHER species richness
island biogeography
The edges slowly degrade due to wind, invasion of species, and increased sunlight. Degradation of edges can lead to habitat fragmentation.
Some species may become more susceptible to predators because of decreased protection from the forest.
Selective logging causes caps in the canopy thus causing an edge effect.
(In ecology, edge effect refers to changes in a population or community along the boundary of a habitat. A clear example of this is when an agricultural field meets a forest)
Habitat fragmentation cuts species off from larger populations thus causing inability to support viable populations.
Tropical Rainforest soil is low in nutrient quality approximately 10x more land is needed for grazing animals and the previously cleared agricultural land is abandoned to clear nearby forest to further grow crops.
**Millions of Brazilian Amazon Rainforest are destroyed every year due to human set forest for agricultural use and by ranchers.
Clear cutting for agriculture and pastures.
there is an increase in:
- diversity and population numbers
- system stability
- biomass
- nutrient hold capacity
as ecosystems mature…
- reproduction
- clearing out competitors
- germination (seed sprouting)
what is fire succession in chaparral (shrubplant community) used for
primary succession= no previous life, exposed rock
secondary succession= already formed land, land on disturbed material
sucession = communities change over time
-Variability in genetic makeup among individs in a pop.
-If too few DNA differences 🡪 genetic bottleneck 🡪extinction.
genetic diversity
- mass hunting
- natural disaster
- loss of food
- ## introduction of non-native/invasive species
causes of bottleneck effect
Transitional zone where 2 or more communities meet 🡪 HIGH BIODIVERSITY
EX. INTERTIDAL ZONES
ecotone
Habitat stress
-Available niches
-Dominance of species
-Geological history
factors that determine SPECIES DIVERSITY
Considered separate species if they cannot interbreed
Same species create viable offspring
species
ex. of a pioneer species:
Lichens: Can be N fixers 🡪 Put Nitrate into soil for other plants to grow! Can also measure air poll
- moss is also a good pioneer species
- species after the pioneer species include: grasses/small plants, then smaller shrubs, then trees
ecological services –> !!!!!!!!!!!NATURAL !!!!!!!!!!!!!!!!!!!!
- provisioning–> “stuff” (matter) ex. water, lumber, food
- regulating v. supporting
- supporting = without these, others couldn’t exist ex. nutrient cycling, photosynthesis, soil formation,
- regulating–> water quality and air quality (BIG PICTURE)
- cultural–> religion, aesthetic/beauty, recreations
An intact coastal wetland or marsh would offer natural protection from hurricane storm surges categorized under regulating ecosystem service.
Coastal wetlands buffer against waves by slowing them down before they reach your property, and they help to drain floodwaters after a storm.
low habitat diversity= likely a lower numbr of specialist spcies and few species that utilize larger territories
Having a limited number of different habitats would inhibit the survival of different types of specialist species and those that control large territories.
relation of low species diversity to different species
“stuff” (matter) ex. water, lumber, food, wood fuel, natural gas, oil, medicinal resources,etc
- any type of benefit to people that can be extracted from nature
provisioning
without these, others couldn’t exist ex. nutrient cycling, photosynthesis, soil formation,
supporting
water quality and air quality (BIG PICTURE)
- benefit provided by the ecosystem that moderates “natural phenomena”
- processes work together to make ecosystems clean, sustainable, functional, and resilient to change
regulating
changes in a population or community along the boundary of a habitat. A clear example of this is when an agricultural field meets a forest)
edge effect
religion, aesthetic/beauty, recreations
- non material benefit, contributes to development and advancement of people
- how ecosystems play a role in local/national/global cultures
cultural
- burning fossil fuels
- deforestation
- industrial agriculture
- overfishing
- pesticide use
- genetically modified crops
- water pollution
ex. of anthropogenic activities
- acid desposition= pH of water and climate disruption
- loss of species and habitat
- monocropping
- loss of species
- loss of genetic variation
- loss of aquatic habitat diversity
biodiversity impact from anthropogenic activities
esources that are present in excess of an organism’s tolerance or in insufficient quantities to meet basic needs of organism.
!!!!!!An organism’s size, age, state of health, or DNA can influence their range of tolerance.!!!!
!!!!The optimal range is the amount of an ABIOTIC FACTOR that produces the HIGHEST POSSIBLE POPULATION.!!!! For water temperature, this would be about 6-10°C.
optimal
The zone of physiologic stress occurs when an abiotic factor exists at levels that are too high or
low to support normal biotic potential. This would be 3-6°C and 10-16°C.
The zone of physiologic stress
The zone of intolerance occurs when a population is ABSENT (or in this case, nearly absent). This
occurs at either extreme of our water temperature graph, below 3°C and above 16°C.
zone of intolerance
Lichens and pioneer species secrete acid onto rocks causing chemical weathering
Edges of forests considered ecotones
