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