unit 4 Population Flashcards
What is ecological succession?
the process of change by which the biotic communities replace each other and by which the physical (abiotic) environment becomes altered over a period of time is called ecological succession
identify the two types of succession.
first-degree (primary succession ) and second-degree (secondary succession)
what are the characteristics of first-degree succession?
- # of species increases rapidly at first
- colonized by pioneer species (they start succession)
- pioneer species are rapid growers and capable of surviving harsh environments
- begins with soil formation from bare rock
- takes a very long time to reach the climax community (dictated by the biome) and stops at the climax community
examples:
landslides mountains fall apart
retreating glaciers
lava from volcanoes
What are the characteristics of second-degree succession ?
- reestablishment after ecological disturbance (catastrophe)
- takes a shorter time because soil formation has already occurred
- organic matter already present
- stops at Climax community
- previously established ecosystem
Examples:
1. Forest fires… controlled or natural
2. clear-cutting of forests
3. floods
4. urban development
5. avalanche
what is the Hardy- Weinberg equilibrium theory?
- it allows us to predict allele frequencies in living populations
- it tells us that allele frequencies tend to remain constant from generation to generation unless acted on by outside forces = evolution
- it allows us to predict what phenotypes/traits will be in a given population now and in the future.
Hardy showed that allele frequencies in a population will remain the same from one generation to the next, as long as the five conditions are met what are they?
- the population is large to ensure no statistical flukes
- random mating (i.e organisms with one genotype do not prefer to mate with organism with a certain genotype)
- no mutations.
- no migration between populations (i.e the population remains static)
- no natural selection (i.e no genotype is more likely to survive than another)
what is symbiosis?
survival of one species might depend on another species
1. commensal
2. parasitic
3. mutalisitc
what is mutualism and what are the benefits?
Mutualism most popular relationship. Organisms and the ecosystems and services that
they provide for take care of the place so that 10,000 generations from now, there will
still be a place”. Mutualism has a strong place in the way that ecosystems survive.
what is commensalism? and what are the benefits
In commensalism, one organism benefits while the other is unaffected. For example, one organism can provide an essential growth factor, such as a vitamin, for another organism. This type of cross-feeding is common in soil organisms.
what is parasitism and what are the benefits?
parasites play a role in regulating populations that have high densities.
what is competition
A rivalry of two or more parties over a shared requirement for a resource in limited supply
what is Gause’s competitive exclusion principle?
“when individuals compete, the organisms alter their niches so as to try to coexist”. No one wants to risk getting hurt. So, for instance, owl and hawk change the time of day they hunt. Plants change when they photosythesize or how fast they reproduce
what are the two types of competition
interspecific and intraspecific
what is interspecific competition ?
- competition between members of different species
i.e same prey - this type of competition can lead to extinction; can lead to greater adaptions
What is the intraspecific competition?
competition between members of the same species i.e after the same mate, space, habitat
this type of competition leads to the evolution of better adaptations within a species.
What is predator-prey population interaction?
Predator kills its prey immediately. Predator is usually big
in size. Predator’s biotic potential is usually very low.
what are some reintroduction considerations someone must think of before releasing animals into an environment?
Factors affecting allele frequency and genetic diversity in the population? What is the impact on Genetic diversity in the population?
Has a subtle effect because rates are generally extremely slow, and the change in allele frequency will be, at most, the same order.
Brings new alleles into the population, either increasing recessive allele or decreasing dominant allele
How does migration affect allele frequency? And what is the impact on Genetic diversity in the population?
Migration of individuals from one population to another can change allele frequencies and even introduce new alleles.
- increases genetic diversity within a population however decreases diversity between populations.
- higher rates of migration lead to higher genetic diversity increasing the longevity of the population.
what are the two ways of getting small populations?
bottleneck effect or founders effect
what is the bottleneck affect?
rapid decline in population due to the anthropogenic or natural catastrophes that kill off most of the population usually who causes this are humans
What is genetic drift?
loss of dominant, recessive allele
- a mating event where, chance plus the fact that few are mating, an allele is lost; this is compounded if the mating pair only produce one offspring at a time
What is biotic potential?
This refers to the reproductive fitness (fecundity) of an organism. If Bp is low, produce a few offspring each season or every couple years. If Bp is high, leave many offspring each season or mate multiple times. a year
What is exponential growth?
J-shaped growth curve for r-stragesists
What is a rapid-growth population pyramid?
It looks like a typical pyramid with a large base that gets smaller as you ascend
this type of population typically has poor health care and short life expectancies. Mostly found in under developed and developing countries
what is a slow or stable growth population pyramid?
there is little change in the lower sections of the pyramid. Only after the upper ages do you see a marked change in population. This type of population pyramid is mostly found in developed countries sometimes middle income countries . These countries have good health care, long life expectancies
what is negative or declining growth population growth?
the middle section of the pyramid is the widest section. This type of population pyramid is mostly found in developed countries. These countries have good health care, long life expectancies and stable governments
however, their birth rates are lower than needed to replace the population
