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grass → cow → wolf → vulture
In the food chain above, vultures represent WHAT LEVEL?
Vultures eat carrion, or dead animals, so they are considered scavengers. Detritivores are heterotrophs that eat decomposing organic matter such as leaf litter. They are usually small.
T OR F
Carbon is released in the form of CO2 through respiration, burning, and decomposition.
types of survivorship curves
PERCENT O F LIFE SPAN JUST MEANS AGE.
WHAT IS THE GROWTH RATE FORMULA?
SHOULD RESULT IN A DECIMAL
During primary succession, which species would most likely be a pioneer species?
b. Fir trees
- A. LICHENS
- Pioneer species colonize vacant habitats, and the first such species in a habitat demonstrate primary succession.
- Succession on rock or lava often begins with lichens. Lichens need very little organic material and can erode rock into soil to provide a growth substrate for other organisms.
WHAT IS SECONDARY SUCCESSION?
Secondary succession occurs when a habitat has been entirely or partially disturbed or destroyed by abandonment, burning, storms, etc.
Which biome is most likely to support the growth of epiphytes?
b. Tropical rain forests
c. Temperate deciduous forests
B: Epiphytes are plants that grow in the canopy of trees, and the tropical rain forest has a rich canopy because of its density and extensive moisture.
DEFINE DENSITY-DEPENDENT LIMITING FACTORS.
- Density-dependent limiting factors include:
- toxic effect of waste products
- Density-dependent factors operate only when the population density reaches a certain level.
- These factors operate most strongly when a population is large and dense.They do not affect small, scattered populations as greatly.
DEFINE DENSITY-INDEPENDENT FACTORS.
- limiting factors that affect all populations in similar ways, regardless of the population size.
- -unusual weather
- -natural disasters
- -seasonal cycles
- -certain human activities—such as damming rivers and clear-cutting forests
Two species of finches are able to utilize the same food supply, but their beaks are different. They are able to coexist on an island because of_________.
although similar, species in the same habitat have evolved characteristics that reduce competition between them. It occurs as a result of resource partitioning.
DEFINE Sympatric speciation
the process through which new species evolve from a single ancestral species while inhabiting the same geographic region.
sympatric and sympatry are terms referring to organisms whose ranges overlap or are even identical, so that they occur together at least in some places.
cladogenesis (= diversifying evolution) - the divergence of two new species from a single ancestral species. (Net increase in species diversity).
anagenesis (= phyletic evolution) - the conversion of an entire population, over time, to a recognizably different. (No net increase in species diversity)
DEFINE Gause's Law
(aka Competitive Exclusion Principle)
In a stable environment, two species cannot coexist if they use exactly the same resources.
DEFINE ALLOPATRIC SPECIATION
A single population is divided into two by a physical, geographic barrier.
DEFDINE PERIPATRIC SPECIATION
- By entering a new ecological niche, a small subset of a large population becomes isolated at the periphery (outside edge of area) of the original population's range.
- Over generations, the small group becomes reproductively isolated from the original population.This is sometimes considered a special case of allopatric speciation.
EX:POLAR BEAR AND THE NOW EXTINCT EURSIAN BROWN BEAR OF IRELAND.
DEFINE PARAPATRIC SPECIATION
- This occurs on a larger scale than parapatric speciation, with large numbers of a population gradually becoming differentiated (due to genetic drift and/or selection) along the range of the population.
- Adjacent demes may be able to interbreed to some degree, but widely separated demes cannot. In such isolation and under different selective pressures, the more widely separated populations undergo reproductive isolation/speciation.
Ring Species: Products of Parapatric Speciation EX: SALAMANDER
DEFINE SYMPATRIC SPECIATION
speciation occurs without physical separation, within the range of the ancestral population.
(This is often due to a sudden genetic event that causes very rapid reproductive isolation of a subset of the original population.)
- Sympatric speciation is well known in plants, which can speciate quickly via polyploidy, eitherautopolyploidy (chromosomes in the new species all from the same ancestral species)
- OR allopolyploidy (chromosomes in the new species come from two different (but related) ancestral species)
NAME THE 4 MODES OF SPECIATION
Lichens consist of fungi and algae. The algae supply sugars through performing photosynthesis while the fungi provide minerals and a place to attach. This is an example of _________.
Because both species benefit, lichens constitute an example of mutualism.
relationship between two organisms where one organism benefits without affecting the other.
EX:ALGAE ON TURTLES SHELL.
DEFINE Interspecific competition
a form of competition in which individuals of different species compete for the same resource in an ecosystem (e.g. food or living space)
NAME 3 TYPES OF NATURAL SELECTION.
- Stabilizing selection
- Directional selection
- Disruptive selection
DEFINE Stabilizing selection
- When selective pressures select against the two extremes of a trait, the population experiences stabilizing selection.
- For example, plant height might be acted on by stabilizing selection. A plant that is too short may not be able to compete with other plants for sunlight. However, extremely tall plants may be more susceptible to wind damage. Combined, these two selection pressures select to maintain plants of medium height. The number of plants of medium height will increase while the numbers of short and tall plants will decrease.
DEFINE Directional selection
one extreme of the trait distribution experiences selection against it. The result is that the population's trait distribution shifts toward the other extreme. In the case of such selection, the mean of the population graph shifts. THINK GIRAFFE NECK.
DEFINE Disruptive Selection
In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. The result is a bimodal, or two-peaked, curve in which the two extremes of the curve create their own smaller curves.
- EX: plant of extremely variable height that is pollinated by three different pollinators, short, medium and tall.
- If the pollinator that preferred medium height disappeared from an area, medium height plants would be selected against and the population would tend toward both short and tall. Such a population, in which multiple distinct forms or morphs exist is said to be polymorphic.
Body parts develop with increased usage and weaken with disuse...WHO'S IDEA?
T OR F
Within the same species, some birds have large bills, while others have small bills.
DISRUPTIVE SELECTION ?
- Disruptive selection occurs when the environment favors alleles for extreme traits. In the example, seasonal changes can make different types of food available at different times of the year, favoring the large or short bills, respectively.
A large population
An isolated population
ALL OF THESE WOULD LEAD UP TO WHAT?
WHAT COULD PROMOTE EVOLUTIONARY CHANGE IN A POPULATION?
which is the introduction or removal of alleles from a population, would allow natural selection to work and could promote evolutionary change
Which of the following would create the greatest amount of genetic variation for a diploid species in a single generation?
a. Crossing over
d. Independent assortment of homologs
e. Random joining of gametes
C: Hybridization between two different species would result in more genetic variation than sexual reproduction within a species.
the process of combining different varieties of organisms to create a hybrid
HAVEY WIENBERG GIVES PERCENTAGES, BUT WHAT IF THE QUESTION ASKS FOR THE NUMBER OF HETEROZYGOUS ?
DIVIDE THE TOTAL POPULATION BY 100 AND THEN MULTIPLY BY THE PERCENT OF THE HETEROZYGOUS (2PQ).
Cellular differentiation, a necessary process in development and maintenance of multicellularity, is regulated by _______ factors.
DEFINE Cellular differentiation
ALSO CALLED SPECIALIZATION OR SPECIALIZED.
the process by which a less specialized cell becomes a more specialized cell type.
Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of tissues and cell types.
Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover.
PROCESS IS NOT REVERSIBLE.
WHAT IS A STOMATIC CELL
BODY CELL. ANYTHING BUT A SEX CELL.
How do cells become different from their parent cells?
asymmetric segregation of cellular determinants.
However, in most cases, determination is the result of inductive signaling between cells.
DEFINE Asymmetric segregation of cellular determinants
- Asymmetric segregation of cellular determinants is based on the asymmetric localization of cytoplasmic molecules (usually proteins or mRNAs) within a cell before it divides.
- During cell division, one daughter cell receives most or all of the localized molecules, while the other daughter cell receives less (or none) of these molecules.
- This results in two different daughter cells, which then take on different cell fates based on differences in gene expression.
Mechanisms of cellular determination..TWO TYPES..Asymmetric segregation AND _______.
- inductive signaling between cells.
NAME 3 TYPES OF INDUCTIVE SIGNALING.