Chapter 4: Evolution, Biological Communities, and Species Flashcards
Charles Darwin
Charles Darwin wrote a manuscript called “On the Origin of Species” which outlined the theory of evolution through natural selection
He voyaged the world aboard the H.M.S. Beagle.
Adaptation
the addition of traits that better allow a species to survive in its environment
*can occur quickly or over a long period of time
- acclimation
- natural selection
Acclimation
an immediate response to a change in the environment Ex. Put a coat on when it gets cold.
an acclimation is not permanent; however, the ability to acclimate is inherited
Natural Selection
The process of better-selected individuals passing their genes on to the next generation. This insures a better chance of species survival. (AKA Survival of the fittest)
Where are traits encoded?
In the DNA of the species
What is the relationship between adaptation, acclimation, and natural selection?
Acclimation and natural selection are just two ways an animal can adapt.
What are mutations?
alterations in an organisms chromosomes *Only mutations in gametes (sex cells) matter. *Mutations in body cells, like skin cancer and lung cancer, are not inherited. Many mutations actually have a negative effect.
Selection Pressures
factors in the environment that favor successful reproduction; the ability to live is reduced for those individuals not possessing those traits Example: In a dry desert climate, only organisms that can live without water for long periods can survive under this “pressure”
What are the limits all species live in?
- physiological stress due to some environmental factor (example: pH, moisture, temperature, nutrients, etc.)
- competition with other species
- predation ( includes parasites and disease)
- luck (sometimes surviving a catastrophe is just luck)
Critical Factor
the single environmental factor closest to a tolerance limit for a given species at a given time (proposed by Justus von Liebig in 1840)
Tolerance Limit
maximum and minimum levels beyond which a particular species cannot survive or is unable to reproduce (proposed by Victor Shelford)
*In some species, like the pupfish, the tolerance limits are different for adults and young fish/eggs.
Indicators
the presence or absence of species can be used to judge environmental conditions Example: lichens are sensitive to sulfur dioxide, therefore if there are no lichens, there is probably sulfer dioxide in the area
Habitat
place or set of environmental conditions in which a particular organism lives
Ecological Niche
either the role played by a species in a biological community or the total set of environmental factors that determine a species distribution (can be multidimensional)
There are two types of niches:
- fundamental
- realized
What is the difference between a fundamental niche and a realized niche?
The fundamental niche is the entire set of conditions that an species could live and reproduce in. The realized niche is the set of condtions that the species actually uses due to reasons like competition or predation.
Habitat Specialists
have more exacting habitat requirements, tend to have lower reproductive rates, and care for their young longer
*Less resilient to environmental change
Endemic
not found anywhere else; highly specialized to exist in a unique habitat (the Serow of Taiwan)
Competitive Exclusion Principle
no two species can occupy the same ecological niche for long; the one that is more efficient in using available resources will exclude the other (proposed by G. F. Gause)
Resource Partitioning
a form of niche evolution that allows several species to utilize different parts of the same resource and coexist within a single habitat or even utilize the same part of the habitat, but at different times
Speciation
the development of a new species
Geographic Isolation (Allopatric Speciation)
this occur when a species becomes separated due to some type of physical barrier or social behavior
Sympatric Speciation
the formation of a new species because of chromosomal changes; doubling or quadrupling of chromosome numbers; this is associated with genetic drift
Genetic Drift
ensures that DNA of two formerly joined populations eventually diverge
What are the types of selection pressures?
- Directional Selection
- Stabilizing Selection
- Disruptive Selection
Stabilizing Selection
Narrows the range of a trait. For example, 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, so the plants are maintained at a medium height.
Directional Selection
The population’s trait shifts toward one extreme over the other. For example, using the familiar example of giraffe necks, there was a selection pressure against short necks, since individuals with short necks could not reach as many leaves on which to feed. As a result, the distribution of neck length shifted to favor individuals with long necks.
Disruptive Selection
In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. For example, imagine a plant of extremely variable height that is pollinated by three different pollinators, one that was attracted to short plants, another that preferred plants of medium height and a third that visited only the tallest plants. If the pollinator that preferred plants of medium height disappeared from an area, medium height plants would be selected against and the population would tend toward both short and tall, but not medium height plants.
Vancomycin
evolution is still at work today, especially with germs. Germs evolve rapidly and become resistant to antibiotics. So, vancomycin is the treatment of last resort because if resistance were to become widespread, we would have no protection from infections
Taxonomy
the study of types of organisms and their relationships
Binomials
last two names for organisms; genus and species; names are in Latin. Ex. Human – Homo sapiens; Corn – Zea mays
What are the six kingdoms of life?
There are 6 kingdoms of life: animals, plants, fungi, protists, bacteria and archaebacteria.
Competition
an antagonistic relationship within a biological community; resources may be in limited supply requiring organisms to compete for them
Examples of limited resources are:
- energy and matter in usable forms (including food)
- living space
- sites for specific activities.
Intraspecific Competition
competition between
organisms of the same species.
Interspecific Competition
competition between
organisms of different species
What are some ways intraspecific competition is reduced in a species population?
- the young of the year disperse
- species exhibit strong territoriality and force offspring or trespassing adults out of the vicinity
- species accomplish resource partitioning between generations
Producers
photosynthetic plants and algae (usually)
Consumers
*anything that eats organic matter created by other organisms
include herbivores (plant eaters), carnivores (meat eaters), omnivores (plant and meat eaters), scavengers (eats only dead animals/plants), detritivores (eats decaying organic material), and decomposers (break down dead or decaying organisms).
Predator
any organism that feeds directly on another living organism
*As prey species mature, their predators will change
*predators will change prey is another food source becomes more abundant
Predation
one organism benefits through receiving nutrition and there is no benefit to the host or prey.
Predator-mediated Competition
a superior competitor in a habitat builds up a larger population than its competing species; predators of the superior competitor take note and increase their hunting pressure on the superior species, reducing its abundance and allowing the other weaker competitor to increase in numbers
What are some adaptations that help avoid predation?
- Toxic chemicals
- Body armor
- Extraordinary speed
- Ability to hide (camo)
- Plants may have thorns, spines, thick bark, bad tastes, or secrete harmful chemicals.
Coevolution
two species (predator and prey especially) exert selective pressure on each other and gradually evolve new features or behaviors together
Example, predators become better at searching and feeding and prey become better at escaping and avoiding
Batesian Mimicry
harmless species may resemble poisonous or
distasteful ones to avoid getting eaten
Example: Monarch Butterfly (bad taste to birds) and the Viceroy Butterfly (which can look like Monarch Butterfly)
Mullerian Mimicry
two species look alike and both are unappealing (like dead leaves) or dangerous (like similar looking bright colored poison frogs); both benefit because predators learn to avoid either species
Symbiosis
2 or more species living closely together; sometimes the relationship can most of the time be helpful or it can be harmful to at least one of the species. They often enhance the survival of one or both partners.
Mutualism
a symbiotic relationship between individuals in which both species benefit from the association
Example: the acacia ant colonies and the acacia tree
Commesalism
type of symbiosis in which one member clearly benefits and the other is apparently neither benefited nor harmed
Example: mosses on trees
Parasitism
a form of predation that may also be considered symbiosis because of the dependency of the parasite on its host
Keystone Species
a species that plays a critical role in a biological community that is out of proportion to its abundance. it is usually the top predator, but it can be anything from plants, to microbacteria, to a kind of fish
What is Primary Productivity and where are the highest and lowest levels of it?
rate of biomass production (it indicates the rate of solar energy converted to chemical energy; 1,000 kcal/m2/year)
Highest Levels: tropical forests, coral reefs, and estuaries (marsh regions)
Lowest Levels: deserts, arctic tundra, high up mountains (anywhere where there are low levels of photosysthesis rates)
What percent of light is reflected when it reaches a leaf? And how much is used to produce carbohydrates?
25%-75% is reflected
0.1%-0.2% is used to produce carbohydrates
*most of the light absorbed is converted into heat and lost into the environment
What is the difference between abundance and diversity?
Abundance is total number of organisms in a biological community.
Diversity is number of different species, niches, and genetic variation present
While moving up from the equator, how are diversity and abundance affected?
Abundance and diversity are usually inversely related. So, while moving from the equator toward the poles, diversity decreases and abundance within species increases .
Example:
the Arctic has huge numbers of insects but few species
What two factors affect what the abundance and diversity levels are in an area?
Climate and history are important factors. For example, Greenland had such a harsh climate that the need to survive through the winter or escape to milder climates becomes the single most important critical factor that overwhelms all other considerations and severely limits the ability of species to specialize or differentiate into new forms. All in all, because of its history, it hasn’t had enough time to diversify.
What is ecological stucture and what are the types of it?
refers to patterns of spatial distribution of both individuals and populations within a community; it also refers to the relation of a particular community to its surroundings
The types of ecological stuctures are distributed randomly, clumped together, or are in highly regular patterns.
Complexity
the number of species at each trophic level and the total number of trophic levels in a community
Example:
If species are clustered with few trophic levels and simple food chains, the complexity will not be high
Many biological communities tend to remain relatively stable and constant over time. What are the three kinds of stability or resiliency in ecosystems?
- Constancy (lack of fluctuations in composition or functions)
- Inertia (resistance to perturbations)
- Renewal (ability to repair damage after disterbances)
In 1955, what did Robert MacArthur propose?
he proposed that the more complex and interconnected a community is, the more stable and resilient it will be in the face of disturbance because if many species occupy the same trophic level, then if one disappears, the others can just fill in for its place
Edge Effects
boundary/relationship between one habitat and another. The boundary is usually sharp and distinct.
Examples: Forest to grassland, ocean to shore
Ecotones
the name for the boundary itself between adjacent communities
What are the two types of ecotones?
There are closed communities where the boundry is sharply divided, and there are open communities where the boundries are gradual or indistinct.
What is the Climax Community?
Communities develop, grow, and change over time. The community that developed last and lasted the longest is the climax community. It is complex and stable.
What is Primary Succession?
organisms begin to make home to a location that has been barren. Ex.sandbar, volcanic flow, mudslide, etc.
What is Secondary Succession?
an existing community is disturbed and a new one develops
What is a pioneer species?
the first “colonists” in primary succession. May be microbes, mosses, lichens, etc.
What are disturbances?
any force that disrupts the established patterns of species diversity and abundance, community structure or properties; these forces can be natural or man-made.
Disturbances generally benefit species because it sets back supreme competitors and allows less-competitive species to persist.
What effects can an introduced species have on an environment?
Introducing non-native species can cause severe disturbances in an ecological community and can alter the community.
Example: Mongooses in Hawaii were brought to control rats but instead killed native birds
Discuss the dangers posed to existing community members when new species are introduced into ecosystems.
New species introduced to an ecosystem can disturb the delicate balance that exists between the original inhabitants. These invasive species sometimes end up dominating existing species and wiping them out, reducing overall biodiversity with not just the extinction of that species, but other species dependent on it too.
What is productivity measured by?
Biological Activity
Which world ecosystems are most productive in terms of biomass? Which are least productive? What units are used in this figure to quantify biomass accumulation?
The most productive ecosystems are tropical rain forests and estuaries. The least productive ecosystems are desert and open ocean. The units to quantify biomass accumulation are 1,000/kcal/m2/year.
