Ecosystems and Population Change Flashcards
What is the study of interactions between organisms and their non-living environments?
Ecology
What are transition areas between ecosystems called?
Ecotones
What are ecotones characterized by?
They are usually characterized by greater biodiversity than either of the overlapping ecosystems
What does the increased biodiversity of ecotones create?
Creates more stable food webs for many organisms
What is an organisms role in an ecosystem (including it place in the food web, habitat, breeding area, etc.) called?
Ecological niche
What occurs if a new species (exotic species) is introduced into an ecosystem?
Competition (with any species that fulfills the same niche)
What does competition result in?
One of the species will be outcompeted and cannot survive in the ecosystem (the entire ecosystem will be disrupted)
What is the maximum number of offspring a species can produce, when resources are unlimited called?
Biotic potential
What four factors determine biotic potential?
- Number of offspring
- Breeding frequency
- Length of reproductive life
- Capacity for survival
What is number of offspring per birth?
Maximum number of offspring in one reproductive cycle
What is breeding frequency?
Number of times a species reproduces (reproductive cycle) per year
What is length of reproductive life?
The age of sexual maturity to the age when reproductive ability is lost
What is capacity for survival?
The number of offspring that survive to reproductive age
What are environmental factors that prevent populations from reaching their biotic potential called?
Limiting factors (environmental resistance)
What are the two types of limiting factors?
- Abiotic factors
2. Biotic factors
What are temperature (too hot/cold), harmful chemicals in the environment, bioaccumulation, and too much/little light examples of?
Abiotic factors (non-living)
What are excessive predators, diseases/parasites, diminished ability to compete, and insufficient food examples of?
Biotic factors (living)
What is the maximum number of individuals of a particular species that can be supported in an ecosystem at a particular time called?
Carrying capacity
What determines carrying capacity?
The availability of food, presence of predators, disease, and other resources
What happens if a population exceeds the carrying capacity?
The population will decline until it re-stabilizes
What will often determine the number of organisms that can live in an ecosystem?
Abiotic factors
What are the two basic rules that govern the effects of abiotic factors?
- Law of minimums
2. Law of tolerance
What does the law of minimums state?
States that the nutrient or resource in the least supply is the one that limits growth (minimal water during a drought)
What does the law of tolerance state?
States that organisms can only tolerate or survive within a particular range of abiotic factors (ex. temperature)
What are the two biotic factors that determine the carrying capacity for a species in an ecosystem?
- Density dependent factors
2. Density independent factors
What do density dependent factors affect?
Affect only large populations because of the density (numbers) of individuals
What are examples of density dependent factors?
Disease, food supply, predators, availability of sunlight/ water due to competition, space
What do density independent factors affect?
Affect all members of a population regardless of the numbers of individuals present
What are examples of density independent factors?
Fire, flood, drought, chemicals, climate change, other natural disasters
What four major abiotic factors limit terrestrial ecosystems?
- Soil (and soil pH)
- Available water
- Temperature
- Sunlight
What are three terrestrial biomes?
- Grasslands (prairies)
- Deciduous forest
- Taiga (Canadian shield)
What are two things that cause terrestrial ecosystems to change?
- Forestry
2. Forest Fires
How does forestry cause terrestrial ecosystems to change?
Deforestation by slash and burn, clear cutting, or by selective cutting
What are forest fires?
A natural ecological process (usually means renewal and rebirth for most ecosystems)
Why are forest fires a sometimes positive occurrence?
Effective at cleaning up dead plant material and stimulating re-growth of young healthy plants. (A quick way of recycling/ decomposing waste and nutrients) (Ash) (nitrates + phosphates)
What are often very diverse and important to the earth’s ecological state?
Aquatic ecosystems
What three major abiotic factors affect aquatic ecosystems?
- Chemical environment (dissolved oxygen)
- Light levels (most important abiotic factor)
- Temperature
What determines if a body of water is a lake or pond?
Depth/visibility
What occurs during winter and summer due to variations in the amount of sun that hits a lake?
Lake statification
What does lake stratification form?
3 layers due to the temperature created by the variation in sunlight
What are the three layers called?
- Epilimnion
- Hypolimnion
- Thermocline
What is the epilimnion?
Top layer; due to sunlight this layer is extremely warm and has lots of O2 (as a result of photosynthesis)
What is the hypolimnion?
Bottom layer; due to a lack of sunlight it is colder and has low amounts of O2 (due to no photosynthesis)… however this is the sight of lots of decomposition and hence lots of nutrients
What is the thermocline?
Transition point; quick transition between the epilimnion and hypolimnion
What zones are part of the epilimnion?
Littoral zone and limnetic zone
What zones are part of the hypolimnion?
Profundal zone and benthos
What zone is shallow and extends outward until the bottom is met?
Littoral zone
What does the littoral zone contain?
Lots of aquatic plants (photosynthesis > O2), different animals. Most Biodiversity!
What zone is open water and goes as deep as the sun goes?
Limnetic zone (euphatic zone)
What does the limnetic zone contain?
Lot’s of plankton, crustaceans, some fish and floating plants (some O2 production due to the phytoplankton and plants)
What zone gets no sunlight, sits beneath the limnetc zone, and is where no photosynthesis occurs?
Profundal zone
What does the profundal zone contain?
Lot’s of nutrients (due to decomposition), low O2 (due to decomposers), some chemosynthesis, low biodiversity, lots of bacteria
What is benthos?
the sludge/mud at the bottom of the lake
What are NEWER lakes that are DEEP, and COLD with LOW NUTRIENT LEVELS; these types of lakes tend to support larger fish, as they have HIGHER OXYGEN CONTENT?
Oligotrophic lakes
What are OLDER lakes that have become filled in with DETRITUS, the water is WARM, SHALLOW, and NUTRIENT RICH; these lakes are on their way to becoming marshes and eventually dry land?
Eutrophic levels
What are three things that determines water quality?
- Bacteria
- Dissolved O2 (DO)
- Biological Oxygen Demand (BOD)
What do scientists use to name and group organisms?
Taxonomy
What is taxonomy?
The science of classification according to presumed relationships among organisms
What type of system do scientists use to classify organisms into series of smaller groups?
A hierarchal system
What order is the hierarchal system?
Domain- bacteria, eukarya, archea Kingdom- monera, protista, plantae, fungi, animalia Phylum- sub-groups of each kingdom Class Order Family Genus Species
What are species?
Organisms that are very similar and can naturally interbreed to produce fertile offspring
When organisms are assigned a scientific name, how is it arranged?
Genus species
What is this naming system called?
Binomial nomenclature (created by Carl Linnaeus)
What does the genus name indicate?
Organisms that are similar (always capitalized) (Homo)
What does the species name indicate?
Organism that are different (always lowercase) (sapiens)
What are the five kingdoms?
- Prokaryotae
- Protista
- Fungi
- Plantae
- Animalia
What does the prokaryote kingdom include?
Bacteria (eubacteria and archaebacteria) (unicellular w/ no cell nucleus)
What does the Protista kingdom include?
Single celled plants and animals (algae) (unicellular w/ a nucleus)
What does the Fungi kingdom include?
Mushrooms, yeasts, moulds (multicellular decomposers)
What does the Plantae kingdom include?
Trees, flowers, mosses, and ferns (multicellular, photosynthesizers)
What does the Animalia kingdom include?
Sponges, worms, crustaceans, insects, and mammals (multicellular and heterotrophs)
Because naming 2-5 million organisms presents challenges, what can be used to overcome this challenge?
Dichotomous keys
What are dichotomous keys used for?
Used to identify and classify organisms based on their characteristics
What is the history of evolution of a species or group of organisms called?
Phylogeny
What is the history, and evolutionary relationships between organisms often shown in?
A phylogenetic tree
What is excessive richness of nutrients in an aquatic ecosystem called?
Eutrophication
What can eutrophication increase?
The rate of succession
What is succession?
Gradual changes in the abiotic and biotic components of an ecosystem (natural or human induced)
What is primary succession?
Gradual changes that begin with the making of soil (after a volcano or glacier receding)
What is secondary succession?
Gradual changes that occur after soil is there, or, if soil is already around (lake succession, farming, after a forest fire)
What are the steps of aquatic succession?
- Big deep oligotrophic lake
- Shallow eutrophic lake
- Pond
- Swamp/slough
- Marsh
- Dried up terrestrial ecosystem with lots of nutrients
What is the theory that states, changes occur and can be seen in the inherited traits of a populations from one generation to another?
Evolution
Who believed, “all living species are decedents of ancestral species and are different from present day ones due to the cumulative changes in the genetic composition of a population” ?
Darwin
What is the best form of evidence to support evolution?
Fossils
What is the study of fossils?
Paleontology
What do fossils provide?
A historical record of organisms that once lived
What are three things that fossils have revealed?
- In the past earth was home to species that are very different from the ones that exist today
- The complexity of organisms has seemed to increase
- Living species and their fossil matches are found in the same geographical regions
How do palaeontologists measure the age of fossils/rock?
Uses radioactive decay to measure the age of an object
What do radioactive elements lose as they decay at a constant rate?
Particles (and mass)
What is the half life of an object?
Is the time it takes for half the sample to decay and become stable
How can palaeontologists estimate the age of fossils?
Measure the age if rock in which fossils are found (creating a chronological evolutionary scale)
What is another type of evolutionary evidence that studies the distribution of different organisms on the surface of the earth?
Biogeography
What has happened to the earth’s continents over long periods of time?
They have shifted position
What has the shifting of continents resulted in?
The redistribution of living organisms
How can it be proved that the continents have shifted?
They can be matched up geographically and biologically
What are the five time periods?
- Permian (Pangea) (225 million years ago)
- Triassic (200 million years ago)
- Jurassic (135 million years ago)
- Cretaceous (65 million years ago)
- Present day (current)
What is anatomical evidence?
Structural evidence; studying similarities and differences in the anatomy of organisms, and in their embryological development to determine ancestral links between organisms
What are three different forms of anatomical evidence?
- Homologous structures
- Analogous structures
- Vestigial features
What are homologous structures?
Features with similar structures, and different functions that indicate an evolutionary relationship between organisms (show evolution from a common ancestor)
What are analogous structures?
Features with similar functions, but very different structures that indicate there is little evolutionary link between organism (shows no common ancestor)
What are vestigial features?
Rudimentary (basic) structures that have no clear function that may have once been important, but are now evolving out of existence (appendix & tailbone)
What is a type of evolutionary evidence that uses DNA to compare organisms?
Biochemical evidence
What will similar organisms have?
More similar DNA and amino acid sequences (monkeys & humans)
What is embryology?
When organisms show similar stages in the development of the embryo or share embryonic structures
Who believed in the inheritance of acquired characteristics?
Lamarck
Lamarck believed that organisms would evolve and develop a certain trait through what?
Desire
How long did Lamarck believe it would take an organism to evolve its desired characteristic?
Within a lifetime
What did Lamarck believe happened to unnecessary traits?
The organism would lose it (use-disuse theory)
What did Lamarck believe happened to these traits?
Could be passed down to offspring (inheritance)
What did Lamarck believe about the direction of evolution?
It was unidirectional
Who believed in natural selection and survival of the fittest?
Darwin
What did Darwin believe about organisms?
That there were many variations among them
How did Darwin believe traits were passed down?
traits that were better adapted to survival and reproductive success would be passed down
What were the 5 parts of Darwin’s theory?
- Variations exist among organisms
- In a changing environment, overpopulation and hence competition will occur for limiting factors
- Specific variations were better adapted to survival than others, only those that survive will sexually reproduce (survival of the fittest)
- The adaptive traits will be inherited and passed down to the offspring
- Natural selection always occurs and is the mechanism for change… each trait has the chance to be passed on, but its likely the better adapted trait would be passed on
What did Darwin believe about the direction of evolution?
It was multidirectional (due to environmental changes)
What determines an organisms traits/characteristics?
Chromosomes
What is the biggest reason for variation?
Mutations
What are mutations?
Random changes in the DNA sequence of a chromosome
What might mutations be?
- Neutral (no effect)
- Harmful (hinder survival and reproductive success)
- Beneficial (improve survival and reproductive success)
What is most biological diversity in organisms a result of?
Random mutations
What involves the production of an organism from two different parents?
Sexual reproduction
What will the offspring of sexual reproduction inherit?
Half the genetic characteristics of both parents, increasing variability
What involves the production of an individual from one parent, resulting in genetically identical offspring?
Asexual reproduction
What does cloning result in?
Decreased genetic diversity/variation and could possibly cause and unstable population
What is the formation of a new species?
Speciation and evolution
How can speciation occur?
A step by step process known as allopatric speciation
What are the steps of allopatric speciation?
- A physical barrier separates a population
- Environmental pressures on the two groups are very different causing the populations to evolve indpendently
- The differences become so extreme that the two populations can no longer interbreed to produce fertile offspring (different species)
What is the theory that states speciation takes place very slowly and is due to natural selection?
Theory of gradualism
What is the theory that states species evolve in bursts very rapidly, followed by longer periods of stability (little change), and again is due to natural selection?
Theory of punctuated equilibrium
What is divergent evolution?
The evolution into many different species, due to different environmental pressures (usually due to a barrier)(Darwin described as descent with modification)
What is convergent evolution?
The development of a similar appearance, structure or behaviours in unrelated species due to similar environmental pressures
What is an example of divergent evolution?
Homologous structures
What is an example of convergent evolution?
Analogous structures
What are adaptations?
Changes that occur that give an organism a better chance at survival
What are structural/physical adaptations?
Changes that occur to the external features (fur)
What are physiological structures?
Changes that occur internally (organs)
What are behavioural adaptations?
Changes to the regular behaviour of an organism (hibernation)
