Bisc 102 Midterm Flashcards
1
Q
Adaptation
A
Any TRAIT that helps an organism survive and reproduce. Can be structural, behavioural, or physiological
2
Q
Structural adaptation
A
ex. crab spiders that mimic the petals of a flower; clam that has a mantle that looks like a fish for dispersion of parasitic larvae; the neck of a giraffe to reduce competition for food or attracting mates; angular fish- light attracts food; peacocks attract mates
3
Q
Behavioural adaptation
A
ex. archer fish shoots insects on branches with a jet of water, correcting for angle; bowerbird decorates nest to attract a mate with objects the colour of its eyes; migration tracks good foraging areas throughout the year
4
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Physiological adaptation
A
desert animals; camels have efficient storage mechanisms; bombardier beetle shoots a hot chemical reaction for defense; human sperm- through number and protective coat
5
Q
Jean Baptiste Lamarck
A
(1744-1829) First suggested that species are not fixed, but change over time. His ideas were –Use and disuse; Inheritance of acquired characteristics (ie. cutting a tail off a mouse)
These processes have been refuted
6
Q
Charles Darwin
A
(1809-1882) Traveled around the world as a naturalist on “The Beatle” Studied finches, tortoises at the Galapacos Islands. Wrote The Origin of Species (1959)
7
Q
Alfred Russel Wallace
A
(1823-1913) Realized the same thing as Darwin around the same time, the two corresponded
8
Q
Natural selection
A
A PROCESS by which the individuals in a population that have the characteristics best suited to the environment survive and reproduce better than other individuals
9
Q
The five steps of evolution by natural selection
A
Observations: competition, variation among individuals, heritable variations
Inference: Selection, Adaptation
10
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Evolution: Step 1- Competition
A
In theory, populations are exponential while in reality they are fairly stable because resources are limited
11
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Evolution: Step 2- Variation among individuals
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Some individuals are better at competing for resources than others
12
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Evolution: Step 3- Heritable variation
A
At least some of the differences in ability to compete for limited resources are heritable
(= genetically based)
13
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Evolution: Step 4- Natural selection
A
Those individuals with traits that allow better survival and/or reproduction have higher fitness (ex. large rabbits eat the most, reproduce the most whereas small rabbits die off from lack of food
14
Q
Evolutionary fitness
A
The number of progeny (offspring) produced
15
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Evolution: Step 5- Adaptation (evolution)
A
The CHANGE in a population over time (ie. Large body is an adaptation for competing for limited carrots)
16
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Three conditions necessary and sufficient for evolution by natural selection
A
- There must be variation in the trait 2. Variation is heritable 3. Variation has fitness consequences
17
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Adaptation does not mean perfection because…
A
- Organisms are adapted to the current environment
2. Natural selection is often constrained
18
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Constraints to natural selection
A
Adaptations are often compromises (consdering all pressures on an organism); Natural selection is constrained by history (there are no 6 limbed vertebrates); Natural selection acts on existing variation (acts more on a population with a large variety)
19
Q
Protocells
A
Abiotically produced collection of molecules, fluid-filled vesicles bounded by a membrane-like structure
20
Q
Define life
A
1) Metabolism (nutrient uptake, processing, waste elimination) 2) Generative process (growth and reproduction/replication 3) Responsive processes (immediate responses to environment, individual adaptation, population adaptation) 4) Control processes (coordination, regulation) 5) Structural organisation (cellular level, organismal level)
21
Q
Proposition by Aristotle
A
(4th century BP) First idea of the origin of life:
Spontaneous generation- ‘Living organisms arise spontaneously from non-living matter’
Evidence: Maggots from dead meat, Mice from wheat seeds, Lice from sweat, Frogs from damp mud
22
Q
Proposition by Louis Pasteur
A
Biogenesis: ‘Life can only originate from pre-existing life’. His experiment used sterilized soup broth in a bottle that bacteria couldn’t enter, and he did not find growth
23
Q
The recipe for life
A
Energy source, raw materials, suitable environment
24
Q
Conditions on the early Earth
A
Extremely high temperatures; Different, Reducing atmosphere (Water vapour, Nitrogen, Carbon dioxide, Methane, Ammonia, Hydrogen, Hydrogen sulfide); No liquid water; Little oxygen; As Earth cooled, water vapour condensed and hydrogen escaped
25
Energy sources
Sun (light, UV); Volcanic eruptions; Lightning
26
Raw materials
Elements present on Earth (CHNOPS); Extraterrestrial sources
27
Extraterrestrial sources
Initially proposed by Arrhenius in early 1900s; Support from a meteorite containing amino acids and one with things that may be fossilized martian bacteria?
28
Origin of life on Earth by chemical evolution
With the right chemical and physical conditions, life could have began in four stages. 1) Abiotic synthesis of monomers 2) Formation of polymers 3) Packaging of polymers into protocells 4) Self-replication
29
Origin of life Stage 1: Spontaneous formation of monomers
Oparin’s hypothesis- a reducing atmosphere, a suitable environment, and energy will cause simple molecules to combine into organic compounds. Problem: The Earth's atmosphere may not have been reducing, though there are alternative "suitable environments" (deep sea vents, volcanoes)
30
Testing Oparin’s hypothesis
Miller -Urey experiments- combining water vapour, methane, ammonia, hydrogen with electricity synthesized sugars, pyrimidine and purine bases, amino acids, ATP.
31
Origin of life Stage 2: Polymer formation
Monomers could have combined to form organic polymers; using the same energy source as stage 1; Clay as substratum for polymerization? Experimental evidence: Dripping solution of amino acids on hot clay results in spontaneous formation of polymers
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Origin of life Stage 3: Protocells
Polymers aggregated into complex, organized, cell-like structures called protocells; Form spontaneously in the lab such as coacervate droplets, liposomes, and proteinoid microspheres
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protocells
Polymers aggregated into complex, organized, cell-like structures; add some living qualities: Structural organisation, Simple homeostasis and metabolism, Simple reproduction
34
Origin of life Step 4: Self-replication (Which came first, genetic material or the enzymes required to catalyze it?)
RNA, Single-stranded genetic material that can form enzymes (ribozymes)
Could have facilitated both replication and reaction catalysis on early Earth
35
Natural selection in an RNA world
Variation among RNA strands due to copying errors+Replication+Some strands better at competing for nucleotides and replicating
->Natural selection for shape, stability, replication accuracy & speed most suited to environment
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RNA world -> DNA world
RNA served as template for assembly of DNA nucleotides, which occured because DNA is a more stable genetic molecule
37
Which protocells would have been the most successful?
Protocells able to take up RNA with superior replication and catalytic abilities would have been more successful than those with inferior or no RNA
38
Prokaryotes
The most ancient organisms; Unicellular; Lived alone on Earth for nearly 2 billion years; Greatest diversity of lifestyles and habitats; They have created the Earth we know
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Prokaryote domains
Bacteria and Archaea (Only 4,500 species described so far)
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Pro vs Eu
Prokaryotic cells are Smaller; Single membrane system; Nucleoid (no nucleus); No walled organelles; No cytoskeleton
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Bacteria
Includes most known prokaryotes; Hugely diverse in metabolism and structure
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Examples of Bacteria
Photosynthetic cyanobacteria; Organisms important in decomposition and nutrient cycles; Some disease organisms (salmonella, chlamydia); 500-1,000 spp of bacteria in your gut!
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Archaea
Key differences from bacteria: Cell wall composition and Details of protein synthesis; They live in harsh and extreme environments, Extremophiles
(‘extreme-lovers’) include Methanogens (methane-makers), Halophiles (salt lovers) and Thermophiles (heat-lovers)
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Why is studying modern prokaryotes important?
Some modern prokaryotes live in environments similar to those in the early Earth; The metabolism of these groups may be similar to the metabolism of ancient groups
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Nutritional diversity in modern prokaryotes
Photo-autotroph (Light + CO2)
Chemo-heterotroph (Organic compounds)
The two below are only in prokaryotes:
Chemo-autotroph (Inorganic chemicals + CO2)
Photo-heterotroph (Light + Organic compounds)
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Respiratory diversity in modern prokaryotes
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Obligate anaeroby (Fermentation/anaerobic respiration)
Facultative anaeroby (O2 if present, or fermentation)
Obligate aeroby (Always O2)
```
47
The first organisms- chemoheterotrophs?
Could have 'eaten' ATP,With depletion of ATP in environment, selection for ability to make ATP; The Evolution of glycolysis occured early, which is further evidence
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The first organisms- hemoautotrophs?
May have oxidised H2S and reduced forms of iron found at Deep-sea vents that were more abundant on early Earth
49
The evolution of photosynthesis
Chemotrophy -> Phototrophy
Likely scenario:
Non-oxygen-producing
photosynthesis->Oxygen-producing photosynthesis
50
Non-oxygenic photosynthesis
Occurs in green and purple sulfur bacteria from anoxic swamps;
H2S and light, gives S2??, ATP, NADH
51
Oxygenic photosynthesis
Occurs in cyanobacteria;
| H2O and light, gives )2, ATP, NADPH
52
Proof oxygenic photosynthesis arose early
2.7 by-old banded iron formations indicate increased atmospheric O2; 3.5 by-old stromatolites = photosynthetic cyanobacteria
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Stromatolites
Cyanobacteria trap sediment, form calcium carbonate mounds; Added oxygen to Precambrian atmosphere (ex Shark Bay)
54
The danger of oxygen
Oxygen can produce highly reactive, short-lived ‘free radicals’; Free radicals inhibit enzymes and damage cells; Probably drove many prokaryotes extinct
55
Adaptations from the appearance of oxygen-- free radicals
Natural selection favoured forms capable of detoxifying oxygen free radicals-- Evolution of protective enzymes and molecules (Vitamins A, C, E, Peroxidases, Carotenoids in plant chloroplasts)
56
Adaptations from the appearance of oxygen-- oxidizing power
Natural selection favoured forms capable of harnessing the oxidizing power of oxygen-- Evolution of aerobic respiration (Evidence: Living purple non-sulfur bacteria use the same ETC for photosynthesis and aerobic respiration)
57
The Evolution of metabolism by natural selection
1. Variation in metabolic pathways
2. Variation heritable (As the environment changes, selection pressures change, modifying existing metabolic pathways in a step-by-step fashion)
3. Some pathway modifications increased the fitness of the organism displaying them
58
Fossil record
Includes:
| partial or complete remains (e.g., bones, shells); traces (e.g., footprints, ‘shadows’)
59
Why is fossil preservation biased?
hard vs soft parts; abundant vs rare species; long-lived vs short-lived species; size of geographical range
60
When did Multicellularity arise?
~ 2 bya – Unicellular eukaryotic organisms;
1.2 bya – Oldest known fossils of multicellular organisms (small algae that already showed some adaptations including different sexes)
61
How did multicellularity begin? Symbiosis
Two different species- how to incorporate the genomes of two species into one
62
How did multicellularity begin? Cellularisation
ie. incorporating mitochondria/chloroplasts in a cell
| no known example
63
How did multicellularity begin? Coloniality
All of the same species. Ex. Many colonial protists, some with cell specialisation such as slime molds
64
What is an animal?
1. Multicellular
2. Heterotrophic
3. Eukaryotic
4. Structural proteins (e.g. collagen), nerve and muscle cells
5. Unique sequence of development, regulated by Hox genes
65
Ediacaran fauna
| ~544 mya!
Earliest known complex multicellular organisms; Can be fond-like, disk-like, or segmented; Lived 610-542 mya; ‘Discovered’ in 1947 in Ediacara Hills; Occur around the world
66
Ediacaran fauna legacy
What happened to them? DId they die out by predation, competition, change in environment? Did they die without descendants or are they ancestral to modern animal phyla? Were they really animals?
67
The Cambrian explosion 535-525 mya
Modern animal phyla appear in the fossil record suddenly, dramatically, simultaneously; All major body plans; Hard body parts; All 35 living phyla
(+ a few more)
68
Burgess Shale – 520-515 mya
Animals include: Gorgonians, sponges
Marella, Ottia, trilobite, Anomalocaris (1m long!), Pikaia (ancestor of vertebrates?)
Wiwaxia (snitch like creature)
69
Why did animal life appear so suddenly?
Threshold oxygen levels crossed; Nutrient levels may have risen, increasing primary productivity and therefore consumer productivity (O2 would have allowed higher metabolism, so larger bodies.)
70
Why did animals diversify so quickly? Ecological causes
New niches arose with evolution of animals; Predation led to selection for increased size
71
Why did animals diversify so quickly? Geological causes
Active metabolism possible with oxygen availability opened new ways of life; Supportive collagen can only be formed in presence of oxygen
72
Why did animals diversify so quickly? Genetic causes
Evolution of Hox complex led to variation in morphology; Early animal genomes were simple and thus easily modified
73
Why did animals diversify so quickly? Climatic causes
Series of freeze-thaw cycles preceded the Cambrian explosion = Snowball Earth hypothesis
74
Alternative: Cambrian animals did NOT diversify quickly
“The Cambrian explosion had a long fuse…”
Chengjian site – 10 my older than Burgess Shale, includes all major animal groups
Molecular clocks suggest most animal phyla diverged >600 mya
Perhaps animals diversified gradually before the Cambrian but were suddenly preserved in the fossil record during the Cambrian
75
What is a land plant?
Multicellular, eukaryotic, autotrophic (P/RBC Algae)
Cellulose in cell walls (P/BC Algae)
Chloroplasts with chlorophyll a b (P/G Algae)
76
Green algae
Chlorophytes- Mostly freshwater, some marine
| Charophytes- All freshwater, Indicators of good water quality
77
Shared features of Charophytes & land plants
Cell wall composition; Cytokinesis; biochemistry; sperm ultrastructure
Suggests close relationship between the two groups
78
Land plant origins
DNA comparisons identify charophytes as closest relatives of land plants; The two groups diverged ~475 mya
79
Characteristics of land plants reflect:
Evolutionary origin of plants from ancestral algae (= ancestral traits); Adaptation of plants to a terrestrial environment (= derived traits)
80
What are the problems faced by land plants?
Desiccation; support; reproduction and development; coping with environmental fluctutations
81
Derived traits of all land plants
Alternation of generations and multicellular embryo develops within the mother plant; Walled spores (with sporopollenin) produced in multicellular sporangia; Gametes produced in multicellular gametangia; Growth of shoots and roots (apical meristems)
82
Alternation of generations
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Gametophyte = multicellular adult with haploid cells that produce gametes by mitosis
Sporophyte = multicellular adult with diploid cells that produce spores by meiosis
```
83
embryophytes
Land plants- refers to their shared derived trait of multicellular, dependent sporophyte embryos on gametophytes
84
Other adaptations to life on land for some plants
Waterproof cuticle to prevent water loss; stomata (exchange of O2 and CO2, prevent moisture loss); Vascuar tissues (Xylem/ phloem); Secondary compounds to protect agaisnt herbivores, UV, pathogens
85
Adaptations of Bryophytes ~475 mya
Include Liverworts, hornworts, and mosses;
Non-vascular plants;
Key adaptations: the 4 derived traits of plants; a waxy cuticle to reduce water loss; stomata to allow exchange of CO2 and O2 (Not present in liverworts)
86
Constraints of Bryophytes
Height: No vascular system, no true roots, no true leaves, Water and nutrients transported by diffusion
Moist environments: Flagellated sperm must swim to egg through a film of water
87
Seedless vascular plants ~420 mya
Ferns, club mosses, and horsetails;
Key adaptation: vascular tissue (xylem & phloem)- Allows for efficient transport of water, nutrients, and sugars, Provides structural support, Reduces height constraint
Also, dominant sporophyte
88
What is the consequence of taller plants being better competitors (from evolution of seedless vascular plants)?
Increased vegetation, Increased photosynthetic activity caused a decrease in atmospheric CO2
89
Constraint of seedless vascular plants
Periodically moist environments- Flagellated sperm must swim to egg through a film of water
90
Gymnosperms ~360 mya
Conifers, ginkgos, cycads, and gnetophytes
Key adaptations: seed- New sporophyte embryo protected in a protective coating with nutrients; Allows for interruption of lifecycle (until conditions are good)
pollen– Male gametophyte protected by spore coat, Sperm travels in pollen, by wind: no need for water
91
Angiosperms ~142 mya
Flowering plants
Key adaptation: flower- Vector pollination increases reproductive success, More economical, Effective even at low population density, Co-evolution of plants and pollinators
Fruit- dispersal of seeds by animal movement
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Fungus
```
Multicellular, eukaryotic, heterotophic (=not a plant)
Absorptive nutrition (=not an animal, the distinguishing feature of fungi)
```
93
Fungal origins
Oldest fungal spore fossils are 460 my old, right after land plants appeared ~ 475 mya.
This is not a coincidence! --Mycorrhizae
94
Mycorrhizae (‘fungus-root’)
Mutualistic association between fungal hyphae and plant root; Fungal hyphae absorb water and minerals better than plant, so plant exchanges sugars for water and nutrients
95
Taxonomy
The science of classification; Naming and organising species into related groups based on similarity of features
96
Linnaean classification
Made life simple by giving binomial names: Genus species
species-Genus-Family-Order-Class-Phylum-Kingdom-Domain
But often reveals little about evolution
97
Phylogenetics
The study of the evolutionary history of related groups of organisms; Organisms are grouped into taxa based on SHARED CHARACTERISTICS that result FROM COMMON ANCESTRY
98
phylogenetic tree
represents a hypothesis about the evolutionary relationships among species or higher taxa
Uses the fossil record, and similarities of anatomy, development, proteins and DNA, when due to homology
99
Sister taxa
Species that share an immediate common ancestor on a phylogenetic tree
100
Node
Represents the common ANCESTOR of all the species branching from the node
101
Rooted phylogenetic tree
has at its base the common ancestor of all taxa shown on that tree
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Derived character
Traits that are shared by a group of related organisms, but not found in their ancestors (have been modified from the ancestral form)
103
Ancestral character
Traits that are shared by a group of related organisms and their ancestor (arose early in the evolutionary history of a taxon)
104
Homologous
Similar traits resulting from shared ancestry
| ex. the forelimbs of vertebrates
105
Analogous
Similar traits resulting from convergent evolution and NOT from shared ancestry
ex. dolphin and Ichthyosaur
106
Monophyletic group (clades)
a common ancestor + ALL of its descendents
| ex. Superorder Cetartiodactyla (deer/whales/hippos/pigs/camels)
107
Paraphyletic group
a common ancestor + some but not all of its descendents ex. Artiodactyls (deer/pigs/hippos/camels NOT whales)
108
Polyphyletic group
all or some of the descendents of two or more ancestors ex. Suborder Suiformes (peccary/pigs/hippos which are more related to whales)
109
Ecology (oikos = home, logos = to study)
The study of interactions between organisms and their environment; Major ecological questions:
•What limits species distribution?
•What determines species abundance?
•What controls species diversity?
•How does energy flow through the environment?
110
The biotic and abiotic environment
Biotic: All the living things that an organism deals with, including members of its own & other species
Abiotic: The physical and chemical features of the environment (water, salt, sun, rocks and soil, temperature)
111
The scope of Ecology
Earth, Ecosystems (Ecosystem ecology), Communities (Community ecology), Populations (Population ecology), Organisms (Organismal ecology)
112
Organismal ecology
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Study of interactions of individual organisms with their abiotic environment
Study Structure (Evolutionary ecology),Physiology (Physiological ecology), Behaviour ( Behavioural ecology)
```
113
Population ecology
Study of the factors that effect population size and composition
114
Community ecology
Study of how the interactions among species affect community structure and organisation
115
Ecosystem ecology
Study of the effect of abiotic factors on community structure
116
Ecosystem
All communities in an area and their physical (abiotic) environment
117
Landscape ecology
Study of interactions among ecosystems, the axchanges of energy, materials and organisms
118
Why ecology is important?
It provides a scientific context for evaluating environmental issues
Know the difference between ecology vs environmentalism
119
Conservation ecology
Managing harmful, invasive species
| Finding the consequences of killing certain species in an ecosystem (ie. top predators)
120
How do ecologists tackle questions about distribution?
Dispersal limits distribution? (Area inaccessible/insufficient time); Behaviour? (Habitat selection); Biotic factors? (Predation, parasitism, competition, disease) Abiotic factors? (Chemical: water, oxygen, salinity, pH, soil nutrients- or Physical: Temperature, light, soil structure, fire, moisture)
121
Dispersal
Movement of individuals away from centres of high population density or from their area of origin
122
Ecological methods
The role of an ecologist is to detect natural patterns, to explain processes that underlie them, and to generalize these explanations.
Observations, Experiments, Predictions
123
What is a population?
A set of individuals of one species living in a given area, using common resources, coping with similar environmental factors, and interacting with one another and with their environment
124
Characteristics of populations
Size & density; Sex ratio; Gene frequencies; Distribution
125
Population dynamics
Changes in population size and density over space and time; Based on what individuals do; Need info on life history
126
Life histories
Scheduled events in an organism's life
| Age of first reproduction; Number of young; Number of reproductive events; Life span; Mortality
127
You can think of life histories coming in packages. Describe "Package A"- Die young
Breed young; Many small babies; Breed often;
| Small body size); (Little parental care
128
You can think of life histories coming in packages. Describe "Package B"- Die old
Breed late; Few large babies; Breed rarely;
| Large body size); (Long parental care
129
"Energy Pies" describe the facts that
An organism’s resources are finite, maintenance is a fixed so there is a trade-offs between growth and reproduction (large body, few young or small body and many young)
130
What determines population size (N)?
Population gains = B and Population losses = D
Assuming immigration=emigration
Comparing births and deaths gives the change in N
131
Per capita rate of increase
b-m, where b=births/individuals and m=deaths/individual
| r greater than 0 means population grows
132
If r is stable, greater than 0...
you get exponential growth, if at the maximum rate it is r-max
133
Carrying capacity
k = Maximum number of individuals that a
particular environment can support
A good environment has high k, a poor environment has low k
134
As N approaches K
r decreases, either from b decreasing, m increasing or both
135
Proportion of the carrying capacity still available for population growth
Given by (K-N)/K
A small N is ~1
A large N near K is ~0
An intermediate N is ~0.5
136
Logistic growth
Given by Nr-max(K-N)/K
| this is the absolute # of individuals added. The number will be small for extreme N, quite large for intermediate N
137
Graph of logistic growth
population vs. time
| Includes establishment phase, boom phase, stabilisation phase
138
Factors affecting r
Limitations on available space; Increased predation; Increased disease; Decreased food availability; Changes in behaviour: Reduced reproduction or Increased emigration
139
Community
Assemblage of populations of various species inhabiting a common environment and interacting with one another
140
Name the 7 interspecific interactions
Competition, predation, herbivory, parasitsm, mutualism, commensalism, disease
141
Competition (-/-)
Interaction between organisms using the same limiting resource (e.g. food, water, light, nesting sites)
Negative effects of competition: reduced growth, reduced reproduction, local exclusion
142
Competitive exclusion principle
Two species competing for the same limiting resource cannot co-exist, restated as:
Two species cannot coexist in a community if they share an identical niche
143
Niche
The ecological role played by a species in a community; The sum total of the organism’s use of biotic and abiotic resources in its environment
Includes: physical limits (temp), nature and amount of food sources, patterns and timing of activities, type of microhabitat
144
Explain "Selection to be different"
Resource partitioning; Realised niche is narrower than fundamental niche
Example, warbler species live on different parts of a tree
145
Predation & herbivory (+/-)
Eating of live prey. Effects: availability of prey is a major determinant of k of predators; Selective predation can alter population structure or life histories of prey; Non-consumptive effects: the ecology of fear
146
The ecology of fear
ex. in yellowstone park, loss of wolves meant elk browsed unimpeded, decreased amounts of vegetation, beaver disappeared, wetlands disappeared. Reintroducing wolves scared elk back into woods, plants regrew, beavers returned, wetlands returned
147
Predator-prey coevolution
Gave predators poison, claws, teeth. Prey developed camouflage, warning colours, spines, plants had poisons
148
Mutualism (+/+)
Symbiotic interaction between two species that benefits both species; Effects on communities: Increase species diversity, Increase distribution range
149
Commensalism (+/0)
Symbiotic interaction between species that benefits only one of the species; Unclear effects on communities. Often when studied, it is found the 0 organism is effected in some way
150
Parasitism/disease (+/-)
Symbiotic interaction in which the parasite or pathogen benefit from living on or in a host that is harmed by the association; reduce host survival/reproduction/density. Major effect on r
151
Parasites (vs. pathogens)
```
Large, multicellular
Live on or in host
‘Steal’ nutrients from host
Usually non-lethal
ex. brown-headed cowbird
```
152
Pathogens (vs. parasites)
Often unicellular
Live in host
Use host to reproduce
Often lethal
153
Food chains
Primary producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers
154
Food webs
Still a simplified version of real life, but good for asking:
What happens when you lose a species? What happens when you add a species?
155
Not all species are equal: Dominant species
Most abundant species in a food web OR Species with highest biomass. expect extinction with loss of dominant species
156
Keystone species
Species that has an influence on community structure that is out of proportion with its abundance; Disappearance can trigger ecological ‘meltdowns’ ex. otters-urchin-kelp relationship
157
Foundation species
Species that exert significant physical change to their environment; Can act as facilitators for other species. Ex. coral, which creates the foundation of the ecosystem. Beavers is another
158
What controls community structure?
May be a top-down processes (predation) or a bottom up processes (nutrient limitation, primary productivity). Experiments will show which is true for the individual community
159
Biomediation
???
160
Ecosystem
All organisms living in a community as well as all the abiotic factors with which they interact. An open system. Can be any size.
161
Ecosystem ecologist’s view of the world
Biogeochemistry (nutrients); Energy (nutrients into life); Organisms (the result of
nutrient-energy interaction)
162
Energy flows, nutrients cycle
energy from sun is lost at every point as heat, with little energy moving to the next
nutrients cycle through the entire thing, as they do not leave the atmosphere
163
Energy flow: Primary production
Amount of light energy converted to chemical energy by autotrophs during a given time period; Primary producers create 150 billion metric tons of organic material each year, from ~ 1% of sun energy that reaches Earth
164
Net primary production =
(Amount of light energy converted to chemical energy per unit time) subtracting (Amount of chemical energy used by autotrophs in respiration)
*** NEW biomass produced
165
What is NPP measure in?
Joules/m2/year or grams/m2/year
166
Which ecosystems are important for NPP
Open ocean- large % of Earth's NPP because of the amount of open ocean
Tropical rain forest- high individual NPP and high %
Reefs- low %, but the highest individual NPP
167
What controls primary production?
Light limitation; Nutrient limitation (nitrogen on land, phosphorus in lakes, iron in the sea)
168
Energy flow: Secondary production
The amount of chemical energy in consumers’ food that is converted to new biomass during a given time period
169
Production efficiency
Energy used for growth and reproduction (net secondary)/Total NRG taken in used for growth, reproduction & respiration(assimilation of primary ie. through respiration, energy is lost to the organism)
170
Trophic efficiency
Proportion of production passing from one trophic level to the next
ie. 10% flower to deer, 10% deer to wolf, 1% flower to wolf
171
Trophic (in)efficiency
Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass.
172
Ecological pyramids
Can be for production, biomass, or numbers- they all have similar shape. There is a limited amount of enery at the top, which constrains the possible number of levels (quaternary is the most!). Trophic inefficiency is what causes few large carnivores.
173
Nutrient (re)cycling
By detrivores and decomposers- consumers that get their energy from detritus, nonliving organic matter
174
Nutrient cycling- Biogeochemical cycles
Can be on a global scale (C, O2, S, N cycling) or a local scale (P, K, Ca normally stay within an ecosystem)
175
Assimilation
N used to form proteins and nucleic acids
176
Ammonification
N returned to soil
177
Nitrification
Conversion of ammonium to nitrate (NH4 to NO2 to NO3)
178
Denitrification
Return of N to atmosphere (under anaerobic conditions)
179
Human impacts on nutrient cycles
Atmospheric nitrous oxide, acid rain, catalyze breakdown of O3, reduction in spp diversity, eutrophication, algal blooms, fish kills, drinking water contamination
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Endosymbiosis
Smaller prokaryotes began living in larger ceslls, eventually becoming a single organism-- the first eukaryotes?
181
Nitrogen fixation
Converting N2 to NH3
182
Heterocytes
Specialized cells in a colony of cyanobacteria that do nitrogen fixation while the others in the colony perform photosynthesis
183
Microphylls and Megaphylls
Branching in leaves of vascular plants (micro is one branch, mega is highly branched
184
Polytomy
A branch point from which more than two descendant groups emerge
185
Semelparity
a single reproductive opportunity in the life of an organism before it dies (ie. salmon)
186
Iteroparity
repeated reproduction
187
K-selection
ex. mature trees growing in an old-growth forest shows that life-history is sensitive to the population density
188
r-selection
found in disturbed habitats, where r is maximized because N is well below K
189
Competitive exclusion
A slight reproductive advantage will eventually lead to local elimination of the inferior competitor when the two are fighting for the same resource.
190
Resource partitioning
the differentiation of niches that enables similar species to coexist in a community
191
Character displacement
ie. the beaks of the finches
the tendancy for characteristics to diverge in sympatric populations of two species to be able to use different resources
192
allopatric
geographically separate
193
Sympatric
geographically overlapping
194
Cryptic coloration
Camouflage
195
Aposematic coloration
Warning coloration, that often use chemical or physical defenses
196
Batesian mimicry
a harmless species mimics a harmful or unpalatable one
197
Mullerian mimicry
two unpalatable species resemble each other
198
The green world hypothesis
Terrestrial herbivores are held in check by a variety of factors, which accounts for the fact that less than one sixth of NPP is consumed
199
Facilitation (+/+)
Having positive effects on the survival and reproduction of other species without living in direct or intimate contact
200
Symbiosis
When individuals of two or more species live in direct and intimate contact with one another
