Bio 200 Lecture Final New Material:
Define ecology: Context of evolution, evolution in the current moment. The study of distribution and abundance of organisms; How organisms interact with the environment, each other, and where we find species. How is ecology related to evolution? Context of evolution, evolution in the current moment. Example being the Galapagos finches, evolution into 13 different species. Ecological factors of now shape the evolution of the future. Abiotic: Nonliving, sun, wind, rain, etc.
Three factors that influence climate: Variation in light intensity, latitude, and variation in local conditions.
Intensity of sunlight on Earth varies: Because the earth is spherical the area of the earth hit by a single beam of sunlight is smaller and more concentrated than it would be than the same area closer to pole. Angle of the sun’s rays = higher at the equator. Same amount of sunlight is more concentrated and a shorter distance, hotter at equator, cooler at the poles. Effect of light intensity on temperature: the light also had to take a shorter path through atmosphere to equator than the poles. The more atmosphere around earth reflects light and reradiates some back into space the more atmosphere you travel through he less light energy will reach the earth to warm it.
Effect of light intensity on rain: Wetness is due to intense sunlight that hits right at the equator. Air is heated at the equator, the hot air rises, spreads to North and South of the equator, cools as it rises (less efficient water holding) condenses and forms belts of rain, cold dry air sinks. Hadley Circulation: Repeats around the earth, Hadley cells, loops of rising and cooling air. Secondary cell, the warm air (dry) stays down until it picks up water and rises again. Climate pattern is belts of temperate forests. Hadley Cells: Loops of rising and cooling air. If you want to learn more check out What is the gold standard method for measuring body composition?
Main effects of rising and sinking air streams: Rising air = rain, sinking air = deserts.
Distribution of rain forests: Right at the equator and areas north and south of the equator.
Distribution of deserts:
Distribution of temperate forests: Right above band of deserts. Polar deserts: dry, lacking sunlight.
What causes the seasons? The angle of earth, 23.5°, profound climate implications.
Topography or terrain:
a. Slope: Individual slopes can have micro climates that affects that organisms that live on them. If a slope is steep and has soil that drains well the slope might be continuously dry, requiring plants living there must be drought resistant. The base of the slope water gathers easily saturating soil, the plants at base of slope might have to be flood If you want to learn more check out What changes about the brain occur during senescence?
We also discuss several other topics like What are the 7 steps in the rational/classical model?
tolerant. Only the area that has enough water for trees to grow in the slope heavy region is in the valley between the steep slopes where water can gather. While its winter here on the grassy slope, the plants are dry. The grasses that grow at base of slope and are much bigger and lusher than those the grasses that grow on the steep slopes. water can gather better at base, even if moisture level is not different at different points at slope If you want to learn more check out What are the five stages of lytic cycle?
b. Orientation to other features: orientation of the slope can be critical for a habitat distinction on slope. south facing slopes receive more sunlight which warms and dries the slope. the vegetation on the Southside is lower and more drought resistant the south slope s a grass land. The north facing slope is covered in woodland. Moist habitat, woodland requires more aster to grow.
c. Elevation: Elevation affects temperature, leads to adiabatic cooling. For every 1000 m of elevation, you lose 6-10°C Hawaiian silvers ward. Can be ice encrusted, local conditions matter, can have amazing effects on climate that you see Don't forget about the age old question of How is ph important to living organisms?
Factors that lead to variation in climate:
a. Rain in the southern hemisphere: At any given gen latitude, there is more rainfall in the southern hemisphere than the northern. 81% of the southern hemisphere is water.
b. Rain Shadows: Coastal mountains cause rain shadows, wind can’t go through it, atmospheric pressure releases and it rains, lush vegetation grows. Once over the mountain, air heats as it condenses downward to the leeward side, very dry. We also discuss several other topics like What is the function of protein?
c. Slope and local drought: Steep slopes can be dry, but water may gather at the bottom.
d. North-vs. south-facing slopes: Northern facing slope has less sunlight and woodland while the south side is dry.
e. Elevation and temperature: Elevation affects temperature, at higher elevations air expands because of lowering atmospheric pressure. Adiabatic cooling is the process of lowering temperatures as elevation increases.
f. Lake effect snow: Water is warmer then air, higher specific heat. The cold air over the warm water picks up water vapor and freezes in cold air, deposits as snow. The lake effect reverses in the summer therefore not a lot of rain.
Adiabatic cooling: Adiabatic cooling is the process of lowering temperatures as elevation increases.
Less predictable global effects on climate:
a. El Nino: Flow of water reverses and warm water piles up on coast of South America.
b. La Nina: Much stronger normal pattern is observed, cold water current reaches further across the Pacific Ocean, lowering ocean temperatures.
c. Pacific decadal oscillation (PDO): Shifts in surface
temperature that lasts for 20-30 years.
Stochasity: Not everything is predictable.
Convergence in traits and habitats: Convergence traits are important because they explain the patterns we find. Example is the honey eater and hummingbird. Convergence is found at all levels on the tree of life. Convergence in habitats explains why a habitat is recognizable to use even if the plants found in the habitat differ radially. Singapore and Costa Rica. Biomes: Defined by temperature and rainfall, dictate the assemblage of species types that are likely to be found in a certain area.
What two main factors define a biome? Temperature and precipitation. Whittaker plots and ways to interpret them: When plotted, most of earths habitats fall into a triangular pattern, Warm and moist, warm and dry, and cold and dry.
Other factors that determine what biome is found in a certain area: Tundra: arctic and high elevations, lower latitudes. Vegetation is low growing plants, permafrost. Growth of plans with shallow root structures, short life cycles, growing season soil is damp. Alpine has no permafrost. Boreal Forest (Taiga): Long cold winter, short summer that can be very warm, no permafrost, big plants, coniferous evergreens in north, predominately evergreen southern beach trees.
Temperate deciduous forest: Northern hemisphere, drastic temperature changes. Constant rain, deciduous trees, and photosynthesize during the summer.
Temperate grassland: Very dry for part of year (winter plains or summer coastal), vegetation grass intensive, herbaceous plants, have to be adapted to grazing and fire, extensive root system.
Hot desert: Least precipitation compared to any other biome, rains in the summer (summer monsoon). Few areas get nearly no rain such as Sahara and anterior of Australia. Cacti store water.
Cold desert: Much more rain then hot desert, extremely cold in the winter. Limited flora, low numbers of species, low growing shrubs. Tropical evergreen forest: Highest productivity (production of biomass), a lot of rain, nutrient poor soils, and epiphytes, plants without true roots and must grow on other plants.
Why don’t biome boundaries exactly match species range boundaries? Most species can cross biome boundaries and most animals and plants are not found throughout an entire biome.
Niche: entire range of resources a species needs to survive. Factors that might be important to a niche: Food size and temperature. Niche partitioning: How organisms use resources and coexist, differentially partition their niches, similar enough though that no resources go to waste. Niche packing: How many separate niches can you fit in a given environment, some resources not even used.
Factors affecting density of niche packing:
Fundamental Niche vs: Realized Niche: Fundamental is an entire area a species could survive in while realized is the area a species actually inhabits. This tells us about amount of competition.
MacArthur’s Warblers: How they managed to coexist, forage in different areas. 5 species of birds living in the same forest inside spruce trees. People to know
∙ Robert Whittaker
∙ Joseph Connell
∙ Robert MacArthur
Organisms to know
∙ Cactus and Euphorbia (member of the Poinsettia family) ∙ Honeyeater and Hummingbird
∙ Chthamalus and Semibalanus barnacles
Types of species interactions:
a. Competition: When two or more species need the same resource -/- b. Predation: When one species eats another, +/-
c. Symbioses: When two or more organisms interact in more or less permanent relationships
1. Parasitism: +,-
2. Mutualism: +,+
3. Commensalism: +,0
4. Ammensalism: -,0
Why is competition hard to “see”?: Not organized
The Ghost of Competition Past: Looking for the evidence that competition used to occur and that’s what forced the organisms to change How do you study competition?
a. Experiments: 1917 Sir Arthur George Tansley
b. Comparisons of sympatric and allopatric populations: Together they do bad, alone they do well.
Exploitation and interference competition: One species lowers resources of another, and one prevents the other from gaining access. Interspecific vs. Intraspecific: Inter=within, Intra=among Resources: Anything one needs to consume to support survival and reproduce.
Resource partitioning: Coexisting with resources.
Temporal partitioning: Similar life style, when together they do things differently in order to survive.
Character displacement: Limiting competition by behavior. Intraspecific competition can lead to less interspecific competition: Allows multiple species to co-exist
Predation can limit competition: Grazers=flowers, allows growth. Disturbance can limit competition: Natural events that lower the population in certain aspects.
Intermediate disturbance theory: Leads to highest diversity. Competitive exclusion: One may adapt better, sympatric species live close while allopatric live apart.
People to know
∙ Arthur Tansley
∙ G.A. Gause
Organisms to know
∙ Galium Saxatile and Pumilum
∙ Bufo woodhousii and Hyla crucifer
∙ Hydrobia sp. (mud snails)
∙ Paramecium caudatum, Aurelia, and bursaria.
a. True predators: all organisms have to eat something, not all consumption is by true predators. Lions who eat water buffalo as well as parasites
b. Parasitism: Do not kill prey, not immediate death, consume parts of still living organisms by attaching themselves or invading the hosts body.
c. Herbivores: whole plants (true predators) part (plant parasites) grazers = grass, woody = browsers.
d. Detrivores: eat already dead things, no negative impact on prey. Extinction via predation: Predators can eliminate their prey species. Example being the Didinium and Paramecium, didinium will eat it all, but then die due to a lack of food source. Mutual elimination, doesn’t happen in nature. Both populations will drop but not go extinct.
Predators lower prey abundance: Complete extinction of prey or predator is not normal. Predators lower the abundance of prey species, lowering the number of prey is the main effect of predation. Keeps species and competition under control.
Predators can restrict prey distribution: Also prey ranges, Australian megapods live east to Wallace’s line, limited to areas. Do not exist is any area where Asian predator’s mammals live.
Predator/prey cycling: Interaction between predators and prey, as one goes up other goes down and vice versa. Example being the snow shoe hair and lynx.
Methods of predator and prey coexistence:
a. Refuges: Give prey relief/hiding from predators.
b. Cycling: Limits effects of strong predation.
c. Predators at low abundance: Predators kept down by other factors. d. Generalist Predators: Multiple prey sources, exist with variety. Prey Evolve Defenses:
a. Crypsis: Hiding in plain sight but disguising well.
b. Chemical Defense: Bombardier beetle sprays an extremely hot liquid.
c. Toxicity: Nudibranchs warn potential predators, warning colorations. d. Armor: Avoid predation because effective, not easy to get to if covered in spines or shell.
e. Behavioral defense: alarm calling is when a predator is sighted, a member makes a loud noise to point him out, therefore the predator can’t sneak up on prey now. Distraction displays are used to confuse predators, such as parents fly away from nest and look hurt to distract predator from babies. Fleeing is used by many species. Herds are one of the most common because predators are less likely to attack a group rather than individuals.
f. Predator satiation: Timing of reproduction, since there are so many, predators can’t get to them all. Fullness or faciated.
Cryptic Coloration: Blending in so you are not seen, disguising yourself well.
Object Mimicry: Trying to look like another non-edible object. Aposematic coloration: Type of warning, avoid these animals. Batesian Mimicry: Nonpoisonous but tries to look poisonous. Mullerian Mimicry: Mimics are both poisonous, but try to mimic each other. Difficult to tell a difference.
How do sessile organisms avoid predation? They use toxicity and armor, as well as aposematic coloration.
How do predators respond to prey defense?
a. Search Images: Find them easily when they’re hidden. b. Avoid/use Toxins: Nudibranchs make use of toxins, lower own risk, attack snakes from behind
c. Get past armor: Tiny feet of bird rest between cactus spines, goat just chews through.
Types of hunting:
a. Ambush: wait until prey arrives, little energy.
b. Stalking: look for prey, dive+eat, or dive+miss.
c. Pursuit: know where prey is, long chase.
Who would you expect to hunt in each way?
Organisms to know
∙ Paramecium and Didinium
∙ Klamath weed and Chrysolina beetle
∙ Lynx and Snowshoe hare
∙ Monarch and Viceroy butterflies
∙ Vine Snake
Coevolution: Species evolve due to interactions with another species.
Symbioses: When two or more organisms interact in more or less permanent relationships.
Types of Symbioses:
a. Parasitism: Long term interaction, benefits one and harms the other. b. Mutualism: Beneficial to both, not detrimental.
c. Commensalism: Transport and housing relationships, one benefits while the other is unaffected
d. Ammensalism: One is harmed, other does not benefit, typically accidents come up in complexities.
Examples of ectoparasites: External parasites, such as fleas, ticks, mistletoe.
Examples of endoparasites: Internal parasites, such as nematodes, Wolbachia, trypanosomes, Schistoscoma.
Parasites can have complex life cycles: Can lead an easy life, ring worm or round worm, absorb nutrients and form baby worms. But the hosts are continuously developing new ways to destroy parasite and must leave the host to spread the disease, unless transmitted from mother to child. Why does parasite spread often decline? Because in order for microparasite population to persist at least one new host must be infected on average before the previously infected host dies. Overtime the % susceptibility goes down, each new host fall under one of three categories, susceptible, currently infected, and recovered. If most of population is susceptible they would be with a newly introduced infection and as it spreads there will be fewer susceptible hosts available.
Examples of Mutualisms: Cleaner fish and customer fish, honey guides and honey badgers.
Human Mutualisms: Eyelash mite, gut fauna (beneficial intestinal bacteria), cornfield.
Types of Mutualism:
a. Trophic: Baseline, use each other for food and nutrients, ex: gut flora. b. Defensive: Symbiont A depends on B in exchange for something (acacia and ants).
c. Dispersive: Sessile organism and a mobile one (like pollinators and plants).
Examples of commensalisms and ammensalisms: Damsel fly, Epiphytic orchids and plants that grow near watering hole in Africa typically get trampled by visiting animals.
Species relationships can change over time: Can be hard to tell what types of relationships are occurring, Polo Verdi tree. Sovaro may not survive without the polo Verdi shade, relationship changes when sovaro grows and now becomes competitor.
Species relationships may be unclear: Ox pecker birds, they peck off insects from the antelopes. Unsure of relationship because we don’t know what the costs or benefits are. If the tick and insects are detrimental to
impale its mutualistic. But if the bird is picking at scabs causing infection or blood loss it could be mildly parasitic.
Communities are formed from groups of species interactions: only as stable as its relationship are, African plan, all the relationships build a web of community.
Keystone species: Species interaction can themselves interact. Hold ecosystems together. Anemone mollusks and starfish.
Organisms to know
∙ Indian Pipe
∙ Dicrocoelium dendriticum, ants, and deer
∙ Cleaner fish and customer fish
∙ Honeyguides and honey badgers
∙ Acacia and Pseudomoyrmex ferruginea ants
∙ Tube worms
∙ Saguaro and paloverde
∙ Oxpecker birds
∙ Pisaster (starfish)
Diversity: Species richness and evenness.
Species Richness: The number of species present, increases with area. Evenness: The relative abundance of the species, how evenly represented the species are.
Species Richness and area: Increases with area.
Species Richness and habitat number (environmental heterogeneity): The more types of habitats you include, the more specialized and varied species you will pick up. Has to do with area, environmental heterogeneous geneity. Heterogeneous environments have more niches and more ways to use their environment.
Latitudinal gradient in species diversity: Over very large areas, this pattern has a hiccup, creating an extremely broad pattern of diversity, a global pattern that some people feel is actually the defining trend in ecology. More species in the tropics then the poles. Smooth drop-off as you move away from the equator.
Hypothesis on the gradient:
a. Climate Stability: Seasons are hard to handle.
b. More competition: So many resources can survive with less tight packing.
c. More predation: More species because more predators, illogical, result of increased diversity. Says there are more species in the tropics because there are more species in the tropics.
d. Increased energy (ecological): Increased productivity, plant biomass per unit area, overwintering tolerance, ambient, no energy lost due to death
e. Evolutionary time (evolutionary):
What makes “increased energy” an ecological hypothesis? Shows living from an ecological perspective.
What are the three factors of increased energy that could lead to more species? Temperature, amount of precipitation, and solar radiation. Historical patterns: World was warmer and wetter.
Eocene-Miocene climate shift: Worldwide climate shift, cooling. Climate developed similar to the modern climate. Newer groups pervade temperate zones.
Niche conservation: When organisms fail to adapt when the environment changes (spruce forest).
Evidence for increased energy: The temperature, the sun. Warm in the tropics, warm areas have more solar energy available. Let to the idea of higher species numbers there.
Problems with the energy hypothesis: Strong correlation between richness and AET does not mean that it causes species richness. They co occur but which, if either are causal. So do you get them because there is more energy? No, only 4 ways to get more species.
Support for the evolutionary time hypothesis: Speciation, extinction, immigration.
Which evolutionary force is at work? Do we know for sure? What is he saying that while evolutionary facts might have caused the gradient. It is modern ecologic ecological forces today that maintain it and may change it. After all today’s ecological factors are tomorrows evolutionary ones nothing says gradient is permanent.
Both ecological and evolutionary forces support the gradient: this is why it is important to look at big questions like this form both the perspective of historical processes (historical time) but also present day ones (ecological factors) also why modern climate crisis is of special interest to those who believe in the importance of niche conservationism species aren't always able to cope with change.
People to Know
∙ Bradford Hawkins
Organisms to Know
What is Krakatau an example of? The theory of island biogeography. Basic outlines of the history of Krakatau: Volcanic island between java and sunatra, Indonesia. Erupted over and over again with disastrous consequences. Most violent in modern time.
Rationales for the new inhabitants of Krakatau (ex: why are there a lot of birds?)
The theory of island Biogeography: Explains how plants and animals distribute in a new environment.
Immigration decreases over time: only novel species count in increasing richness
Extinction increases over time: Not likely to compete at first, once more competition, extinction will increase.
Equilibrium species number/S*: equilibrium, when we combine extinction and immigration rates and they balance each other, stable point. Time to equilibrium varies by species group: Curves can be affected by different factors, were not sure.
Island Size: Large islands have a lower extinction rate, large has highest diversity.
Island Isolation: Isolation lowers immigration rate, close to mainland = highest diversity.
Terrestrial Islands: Little islands of natural habitats, destroying our environment.
How are terrestrial islands different than oceanic ones? Relaxation: term for loss of species that occurs after fragmentation. Immigration must be possible to prevent extinction: As more come, less will leave, diversity.
Reserve Design: Large reserves are critical, size matters
Corriders: Critical, need to be between habitat areas, connect to each other. Don’t need to be prime habitat but can’t be so bad that organisms cannot cross. Certain that you have an immigration curve.
Charasmatic megafauna: Tiger vs beetle, things people may change over others.
Specialists: Can thrive only in a narrow range of environmental conditions or has a limited diet.