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Animal behavior and Ecology (Population Ecology (Human population growth,…
Animal behavior and Ecology
Animal Behavior
Discrete sensory inputs can stimulate both simple and complex behavior:
Fixed action patterns: a sequence of unlearned acts directly linked to a simple stimulus
ex: a male stickleback fish attacks other males that invade its nesting territory; the red belly acts a sign stimulus
sign stimulus: a trigger for the behavior is an external cue
Migration: a regular, long distance change in location
ex: a wide variety of birds, fishes, and other animals use environmental cues to guide migration
some migratory animals track their position relative to the sun
ex: migrating birds orient differently relative to the sun at distinct times of the day
Behavioral rhythms
influenced by the periods of daylight and darkness in the environment
ex: some bird species have shown that an artificial environment with extended daylight can induce out of season migratory behavior
can also be linked to the timing of the new and full moon
ex: the male's claw waving courtship behavior
Animal signals and communication
signal: a stimulus transmitted from one organism to another
ex: most terrestrial mammals are nocturnal, they use olfactory and auditory signals
ex: humans use primarily visual and auditory communication
Pheromones: animals that communicate through odors or tastes emit this chemical substance
ex: fruit fly courtship
ex: in a honey bee colony, pheromones produced by the queen and her daughters, the workers, maintain the hive's complex social order
can serve as an alarm signal
Learning establishes specific links between experience and behavior
cross-fostering study: the young of 1 species are placed in the care of adults from another species in the same or a similar environment
learning: the modification of behavior as a result of specific experiences
involves the formation of memories by specific changes in neuronal connectivity
imprinting: the establishment of a long lasting behavioral response to a particular individual or object
can only take place during a specific time period in development called the sensitive period
ex; young gulls imprint on their parents and learn basic behavior, while the parent learns to recognize its offspring
spatial learning: the establishment of a memory that reflects the environment's spatial structure
ex: a wasp returning to its nest by learning its position relatiive to visible landmarks
cognitive map: a representation in an animals nervous system of the spatial relationships between objects in its surroundings
Associative learning: the ability to associate one environmental feature with another
ex: a blue jay ingesting and then vomiting a monarch butterfly, it learned to avoid that species
trial and error learning: an animal first learns to associate one of its behaviors w/ a reward or punishment and then tends to repeat or avoid that behavior
Cognition: the process of knowing that involves awareness, reasoning, recollection, and judgement
ex: a honeybee can distinguish on the basis of same and different
problem solving: the cognitive activity of devising a method to proceed from one state to another in the face of real or apparent obstacles
social learning: when animals learn to solve problems by observing the behavior of others
ex: a young chimpanzee learning to crack oil palm nuts by observing an experienced chimpanzee
Culture: a system of information transfer through social learning or teaching that influences the behavior of individuals in a population
Selection for individual survival and reproductive success can explain diverse behaviors
evolution of foraging behavior:
Foraging: eating, and also any activity an animal uses to search for, recognize, and capture food items
ex: fruit fly; low population density yields sufficient food, while long distance foraging would result in unnecessary energy expenditure
a potential cost for a forager is risk of predation
Mating behavior and mate choice:
Monogamous: one male mating with one female
Ex: western gulls; males and females are hard to distinguish
Polygamous: an individual of one sex mating w/ several of the other
ex: elk; the male is often highly ornamented
intersexual selection: competition between members of one sex for mates
ex: a face off between male stalk eyed flies competent for female attention
mate choice can also be influenced by imprinting
ex: female zebra finch chicks that had imprinted on artificially ornamented fathers preferred ornamented males as adult mates
mate choice copying: a behavior in which individuals in a population copy the mate choice of others
ex: female guppies prefer males that are associated with another female
Genetic analyses and the concept of inclusive fitness provide a basis for studying the evolution of behavior
Genetic basis of behavior:
ex: during courtship, the male fruit fly carries a single gene called fru, which controls the ritual
if the gene is mutated to an inactive form, males don't court or mate w/ females
differences in behavior can also come from variation in the activity or amount of a gene product
ex: male praire voles associated closely w/ their mates and care for their young
antidiuretic hormone (ADH) or vasopressin: is a peptide neurotransmitter that is released during mating
Genetic variation and the evolution of behavior:
variation in prey selection
influenced more by genetics rather than the environment
ex: coastal Gartner snakes prefer banana slugs, even their young's where they lived in a different environment preferred banana slugs
Iclusive fitness:
altruism: to describe a behavior that reduces an animal's individual fitness but increases the fitness of other individual's in the population
ex: a naked mole rat, the queen, is being protected by other males as she is nursing
reciprocal altruism: altruism between unrelated animals
ex: a baboon helping an unrelated companion in a fight
when parents sacrifice their own well being to reproduce, it increases the fitness of the parent
inclusive fitness is the total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables other close relatives to produce offspring
Intro to Ecology & the Biosphere
Earth's climate varies by latitude and season & is changing rapidly
climate varies seasonally and can be modified by factors such as large bodies of water & mountain ranges
Seasonal variation in sunlight intensity:
March equinox: equator faces sun directly, all regions on earth experience 12 hours of daylight & 12 hrs of darkness
June Solstice: northern hemisphere tilts toward sun and has longest day and shortest night; the opposite for Southern Hemisphere
September equinox: equator faces sun directly, all regions on earth experience 12 hrs of daylight & 12 hrs of darkness
December solstice: northern hemisphere tilts away from sun & has shortest day and longest night; opposite for Southern Hemisphere
ocean currents influence climate along the coasts of continents
water is warmed at the equator and flows north and south towards the poles, where it cools
ex: during a hot day, when the land is warmer than the water, air over the land heats up and rises, drawing a cool breeze from the water across the land
mountain influences air flow over land & the amount of sunlight reaching an area
when warm most air approaches a mountain, the air rises and cools, releasing moisture on the windward side of the peak
on the leeward side of the mountain, cooler , dry air descends, absorbing moisture and producing a rain shadow
south-facing slopes in the northern hemisphere receive more sunlight that north facing slopes
Microclimate: localized patterns in climate conditions
casting shade, altering evaporation from soil, or changing wind patterns influence microclimate
Climate change: a directional change to the global climate that lasts 3 decades or more
climate changing by wind and participation patterns are shifting, earth is getting warmer, and extreme weather events are occurring more frequently
climate change affects animals, basically making them move to a different location
some species are facing a shortage of suitable replacement habitat
some species can't migrate quickly enough
The distribution of terrestrial biomes is controlled by climate and disturbance
Biomes: major life zones characterized by vegetation type in terrestrial biomes
mean temperature and precipitation play a role of determining where biomes exist
most terrestrial biomes are named for major physical or climatic features and for their predominant vegetation
The terrestrial biomes:
Tropical forest: near the equator, its precipitation is wet or dry, it's temp is hot, filled with trees and a variety of animals
Desert: located near 30 degrees latitude, has low precipitation, it's hot during the day and cold during the night, cacti is the dominant plant, and has animals such as snakes and scorpions
Savana: near the equator, typically dry, not truly hot, mostly grass and large grazing animals, lions
Chaparral: mid-latitude, has both wet and dry season, has hot summer, has shrubs, deers and reptiles (large variation in animals)
Temperate grassland: located in 30-60 celcius latitude, has dry winter and wet summers, it's temperature varies in a big range, grasses and has large grazing animals and praire animals
Northern coniferous forest: located in northern USA, Eurasia, and all of Canada, it's precipitation varies, has cold temperature, consist of coniferous and moose
Temperate Broadleaf Forest: located in midlatitudes of the northern hemisphere, wet, has deciduous trees, consist of mammals, birds and insects
Tundra: located on top of mountains (arctic), very dry, cold temperature, consist of mosses, shrubs, and large grazing animals
Aquatic biomes are diverse and dynamic system that cover most of Earth
Zonation in Aquatic biomes:
Photic zone: the region where there is sufficient light for photosythesis
Aphotic zone: the region where little light penetrates
Abyssal zone: deep in the aphasic zone; the part of the ocean 2,000-6,000 m below the surface
Benthic zone: the bottom of all aquatic zones, deep or shallow
benthos: the communities of organisms that live in the benthic zone
detritus: a major source of food for many benthic species; dead organic matter; it rains down from the productive surface waters of the photic zone
thermocline: separates the more uniformly warm upper layer from more uniformly cold deeper waters
seasonal turnover causes the lake waters to be well oxygenated at all depths in spring and autumn
in winter & summer, when the lake is stratified by temp, the oxygen concentration decreases with depth
The aquatic biomes:
Lakes:
Physical environment: standing bodies of water range from ponds to lakes, light decreases w/ depth, temp lakes may have a seasonal thermocline
Chemical: differ from lakes and season; oligotrophic lakes tend to be nutrient poor and oxygen rich; eutrophic lakes are nutrient rich and often depleted of oxygen in the deepest zone in the summer
wetlands:
physical environment: inundated by water at least some of the time and that supports plants adapted to water saturated soil
chemical: the water and the soils are low in dissolved oxygen wetlands have a high capacity to filter dissolved nutrients and chemical pollutants
Streams and rivers:
physical environment: the speed and volume of their flow; head water streams are cold, clear, swift; downstream is warmer and more turbid
chemical environment: headwaters are rich in oxygen while downstream may contain substantial oxygen but there has been organic enrichment
Estuaries:
physical environment: transition between river and sea
Chemical environment: salinity varies spatially w/in estuaries and the rise and fall of the tides; nutrients from the river make estuaries
Intertidal zones:
Physical environment: submerged and exposed by the tides; upper zones experience longer exposures to air and greater variations in temp. and salinity
chemical environment: oxygen and nutrient levels are generally high and are renewed w/ each turn of the tides
Oceanic pelagic zone:
physical environment: a vast realm of open blue water constantly mixed by wind driven oceanic currents
chemical: oxygen levels are high; nutrient concentration are lower than in coastal water; turnover between fall and spring renews nutrients in the photic zones of temperate and high latitude ocean areas
Coral reefs:
Physical environment: shallow reef- building corals live in the photic zone with high water clarity, near islands and along the edge of some continents; diverse
chemical environment: corals require high oxygen levels and are excluded by high inputs of fresh water and nutrients
Marine benthic zone:
physical environment: seafloor below the surface waters of the coastal, or neritic zones, and the offshore pelagic zone; water temp declines w/ depth, while pressure increases
chemical environment: except in areas of organic enrichment, oxygen is usually present at sufficient concentrations to support diverse animal life
Interactions between organism and the environment limit the distribution of species
Dispersal: the movement of individuals or gametes away from their area of origin or from centers of high population density
ex: kangaroos have not reached Africa under their own power, birds have because they disperse so rapidly
Biotic factors
other species limit the distribution of a species
the ability of a species to survive and reproduce is reduced by it's interactions w/ other species
ex: predators bc they kill their prey
Abiotic factors:
temperature:
Biological process; cells may rupture if the water they contain freezes and the proteins of most organisms denature at temps above 45 degrees Celsius
climate change has made species alter their geographic ranges
Water and oxygen:
the variation in water availability among habitats
water affects oxygen availability in aquatic environments and in flooded soils, where the slow diffusion of oxygen in water can limit cellular respiration and other processes
Salinity:
the salt concentration of water in the environment affects the water balance of organisms through osmosis
sunlight:
too little sunlight can limit the distribution of photosynthetic species
too much light can also limit the survival of organism
Rocks and soil:
the pH, mineral composition, and physical structure of rocks and soil limit the distribution of plants and thus the animals that feed on them
Population Ecology
Biotic and abiotic factors that affect population density, dispersion, and demographics
Density and dispersion:
the density of a population is the # of individuals per unit are or volume
changes as individuals are added or removed from a population
adding: birth and immigration
removing: death or emigration
dispersion: is the pattern of spacing among individuals w/ the boundaries of the population
Clumped: a pattern of dispersion
ex: sea stars group together where food is abundant
Uniform: another pattern of dispersion
ex: nesting king penguins exhibit nearly uniform spacing, maintained by aggressive interactions between neighbors
random: the position of each individual in a population is independent of other individual
ex: dandelions grow from windblown seeds that land at random and later germinate
survivorship curves: a lot of the proportion or #'s that cohort still alive at each age
type 3: drops sharply at the start; high death rates for the young
ex: sea turtles
type 2: constant death rate over the organisms life span
ex: squirrel
type 1: low death rates during early and middle life, then drops steeply as death rates increase among older age
ex: humans
Reproductive rates:
reproductive output for sexual organisms is typically measured as the average number of female offspring produced by female offspring
The exponential model
exponential population growth: when a population increases in size by a constant proportion at each instant in time
ex: a population whose members all have access to abundant food and are free to reproduce at their physiological capacity
intrinsic rate of increase: the r; refers to per capita rate at which an exponentially growing population increases in size at each instant in time
dN/dt = rN
The logistic model:
Logistic population growth: shows the per capita rate of population growth approaching zero as the population size gets near the carrying capacity
carrying capacity (K): the maximum population size that a particular environment can sustain
ex: carrying capacity for bats may be high in habitat w/ abundant flying insects but lower where is abundant food but fewer suitable shelters
dN/dt = rN (K-N)/ K
Important in conservation biology for predicting how rapidly a particular population might increase in numbers after it has been reduced to a small size
Life history traits are products of natural selection
Life history: the traits that affect an organism's schedule of reproduction and survival
when reproduction begins
ex: a loggerhead turtle is about 30 years old when it lays it eggs
how often they reproduce
ex: the coho salmon ungergo a one shot pattern of Big Bang reproduction (semelparity); reproduce one time
Interoparity: repeated reproduction
how many offsprings they produce
ex: white rhino produce a single calf
K-selection: selection of traits that are advantageous at high densities
r-selection: selection for traits that maximize reproductive success in uncrowded environments
Density- dependent factors regulate population growth
Density independent: a birth rate or death rate that does not change w/ population density
ex: the mortality of dune fescue grass is mainly due to physical factors that kill similar proportions of a local population
density dependent: a death rate that increases w/ population density or a birth rate that falls w/ rising density
ex: dune fescue declines as population density increases, in part bc water or nutrients become more scarce
competition for resources: increasing population density intensities competition for nutrients and other resources, reducing reproductive rates
disease: if the transmission rate of a disease increases as a population becomes more crowded, then the disease's impact is density dependent
predation: if a predator captures more food as the population density of the prey increases
territoriality: can limit population density when space becomes the resource for which individuals compete
intrinsic factors: regulate population size
toxic waste: ex such as yeast, are use to convert carbohydrates to ethanol in winemaking; the ethanol that accumulates in the wine is toxic to yeasts and contribute to density dependent regulation of yeast pop size
negative feedback between population density and the rates of birth and death, a population can increase in size indefinitely
increased density cause population growth rates to decline by affecting reproduction, growth, and survival
Population dynamics: are influenced by many factors and in turn affect other species
metapopulation: immigration and emigration are particularly important when a # of local populations are linked
Human population growth
History:
in 1650, about 500 million people inhabited earth, our population doubled to 1 billion w/in the next 2 centuries
doubled again to 2 billion by 1930
doubled yet again to 4 billion by 1975
the global population is now more than 7.2 billion people and is increasing by about 78 million each year
demographic transition: the movement from high birth and death rates toward low birth and death rates
age structure affects population growth
ex: United States is relatively even until the older ages
infant mortality and life expectancy at birth vary widely in different countries
ecological footprint: summarizes the aggregate land and water area required by each person, city, or nation to produce all the resources in consumes and to absorb all waste it generates
1.7 global hectare per person
global hectares: represents a hectare of land or water w/ a productivity equal to the average of all biologically productive areas on earth
food will be the main limiting factor that will eventually limit the growth of the population
Technology has substantially increased earth's carrying capacity, but no population can grow indefinitely