Term
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Definition
describes age-specific fecundity
can be used to predict population growth trends
useful for understanding life history stories
often defined for females producing daughters |
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Term
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Definition
fecundity
realized fecundity:avg offspring produced over lifetime
reproductive value |
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Term
| net reproductive rate [NRR] |
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Definition
sum of all realized fecundity
can give info on population stability
=1.0 stable
<1.0 declining
>1.0 increasing |
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Term
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Definition
Leopard Sharks: model fishing practices to see how it will affect population size
Manatees |
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Term
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Definition
mean expected reproduction of age x individual from age x until death
begins at 1.0 in stable population
initially usually increases with age then slowly decreases |
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Term
| Residual reproductive value |
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Definition
is a function of survivorship to each future age times
the fecundity at that age when it is reached |
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Term
Population age distributions
a. General concepts |
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Definition
Age distributions show the proportion of
individuals of each age class represented in a population
Usually, the proportion of members of each sex are plotted on either side of the figure
The age distribution reflects whether the population is stable, increasing, or decreasing |
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Term
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Definition
Proportion of individuals in each age class remains stable through time (from generation to generation)
The population itself may not be stable (i.e., it may be increasing or decreasing)
Stable age distribution is quickly reached (several generations) under constant age- specific survivorship (lx) and fecundity (bx) schedules; i.e., if the life/fertility table stays the same |
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Term
Intrinsic rate of natural increase (rm)
a. General information |
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Definition
Also called “innate capacity for increase” and
Represents theoretically how fast a population can grow
“r” represents population growth rate (r = b-d in a closed population), “m” represents maximum
b = birth rate
d = death rate
Defined under ideal conditions (unlimited resources, no inter/intraspecific interactions like competition or predation
Defined under specific set of physical conditions (e.g., temperature, salinity, humidity, etc.)
Instantaneous rate of change of population size expressed per unit time per individual
rm > 0 for any population; why? r = b-d in a closed
population |
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Term
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Definition
1. Number of offspring produced per female
2. Generation time (= age when “average” offspring is born; related to age of first reproduction |
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Term
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Definition
a. Definition: average period between birth of an individual and the birth of its offspring
b. Calculating T: Σxlxbx/Σlxbx
c. What it really means |
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Term
| The importance of generation time: fruit flies |
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Definition
these two races [sub-species] of fruit flies have the same r,; that is their populations increase @ the same rate
generation time influences how fast populations grow |
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Term
| The importance of generation time: human population growth |
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Definition
| human populations in developing countries grow fast because they have more kids and a shorter generation time |
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Term
Population growth under a stable age distribution
a. Exponential growth |
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Definition
Can be modeled mathematically once the population reaches a stable age distribution
Density-independent: unlimited resources, no competition
J-shaped curve
dN/dt = rmN; N = population size, t = time
Growth is fast when:
Population size in high
rm is high (but rm is a constant) |
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Term
Population growth under a stable age
distribution
b. Logistic growth |
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Definition
Density-dependent: as population size increases, per capita growth slows
S-shaped curve
dN/dt = rmN (K-N)/K;
K = carrying capacity of the environment
Growth is fastest when:
N = 1/2 K |
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Term
logistic growth
when N is small
N=large
N>K [barely]
N |
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Definition
dN/dt=rmN resembles exponential growth
dN/dt=0 b/c N=K therefore no population growth
dN/dt=negative population=decreasing to K
dN/dt=positive population=increasing to K |
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Term
| real population growth: should oscillate around k, but K can change over time |
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Definition
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Term
Fishery application of population growth: Maximum sustainable yield (MSY)
At what size is a population growing fastest? |
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Definition
when N=1/2 K
therefore if you can harvest @ a rate to keep the population around 1/2 K it will rebound the fastest |
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Term
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Definition
Obsolete approach to
Based on the environment
r- vs K-selection falls along a continuum
However, lots of organisms characteristic of stable or unstable environments don’t follow the r-/K-selection predictions |
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Term
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Definition
| Organisms adapted to temporary, unstable environments with lax competition (e.g.,tree fall gaps, temporary ponds, etc.): selection favors organisms with good dispersal ability and that maximize r (i.e., have high rm) |
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Term
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Definition
| Organisms adapted to stable habitats (climax forests, coral reefs, etc.): selection favors organisms adapted to live at carrying capacity such as good competitive ability for limited resources and consequently characteristics typical of low rm |
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Term
Age-specific trade-offs to maximize lifetime fitness
theory |
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Definition
Based on competing demands of survivorship, growth, and reproduction allocation (e.g., of energy)
At each age, organism allocate differentially to reproduction vs survivorship vs growth
Involves trading off earlier vs later reproduction, and quality vs quantity of offspring
Natural selection therefore maximizes fitness from each age on (i.e., maximizes reproductive value at each age)
Life history should therefore be moulded by age-specific survivorship schedule (i.e., life table information)
Changes in age-specific mortality should select for changes in life history |
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Term
Age-specific trade-offs , cont.
a. Theory, cont. |
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Definition
Increased adult mortality should select for:
Earlier maturation
Slower growth
Higher reproductive effort
Increased juvenile mortality should select for:
Faster growth
Later maturation
Lower reproductive effort |
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Term
Age-specific trade-offs , cont.
b. Guppies |
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Definition
Transplanted guppies from cichlid stream [adult predator] to killifish stream [juvenille predator], predicted evolution w/30-60 generations [11 years]
more energy used for reproduction in cichlid stream, opposite in killifish stream
Result:
later maturation
lower reproductive effort
fewer and larger offspring per brood
heritable, therefore evolutionary changes
tested evolutionarily by doing a common garden experiment |
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Term
Age-specific trade-offs , cont.
c. Application to harvesting (fishing, hunting) |
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Definition
fished populations overtime will be evolutionarily affected to counter fishing pressures
theory vs reality
simulated fishery w/ silversides
results
if you harvest only large fish the fish become smaller over evolutionary time
if you harvest only small fish you get more large fish over time
overtime cod have become smaller due to human harvesting pressures |
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Term
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Definition
| Understanding behavioral patterns as responses to the environment |
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Term
Sexual reproduction
Why sex? |
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Definition
Advantages of asexual reproduction (including “cost of meiosis”)
Advantages of sexual reproduction
Environmental variability, the Red Queen hypothesis, and parasite/pathogen evolution |
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Term
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Definition
Limitations to male vs female reproduction & “typical” strategies
Males: often limited by access to females
Females: often limited by offspring quality
Male promiscuity vs female choosiness: polygyny
Most mammals “relatively” polygynous
“Polygynous” females: often mate with multiple males:
Re-supplying sperm reserves
Allowing for sperm competition or cryptic female choice
Providing diversity in offspring |
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Term
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Definition
Resource defense polygyny: males control resources needed by females; e.g., territorial red wing blackbirds
Harem defense polygyny: males control groups of females; e.g., male coalitions of lions
Male dominance polygyny: some males are dominant over others (sometimes form dominance hierarchies); e.g.,
lekking birds |
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Term
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Definition
When resources are limited and dispersed, a female may trade off a better male for sole access to a lesser male’s resources and parental care, and a male may trade off having multiple mates in favor of providing care to a single group of offspring → MONOGAMY
Social monogamy (90% of bird species) & extra-pair copulations (EPCs)
Participating males gain extra fitness
Females gain better genes for their offspring |
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Term
| Benefits and costs of polygyny |
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Definition
Benefits of polygyny
Males: multiple mates
Females: Good genes and/or
better resources
Costs of polygyny
Shared parental care of male
Shared resources of offspring |
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Term
Why do paired males “go along”
with EPC's? |
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Definition
1. the male has a genetic investment in the nest, therefore abandoning them leaves them with zero fitness
2. females mate w/ other males when male is unaware, and if they do not see a difference in the chicks they just don't know |
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Term
| Mating systems: Polyandry |
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Definition
Uncommon
Occurs when female reproduction is limited by access to mates & male reproduction is not
Unknown what environmental correlates would favor this
Parental care often provided by males (only) |
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Term
| Mating systems: Sequential sex change |
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Definition
Protogynous (female first)
Protandrous (male first)
Size advantage model = highest fitness occurs when:
A particular sex when young (and small)
The other sex when old (and large)
Bluehead wrasse: social control of a protogynous hermaphrodite |
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Term
Territoriality
a. General concepts |
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Definition
Home range: area animal utilizes during its
normal, daily activities
Territory: actively defended portion of the home
range
Territoriality is an adaptation to limited resources (food, space, mates, offspring, etc.)
Resources are most actively defended against organisms with high resource overlap (e.g., conspecifics)
“Keep-out signals” (scent, sound, visual displays, etc.) allow territorial defense without direct, physical contact |
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Term
Grouping behavior
a. General concepts |
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Definition
Animals often form groups to:
Increase access to mates or other non-food resources
Increase foraging success
Better defend themselves against predators
Based on pay-off to the individual (i.e., being in the group increasesindividual fitness) |
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Term
Grouping behavior
b. Group foraging |
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Definition
Favored when individual’s food/time increases due to:
1. Increasing size of prey
2. Protecting captured prey
3. Making prey more available
Advantages to increasing prey size and prey defense are greatest in open habitats (can’t ambush but can use pack to run down prey; can’t hide prey); most group-hunting carnivores live in savanna, prairie, & tundra
Group hunting is a (the?) major force leading to evolution of social groups |
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Term
Grouping behavior
c. Group defense |
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Definition
Safety in numbers vs providing banquet for predators
Favored when individual’s protection increases due to:
1. Dilution effect
2. Confusion effect
3. Many-eyes effect (increased sensory perception)
4. Being able to defend against/discourage a predator |
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Term
Human behavioral ecology
a. E.O. Wilson’s Sociobiology (1995) & evolutionary biology in the social sciences
Early controversies & contemporary fields |
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Definition
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Term
Human behavioral ecology
b. The nature of mate attractiveness |
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Definition
What traits are attractive and why?
Does attractiveness “signal” something?
If so, are there universal traits associated with attractiveness?
My son in preschool
Facial symmetry
Hip-to-waist ratio |
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Term
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Definition
if the predator can only attack one therefore if you are in a group you decrease the odds of you being the one eaten
ex. Bats, minnows and dilution effect
-minnows lay eggs in bass broods
-Bass takes care of minnow eggs
-beneficial to bass b/c it dilutes the brood so that Bass have a higher fitness rate |
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Term
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Definition
organisms form a group tat makes it difficult to follow prey
ex. schools of fish |
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Term
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Definition
| increased sensory perception-more eyes looking out for predators |
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Term
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Definition
many organisms in defense mode is discouraging to predators
ex. Lobsters and birds |
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Term
Human behavioral ecology
c. Human mating/dating behavior |
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Definition
The double standard & the age differential: are
differences hard-wired?
Mating systems in human societies, resources, & the
polygyny threshold |
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Term
Human behavioral ecology
d. “Concealed” ovulation |
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Definition
Why in humans?
Treatment of females (by males) in other primates (concealed ovulation leads to marriage bond?)
Arranged marriages (concealed ovulation result of marriage bond?)
How concealed is ovulation?
Results of studies on female attractiveness (scent, facial attractiveness, body symmetry, decreased waist-to-hip, increased verbal creativity & fluency) and earnings in “gentlemen’s clubs” |
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Term
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Definition
| Both participants negatively affected because they share a common, limited resource |
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Term
| Mechanisms of competition |
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Definition
Scramble (or exploitative) competition
Interference (or contest) competition |
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Term
| Interference (or contest) competition |
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Definition
| individuals negatively impact competitors because they exclude their access to the resource (interact directly); e.g., territoriality; |
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Term
| Scramble (or exploitative) competition |
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Definition
| individuals negatively impact competitors because they deplete the resource (interact indirectly) ; e.g., spiders and carnivorous plants |
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Term
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Definition
| competitive interactions are often discussed with respect to an organisms niche |
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Term
| Hutchison’s hypervolume model |
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Definition
n-dimensional hypervolume enclosing the complete range of conditions under which an organisms can live
Resources and other conditions in the environment consist of the axes n is the number of axes |
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Term
| Fundamental vs realized niche |
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Definition
Fundamental niche: potential, idealized niche
Realized niche: actually occupied niche in the presence of
biological interactions (e..g., competition, predation) |
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Term
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Definition
| describes how specialized or generalized a species is with respect to a resource axis |
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Term
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Definition
| describes how much two or more species overlap in their realized niches |
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Term
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Definition
a group of species that shares resources, has high niche overlap, and are potential competitors
E.g., a guild of frugivorous birds; a reef herbivore guild |
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Term
| Effects of competition on niche breadth |
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Definition
a. Intraspecific competition: Leads to a broadening of niche breadth
b. Interspecific competition: Leads to a narrowing of niche breadth |
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Term
| Hypothetical competition example |
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Definition
A small founding group of a frugivore (lizard?) population on an uninhabited (by frugivores) area with a variety of flowering plant species
-@ first the lizard will be selective about what fruit they consume
-as population increases the niche breadth would increase
Introduction of other frugivores
-the lizards niche would decrease because the lizards would be forced to specialize in a resource they are best adapted for |
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Term
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Definition
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Term
Effects and evidence of interspecific competition
a. Competitive exclusion |
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Definition
(Gause’s principle; the principle of competitive exclusion: Two species cannot coexist indefinitely when the same resource limits both species)
Competitive exclusion: extirpation of one species by another via competition
Experimental evidence: |
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Term
Effects and evidence of interspecific competition
b. Resource partitioning |
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Definition
differential use of a common resource, usually by utilization of different subsets of available resources, in response to or to avoid competition
Partitioned resources are usually food, space, and/or time
Most studied in sympatric, closely-related species |
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Term
Effects and evidence of interspecific competition
b. Resource partitioning, cont: MacArthur’s warblers |
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Definition
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Term
Effects and evidence of interspecific competition
c. Character displacement |
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Definition
Evolutionary divergence in ecology, morphology, physiology, or behavior between two (or more) species in sympatry, but not in allopatry, due to competition
E.g., Galapagos finches |
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Term
Effects and evidence of interspecific competition
d. Competitive release |
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Definition
Niche expansion due to a decrease in interspecific competition
E.g., studies like the Cocos Island spider |
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Term
Mutualism: both participants benefit
1. Three general categories |
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Definition
Trophic: both participants gain energy/nutrients; e.g., coral-
zooxanthellae
Defensive: one participant gains protection from consumers by providing benefit, usually food source; e.g., Acacia tree/acacia ants
Dispersive: one participant facilitates dispersal of other, usually for a food reward; e.g., pollination, seed dispersal |
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Term
| Interactions fall along a mutualism-parasitism continuum that may change temporally or evolutionarily |
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Definition
Temporally, mutualistic interactions may be commensalistic or parasitic, sometimes in response to environmental conditions
Evolutionarily, mutualists may evolve to exploit their symbiont (i.e., to “cheat”) if there is a cost associated with being a mutualist
E.g., cleaning interactions; root mycorrhizal fungi |
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Term
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Definition
a. Termite-gut endosymbiotic flagellates: cellulose breakdown (trophic mutualism)
b. Endosymbiotic flagellate-gut bacteria (Hongoh et al. 2008): N-fixation (trophic mutualism) |
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Term
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Definition
One organism benefits, usually
by getting a food source, reducing the fitness
of the host but usually not killing it |
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Term
Parasitism General concepts
a. Often classified as being external or
internal |
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Definition
External: ticks, isopods/copepods, mistletoe, botflies (?), etc
Internal: trematodes, tapeworms, nematodes,
acanthocephalans, etc. |
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Term
| Some parasites don’t live on/in host |
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Definition
Brood or nest parasites: lay eggs in nests of others (conspecifics or heterospecifics)
Nectar robbers: drink nectar but don’t pollinate
Floral mimics: attract pollinators but don’t provide nectar
Kleptoparasites: steal food
Sexual parasites: exploit another’s reproductive system |
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Term
. Adaptations of parasites
a. Internal parasites are classic
r-selectors: |
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Definition
Adaptations to patchy, temporary environments
High reproductive capacities
Good dispersal ability (often through complex life cycles using secondary hosts) |
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Term
Adaptations of parasites
b. Evolution of reduced virulence |
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Definition
| Natural selection sometimes favors evolution toward commensalism |
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Term
Adaptations of parasites
c. Host-altered behaviors |
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Definition
| Parasites alter behavior of hosts to parasite’s benefit, often by manipulating host to more efficiently complete the parasite’s life cycle |
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Term
. Adaptations of hosts
a. Evolution of resistance to parasite/pathogen
b. Sexual reproduction: Red Queen Model |
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Definition
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Term
| More examples/applications of parasitism |
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Definition
a. Invasive hares in Australia: why did the hare population recover?
b. Darwinian medicine: “Every medical phenomenon has both a mechanistic and an evolutionary explanation” (LeGrand & Brown 2002)”
Disease symptoms (e.g., coughing, sneezing, fevers): host-altered behaviors or evolutionary responses to parasites/pathogens? E.g., sequestering of iron, morning sickness |
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Term
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Definition
| parasitoid starts out like parasite but ultimately kills host |
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Term
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Definition
1. Adults are free-living and lay eggs on or in animal host (usually an insect or spider), larvae develop in host initially doing little harm, eventually consuming and killing host
2. Many flies and wasps are parasitoids
3. Often used in biological control |
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Term
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Definition
Alien is essentially a parasitoid
A plant-wasp defensive mutualism:
Plant juices + caterpillar saliva create fragrance
Fragrance attracts parasitoid wasp |
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Term
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Definition
| one organism benefits, the other not affected positively or negatively |
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Term
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Definition
1. Difficult (impossible?) to “demonstrate”: How do you show that one species does not impact another? How do you show “no effect”?
2. Possible examples
Cattle egret and cattle
Wasps and katydids |
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Term
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Definition
| asymmetrical competition; one species has a strong negative (“competitive”) effect on the other, but the reverse interaction is negligible |
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Term
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Definition
1. Assemblage of populations in a prescribed area or habitat
2. Are communities natural, functional units?
Association concept (Clements): superorganism, species tightly bound together through evolutionary history Individualistic concept (Gleason): similarities in requirements
3. Do communities have boundaries?
Closed communities vs Open communities
4. What determines community structure?
Equilibrium communities: density-dependent deterministic forces
Non-equilibrium communities: density-independent stochastic forces
Persistence vs resilience |
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Term
| Species richness increases with patch (“island”) size |
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Definition
Diversity on islands is predictable: S = cAz
Take log of both sides: linear
log S = log c + z log A (i.e., y = b + mx)
S = species richness A = island area
z = slope (usually about 0.20-0.34)
c = constant; reflects overall diversity of group studies |
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Term
| Equilibrium Theory of Island Biogeography |
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Definition
Rationale: if island diversity is predictable, it must
be “determined” by something
The theory: determined by the balance between: Rate of immigration of new species onto the island AND Rate of extinction of species already on the island
When the rates are equal, species are not increasing or decreasing, and the island is at its equilibrium (predicted) diversity
If rates are unequal, the greater rate will return species richness to equilibrium |
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Term
Influences on rates:
Immigration: distance from source pool
Extinction: island size
Graphical representations with differing distances & source pools: Impacts on equilibrium species richness |
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Definition
Implications for conservation
biology?
Minimizing extinction
Maximizing immigration |
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Term
| Hypotheses accounting for diversity differences |
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Definition
a. Time: Older communities are more diverse
Ecological time: cumulative dispersal; fish in Canadian rivers
Evolutionary time: cladogenesis; Lake Baikal benthic invertebrates
b. Spatial heterogeneity: More types of spaces support more species
c. Disturbance: Intermediate disturbances prevent competitive exclusion (Connell’s intermediate disturbance hypothesis); physical or biological
d. Niche diversification: Interspecific competition favors narrow niches and allows more species to coexist
e. Productivity: Increased food resources allow for narrower niches & more species
f. Environmental stability: Unstable environments force organisms to be more generalistic, stability favors narrow niches and diversity
g. Neutral theory (Hubbell): Species are competitively equal, are added to a community by immigration & evolution, go extinct by random processes; larger areas have lower extinction and increased richness |
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