ecology 2 (population ecology) Flashcards
population
individuals of one species simultaneously occupying the same general area, utilizing the same resources and influenced by similar environmental factors
population ecology
study of how biotic and abiotic factors influence density, distribution, abundance and age structure of populations
density of population
number of individuals per unit area or volume
dispersion of population
pattern of spacing among individuals within the boundaries of population
what factors influence population size
birth, death, immigration, emigration
patterns of dispersion (estimate population size)
random dispersion, clumped dispersion, uniform dispersion
Mark recapture technique
technique used to estimate the size of a population when it’s not practical to count every individual
mark recapture technique equation
N = (M * C)/R
N= number of individuals population (estimation)
M = number of markered individuals
C = number of captured individuals (marked and unmarked)
R= number of recaptured individuals (captured individuals marked)
mark and capture technique assumptions
- birth, deaths, immigration, and emigration equal rates
-short time between capture and recapture
exponential growth of population
the number of individuals added over increment of time is proportional to the size of the population at the start of that time interval
what does exponential growth of population take into account
births/death rates
exponential growth of population assumptions
-continuous reproduction
-immigration and emigration are equal
-identical individuals (in terms of reproduction)
-constant environment
**unlimited resources (including space)
equation for change in size of population over time
dN/dt = r * N
r=intrinsic rate of change; individual reproduction rate
N = population size at beginning of time increment
what variable impacts exponential growth of population
r (reproduction on individual bases)
when do populations grow exponentially
- organisms protected from predation
-invasive species introduced
-rebounding from massive population crash
-new adaptation that improves how they cope with their environment
-population growth rates are density independent
what does the assumption that populations are density independent mean
assuming infinite space available
density-dependent
logistic growth model; environment has carrying capacity and finite resources
key difference between logistic and exponential population growth
exponential: unlimited resources
logistic: limited resources
differdnce between B D and b d
B = birth rate
D= death rate
b= birth rate per capita
d = death rate per capita
what is N
population size
life history strategy
the way an organism allocates its energy and resources throughout its life, balancing between growth, survival, and reproduction
r-selected species
lots of offspring with not much parental care-> few survive
-unstable environment
-external fertilization
K-selected species
few offspring with lots of parental care
-stable environment
-internal fertilization
metapopulation
patches of individuals connected by occasional movements between patches
sink populations
ow-quality habitat where the population would decline without immigration from the source population
source population
high-quality habitat where the population increases; provides for sink population
decline of which kind of population would impact the metapopulation more
source population decline
cooridors
help increase immigration rates and rescue isolated patches in metapopulations
what will an optimal life history do
maximize fitness
what factors impact life history
- natural selection
- environmental conditions
- reproductive trade offs
trade offs: reproducing more offspring effect on the patent
higher mortality
trade offs: when do parents produce most offspring
- bigger
-older
-better at coping with environment
4 types of population age structures
stable, shrinking, slow growth and rapid growth
human reproductive age
15-65
demographic transition
model that describes the historical shift in birth and death rates as a country or region progresses through economic development, education, and technological advancement
demographic transition steps
1) b and d rates high; pop. equilibrium
2) sanitation increase so d rates decrease; increase pop
3) more opportunities for women, b rate drops; decrease pop
4)b and d rates low; stable pop
ecological footprint
a metric that measures how much of the Earth’s resources and services a person, population, or the entire planet demands
foraging
the process by which an organism actively searches for and acquires food sources, including locating, capturing, and consuming nutrients
profit
the ratio of the energy gained from a food item to the time (benefit) and energy it takes to obtain it (cost); cost: benefit ratio
searching time
time predators spend hunting/ planning how to get food
handling time
time predators spend handling/ getting ready to eat their food
monogamy
a mating system where a male and female pair bond
polygyny
a mating system where a single male mates with multiple females
*female cares for young
*sexual dimorphism
polyandry
a reproductive strategy where a female mates with more than one male
*male cares for young
*larger female
sexual selection
mechanism of evolution where organisms of one sex choose mates from the other sex
sexual dimorphism
he distinct physical differences in appearance between males and females of the same species
reciprocal altruism
a behavioral strategy where an organism acts in a way that benefits another organism, with the expectation that the other organism will act similarly in the future
kin selection
a form of natural selection where an organism behaves in a way that benefits the reproductive success of its close relatives, even if it comes at a cost to its own survival and reproduction, essentially promoting the spread of shared genes within a population
coefficient of relatedness
r; proportion of alleles likely to be shared with certain relative
ex. siblings r=0,5, cousins r=0.125
Eusociality
the most extreme form of altruism where workers (females) hlp a queen raise offspring
hamilton’s rule
rB>C
r = coefficient of relatedness
b = benefit
c= cost
altruistic cost benefit analysis
most common type of polygomy
polygyny: 1 male with many females
intersexual selection
member of opp. sex chooses mate based on charactistics
intrasexual selection
members of one sex compete for partners
agonistic behaviors
male-male conflict/ competition for mate: fighting or ritualized sparring
*usually produces larger males as the winners (larger) get to reproduce
alternative male strategies; different morphs of males
1) large dominant male who guards female/ fights males
2) males that mimic females to sneak in
3) very small males that sneak in while big males fight
haplodiploidy
females are diploid and males are haploid;
* sisters are either 0.5 or 1 related
*offspring 0.5 related to mother
many eyes hypothesis
bigger groups/ more likely a predator will be spotted
selfish herd hypothesis
being in the center of a group minimizes individual danger
predator prey population size relationship
population sizes fluctuate together
mate guarding hypothesis
males protect females from being fertilized by other males; monogamy
male assistance hypothesis
male helps female raise offspring; monogamy
female enforced monogamy
female interferes with male mating with anyone else so there are more resources for her and her offspring; monogamy
resource based polygamy
patchy resource distribution leads to females visiting patches for resrouces
harem mating structure
females congregate in a male controlled area -> 1 male many females
communal courting/Lekking
a mating ritual where males gather in a display area to attract females for mating
competition
a biological interaction that occurs when organisms or species compete for a limited resource, such as food, water, or territory
intraspecific
ecological interactions that happen between individuals of the same species
interspecific
interactions that occur between two or more different species in an ecological community
competitive exclusion
the principle that two species with identical niches (competing for the exact same limited resources) cannot coexist indefinitely
limiting resource
specific environmental factor, like food, water, space, or nutrients, that is present in such a limited quantity that it restricts the growth and population size of an organism within an ecosystem
resource partitioning
the division of limited resources among different species within a habitat, allowing them to coexist by avoiding direct competition for the same resources
character displacement
selective pressure favors character traits that give a greater efficiency in using realized niche; similar species develop different traits to reduce competition for resources and mates in the same environment
predation
antagonistic interactions
deceptive markings
color patterns or other features that help organisms avoid predators or prey (camouflage, mimicry, eyespots)
cryptic coloration
a defense mechanism that organisms use to hide their appearance and blend in with their surroundings
aposematic coloration
use bright colors or patterns to signal to predators that they are dangerous, poisonous, or otherwise unpalatable
Batesian mimicry
a biological phenomenon where a harmless organism mimics the appearance or behavior of a dangerous or toxic organism to avoid predators (mimic is not toxic)
Müllerian mimicry
multiple species that are well-defended and have similar predators mimic each other’s warning signals (both species toxic)
herbivory
the act of animals eating plant parts, such as leaves, stems, roots, flowers, fruits, or seeds
plant defense mechanisms
-masting (some years produce lots of seeds and other years no production)
-structural defense
-chemical defense
secondary compounds
toxic chemicals plants produce that reduce herbivory
parasitism
one organism benefits at the expense of the other organism
mutualism
a symbiotic relationship between two or more species where both organisms benefit from their interaction
commensalism
a long-term biological interaction in which members of one species gain benefits while those of the other species neither benefit nor are harmed.
dominant species
most abundant species in either numbers of biomass in the biome (usually biome named after them)
keystone species
control distribution/ abundance of predator but not most abundant themselves
*node in interaction network
ecosystem engineer
cause physical/chemical changes in the environment that affects other species
ex. beavers building dams
trophic interactions
the feeding relationships between organisms in an ecosystem, and how energy and nutrients flow between them
food web
complex network of interconnected food chains within an ecosystem
interaction web
he complex network of relationships between different species within an ecosystem. (predation, competition, mutualism interactions, etc)
interaction strength
measure of the effect of one species on the population size of another species
*removal experiment
*not all trophic interactions equally as important
disturbance
removes species, biomass, individuals, and/or resources from environment
disturbance regime
the cumulative effect of short-term disturbance events that occur over time and space
succession
the process by which natural communities replace each other/ re develop over time
primary succession
occurs when no soil exists when succession begins
secondary succession
occurs when soil/preexisting vegetation is present when succession begins
species richness
the number of different species represented in an ecological community
species evenness
a measure of how similar the abundance of each species is in a community (relative ratios of species)
why do small ground fires that maintain habitats turn into large fires over time
oak savanna biome (open understories) turn into forest -> spread fire to canopy -> kills trees
2 ways to study succession
- look at the same area over time
-look at different areas in different stages of succession
how do disturbances effect diversity
- create opportunities for new species to colonize an area
-prevent dominant species from completely taking over
-higher species richness
*disturbances occur at an “intermediate” level of frequency and intensity
