Bio 1MO3 Final

What is a population?

a group of individuals of the same species living in the same area at the same time

what is population ecology

study of how and why the number of individuals in a population changes over time

what is the range of a species

the geographic distribution, determined by biotic and abiotic factors

example of the global range of the lizard zootoca vivipara

common resident from ireland in western europe to japan in eastern asia

example of the regional range of the lizard zootoca vivipara

within the british isles, it is widespread, but missing from some places

example of the local range of the lizard zootoca vivipara

zooming into local scale, the lizards distribution is clumped according to where there is a suitable habitat

What is population density?

Number of individuals per unit area

what are the 3 types of arrangement within a population

1. random, if the position of each individual is independent of the others
2. clumped, if the quality of the habitat is patchy or the organisms are social
3. uniform, if negative interactions occur among individuals that space them out evenly

what determines the overall distribution pattern in a habitat

proximate causes, such as physiological and behavioural mechanisms

ultimate causes, such as evolutionary adaptations

if a species range is small, what might you notice in the population

a single population of interbreeding individuals

if a range is large, what might you notice in the population

may consist of many populations, sometimes contiguous and sometimes isolated in space

What is a metapopulation?

a population of populations connected by migration

Why do metapopulations exist in nature?

The habitats that are available or occupied are patchy.

how are sedentary species counted

using transects and quadrat plots

how are mobile species counted

mark-recapture method

Why are populations dynamic?

They change in size and composition over time.

what is complete count of species

count all the species in an area, assisted w aerial flyovers or drive approach
expensive and time consuming

What is the mark-recapture method?

animals are captured, marked, and then recaptured after a period of time
ratio of marked/unmarked helps estimate total population size

what is the quadrat sampling method

usually used for species with limited mobility. they count the number of individuals in a certain part of the land and then apply that to the larger landscape

What is transect sampling?

using a rope/measuring tape that has been marked at specific intervals and at each interval the number and type of species are recorded

how to calculate population size using mark-recapture method

number of marked individuals M in the total population N = avg percentage of marked individuals found in each recapture sample n
M/N = m/n
N= Mn/m

Lets say you want to know how many turtles are present in Cootes Paradise. On the first day, you capture and mark 24 turtles. A week later, you then catch 60 turtles, of which only 15 are marked and 45 are unmarked. What is the estimated population of turtles in cootes paradise?

96

key assumptions about the mark-recapture method

- individuals are not moving in and out of the study area
- individuals mix between captures
- no bias exists regarding which individuals are caught in each recapture
- individuaks do not learn to avoid or seek out traps after being caught once
-individuals do not change their behaviour, attract, and or deter predators or mates, or die as a result of being marked or trapped

What is demography?

change in population structure through time
- birth, death, immigration and emigration

what is population immigration

when individuals enter a population by moving from another population

what is population emigration

occurs when individuals leave a population to join another one

What is the age structure of a population?

proportion of individuals in different age groups

what is a generation in biology

the average time between a mothers first offspring and that of her daughter

what does a life table tell us

the probability that an individual will survive and reproduce in any given time interval over the course of its lifetimr

how do biologists construct life tables for short-lived and long-lived species

tracking short-lived species for their whole lives
- hard, but yields a lot of info

or for long live species, biologists can take a snapshot of a populations age structure at a given time
- easier, but less info

by monitoring a population daily, what can biologists calculate

the number of individuals that survived each year in each particular age group as well as how many offspring each female produced

how long do female zootoca vivipara lizards live

seven years

What is a cohort ?

group of individuals of the same age that can be followed through time

what is survivorship

the proportion of offspring produced that survive, on average, to a particular age

What is a survivorship curve?

a plot of the logarithm of the number of survivors versus age

it helps recognize general patterns in survivorship and make comparisons among populaions or species

what are the three types or survivorship curves, and explain them + give examples

1. type 1 curve
survivorship throughout life is high, and most individuals approach the maximum life span of the species
- eg humans

2. type 2 curve
most individuals experience relatively constant survivorship over their lifetimes
- eg songbirds

3. type 3 curve - result from high death rates early in life, with high survivorship after maturity
- eg plants

what type of survivor ship did the tyrannosaur albertosaurus sarcophagus have

type 2
-high newborn morality vs low juvenile morality
- morality then ncreases at sexual maturity

what factors cause morality in the tyrannosaur albertosaurus

male-male interactions
cost of parental care
egg laying

what is fecundity

the number of female offspring produced by each female in the population

What is age-specific fecundity?

the average number of female offspring produced by a female in each age class

What does the net reproductive rate tell you?

whether the population is increasing or decreasing
- depends on immigration and emigration being insignificant
- when the rate is >1, inc
- when rate is <1, dec

how to calculate reproductive rate

sum of (survivorship at age x * fecundity at age x) = reproductive rate

what may cause the life table of a species to vary dramatically

the populations being located in different abiotic and biotic environments

Why do fitness trade-offs occur?

because every individual has a restricted amount of time and energy at its disposal-meaning that its resources are limited

example of a fitness trade off in females

if a female devotes a lot of energy to producing many offspring, she cannot devote that same energy to her immune system, growth, nutrient stores, or other traits that increase survival

what does an organisms life history describe

how an individual allocates resources to growth, reproduction, and activities or strictures that are related to survival

population growth rate formula

(Births-Deaths)+(Immigration-Emigration)

exponential growth equation

n/t = (b-d)N
where b is birth rate, d is death rate, and N is number of individuals

what is the intrinsic rate of increase

When birthrates are as high as possible and death rates are as low as possible, r reaches a maximum value called the intrinsic rate of increase

example of species that have a high rmax

Species that breed at a young age and produce many offspring
- example fruit flies

example of species that have a low rmax

species that take a long time to mature and have few offspring per year
- example giant pandas or palm trees

what does the instantaneous growth rate tell you

the instantaneous growth rate (r) will tell you what the population is doing at that moment in time
- r is always less than or equal to rmax
- r is often much less than rmax because conditions are rarely optimal

in what two circumstances is exponential growth common

1. a few individuals colonize a new habitat with plentiful resources
2. a population has been devastated by a storm or some other type of catastophe and then begins to recover, starting with a few surviving individuals

what is density independent growth

States that per capita birth and death rates are independent (i.e. not a function of) the density of the population`

what is density dependent growth

Occurs when per capita birth and death rates depend on (are a function of) the density of the population.

what is the carrying capacity

the maximum number of individuals in a population that can be supported in a particular habitat over a sustained period of time

if the population is below the carrying capacity, will the population continue to grow

yes

When N is small, (K-N)/K is ______ and the growth rate is ____

close to 1, high

When N is large, (K-N)/K ______

gets smaller

When N is the same as the carrying capacity, (K-N).K is ______ and the growth rate ____

0, stops

what is logistic population growth

A change in growth rate that occurs as population size reaches carrying capacity

is exponential growth density dependent or independent?

independent

is logistic growth density dependent or independent?

dependent

what are the three distinct states of density dependent growth

1. initially, growth is exponential (r is constant
2. growth rate begins to decline ( N increases) when competition for density-dependent factors begins to occur
3. growth rate reaches 0 at the carrying capacity (N vs. t is flat)

what are density independent factors

abiotic limiting factors, such as variation in weather patterns, that change birth and death rates irrespective of population size

What are density dependent factors?

Limiting factors whose intensity is related to population size. usually biotic, and can limit growth in natural populations
eg. competition for resources

What are some density dependent factors?

disease, competition, predation

What are intraspecific interactions?

interactions within a species, such as competition among members of a cohort for food

What are interspecific interactions?

interactions between species, such as predation, parasitism or competition among species for food

why are population curves always in flux

For any species, some habitats are better than others due to differences in food availability, space, and other density-dependent factors. Conditions in some years are better than in others. k varies among species and populations over time

define population dynamics

the changes in populations through time

two examples of species that cycle

snowshoe hare and lynx

explain the snowshoe hare and lynx cycle

to begin with, snowshoe hares are herbivores. Lynx are predators, and they eat snowshoe hares. there are more hares than lynx. The populations cycle every 10 years on average, but changes in lynx density lag behind changes in hare density by about two years

what is the bottom up hypothesis about the hare-lynx cycle

When hare populations reach high density, hares use up all their food and starve; in response, lynx also starve

what is the top-down hypothesis about the hare-lynx cycle

Lynx populations reach high density in response to increases in hare density. At high density, lynx eat so many hares that the prey population crashes.

example of a metapopulation

glanville fritillaries (butterfly)
they occupy isolated patches of habitat within their geographic range

There is a balance between _____ and recolonization within a metapopulation

extinction

what do mark-recapture studies show about recolonization in a meta population

mark-recapture studies show that migration rate is high enough to suggest that patches where a population has gone extinct will eventually be recolonized

what is a population's age structure

the proportion of individuals that are at each possible age - has a dramatic influence on the populations growth over time

what is an age pyramid

the age structure of a population tends to be uniform in developed countries and bottom heavy in developing countries

explain population momentum

overall population size will increase dramatically in developing nations over the course of our lifetime. part of this is because of increased survivorship. another part comes from the fact that these populations now have more young women, so overall birthrate remains high, even if fecundity has decreased

what are some negative effects of human overpopulation

habitat loss, species extinction, declines in living standards, political instability, and shortages of resources

if the world's average fertility stays at its current level, what will the population be by 2050

11 billion

What is zero population growth?

A decline of the total fertility rate to the point where the natural increase rate equals zero.

what factors impact the decision of how many children women have

how much access women have to education and reliable birth control methods
overall economic development
access to quality health care

what do levels of mortality and fecundity look like in endangered species

high juvenile mortality
low adult mortality
low fecundity

which subpopulations within a larger metapopulation are most likely to survice

1. larger population size
2. occupy larger geographical areas
3. are closer to neighbouring populations
4. have higher genetic diversity

impact of habitat destruction on small populations

leaves them isolated in pockets of intact habitat

what is a biological community

an assemblage of populations of various species living close enough for potential interaction

What is commensalism?

A relationship in which one organism benefits and the other is neither helped nor harmed (+/0)
ir can be conditional, starting off not causing a fitness reduction, but eventually becoming a problem

What is mutualism?

both organisms benefit in fitness (+/+)

What are consumption interactions

when one organism eats or absorbs nutrients from another, increasing the consumers fitness but decreasing the victim's fitness (+/-)

what are competition interactions

individuals use the same resources -- resulting in lower fitness for both (-/-)

how are epiphytic orchids and their host trees an example of commensalism

the orchids benefit from being held up by the host plant, and the host plant does not suffer any harm from the orchid

how can the relationship between epiphytic orchids and their host trees become competitive

if too many orchids live in a tree, the interaction becomes competitive as they fight for access to sunlight

why is there no real "winner" in competition interactions

competing is energetically costly, so even the winner would have been better off not having to compete at all

What is intraspecific competition?

competition between members of the same species

what is interspecific competition

when members of different species use the same limiting resources

What is a niche?

the range of resources that the species is able to use or the range of conditions it can tolerate

what is symmetric competition

each species experiences a roughly equal decrease in fitness