ecology exam 2: chapters 8-13

define population

group of individuals of the same species that inhabit an area

define subpopulation

local section of a larger species population

metapopulation

population broken into subpopulation sets

Define unitary

formed through sexual reproduction and develops into a genetically unique organism

Define modular

basic unit of construction that develops by branching

define endemic

restricted to a certain specific region or area

define ubiquitous

widespread geographic distribution

Define geographic range

the distribution of individuals of a species in/over a certain area

Compare density and abundance

Density is how clumped and abundance is a number. Depends on how big the area you’re looking at is. A species can be endemic to be locally abundant (high density) or can be top predators because they have high ranges (low density)

define random population

individuals are distributed randomly across an area

define uniform populations

individuals are distributed evenly across space

define clumped populations

individuals are grouped around a certain area(s) depending on resources/predators/microclimates/etc

formula for calculating population size using mark recapture data

population size = (recaptured specimens x marked specimens)/ new specimens = (nM)/R

Explain the assumptions involved with the mark recapture technique

Some mice are “trap happy” and so are overrepresented in the data. Also assumes that the population is closed, animal movements are random, and time between captures is long enough.

Explain what a quadrat is and how it is used to estimate population size.

It is a rectangle or square that is used to help estimate population size by averaging counts across the landscape.

How would your methods be different in random, uniform, and clumped distributions?

Depending on where the populations are grouped or not grouped, the population size can be calculated to be different than what it actually is.

Predict how population size might change in the future based on age pyramid data

Triangle shaped with base on bottom indicates a growing population because of lots of people who could reproduce. Uniform rectangle shaped indicates a stable population with almost zero growth. Triangle with base on top indicates a declining population.

Define dispersal:

Leaving from birth area to go to another area

Define emigration:

movement out of an area

Define immigration:

movement into an area

Define migration:

seasonal/directional movement between regions

Define r in an exponential growth model:

it is the rate of increase, which is birth rate - death rate

Explain the effects different values of r can have on the slope of an exponential growth curve model

r<0 = decrease over time = negative slope

r>0 = increase over time = positive slope

Describe how birth, death, immigration, and emigration contribute to or affect population size.

As birth rates go down, death rates go up. Is also changed by fecundity, starvation, disease, or increased predation

Type 1 survivorship curve (example: humans)-

stable then goes down. Good survivorship at early to young life, selects for quality in offspring, larger offspring

Type 2 survivorship curve (example: birds)-

stable downwards trend. Same amount of death chance at any point in life

Type 3 survivorship curve (example: fish)-

goes down a lot then becomes stable. Severe mortality at young age, selection for number of offspring, small offspring

Define demographic stochasticity:

random variation in birth and death rates that happen from year to year

Define environmental stochasticity:

random variation in environmental conditions that effects birth/death rates

List the costs and benefits of sexual vs. asexual reproduction

Sexual reproduction costs lots of energy and time, and better-quality offspring with unique genetic makeup. Asexual reproduction requires less energy and time and has lots of offspring that are genetically identical.

Define dioecious:

separate male and female parts/individuals

Define monecious:

male/female flowers on same plant

Define hermaphrodite:

produces both male and female gametes, either at the same time or at different life stages.

Simultaneous hermaphrodites:

produce male and female gametes at the same time all the time. Examples are deep sea fish and earthworms

Sequential hermaphrodites:

change sex with age. Examples are reef fish, mollusks, and echinoderms.

Explain the difference between precocial and altricial young and the costs and benefits of both

Precocial young are highly developed at birth, require a long gestation, open eyes, usually herbivores (?), nest on ground, little to no parental care. Altricial young are low developed at birth, short gestation, lot of parental care, naked and small, eyes closed, usually carnivores (?), nest above ground or well protected nest

List the characteristics of K-strategists and r-strategists

K strategists invest highly in offspring size and offspring protection but less in number of offspring. R-Strategists invest in lots of babies but less into the quality/size/protection of those babies

Individual costs of reproduction by sex

for females lots of energy is spent on making and caring for the offering. For males energy is spent on defending mate/nest/territory/offspring

Reproductive effort and how organisms deal with high mortality at different times in their life cycle:

Species with high juvenile mortality have a delayed maturity and reduced reproductive effort (example: frogs). Species with high adult mortality have early maturity and increased reproductive effort

The different tradeoffs associated with the number and size of offspring:

More effort put into more babies leads to less adult survival. More offspring leads to less offspring survival

The different tradeoffs associated with reproductive strategies related to the timing of reproduction:

semelparous individuals reproduce once in lifetime (mayflies, cicadas), while iteroparous reproduce more than once in a lifetime

Social monogamy

males and females associate in pairs at least during reproductive season, and offspring benefit from 2 parents

Genetic monogamy:

social monogamy with exclusive mating

Polygamy:

one individual has multiple mates

Polyandrous:

1 female with multiple males

Polygynous:

1 male with multiple females

Promiscuity:

every individual has multiple mates

Define and give examples of sexual selection, including the sexy-son hypothesis

Sexual selection is selection for traits that females use to assess male quality. Examples are birds of paradise and peacocks. Sexy son hypothesis is when genetic late preferences that start as random but become heritable because females select make traits that other females like can depend on resources.

Explain the importance of resource defense in the mate selection process

Males defend territories that can house multiple females , which makes them a better mate because clumped resources

Define carrying capacity (K):

maximum population that an area can realistically have without loss in the population

Define and recognize the inflection point in the logistic model of population growth:

when the population growth rate is at its maximum, which occurs at half the carrying capacity

Define and recognize density-dependent mortality:

more crowded, higher mortality rate, stress, competition, and limited resources

Define and recognize density-dependent fecundity:

more crowded, less babies, because of stress, competition, and limited resources

Scramble competition:

growth and reproduction is depressed equally across all individuals as population density increases

Contest competition:

when some individuals claim enough resources while denying others a share

Explain difference between exploitation and interference

Exploitation is when organisms do not compete through direct contact with each other, while interference is when individuals interact directly to prevent the other from accessing resources.

Define Allee Effect and understand why it happens in small populations

In small population individuals may have lower survival rates, fewer babies, or reduced overall growth due to stress, overcrowding, etc

Self-thinning:

progressive decline in density of plants as individual organisms grow larger, so fewer but bigger individuals occupy the same area

Fundamental niche:

total range of environmental conditions under which a species can survive and reproduce

Realized niche:

range that the species actually inhabits due to competition and species interaction

Define competitive release:

expansion of a species’ niche when competition is reduced or removed, allowing the species to have access to more resources

Explain how species may partition resources to coexist within an environment:

dividing resources so competition is reduced below the level that causes exclusion