Chapter 5 - Birth, Death and Movement (CHAPTER + SLIDES) Flashcards
slides notes are included!!
Population
a group of individuals of one species
- birth death and movement change and alter the population (size and more)
Unitary organism
Single, functional entity
Modular organism
Repeated production of “modules” => such as leaves on a plant
- these are mostly rooted organisms, that have an indeterminate program of development
Genet
single-celled zygote developed
- can estimate development with indices of abundance and stuff rather than just counting.,
Module
an offshoot formed by vegitative growth
Generalized life history
- Birth
- Pre-reproduvtive
- Reproductive
- Post-reproductive (unusal to have)
- Senescence death
this is common for unitary organisms
all organisms require a growth period
Annuals
one generatrion each year
Perennials / Others
extended life cycle
- some fit many generations in one year
Growth and reproduction require resources
Therefore it creates conflict and you might lose some growth for reproduction and viceversa since you need to allocate resources
Biennal plants
Year 1 = Vegetative growth
Year 2 = flowering and death
- if the flower is cut before the seeds are made though the plant will survive and try again to grow. So the death is determined by the flowering.
Iteroparous Species
Breeds reptitdley devoting some resources during a breeding episode to survival for further breeding episodes.
Semelparous species
Do not set aside resources, so they die shortly after reproduction
Annual life cycles
Grasshoppers
- annual & iteroparous
Annual plants
- usually semelparous
- most annuals spend 1 dominant phase as seeds, spores, eggs, or cysts and this phase can last YEARRRSS before they decide to grow.
Seed bank
large population of dormant seeds buried in soils
Ephemeral Plant cycle
Short-lived plants
- such as in sand dunes and deserts
- depends on the dormant stage to survive
- then eventually when conditions are right they flower for up to only like 8 weeks.
Plants with larger life periods
- Photoperiod can trigger mating in flowering plants
- the population is maintained partially by adult survival partially by birth
- sometimes if there is little seasonal variation you’ll gateher continous breeders that dont stop.
- Sometimes there is semelpary in biennal plants such in bamboo that can live for 100 years without reproducing
- same thing occurs with salmon in the pacific.
- the size of a plant is more useful for determining its surivial and chances of reproduction rather than its age.
Monitoring Birth and death Quantitatevley
Life tables!!
The ones with the colusm that are diagonal and you can see just one group per year
Cohort
All individuals born in a particular period
Cohort life table
Survivorship of members of cohort over time
Static life table
the survivorship of members at different ages.
Age-specific fecundity schedules
How much individuals of different ages contribute to births in the population as a whole
Annuals as life tables
COHORT LIFE TABLES (non-overlapping generations)
- this is possible because its possible to follow them from the first birth to untill the last death
- you can mark individuals easily incase of there being overlap (they did it with marmots)
- compare dynamics of two isolated populations
- but you must standardize the raw data if youre doing comparisons.C
Cohort life table signs
Ax = number alive at the start
Lx = Proportion of that surviving
Fx = female number produced by age class
Mx = femal surviving (fecundity)
MxLx = Female surviving per class (fecundity)
- you can find the basic preprodctive rate (R0) by getting the sum of all LxMx
R0
Basic reproductive rate
R0 = 1 (steady)
R0 < 1 (decreasing population)
R0 > 1 (increasing population)
Survivorship curves
Plots of logs (Lx) BUT NOT A LOG SCALE, ITS A BUNCH OF LOGS PLOTTED.
Static life table uses
only with careful interpreation
Classification of survivorship curves
X axis = AGE
Y axis (log10(Lx))
Type I = starts up then curves outwards to down
Type II = straight line from up to down
Type III = starts up then curves inwards to down
Y axis (risk of mortality)
Type I = Starts down then curves to up
Type II = Straight horizontal line
Type III = starts up then curves inwards to down
Generalized spacial pattern
1) Aggregated (clumped)
2) Random
3) regular (evenly) spaced
- movement and special distribution (AKA dispersal) are linked
Migration
Mass directional movement of large numbers of a species from one location to another
- perception of the pattern of movement depends on its scale
The average density
The total numebr of individuals divided by the total size of the habitat (this depends on the habitat definition)
Dispersal is important to determine the abundance that we observe
Because it gets the organisms there in the first place
- invasions thend to be driven by acts of dispersal too
- dispersal can be density dependent
- inverse density dependenence??? could occur maybe i dont really understand this
Inverse density dependence
a pattern often attributed to the avoidance of inbreeding between closely related individuals (and the lowered offspringfitness that would result), since on average, at low densities, a high proportion of those you grow up with are likely to be your close relatives.
- i really dont get this
Scales in population distribution
Large Scale = Clumped in certain enviornments
Medium Scale = Aggregation based on specific habitats
Small Scale = Randomly distributed / spaced to avoid competition
Impact of intraspecific competition on populations
Crowding can be more important than density
- especially in modular organisms
The birth and death rates are density dependent
- so you can see their graphs cross
- they tend to cross when densities are equal
- their carrying capacity is the point in the graph where they cross (K)
Carrying capacity
Density < K, then the births are > deaths = so increased population
Density > K, then the births are < deaths = so decreased population
Populations tend to settle at K for intraspecific competition.
Exponential Growth
Populations at low densities that frow by simple multiplaction over successful intervals of time
Rate of increase
The population’s intrinsic rate of natural increase (r)
r = 0 at carrying capacity
- reduction at carryinc capacity will show a logistic growth (NOT AN exponential growth)
Net recruitment
The number of births minus the number of deaths in a population over a period of time
- low density will result in a low net recruitment
Life history patterns
- Useful patterns that link different types of life history and habitat
1) Cost of reproduction
- trade off resources and growth for reproduction
2) Rapid multiplication (short-lived)
- typical for terrestrial organisms that invade disturbed lands (such as weeds)
- or for newly opened enviornments
- BUT THEY ARE NATURAL SELECTIONS favorite lifestyle
r species (r-selecting)
higher rates of multiplication but short lifestyle
- many small progeny-
K species (K-selecting)
lower rates of multiplication but high resources and so longer lifestyle
- more successful in leaving descendants and are usually crowded
- few large progeny
r/K scheme evidence
true in plants not so true in fish
