BIS2B MT1

Properties of life

order and organization

energy processing

growth and development

evolutionary change

regulation (homeostasis)

reproduction

response to stimulii

what is the smallest unit of life?

The smallest unit of life is a cell, which is capable of performing all the fundamental functions of living organisms.

what is ecology?

Ecology is the study of interactions between organisms and their environment, including relationships within and between species, as well as with abiotic factors.

biotic interactions

are interactions among living organisms, such as predation, competition, and mutualism. (bee feeding from flower)

abiotic interactions

are interactions between living organisms and non-living elements of their environment, such as temperature, water, and nutrients. (precipitation or rainfall)

what is evolution?

Evolution is the process through which populations of organisms change over time through genetic variation, natural selection, and adaptation.

What do ecology and evolution have in common?

mate choice, natural selection, competition, phenotype, mutualism, mutation

what is biodiversity?

the variety of life on earth

How do we organize and classify biodiversity?

Biodiversity is organized and classified using taxonomic categories such as species, genus, family, order, and higher ranks that reflect evolutionary relationships like class, phylum, and kingdom. Morphological variation widens as we climb up the categories.

species richness

the number of different species present in a given area, contributing to overall biodiversity.

species evenness

the relative abundance of each species

species diversity example

includes both species richness and species evenness in a community, providing insights into the complexity and health of ecosystems.

biodiversity “hotspots”

places with many species that are endemic (occur in no other regions)

climate

average and annual variationin temperature and precipitation patterns in a region over the long-term

also a major determinant of the types of plants in an area

orographic uplift

air driven aloft by mountains

rainshadow

reduced rainfall in the lee of mountain ranges

regional precipitation patterns: orographic uplift and rain shadows

weather

temperature and precipitation over a short period of time (days to weeks)

climatographs

describing climate in a single graph

tradeoff

the relationship between the benefits of a trait in one context and its costs in another context

The Principle of Allocation

Each organism has a limited amount of resources it can use for all life processes: obtaining food, escaping predators and resisting pathogens, reproduction, growth and metabolic functions.

Resources allocated to one function cannot be applied to another function.

All allocation decisions result in trade-offs: allocation tradeoffs like the number of offspring and investment per offspring

Autotrophs (self-feeding)

can live exclusively on inorganic sources of carbon, nitrogen, and other essential resources

heterotrophs (other-feeding)

use organic molecules (formed by other organisms) as source of carbon, nitrogen, energy and other essential resources

photoautotrophs

use light as the energy source

photosynthesis

Liebig’s law of the minimum

growth is not determined by the total amount of all resources available, but by the amount of the resource that is most scarce compared to how much the plant needs

more roots, fewer shoots

obtain more N & water, less C

more shoots, fewer roots

obtain more C for growth, less N & water

root to shoot ratio

ratio of below ground to above ground biomass

herbivores

consume plant material — long guts, detoxification enzymes, grinding dentition

carnivores

attack and consume animal material — adaptations for pursuit and subdual prey

omnivores

consume both plant and animal matter — generalist morphologies

detritivores

consume dead plant or animal matter — adaptations to subsist on low quality food

how do generalists choose among different prey?

1. Effort required to capture and consume prey (costs)

   • search costs

   • relative size and mobility of predator and prey

   • physical defenses (spines, shells, ability to hide or escape)

   • defenses that are toxic or reduce digestibility

2. Value of the prey (rewards)

   • energy content

what other goals do foragers have when feeding?

1. avoid predators or harsh abiotic conditions

2. find mates or protect offspring

3. obtain specific micronutrients or vitamins

Adaptation

evolutionary change in genotype that maximizes performance

ex. innuit people have lived above the arctic circle for 10,000+ years: have developed barrel shaped bodies, short limbs, subcutaneous fat all over body

** the ability to acclimate is an adaptation- and it varies among species

acclimation

change in phenotype within an individual’s lifetime to maximize performance (usually reversible)

ex. world’s greatest long distance, cold water swimmer optimized at 40% body fat

endotherms

body temperature is determined primarily by metabolic energy

ex. humans, mammals

** high benefit-high cost strategy that only works when resources are predictably abundant

ectotherms

body temperature is determined primarily by external conditions

ex. reptiles

** rely on morphological and behavioral mechanisms of temperature regulation (burrow for warmth at night, use sun and rocks for warmth during the day, shade/water to cool down)

transpiration

evaporation of water through stomata

C3 photosynthesis

the most common and ancient system

• conduct photosynthesis using RUBISCO enzyme in mesophyll

• does well in low temp, light, and wet conditions

• stomata stay open longer and much water is lost per C gained

  • ex. crops like wheat and rice

C4 photosynthesis

evolved later (many times); more water efficient

• uses PEP carboxylase to fix carbon, allowing stomata to remain closed during heat, resulting in less water loss. Common in hot, dry environments, with crops like corn and sugarcane.

• plants spatially separate uptake of CO2 and its fixation

• ex. some grasses, weeds, and shrubs

  inefficient at low light, temp, or wet conditions

Fundamental Niche

the set of environmental conditions (e.g. temperature, moisture, salinity) under which individuals of a species can grow and reproduce

• where it could be

Realized Niche

where it is actually found

• smaller than fundamental

• where does it actually occur after accounting for biotic interactions (like parasites)

Probability of being eaten

P(detection) x P(capture) x P(consumption)

** reducing any of these terms reduces predation… BUT these adaptations also have costs

Avoid detection techniques

Fixed or Flexible Camouflage/Crypsis

• Costs: limited mobility, tied to particular habitat types

Shelter/Burrow

• Costs: reduced feeding time, energy spent maintaining shelter

Avoid capture

herding together

• reduced predator efficiency, cooperative defense

  • costs: energy spent on group coordination, increased competition for resources

Avoid consumption

Plants cannot avoid detection or capture

• chemical defenses (foxglove; cardiac glycoside)

• physical defenses (raspberry thorns)

Slow/obvious animals are easy to catch

• sea slug (toxins)

  • pangolin (armor)

Other costs of defense

fast growing plants are more susceptible to herbivores

Semelparous

organisms that reproduce once and then die

ex. lobelia telekii

• harsher environment

iteroparous

organisms that reproduce many times

ex. lobelia keniensis

R-selected “fast”

many, small highly dispersed offspring

small body size

short life, early reproduction

allocate to rapid growth and high reproduction

little parental care

semelparity (reproduce one time before death)

K-selected “slow”

fewer, higher quality offspring

large body size

long life expectancy, delayed reproduction

allocate to defense, persistence

high parental care and investment

iteroparity (reproduce many times before death)

Environmental: r-selected

environmental conditions keep populations at low density

habitat is

• unpredictable, variable

• harsh, distured

mortality is independent of other organisms and often catastrophic

Environmental: k-selected

environmental conditions allow populations to reach high density

habitat is

• predictable

• favorable for growth & survival

mortality is often caused by interactions with other organisms

Population

collections of organisms of the same species living in the same place at the same time are called a population

Rate of change in population size over time

dN/dt = (b-d + i-e) * N

N = population size

t = time

b = birthrate

d = death rate

i = immigration rate (come)

e = emigration (leave)

open population

numbers change due to immigration and emigration from outside the population in addition to births and deaths

closed population

numbers change only due to births and deaths

per-capita growth rate (r)

b-d = (birth rate - death rate) = the (r)

closed system population growth equation

dN/dt = rN

Integrate from 0 to time t to predict population size at time t:

Nt = N0 e^(rt)

Nt = # at time = t

N0 = # at time = 0

e = 2.717 (base of natural long or ln)

r = per capita growth rate (b-d)/intristic rate of increase

t = time

doubling time

time required for population to increase by 100% (double in size)

** bigger r = smaller doubling time

Exponential

the per-capita growth rate is constant or density independent

logistic (asymptotic or sigmoidal)

the per-capita growth rate varies with population density or is density dependent

density independent limitations

agent of mortality is not triggered by population density

density dependent regulation

per individual birth and death rates depend on density

ex. competition for resources, predation, starvation, disease, weather

carrying capacity (K)

the maximum population size that can be supported by available resources or physical space

logistic population growth: including density dependence

Demography

a study of the vital statistics (birth, death) of a population and how they vary with age

life table

vital statistics of a cohort (group of individuals born about the same time

direct method: follow a cohort through time

indirect method: determine the age of death from remains (skulls, etc)

survivorship (lx)

proportion of individuals surving to age or stage x

Type I survivorship curve

low mortality until the latter stages of life (humans, large mammals, dinosaurs?)

Type II survivorship curve

probability of surviving to the next year is independent of age (birds)

Type III survivorship curve

high juvenile mortality but low adult mortality (most common, most invert, plants)

fecundity (mx)

average number of offspring produced by individual of age x

Net reproductive rate (R0)

average number of offspring produced by an individual during its entire lifetime

** R0 = the product of survival and fecundity, summed over all age classes = S lxmx

r=0

stable population age distribution given by the survivorship curve lx

r>0

growing populations have an excess of individuals in younger ages

r<0

decreasing populatios have an excess of individuals in older ages

lowered rates are:

1. optimal because of the competitive environment in which offspring are raised

2. a consequence of non-genetic (cultural) mechanisms of inheritance

3. a maladaptive by-product of rapid environmental change that has no adaptive value