INB 373 Exam 2

Explain why the physical environment is the ultimate determinant of the geographic distribution of a species.

1. organism gets energy and resources from its physical environment

2. organisms need these things to survive, reproduce, and grow

3. physical environment is the ultimate constraint on geographical distribution

Differentiate between adaptation and acclimatization.

Adaptation→ long-term genetic, physiological, morphologic, or behavioral changes to enhance fitness in a population or environment

• natural selection, long-term, generational, genetic

Acclimatization→ short-term adjustment through physiological, morphological, or behavioral changes to minimize stress from environment

• reversible, individual, short-term

How can adaptation and acclimatization may result in trade-offs with other functions.

acclimation and adaptation require investment of energy and resources by organism, some trade-offs include:

• marine species develop thermal resistance at cost of reduced reproduction

• organisms might trade off large size for higher number of offspring

Describe how the body temperature of an organism influences its functioning.

Temperature regulates:

• enzyme activity→ metabolism

• physiological function→ movement and organ function

• thermoregulation

differentiate:

• Ectotherm

• Endotherm

• Homeotherm

• Poikilotherm

• Ectotherm→ org receives heat from outside

  • ex. reptiles and amphibians

• Endotherm→ org generates heat from within

  • ex. birds and mammals

• Homeotherm→ org that maintains constant body temp

  • ex. mammals

• Poikilotherm→ org allows body temp to vary

  • ex. reptiles

Identify the heat exchange mechanisms used by plants and animals to regulate their body temperatures.

• loss of energy at night via IR radiation?

  • create burrows or nurse plants

• air is too cold?

  • get closer to warmer ground

  • locate in sun

• soil is too hot?

  • locate up the ground

  • be nocturnal

List the four factors that influence the movement of water from a high-energy state to a low-energy state in biological systems.

1. Osmotic potential→ water flows from high water conc to low water conc (water moves towards solutes)

2. Pressure potential (turgor) → pressure on water, water flows from high pressure to low (low pressure to even lower)

3. Gravitational pressure→ uphill to downhill

4. Matric potential→ interacting with differences forces (important in soil bc of various pressures)

How organisms can control water gains and losses by adjusting resistance to water movement? Are trade-offs involved?

• adjust water movement

  • close stomata or skin adaptation

define:

• Hyperosmotic

• Iso-osmotic

• Hypo-osmotic

• Hyperosmotic→ more saline in environment than org cells

  • Cells shrink (most saltwater orgs)

• Iso-osmotic→ same salinity in environment and org cells

  • Many marine orgs

• Hypo-osmotic→ less saline in environment than org cells

  • Cell swells (most freshwater orgs)

Differentiate autotrophy from heterotrophy.

• autotrophy→ convert energy from sunlight or inorganic chemicals into energy stored in C-C bonds of carbs

• heterotrophy→ acquire energy by consuming organic compounds from other organisms (dead or alive)

Chemosynthesis

→ process uses chemical energy to create food, rather than sunlight.

bacteria and archaea oxidize inorganic substrate to obtain E— used to fix carbon and synthesize sugars through C-C bonds

Outline the steps in the light-driven reactions and carbon reactions of photosynthesis, describing their outcomes and how they produce energy-rich compounds in photoautotrophs.

1. light-driven rxns→ light energy is harvested and used to split water to provide electrons to make ATP and NADPH

2. carbon (dark-driven) rxns→ CO2 is fixed to calvin cycle and carbohydrates are synthesized

Illustrate how photosynthetic organisms acclimatize and adapt to variations in the intensity of light.

• more light→ more photosynthesis but to a limit

  • light saturation curve— autotrophs have ability to acclimate through different leaf morphology

Evaluate the trade-offs that result when a plant controls water loss

• more water→ plants open stomates, increase CO2 uptake, release O2

  • water conversation vs energy gain

• closing stomates (low water) → increase chance of light damage

  • no calvin cycle→ energy acclimates→ damage membranes

  • plants have mechanisms to dissipate E as heat

Describe how temperature influences photosynthetic rates.

• temperature→ impacts enzymes and membranes

• plants acclimate to best grow in environment

through its effect on enzymes and chloroplast membranes.

Explain the difference between photosynthesis and photorespiration and evaluate conditions where photorespiration is detrimental to plant growth.

• photosynthesis→ convert light E into chemical E using CO2 and water

  • rubisco binds CO2 to initiate carbon fixation

• photorespiration→ wasteful process where rubisco binds O2 instead of CO2— reduce photosynthesis efficiency

  • detrimental to plants growth when hot, high light intensity, and low CO2 concentrations

Summarize how biochemical and anatomical adaptations associated with the C4 photosynthetic pathway minimize photorespiration, thereby enhancing photosynthesis rates.

C4 pathways: reduces photorespiration (evolved independently several times→ great adaptation)

• Pathway big picture: separating the light and dark reactions, occur in different tissues

  • spatial separation of events

• Trade-off: need specialized cells (energy), need PEPcase

Ex. grasses on campus → # of C4 plants increases with temperature

Describe how crassulacean acid metabolism reduces water loss relative to the C3 or C4 photosynthetic pathways.

Crassulacean Acid Metabolism (CAM) pathway: during day stomates closed and night stomates open to get carbon

• Pathway big picture: temporal separation of dark and light reactions

• Nighttime CO2 uptake so water loss minimized during transpiration when evap rates are high

Ex. mostly succulents & epiphytic→ cactus and pineapples

Life history

the pattern of survival and reproduction (and growth) events that are typical for a species, essentially describing the key stages of an organism's lifecycle

Summarize the key characteristics that make up the life history of an organism.

• age and size at sexual maturity

• amount and timing of reproduction

• survival and mortality rates

• dispersal and dormancy

How genetics and the environment act as controls on life history traits.

• genetic control

  • subject to natural selection→ favors survival and reproductive fitness

  • adaptations

• environmental control

  • phenotypic plasticity— one genotype can produce diff phenotypes under different conditions

  • ex. toads omnivore morph selected in ponds not at risk for drying up and carnivore morph selected for in risky pons

What are the benefits and costs associated with sexual reproduction.

• advantage: recombination

  • promote genetic variation→ better adaptations

• disadvantage: cost of producing males

  • males cannot help grow population— only role is to provide half of genome

  • recombination can get rid of favorable genes

What are the benefits and costs associated with asexual reproduction.

• advantage:

  • rapid population growth

  • less E and resources required

• disadvantage:

  • lack genetic diversity→ vulnerable to environmental changes

Describe how additional complexity in a life cycle, such as larval and adult forms, may benefit a species.

→ at least two stages with different body forms that live in different habitats and eat different foods

• metamorphosis→ abrupt transition bt larval and juvenile stages (insects)

• benefits?

  • dispersal: movement of orgs or pops from their birthplace→ reduce competition, use outside resources, colonize new area, escape disease/predation

  • dormancy: suspend growth to survive bad conditions→ small seeds, spores, and eggs allow less metabolic energy to stay alive

Illustrate how the number of offspring may affect the size of those offspring.

organisms tend to produce large number of small offspring OR small number of large offspring

Explain how providing care to offspring may compromise other functions in adults.

More # in clutch— more chances of having offspring survive but more energy investment from parent

Less # in clutch— less energy to invest but fewer chances of offspring survive

optimize max # of offspring to survive→ trade-offs

How does resource allocation to offspring impact parent?

Allocating resources to reproduction can decrease individuals growth rate/survival rate/potential for future reproductive success

→ lower ability to forage, increase predation, increase risk of disease

Contrast the benefits and costs associated with small size in early life cycle stages.

• benefits? lower E requirement, rapid reproduction, dispersal, access to niches

• costs? higher predation, less competitive, vulnerable to environmental change

How adaptations at specific stages in a complex life cycle may benefit the species.

flexibility to respond to different selective pressures in different life stages

ex. animals larval stage allows for prioritizing feeding while adult for dispersal and reproduction

Compare the benefits of semelparity and iteroparity in the context of total lifetime reproduction of an organism.

• semelparity→ reproduce once in a lifetime (ex. salmon)

  • benefit? maximize reproductive output (large # offspring at once) + energy efficient (one big investment)

  • cost? high mortality risk (failure means no chance of reproduction)

• iteroparity→ reproduce multiple times in a lifetime (ex. humans)

  • benefits? multiple reproductive opps (if one fails future may succeed)

  • costs? energy trade-off (reproduction spread out means multiple investment periods)

Evaluate the environmental conditions that would favor the persistence of r-selected and K-selected species.

• Live fast, Die young→ r–selection

  • Selection for high population growth rates→ frequent disturbances

  • Favor short life spans, rapid development, early maturation, low parental investment, high reproduction rates

  • Ex. most insects, small vertebrates (mice), weedy plants (flax)

• Steady wins the race→ k-selection

  • Selection for lower growth rates in populations that are near or at k→ stable conditions

  • Favor long-lived, develop slowly, late maturation, invest heavily in each offspring, low reproductive rate

  • Ex. large mammals (elephant) and reptiles, oak and maple trees

Describe the trade-offs in plant allocation described in Grime’s competitive/stress/ruderal model.

→ categorizes plant strategies based on their adaptation to environmental stress and disturbance, classifying plants as competitors, stress-tolerators, or ruderals.

• Stress→ any biotic factor that limits growth

• Disturbance→ any process that destroys plant biomass

• Triangular model:

  • Competitive (high comp)

  • Ruderal (high disturbance)

  • Stress-tolerant (high stress)

Show how differences in species size or age can be accounted for in describing the allocation of energy and resources to reproduction and other life history stages.

Size vs Age trade-offs:

• growth vs reproduction energy allocation

• survival vs offspring quantity

• parental investment vs independence

How natural selection can lead to the evolution of adaptive behaviors.

Behavior is adaptive→ NS should favor individuals whose behavior make them efficient at…

• foraging

• getting mates

• avoiding predators

How can behavior be grouped?

• Proximate cause→ immediate, mechanical influence

  • hereditary, developmental, structural, cognitive, psychological, or physiological; aspects of behavior

  • Ex. bird migration→ find food

• Ultimate cause→ historical reason why an organism has a trait in terms of NS

  • Why has this behavior been adapted?

  • Ex. snakes came from lizards who were able to open jaws wide… overtime as the legs dropped their prey changed and jaws continued to get larger/disconnect

  • Ex. bird migration→ season pattern where birds that migrated were able to survive and reproduce so migration was adapted

Explain the theory of optimal foraging by outlining the factors that influence the net benefit of foraging.

Optimal foraging→ NS works on organisms to maximize energy acquired per unit of feeding time

• How much energy the animal gets relative to amount of time it spends searching (s) and handling/eat (h) food

• Spend more time looking for prey than actually getting E gain→ move on

Summarize what determines optimal foraging in an area with different food densities with reference to the marginal value theorem.

marginal value theorem→ animals foraging in an area with patches of food/resources of different densities will deplete rich patches 1st and leave them once density of region is the same as average of the entire area

Describe how the presence of predators can impact foraging behavior.

• avoid being see by predators

• detect predators

• prevent attack

• escape once attacked

ex. antipredator behaviors: slugs have spikes, sea otters sleep with one eye open, butterflies confuse predators with eye-looking-wings

Describe examples of the behaviors utilized by animals to increase their access to mates.

sexual reproduction has high sexual dimorphism

males often larger and brighter, have weapons like horns, and perform dances or rituals to attract females

What conditions favor selectivity by females versus males?

1. anisogamy: eggs vs sperm in size (eggs have a reproductive cost)

2. females put more resources into raising offspring

3. reproductive potential higher for males than females

intrasexual vs intersexual selection

• Intrasexual selection→ bt same sex

  • competition between males

• Intersexual selection→ charming the other sex, courtship

  • sexual dimorphism

Examples of female choice selection hypothesis’ (2)

• Handicap hypothesis: a male that can support a costly and uniquely ornament is likely to be vigorous, with overall high genetic quality

  • Ex. european green lizard– brighter males have lower rates of blood parasite infections and are selected for

• Sexy son hypothesis: females receives indirect genetic benefits through her sons who will themselves be attractive females and produce many grand-offspring

  • Ex. stalk-eyed flies– females choose mates from their population of males when mixed with males of their own and outside populations

    • Females choose what they know!

Describe the potential benefits and costs of species living in groups.

• Safer bc watch out for predators more

  • Ex. hawks predate pigeons (larger group–less likely to be eaten)

• Easier to deprive area of resource

  • Ex. larger groups spend more time searching for food than eating

• Optimal group size? There is a cost to joining a group at some point

population

Populations→ group of interacting organisms in the same place, at the same time, in the same species

population density

Density→ number of individuals per unit area or volume

Population size (“N”)

→ number of individuals in a population

• density X area or volume occupied by population = estimate of “N”

• Methods depend on species

Compare the different ways in which individuals are defined, including the terms clones, genets, and ramets.

• clone→ genetically identical individual from a single parent through asexual reproduction

• genet→ group of ramets that originate from a single seed

• ramet→ single physiological individual produced by clonal propagation

Compare the different methods used to measure the abundance of individuals within populations or species.

• capture, mark, recapture at some distance away

• remove individuals, then measure recolonization

• measure colonization in empty sites

Describe the relationship between populations, metapopulations, and geographic ranges for species.

• Population— group of interacting organisms in the same place, at the same time, in the same species

• Subpopulations— one population connected through high rates of migration– population dynamics allows behaviors to be same

• Metapopulation— multiple populations within a smaller area (higher rates of migration but low enough to have own dynamics)

Compare the different dispersion patterns of populations.

dispersion of individuals within a pop ~ spacing with respect to one another

• regular distribution→ over dispersed

• random distribution→

• clumped (heterogenous) distribution→ under-dispersed

Describe the ways clumped distribution occurs.

• species kept out of its fundamental niche by competition, pathogens, predation

  • fundamental vs realized niche

• fragmented habitat

• edge effect- edge of habitat are different from center

  • different temp/winds

  • easier predation, more human disturbance

  • ex. nest parasites thrive in edge bc replace eggs with own

• corridor- linkage between two suitable habitat patches

Describe the factors important to the suitability of habitat for populations and species.

The suitability of habitat depends on both abiotic and biotic features of the environment, including factors that affect physiological tolerances, resources, and species interactions.

Explain how the distribution and abundance of species can reflect their evolutionary and geologic history.

• evolutionary?

  • distribution reflects origins, adaptation, and diversification

  • ex. marsupials abundant in Australia due to early isolation→ adaptive radiation bc of continental drift

• geologic?

  • events like continental drift, glaciation, mountain formation, etc.

Differentiate source and sink sites (context of migration).

• source→ local demographic surplus arises in good quality habitats

  • provide migrants to sink habitats

• sink→ local demographic deficit occurs in habitats of poor quality

  • habitats are mainatned with migration from source areas

Describe how the rates of colonization and extinction of populations affect metapopulations.

→Higher rates of migration but low enough rates that each population has own dynamics

• Pattern of extinction and recolonization of patches

  • recolonization→ new subpops establish in unoccupied habitats

  • extinction of subpops causes decline in metapop

Hard to prove– few real examples

List the different patterns of population growth observed in nature.

1. exponential growth→ rapid increase in number of individuals in the population (like J shape)

2. logistic growth→ similar to exponential but stabilizes at carrying capacity at the end (like S shape)

3. fluctuating→ variation in population going up and down (slow growth rates)

4. cycling→ pattern of up and downs depending on season

Describe the special case of population cycling.

• Not damped oscillation→ N really high at one end and really low other end– what does nutrient level allow→ overshoots and undershoots depending on timeline

• Damped oscillation→ up and down around carrying capacity

• No oscillation→ slow growing species where take long time to reach carrying capacity or really fast growing species

Justify why fluctuations in population growth rate can increase a population’s risk of extinction.

fluctuating populations show slower growth rates- result in smaller population sizes with greater risk of extinction

List and describe the ways that chance events can drive small populations to extinction.

• genetic drift→ random increase in freq if bad alleles, loss of good alleles

• demographic stochasticity→ by chance particularly low survival or fecundity rates

• catastrophes→ environmental stochasticity

Define geometric population growth.

→ also known as discrete model, measured population growth in set time intervals (like once a month)

• population begins at N₀

• constant growth rate of λ

  • λ>1 means pop grew

  • λ<1 means pop declined

  • λ=1 means pop size constant

• N₁=N₀*λ

Define exponential population growth.

→ birth and deaths happen continuously and rate at which they happen does not chance over time

• parameter is r:

  • r>0 means pop grew

  • r<0 means pop declined

  • r=0 means pop size constant

• N_t=N₀*e^rt

Define density-independent factors and describe how they affect population size and growth rate.

→ affect per capita growth rate independent of population density

ex. natural disasters like tsunami, forest fires, hurricane

impact? direct mortality, reduced reproductive success, population decline

Define density-dependent factors and describe how they affect population size and growth rate.

→ limiting factors that affect population size and growth rate based on population density

ex. competition, disease, predation

• positive density dep→ positive feedback loop

  • N increases→ survival or fecundity increases

  • ex. whales hunted, lower N means less chance of mating

• negative density dep→ negative feedback loop

  • N increases→ survival or fecundity decreases

  • ex. too many sheep in New Zealand led to overgrazing

Describe the growth patterns of the U.S. population.

Combination of logistic and fluctuated growth

Justify the use of life tables to determine population growth and size.

→ provide a structured method to analyze age-specific mortality and fertility rates

-can use them to make pop growth prediction

-can compare diff populations

Describe how age structure influences population growth and population size.

→ age structures shape fertility and reproductive stages

• age-based diff in avg fecundity

• age-based diff in survival rates

• Ex. compare

  • Sea turtle pop A mostly animals > 20 yo (reproductive)

  • Sea turtles mostly juvenile <5 yo (pre-reproductive)

Describe how size structure influences population growth and population size.

• size-based diff in avg fecundity

• size-based diff in survival rates

• Ex. plants, coral, etc: differences among individuals size-based, more than age-based

Describe how sex structure influences population growth and population size.

• sex-based diff in avg fecundity

• Sex-based diff in survival rates

• Ex. each female has 5 offspring/yr

  • Moud pop A has 50 males & 50 females

  • Mouse pop B has 80 males & 20 females

Compare the three types of survivorship curves.

• Type 1 survivorship curve: most individuals survive to old age

  • Ex. doll sheep→ make it to old age and get slow and die

• Type 2 survivorship curve: individuals face a constant risk of mortality at all ages

  • Ex. bird has constant mortality

• Type 3 survivorship curve: most individuals die young

  • Barnacle→ make lots of offspring but few attach to rocks so immediate newborn high death rate

Outline the simple epidemiological models categories (3)

• Susceptible→ can age out as immune system grows

  • all hosts susceptible when I and R are ~0

• Infected

• Removed (or recovered) → recover naturally or vaccinated

  • need majority of pop in this section to stop spread of disease

Epidemiology

→ science of disease dynamics at the level of the host population–essentially applied populated dynamics

• Work for university, NIH, public health, etc

• Not same as pathogen dynamics within a host (that is molecular biologist)

Structures of populations

Stage structure→ different selective pressures (and fitness) on individuals within a population at different life stages

• spatial structure→ refers to the geographic arrangement of individuals or populations

  • abundance

  • density

  • dispersal

• temporal structure→ examines how populations change over time

  • predation

  • competition

  • disease

Behavioral Ecology

→ study of the ecological and evolutionary basis of animal behavior

• Behavior= genes + environment

• Behavior is adaptive→ NS should favor individuals whose behaviors make them efficient at…

  • Foraging

  • Getting mates

  • Avoiding predators

• Trade-offs?

  • Foraging vs Survival

  • Prey choice vs Time spent

  • Living in a group→ don't get eaten but still get to eat!

Sexual selection

→ individuals with certain characteristics gain an advantage over other of the same sex solely with respect to mating success

Ecological factors affect mating system

Dependent on resource availability and distribution

• Resources are clumped→ one male controlling territory so more polygyny

• Resources scattered evenly→ monogamy more common

Physiological ecology

→ study of interactions bt orgs and their environment and how these interactions influence their survival and determines their geographical ranges

• Availability of energy and resources

• Extreme conditions can exceed tolerance limits

  • Plants cant move→ good indicators of physical environment

Climate envelope

→ range of conditions over which a species occurs, can predict response to a climate change

• Actual distribution: where a species currently lives

• Potential distribution: where a species could live→ climate envelope

  • Ex. Aspen trees→ limitations: flowers surviving frost, fruit ripening

How to organisms and populations cope with a changing environment

• Tolerance

• Avoidance: migration, range shift (butterfly go up mountain for ideal temp), dormancy

• Acclimate: individual, short-term, reversible process

  • Genetic underpinning

• Adaptation: natural selection meaning this is on population/species level, long-term (genetic change)

What are ecotypes?

→ populations with different adaptation to unique environments

• Ex. hypoxia at high altitudes

  • Andean→ human pop have high RBC concentration and large lung capacity

  • Tibetan→ human pop have faster breathing rates and higher blood flows

How do plants deal with dry vs salty soils?

• Dry soils:

  • Higher concentration of organic solutes

  • Grow only during wet season

  • Close stomates

  • Shed small roots during drought

  • Store water (succulents)

  • Small leaves hence cool– evap slower

  • Thick boundary layer

• Salty soils:

  • Salt exclusion (proton pump to get rid salt)

  • Salt excretion

  • Organic solutes to maintain (-) root potential

  • Salt tolerance

What is water potential and how does it look on a plant?

Potential→ water moves from places of higher water potential to lower water potential (from + to - potential)