Ecology Exam 2

Soil

layer of chemically and biologically altered material over parental material or bedrock

Parental material

Rock or material that soil is created from*

Leaching

Precipitation/groundwater removes some substances from soil by dissolving them and moving them down to lower layers

Weathering

Physical and chemical alteration of rock material near Earth’s surface; occurs when surface water penetrates parent material

Water potential

measure of the potential energy of the water, indicating its tendency to move from one area to another

Dependent on: gravity, pressure, osmotic potential, matrix potential

Matrix potential

Energy by the electric attractive forces between the water molecules and the matrix of soil particles

Field capacity

Maximum amount of water held by soil particles against the force of gravity (gravity = attractive forces in soil)

Wilting point

Water potential at which most plants can no longer retrieve water from the soil; point at which water potential in plant is unable to counteract matrix potential and absorb water, despite the presence of water

Loam

mixture of sand, silt and clay; the best soil for growing plants (40% sand, 40% silt, 20% clay)

Cation exchange capacity

ability of a soil to retain cations; determines fertility of a soil

Transpiration

Process by which leaves can generate water potential as water evaporates from the surfaces of leaf cells into the air spaces within the leaves

Stomata

perforations that allow for water to leave the plant, but also for exchange of O2 and CO2

Cohesion-tension theory

explanation of the mechanism of water movement from roots to leaves due to water cohesion and water tension

Photosynthesis

two part chemical reaction: light reaction, Calvin cycle

Calvin Cycle

ATP and NADPH are used to fix carbon dioxide and produce chemical energy as sugars

C3 photosynthesis

widespread photosynthetic pathway occurring in mesophyll cells; in algae, aquatic plants, and most terrestrial plants

(CO2 + RuBP = G3P as main sugar)

C4 photosynthesis

photosynthesis steps are separated into space (Co2 assimilation in mesophyll cells, rest in bundle sheath cells); in some herbaceous plants in hot and dry climates (sugarcane, sorghum, corn, etc)

CAM photosynthesis

Same biochemical pathway than C4, but separated in time rather than space (stomata open at night, close during day); happens entirely in the mesophyll cell; some succulents from water stressed environments (cacti, pineapple, etc)

Mesophyll cells

exclusively where C3 photosynthesis occurs

Bundle sheath cells

where part of calvin cycle happens in C4

Malic acid

form that carbon is stored as in C4 photosynthesis; is transported to budle sheath cells and is broken int CO2 and pyruvate

Radiation

gain and loss of heat from sun and organisms

Conduction

gain and loss of heat between objects

Convection

gain and loss of heat by movement of gases and liquids

Evaporation

gain and loss of heat by energy used to evaporate a liquid

Thermal inertia

property of a material to resist changes in temperature by both storing and delaying the transmission of heat (smaller organism=lower thermal inertia)

Blood shunting

blood vessels can be shut off using precapillary sphincters, directing the blood back to the heart rather than extremities to prevent heat loss

Temporal environment variation

-predictable variation: day/night, seasons, etc

-unpredictable variation: quick weather changes/events

Spatial environmental variation

-large scale: climate, topography, soil type

-small scale: structure of plants, animal activity, soil composition

Phenotypic trade off

organisms can adapt only to a specific environment; one phenotype experiences high fitness in one environment, another phenotype experiences higher fitness in another environment

Phenotypic plasticity

response to environmental variation by evolving morphology, physiology, behavior, growth, development, reproduction, etc.

Environmental cues

Cues that trigger phenotypic elasticity

• biotic cues

• abiotic cues

Biotic cues

“enemies” (predators, herbivores, parasites, pathogens), competitors, mates

Abiotic cues

temperature, water availability, salinity oxygen, photoperiod, etc

Migration

seasonal movement of animals from one region to another

Diapause

a period of suspended development in an insect or other invertebrate, especially during unfavorable environmental conditions*

Endotherms

produce own body heat (mammals, birds)

Ectotherms

body heat is taken from environment

Hibernation

endotherms reduce heart rate and body temperature*

Torpor

brief periods of dormancy in birds and mammals to cope with low temperatures

Aestivation

shutting down of metabolic process in snails, desert tortoises, and crocodiles in hot and dry summers

Optimal foraging theory

model that describes foraging behavior considering costs and benefits of different foraging strategies

Four possible responses to food variation:

• central place foraging

• risk-sensitive foraging

• optimal diet composition

• diet mixing

Central place foraging

requires acquired food to be brought to a central place

Risk-sensitive foraging

incorporates the risk of predation when making foraging decisions

Optimal diet composition

choice from a range of food items to weigh trade-off of energy vs handling time, and abundance of prey

Life history

schedule of growth, development, reproduction, and longevity

Life history traits

• time to sexual maturity

• fecundity

• parity

• parental investment

• longevity

Fecundity

number of offspring per reproductive period

Parity

number of reproduction events

Parental investment

time and energy given to offspring

Longevity

life expectancy

Competitors

plants that are efficient at resource capture and utilization, often exhibiting large root systems or tall growth to maximize resource acquisition in environments with abundant resources but minimal threats

Stress tolerators

species adapted to survive in harsh conditions with limited resources; typically grow slowly, have slow metabolism, and invest in mechanisms for maintenance and survival, such as detoxification or defenses

Ruderals

hort-lived and fast-growing plants that focus on rapid seed production and dispersal to quickly colonize disturbed areas

Metamorphosis

process of transformation from an immature form to an adult form in two or more distinct stages, involving significant physical changes in body structure, physiology, and behavior

Semelparity

One reproductive event per lifetime

Iteroparity

multiple reproductive events per lifetime

Senescence

increased likelihood of dying as aging occurs

Vegetative reproduction

somatic tissues of the parent produce clones

Parthenogenesis

Embryos are produced from germ lines but without fertilization; normally in egg-producing organisms; offspring can be clones (no meiosis) or genetically variable (meiosis)

Simultaneous hermaphrodites

have both male and female reproductive organs; can sometimes self fertilize

Sequential hermaphrodites

sex changes throughout lifespan

Indeterminate growth 

ongoing process of growth in an organism, which adds new cells and allows the organism to continue to increase in size, produce new parts, or grow after reaching sexual maturity

Isogamy

Organisms produce similar gametes in both males/females

Anisogamy 

Each parent produces a different gamete (i.e. sperm/eggs)

Hermaphroditism

Organism produces both large and small gametes

Sexual dimorphism

observable differences in physical and behavioral traits between males and females of the same species

Haplodiploidy

sex-determination system where males are haploid (developing from unfertilized eggs) and females are diploid (developing from fertilized eggs)

Hymenopterans

bees, wasps, ants, etc.

Frequency dependent selection

if all sexxes have similar fertility, the rarer sex in the population is favored over the commonest sex by natural selection

Primary sexual traits

traits related to fertilization (eg. gonads)

Secondary sexual traits

traits not related directly to fertilization (eg. body size, ornaments, armaments, behaviors)

Mating systems

methods of mating interactions

• promiscuity

• polygamy

• monogamy

• extra pair copulation

Promiscuity 

individuals mate with multiple partners and do not create a lasting social bond

Polygamy

individuals form long-term social bonds with multiple mates

• polyandry

• polygyny

Polyandry

females mating with multiple males; males offer a reward for mating (prey or spermatiphore)

Polygyny

males mating with multiple females

• harem 

• lek

• territory 

Monogamy

species form a social bond at least while rearing offspring

Extra pair copulation

mating outside of a recognized pair bond, often in socially monogamous species

Harem

a polygynous mating system where one male defends a group of females and their offspring for the purpose of exclusive or favored mating

Lek

an area where males of a particular species gather to display and attract females for mating, without any other resources being offered

Territory

a specific area that an animal aggressively defends from conspecifics (individuals of the same species) to secure access to resources and opportunities for mating

Sex roles

role of each sex in reproductive interactions

Material benefit

food, quality of territory, location to lay eggs, etc

Non-material benefit

good genes hypothesis, good health hypothesis

Runaway sexual selection

process where mate choice and trait elaboration create a positive feedback loop, leading to the evolution of increasingly exaggerated ornaments or behaviors that may be costly to survival

Handicap

individuals with high fitness can afford to produce costly, elaborate, or disadvantageous signals to honestly communicate their genetic quality to potential mates or rivals

Honest trait

biological signal that reliably conveys accurate information about an individual's quality or condition to other organisms (ie. vibrant feathers in male peacock)

Sexual conflict

mating partners behave according to their own self-interest leading to conflict

Mate guarding

one individual prevents the other from participating in extra-pair copulation

Copulatory plugs

plugs make future mating impossible

Infanticide

new dominant male kills offspring of last male to increase own fitness

Traumatic insemination

physical harm to females upon mating to ensure the female lives shorter and lays fewer eggs the more males they mate with

Good genes hypothesis

the idea that females choose mates exhibiting certain traits because these traits signal underlying superior genetic quality, which increases the offspring's chances of survival and reproductive success

Good health hypothesis

individuals choose mates based on traits that honestly signal superior genetic quality

What materials does soil contain?

minerals, decomposing organic matter, community of microorganisms, invertebrates and insects

What does soil composition depend on?

parental material, climate, vegetation, age, local topography 

What impacts water potential?

gravity, pressure, osmotic potential, matrix potential

What is the soil composition of dry climates? Why?

Little rainfall causes slow parent material breakdown and sparse plant growth; little organic material is added to soil; shallow soils with close-lying bedrock layer