mini mod.: biomes to population

Question 1

defining biomes

Answer 1

• embracing each region with its characteristic climate, day-length, topography, flora and fauna
• Community of plants and animals that have common characteristics for the environment they exist in.
• Distinct biological communities that have formed in response to shared physical climate.
• Broader term then ‘habitat’; biome can comprise a variety of habitats.

Question 2

 Tropical rainforest

Answer 2

no dry season
10 degrees N - 10 degrees S (2 tropics)
mean temp >18degreesC
1680mm - >10m rainfall
high biodiversity

one of most threatened biome
large scale fragmentation
patch isolation reduces

Question 3

Borel forest/taiga

Answer 3

Worlds largest biome(except ocean) at 29%
High N latitudes- 50°N to 70°N
Mostly pines, spruce and larches

Terrestrial biome
Lowest av. temp after tundra
Sub arctic climate
Summer <4months
Winter 5-8months
Temp 30- -54°C

2 major types:
Southern-closed canopy forest
Close spaced trees+mossy ground cover
Clearings with shrubs+wildflowers common

Northern-lichen woodland or sparse taiga
Trees more spaced and lichen ground cover
Forest cover often stunted in growth form

Question 4

Temperate deciduous forest

Answer 4

• Dominated by trees that lose their leaves each year.
• Found in areas with warm moist summers and mild winters.
• Three major areas occur in Northern Hemisphere:
  
  • NorthAmerica(mainlyEastern)
  • EastAsia
  • Europe
• Typical trees: oak, maple, beech and elm (Northern) and southern beech, Northofagus spp. (Southern).
• Diversity tree species higher:
• where winter milder
• mountainous regions that provide array of soil types.
• Largest intact, temperate deciduous forest in the world is protected inside 6 million acre Adirondack Park, upstate New York.

Humans colonized areas:
* Harvested wood for timber and charcoal.
* Many forests small fragments dissected by fields and roads.
* Introduction of exotic diseases a threat to forest trees (e.g. chestnut and elm).
* Animals such as deer (clearing rather than forest animals), expanded range and proliferated.

Question 5

Desert

Answer 5

• Barren area of landscape where little precipitation occurs.
• Usually experiences from 25 to 200 mm per year of precipitation; in some years no precipitation at all.
• Living conditions hostile for plant and animal life.
• Lack of vegetation exposes ground to denudation.
• 33 % of Earth’s land surface is arid or semi-arid.

Deserts classified by:
* precipitation
* temperature
* causes of desertification
* geographical location.

Three types of desert climates:
* Hot–between30°S and 30°N (horse latitudes)
* Mild - west coasts of continents; near-tropical locations
* Cold - typically located in temperate zones.
(Arctic and Antarctic regions have polar climates.)

• Stenocara gracilipes, beetle native to Namib Desert, Southern Africa.
• Very arid area: 1.4 cm rain per year.
• Beetle survives by collecting water on rough back surface from early morning fogs and humid air.
• Deserts increasingly seen as sources for solar energy.
• Mojave Desert (USA) Solar Park – large areas covered in mirrors; combined capacity 354 MW.
• Sahara Desert – estimated all of the world’s electricity needs could be supplied from from 10% of Sahara. Major European interest – DESERTEC.
• Negev Desert, Israel. Many solar plants with eventual aim to supply all of Israel’s needs for electricity.

Question 6

Anthromes

Answer 6

• Also known as Anthropogenic or Human Biomes
• Globally significant ecological patterns created by sustained interactions between humans and biomes / ecosystems.
• They include:
• Urban
• Village
• Cropland
• Rangeland
• Seminatural anthromes.

Question 7

Ecosystem definition

Answer 7

Whole community of living organisms in conjunction with the non-living components of their environment (e.g. air, water and mineral soil)

Biotic and abiotic components linked together through nutrient cycles and energy flows.

include:
* Primary producers
* Decomposers and detritivores
* Pool of dead organic matter
* Herbivores, carnivores and parasites
* Physico-chemical environment
* source and sink for energy and matter

Question 8

Productivity

Answer 8

PHOTOSYNTHESIS and RESPIRATION : opposing processes driving global carbon cycle
* Photosynthesis: terrestrial plants use atmospheric CO2 as carbon source
* Respiration: plants (animals and micro-organisms) release carbon locked in photosynthetic products back to atmospheric and hydrospheric carbon compartments

• Primary Productivity: rate biomass produced per unit area by plants, the primary producers (expressed: Jm-2day-1; kgha-1year-1; gCm-2year-1)
• Gross Primary Productivty (GPP): total fixation of energy by photosynthesis
• Autotrophic Respiration (RA): proportion energy fixed by photosynthesis lost by respiration
• Net Primary Productivity: difference between GPP and RA; represents actual rate of production of new biomass available for consumption by heterotrophic organisms (bacteria, fungi and animals).
  GPR-RA=NPP
• Secondary Productivity: rate production of biomass by heterotrophs.

Question 9

Patterns in primary productivity

Answer 9

• Latitudinal trends in productivity
• Seasonal / annual trends in primary productivity
• Autochthonous and allochthonous
• Variations in productivity to biomass relationship
• Seasonal trends and latitudinal trends

autochtohonous and allochthonous
Ecosystems can receive organic matter from sources other than its own photosynthesis (e.g. import of dead organic matter prodced elsewhere)
* Organic matter produced by photosynthesis within an ecosystem’s boundaries: autochthonous
* Organic matter imported from elsewhere: allochthonous

Question 10

energy efficiency

Answer 10

Consumption efficiency
= Energy consumed (C) / Energy available (T)

assimilation efficiency = energy assimilated (A) / energy consumed (C)

growth (production) efficiency = energy fixed in tissue (P) / energy assimilated (A)

• Ecological efficiencies vary according to metabolic costs:
• Endotherms – warm blooded animals – high metabolic costs; over 90% of energy income may be spent in maintaining body temperature
• Ectotherms – cold blooded animals – rely on external heat sources; can devote more of their energy to production.

Production efficiency: percentage of assimilated energy incorporated into new biomass

Question 11

Communities-definition

Answer 11

A naturally occurring group of plants, animals and other organisms interacting in a unique habitat.
The complex range of interactions between the component species provides an important level of biological diversity in addition to genetics and species.

Question 12

Mutualism

Answer 12

Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other.
Similar interactions within a species are known as co-operation.

Question 13

Mutualistic protectors

Answer 13

• Cleaner and client fish: striped cleaner wrasse Labroides dimidiatus
• Establishes “cleaning station“ (cave or overhang); swims in a bobbing, dance- like motion. Larger fish come to the cleaning station for ectoparasite removal.
• Swims around the fish picking off and eating the parasites. Often enters the mouth and gill chamber of large fish
• Cleaner gain food source
• Clients protected from infection
• Community-wide implications of cleaner- client interactions

Question 14

Farming mutualism

Answer 14

• Leaf-cutting ants: social insects.
• Evolved advanced agricultural system
• Fungus only grows in the underground chambers of the ants’ nest
• Different ant species use different species of fungus - all Lepiotaceae family.
• Ants actively cultivate their fungus and maintain it free from pests and mouldsRelationship augmented by another partner
  * bacterium that grows on the ants secretes chemicals which protect the fungus from moulds - portable antimicrobials.
• When ants bring back toxic leaves, fungus secretes a chemical that warns the ant not to collect any more of that type of leaf.

Question 15

Pollination mutualism

Answer 15

Nectar and pollen offered as reward
* Reduces wastage of pollen
* Costs: pollinator attraction, disease transfer
* Pollinators par excellence - insects

Question 16

Mutualism – gut inhabitants

Answer 16

the rumen -
* exists in- Cows, sheep, goats and camels.
* role- Microbial populations collaborate to digest cellulose and other polysaccharides producing carbon dioxide, methane and organic acids.
* microbial content-
* Fungi - digest lignin and cellulose
* Bacteria
* Protozoa
*size- In sheep~6L; in cows~ 50-150 L

Question 17

Interspecific competition

Answer 17

• Individuals of one species suffer a reduction in fecundity, growth or survivorship as a result of resource exploitation or interference by individuals of another species
• Competition likely to affect the population dynamics of the competing species, and this in turn, can influence the species’ distribution and evolution.
• Either species alone, higher temperature led to increased aggression
• Effect reversed when Dolly Varden charr in presence of white- spotted charr
• At higher temperatures Dolly Varden charr suppressed from obtaining favourable foraging positions when white-spotted charr present
• Dolly Varden charr also suffered lower growth rates

Example:
* Galium hercynicum grows naturally in UK at acidic sites; G. pumilum confined to more calcareous soils.
* Alone – both species thrive on both soils
* Together – only G. hercynicum grew successfully on acidic soil and only G. pumilum on calcareous soil
* Together species compete; one species competitively excluded. Outcome is habitat–dependent.

• All three species grew well alone, reaching stable carrying capacities in tubes of liquid medium
• P.aurelia and P.caudatum together. P. caudatum always declined to the point of extinction, leaving P.aurelia as victor
• P. caudatum and P.busaria together. Neither species suffered a decline to point of extinction. Stable densities much lower than when grown alone – indicating competition.

Question 18

Gauses principle; competitive
exclusion principle

Answer 18

If two competing species coexist in a stable environment, then they do so as a result of niche differentiation, i.e. differentiation of their realized niches.
If, however, there is no such differentation, or if it is precluded by the habitat, then one competing species will eliminate or exclude the other.

Question 19

Population definition

Answer 19

Population-A group of organisms of one species
* usually separated in some degree from other groups of the same species by geographical, topographical or by some boundary chosen by investigator
* In practice we usually have to deal with a set of animals or plants that really forms only a section of the “ideal” population.

Question 20

Distributions

Answer 20

random spatial distribution - rare, hard to determine between truly random or largely “clumpy”

contagious spatial distribution - most common, safer, social interaction, mating/parenting, resources clumped

regular spatial distribution - not as common, used because of scarcity of resources

Question 21

Population dynamics

Answer 21

Populations exhibit dynamic behaviour through the action of changing rates of: emigration, immigration, birth , death
* It is the quantification and explanation of these numerical changes that concern the population ecologist.

Question 22

Patterns of growth

Answer 22

When populations are sparse and uncrowded they may grow rapidly.
* Populations at these low densities grow by simple multiplication over successive intervals of time
* This is exponential growth
* The rate of increase is the population’s intrinsic rate of natural increase (r)

N=number in population
t=time

dN/dt = rN

exponential growth:
* Unless unlimited, populations that behave in this way would soon run out of resources.
* Competing individuals that fail to find resources they need may grow more slowly or even die; survivors may reproduce later and less; or, if they are mobile, they move further apart or migrate elsewhere

Question 23

Carrying capacity

Answer 23

• As density increases competition between individuals generally reduces per capita birth rate and increases death rate.
• There is an overall tendency in most populations where intraspecific competition occurs to settle at the carrying capacity (K).
• At K birth rate = death rate
• Rate of increase falls to zero when the
  population reaches K.
• A steady reduction in the rate of increase as densities moves towards K gives rise to population growth that is S-shaped
• This pattern is often called logistic growth

Question 24

 Logistic growth

Answer 24

dN/dt = rN((K-N)/K)

Question 25

Density dependence

Answer 25

• Logistic equation implies an inverse relationship between population density and rate of increase, r, of a population
• This is referred to as a density dependent effect
• We also refer to density dependence and density independence

direct, inverse and density independence

Question 26

Intraspecific competition

Answer 26

A J Nicholson recognised two extreme forms of competition:
* contest competition
* scramble competition

scramble:
* Resource is shared amongst all the competing animals
* Sharing would be equal and the mortality would raise immediately from 0 to 100% when the resource per capita becomes just insufficient for survival

contest:
* Each successful animal gets all it requires.
* The unsuccessful animals get insufficient for survival and reproduction.
* Mortality increases with density
eg: * Competition between solitary wasps for limited number of nest holes
* Imagine - 100 nest holes
* 100 or fewer competitors there is no shortage
* 200 competitors - only 100 holes - 50% fail to breed
* 1000 competitors - 90% fail to breed

Question 27

 R – selected species

Answer 27

• Potential to multiply rapidly - producing large numbers of progeny early in the life cycle.
• Strategy advantageous in environments that are short- lived.
• Allows organisms to colonise new habitats quickly and exploit new resources.
• Spend most of their life in the exponential, r-dominated part of population growth.

Question 28

K selected species

Answer 28

• Organisms with different life histories survive in habitats where there is intense competition for limited resources.
• Successful individuals are those that capture, and often hold on to, the larger share of resources.
• Those that win in struggle for existence do so because they have grown faster (rather than reproducing) or some other activity (e.g. aggression) has favoured them.

Question 29

 R- K continuum

Answer 29

most species somewhere in the middle of a r-K continuum