Bio test ecology
A.4.2 Conservation and biodiversity
A.4.2.1 Biodiversity as the variety of life in all forms, levels, and combinations
Biodiversity
Describes the variety and variability of all living organisms within a given ecological area
Compare ecosystem diversity, species diversity and genetic diversity
3 main categories
Ecosystem diversity
The variety of different ecosystems or habitats present within a specific geographic area
Forests, grasslands, wetlands, coral reefs, deserts, etc.
Species diversity
The number of different species and the relative abundance of each species in a given area
Influenced by factors such as environmental conditions, ecological interactions, and evolutionary history
Genetic diversity
The variety of genes within the same species
Higher genetic diversity allows for a wider range of traits and adaptations, making a species more resilient to environmental changes, diseases, etc.
A.4.2.2 Comparisons between current number of species on Earth and past levels of biodiversity
Approximate number of species that have been discovered
About 8.7M, but we’ve only identified 1.7M of them
Compare the biodiversity of today with estimates for previous years
Fossil evidence suggests that there are currently more species alive on earth today than at any time in the past
NOS concept: Patterns can be observed and interpreted in different ways
The current system of taxonomic classification is an example of pattern recognition
But the same observations can be classified in different ways
A direct example of this are two main competing approaches to the classification of species
ñSplitters
Favor recognizing and naming a larger number of species or subgroups within a taxonomic group
Lumpers
Prefer to group together populations or variations within a taxonomic group into a smaller number of species
Take into account multiple factors like evolutionary history, genetic information, morphological traits, and ecological considerations.
A.4.2.3 Causes of anthropogenic species extinction
Anthropogenic
Environmental change caused or influenced by humans, either indirectly or directly
Extinction
Natural process
If balanced by evolution of new species, biodiversity does not decrease
The total cessation of a species or higher taxon level, reducing the overall level of biodiversity
Can result gradually, as one population of organisms progressively evolves into something else
Alternatively a species may not leave any identifiable descendants and simply cease to exist
Mass extinction event
A widespread and rapid decrease in the biodiversity on earth
There have been 5 documented mass extinction events
Evidence suggests that human activity is causing the 6th mass extinction
Holocene extinction
Case studies of specific extinction
Giant moa
A flightless bird native to New Zealand
They went extinct for several reasons related to human activity
Overhunting
Habitat loss from land use
Predation by introduced species
Caribbean monk seal
A marine species that lived in the oceans around the gulf of Mexico and the Caribbean
Went extinct because of human activity
Overhunting for blubber and oil
Habitat loss and source degradation
Disease and natural disasters
Tasmanian tiger
Carnivorous marsupial that was native to the Australian mainland and the island of Tasmania
Factors for extinction
Overhunting
Bounties
Habitat loss from land use (agriculture)
A.4.2.4 Causes of ecosystem loss
Ecosystem
All of the interacting living and nonliving factors in an environment
Ecosystem loss can have natural or anthropogenic cause
A.4.2.5 Evidence for a biodiversity crisis
IPBES
Set up by 90 governments to compile and report on global biodiversity loss
Role
Estimated that around 1M species are threatened with extinction
Evidence for a biodiveristy crisis
Habitat loss/land use change
Number of local varieties and breeds of domesticated plants and animals and their wild relatives has been reduced sharply as a result of land use change
Primarily driven by agriculture, forestry and urbanization
Climate change + pollution
Declining population size/ extinction rates
Standard rate of extinction in earths geological and biological history before humans became primary contributors to extinctions
Invasive species
How to monitor biodiversity
Monitoring
Repeated measurements of a species or ecosystem over time, to detect changes and trends
Population size
Range
Geographical area in which a species is found
Diversity
Variety of species in an area
How monitoring assesses biodiversity
Species richness
Number of different species in an area
More species = greater richness
Species evenness
Relative abundance of the different species in an area
Similar abundance = more evenness
Who monitors biodiversity
Citizen scientists
Collect large amounts of data over wild areas and long periods
Examples
RSPB Big Garden Birdwatch
iNaturalist
Limitation
Data from non experts can be less accurate, so it needs checking by scientists
A.2.4.6 Causes of the current biodiversity crisis
Overfishing
Urbanisation
Deforestation
Pollution
Climate effects
Pest spread
A.2.4.7 Need for several approaches to conservation of biodiversity
Biodiversity conservation
The protection and maintenance of natural resources
Can be in situ (on site) or ex situ (off site)
In situ
Preservation of plant and animal species within their habitat
Protection and maintenance of natural resrouces in order to preserve biodiverisy over a long time
Rewilding
Active or passive restoration of damaged ecosystems until they become self-sustaining
Can involve reintroducing apex predators and keystone species, reconnecting habitats, and reducing human impact
Active
humans intervene directly
Passive
human steps back and lets nature recover
Example
wolves reintroduced in Yellowstone
Reclamation
Restoring an area that has been used for human activity back to a natural ecosystem
Further interventions may be needed to prevent habitat degradation or competition from invasive species
Advantages
Allows species to live in their natural environment
Such areas provide a place to return animals from breeding programs as they provide realistic conditions for reintegration
Reserves in different areas can share information and provide a place for scientific study/developing public awareness
Disadvantages
Requires active management to ensure that an appropriate and sustainable ecological balance is maintained
Interventions may be required to prevent habitat degradation or competition from invasive species
Legislation often necessary to ensure adequate funding for policing and education
Ex situ
Involves preservation of plant and animal species outside their natural habitats
Typically required for critically endangered species when urgent intervention is required
Captive breeding programs
Animals are bred in zoo’s or wildlife centers to increase population numbers, with the aim of reintroducing them into wild
Botanical gardens
Rare and endangered plants are grown and protected, and can be used for research, breeding and reintroduction
Seed and tissue banks
Seeds or tissue samples are stored securely, often frozen, to preserve the genetic diversity of species for the future
Germplasm
The genetic material of plants, animals, or microorganisms that can be used for breeding, preservation, and propagation of species
Advantages
Greater control of essential conditions
Improves the chances of successful breeding
Disadvantages
Does not prevent the potential destruction of their natural habitats
Species less likely to be successfully reintroduced into the wild
Increases inbreeding by restricting the gene pool and restricts the evolution of the species
A.4.2.8 Selection of evolutionary distinct and globally endangered species for conservation prioritization in the EDGE of Existence programme
EDGE
Evolutionary
Distinct
Globally
Endangered species
Aims to prioritize the conservation of these species
Purpose
Identifies species that are both highly endangered and evolutionarily unique, with few or no close relatives
Advises governments and conservation groups on which species to prioritize, but it does not decide what action is taken
Other factors can also affect which species are prioritised
Keystone species
May not be globally endangered by can still be high priority because of their essential role in their ecosystem
If lost, the whole ecosystem can collapse
Culturally significant species
Prioritized for cultural, economic, or political reasons
Criteria used to determine which animal species are most deserving of conservation
If the species has few or no close relatives
If the species in danger of extinction
Rationale behind focusing conservation efforts on edge species
Evolutionary distinctiveness
How unique the species is
Global endangerment
How threatened it is
Conservation efficiency
How efficient will the efforts be
Ecological uniqueness
What significant ecological roles the species plays
Scoring system
Extinct → threatened → least concern
B.4.1 Adaptation to environment
B.4.1.1 Habitat as the place in which a community, species, population or organisms live
Habitat
Environment in which a species normally lives
A place providing basic needs
food, shelter, water, space
Can be geographic place or physical loaction
Can also apply to one organism or a whole population
How to describe
Latitude and logitude
climate
soil type
water availability
flora and fauna
altitude
human impact
sunlight exposure
Geographic location
Specific area or region where a species is found
continents, countries, islands
Physical location
Immediate environment where a species lives,
terrains, types of vegetation
Both locations are essential in defining a habitat because they ocllectively determine the sustainability of an environment for a species
B.4.1.2 Adaptations of organisms to the abiotic environment
Adaptation
Features of organisms that aid their survival by allowing them to be better suited to their environment
Different types of adaptations
Structural
Physiological
Biochemical
Behavioral
Developmental
Adaptations of Marram grass
Desert plants and plants that grow in high salinity posses adaptations for water conservation
Adaptations of marram grass to live in sand dune environment
Marram grass is adapted to live in sandy, coastal environments
Rolled leaves
Roll body inward to not release as much water
Stomata in pits
Pores that are surrounded by hairs, traps water vapor and reduces transpiration
Rhizomes
Underground stems that grow up as sand accumulates and can extend deep into the ground for water
Not roots
B.4.1.3 Abiotic variables affecting species distribution
Distribution
Where the species lives in the world, so it can be shown on a map
Abiotic factors for plant distribution
Temperature
Water availability
Light intensity
Soil pH
Soil salinity
Availability of mineral nutrients
All plants have a range of tolerance for each factor
Plants from the tropics are not adapted to survive frosts, so they wouldn’t survive in northern regions
Abiotic factors for animal distribution
Water availability
Temperature
Extremes of temperature require special adaptations
Elephants have large ears to dissipate heat
Polar bears have small ears to minimize heat loss
B.4.1.4 Range of tolerance of a limiting factor
Many plants will only grow in a soil within a specific pH range, some require full sunlight, and some only grow in the shade
Animals
salt concentration in aquatic habitats and temperature
B.4.1.5 Conditions required for coral reef formation
Abiotic conditions required
Corals are animals
In a symbiotic relationship with algae
Receive nutrition from photosynthetic zooxanthellae that live within the polyp
Temperature
Can’t survive in lower temps
Increase in temp causes the algae to leave the coral tissue
less than 18º and more than 35º is where it can’t survive
Water depth
Only survives at shallow depths where light can penetrate
pH
Low pH conditions reduce the availability of carbonate ions the coral needs
Salinity
Need a certain concentration of salt to survive
Water clarity
Needs to be clear for light to penetrate
B.4.1.6 Abiotic factors as the determinants of terrestrial biome distribution
Biome
Geographical areas that have a particular climate and sustain a specific community of flora and fauna
Factors
Temperature
Precipitation
B.4.1.7 Biomes as groups of ecosystems with similar communities due to similar abiotic conditions and convergents evolution
Climate conditions that characterize
Tropical rainforest
Hot climate
25º-30º
High precipitation
Large diversity in species and vegitation
Temperate forest
Deciduous forests
Moderate temperatures
Clear seasonal changes
They have a growing period of about 200 days during 4-6 frost free months
Taiga
Cold and icy
0º-15º
Small amount of precipitation
Coniferous trees are densely packed
Little species variation
Grassland
Moderate temperature
Moderate precipitation
Grasses are dominant vegitation
Trees and shrubs are absent
Tundra
Freezing temperatures
<0º
Little precipitation
Vegetation is low growing
Perennial plants may grow during the summer
Hot desert
Extreme temperature conditions
>30º during day, <0º at night
Very low precipitation
Dominant plant species are xerophytes which are adapted for water conservation
Convergent evolution
The independent development of similar traits in unrelated or distantly related species
Happens when different lineages face similar environmental pressures or ecological niches, resulting in analogous structures
Wings in bats and birds
Unrelated species independently evolve similar traits
B.4.1.8 Adaptations to life in hot deserts and tropical rainforests
Hot deserts
Animals
Fennec Fox
Small nocturnal fox in Sahara desert
Water conservation
Has kidneys adapted to restrict water loss
Temperature regulation
Can dissipate heat efficiently due to its large ears
Burrowing
Digs burrows to create a cooler microenvironment to escape day heat and raise its young
Paws
Covered in thick fur, protecting them from the hot sand and helping in digging
Nocturnal lifestyle
Being active at night and nesting in burrows during the day
avoids extreme heat of desert sun
Ventilation rate
Can be increased to more than 600breathspm to cause heat loss
Plants
Saguaro cactus
Found in the Sonoran desert in North America
Photosynthesis adaptation
Special form of it known Crassulacean Acid Metabolism
Allows stomata to open and take in CO2 during cooler night and store it for photosynthesis during the day
minimizes water loss
Water storage
Can absorb and store large amounts of water during rainfall
Tissues can swell to hold water for a long time
Wide spreading root system
to collect water from up to 30m from stem
Deep tap roots
Collect water from up to 1m down in the soil
Pleated stems
Allows for shrinkage in droughts and swelling after it rains
Thick waxy skin
Reduces water loss through evaporation
On the epidermis
Spines
Modified leaves that reduce water loss
Provide shade
Offer protection from herbivores
Tropical rainforest
Animal
Spider monkey
Long limbs and strong claws
Can grasp branches, lianas, and pick fruit
Feet that can act like hands
Grasp branches and allowing arms to be used for other purposes
Long tail can also grab onto branches
Highly developed larynx
Can make a wide range of sounds to be made to communicate in the dense rainforest canopy
Breeding year round
Breeding at any time of the year, as there is a constant supply of food
Plant
Merati
Height
Can grow to over 100m high
Overtops other trees
Avoids competition
Trunk
Made of dense hardwood
Smooth outside and sheds water from rain easily
Buttressed
Huge plant like ridges that group at the trunk for support
Leaf shape
Broad, oval shaped leaves with pointed tips to shed rainwater easily
Also evergreen
The tree will not shed leaves during the different seasons
Flowering
Flowers/seeds are produced in large quantities only once every 5 years to deter species that eat the seeds
Hot deserts
Low growing plants (xerotypes)
Thick waxy cuticles
Animals burrow during the day
Some animals have specialized organs for water reabsorption
Camels store fats in a specialized hump to reduce overheating
Tropical rainforests
High growing plants (epiphytes) compete for light
Emergent trees can grow above the canopy
Some animals are nocturnal or rely on special sight for low sunlight
Some animals have special limbs for climbing
Camoflauge or mimicry
B.4.2 Ecological niches
B.4.2.1 Ecological niche as the role of a species in an ecosystem
One of the central hypothesis in ecology is:
“an ecological niche is the functional role of a species in an ecosystem, including its habitat, resource use, activity patterns, and interactions with other organisms and the environment”
Comprised of various components
Abiotic: The habitat in which an organism lives and the resources within the environment (light, temp, water, soil pH, gases)
Biotic: The activity patterns of the organism and its interactions with other species (competition, predation, food availability, disease)
Zone of Tolerance
The range of values of an abiotic factor in which an organism can survive
Example: Rainbow trout
5-15º preferable conditions
15-20º increases thermal stress, trout has a hard time maintaining body functions
B.4.2.2 Differences between organisms that are obligate anaerobes, facultative anaerobes and obligate aerobes
Living things have different oxygen needs
Organisms can be classified based off of their oxygen need
Obligate aerobes
Organisms that require a continuous oxygen supply, so only live in oxic environments (all plants and animals)
Obligate anaerobes
Organisms inhibited or killed by oxygen so only live in anoxic environments (tetanus bacteria)
Facultative anaerobes
Organisms that use oxygen if available so live in oxic or anoxic environments (yeast)
Some organisms can live in anoxic environments, places where molecular oxygen has been depleted or is absent
Swamps, peat, intestinal tracks of animals, deep in lakes or seas
Winogradsky Column
A simple glass container used to grow many types of bacteria at ones
B.4.2.3 Photosynthesis as the mode of nutrition in plants, algae, and several groups of photosynthetic prokaryotes
In photosynthesis, energy from sunlight is used for fixing carbon dioxide and using carbon from it to produce sugars, amino acids, and the many other carbon compounds on which life is based
Three groups of photosynthesis
Plants, including mosses, ferns, conifers, flowering plants
Eukaryotic algae including seaweeds that grow on rocky shores and unicellular algae such as chlorella
Several groups of bacteria including cyanobacteria and purple bacteria
Photosynthesis therefore occurs in two of the three domains of life: in eukaryotes and bacteria, but not in archaea
B.4.2.4 Holozoic nutrition in animals
Many animals perform holozoic nutrition
Whole pieces of food are swallowed before being fully digested
May be distinguished according to their feeding patterns
Consumers
Feed on living or recently killed organisms
Herbivores, carnivores, omnivores
Scavengers
Feed on dead and decaying carcasses rather than hunting live pray
Hyenas, carrion birds
Detritovores
Feed on non-living organic matter such as detritus and leaf litter
Beetles, crabs, earthworms
Some animals digest their food externally so they are not holozoic
B.4.2.5 Mixotrophic nutrition in some protists
Mixotrophs
plants and algae use a combination of different modes of nutrition
venus flytrap
Certain organisms may use both autotrophic and heterotrophic modes of nutrition, depending on resource availability
There are mixotrophs and can be either oblicate or facultative
Obligate mixotrophs are organisms that need both modes of nutrition for survival
Euglena gracilis
protist that carries out photosynthesis when there is enough lifht, but also consumes detritus through endoxytossi
B.4.2.6 Saprotrophic nutrition in some fungi and bacteria
Saprotrophs
Live in or on nonliving organic matter, secreting digestive enzymes into it and absorbing digestive products
Digest first, then absorb
B.4.2.7 Diversity of nutrition in archaea
Three domains of life
Archaea
Unicellular with no nuclear
Bacteria
Similar to archaea
Eukaryotes
Some types of archaea are adapted to extreme environments
Archaea are a metabolically diverse group of organisms capable of performing a variety of modes of nutrition
Some of these nutritional processes are unique to archaeans and these organisms commonly form mutualistic relationships
Archaea can be categorized into three main nutritional groups according to their energy source
Phototrophs
use light as an energy source to produce ATP but dont undergo photosynthesis or make oxygen
Lithotrophs
use a variety of inorganic compounds to produce ATP
Organotrophs
use organic compounds to produce ATP
heterotrophic nutritions
B.4.2.8 Relationship between dentition and the diet of omnivores and herbivores and herbivorous representative members of the family Hominidae
Hominidae diets
family of great apes like gorillas and chimpanzees and modern and ancestral humans
feed predominantly on plant matter and have broader jaw muscles, larger premolars, and thicker tooth enamel for grinding tough vegetation
Hominids that eat more meat have smaller jaws and teeth for chewing softer animal tissue, while incisor teeth and canines are tightly packed to enable cutting and tearing
Teeth can also play a role in aggresive posturing (baring teeth, opening jaw), which is why gorillas have large canines while being mainly herbivorious
Mechanism for survival
Comparison of the jaws and dentition of extinct hominin (human) fossil demonstrates an evolutionary shift towards a higher proportion of meat in the diet
Jaws are narrower with smaller teeth
Evidence of evolutionary change
B.4.2.9 Adaptations of herbivores for deeding on plants and of plants for resisting herbivory
Animals that feed exclusively on plants
Structural feathers that adapt them to their diet
Most insects are herbivores
Beetles and others have jaw like structures for biting off, chewing, and ingesting pieces of leaf
Aphids and others have tubular mouthpieces to pierce the phloem
Herbivores are a type of heterotrophic consumer that feed principally on plant matter
Plants have evolved defenses to resist herbivory, while herbivores have developed adaptations to evolve
Herbivore adaptations
Specialized mouthparts
Insects may have stylets or mandibles to assist in piercing or cutting through plant matter
Digestive systems
ruminant animals have multiple compartments in their stomach to allow for the regurgitation and breakdown of food
Micro biotic bacteria
the gut flora in ruminants aid in the breakdown of plant sugars
Metabolic processes
certain animals produce chemicals capable of neutralizing the toxic compounds produced by specific plants
Plant defences
Physical structures
Spines and thorns act as deterrents, while thick bark and waxy cuticles can restrict ingestion
Chemical compounds
seeds and leaves may contain toxic compounds or bitter tasting chemicals to reduce feeding
How do aphids feed on plants?
Aphids are tiny, soft bodied insects that feed on plant sap
Aphids feed on plant sap by inserting a needle like structure called a stylet directly into the plant’s nutrient transporting tissues
They use a piercing-sucking mouthpart called a stylet to insert into a plant sieve tube (phloem), allowing the high hydrostatic pressure of the sap to force the fluid into their gut
Adaptation
Piercing/sucking
Chewing
Milkweed plant
make glycosides to deter herbivores
but aphids can not only tolerate it but can make itself toxic to predators by accumulating them in their own body
It doesn’t kill the aphid to consume it, but it does make them toxic to the next consumer
B.4.2.10 Adaptations of predators for finding, catching, and killing prey and of prey animals for resisting predation
California mountain lion
Rotating independent ears (can rotate 180º to find exact location of prey)
Binocular vision
forward facing eyes provide excellent depth perception for judging distances during a stalk or pounce
Polar bear
Camouflage
Clear fur that allows them to blend into the icy background when hunting seals
Northern pacific rattlesnake
Venom (chemical adaptation)
immobilizes the prey while liquefying its internal tissues from the inside out
Grizzly bears (behavioral adaptations)
Learning to ambush strategies for catching migrating salmon either by trial and error or copying others
Monarch butterflies (physical adaptation)
Bright orange and black warning colors to show that they are poisonous
Stick bugs (behavioral adaptation)
Mimicry is when animals disguise themselves as something to avoid or confuse predators
Camouflage as a way for prey to avoid their predators
Animals that can change the color and texture of their skin are called chromatophores
How long does it take for something to adapt?
Behavioral
relatively quickly
Structural
Much longer due to the necessity of a genetic change
Chemical
Slowest to change, because new enzymes may be needed or new ways of regulating enzymes
may take millions of years
B.4.2.11 Adaptations of plant form for harvesting light
Plants have evolved a variety of adaptations to optimize light harvesting
In environments where there is enough water for abundant plant growth and temperatures are suitable for photosynthesis, plants compete for light
Examples
Height
Leaf surface area
Trees and some shrubs
Compete for sunlight by growing taller
The taller trees form the canopy layer, receiving the most sunlight
Emergent layer
Made from a few trees that grow taller than the canopy
Large leaves
Increase the area available for photosynthesis, allowing plants to absorb more sunlight
Understory plants
Shade tolerant
Have adaptations that allow them to photosynthesize efficiently in low-light conditions found under the canopy
These plants often have larger, thinner leaves compared to those exposed to full sunlight, maximizing the surface are for light absorption
Lianas
Woody vines that climb up the trunks of other trees to reach the sunlight in the upper canopy
This strategy allows them to access the light available at the top of the forest without investing energy into developing a robust trunk to support themselves
Epiphytes
Grow on the surface of other plants, particularly on branches and trunks in the canopy, without rooting in the soil
Orchids and bromeliads, capture light and moisture from the air and debris around them
Strangler epiphytes eventually smother the host plant
B.4.2.12 Fundamental and Realized Niches
Where an organism could live vs where it actually lives
Some species may not be able to occupy their entire niche due to the presence or absence of other species
A species may instead occupy a smaller subset of their niche than is theoretically possible
Fundamental niche
The full range of conditions and resources where a species could survive in and reproduce, without competition or other biotic restrictions
Realized niche
The actual range of conditions and resources the species uses, after factors such as competition, predation, and other biotic interactions are condsidered
Fundamental niche is larger
Competition plays a major role in differentiating the realized niche of an organism from its fundamental niche
B.4.2.13 Competitive exclusion and the uniqueness of ecological niches
No two species can share the exact same niche as this would lead to direct competition for space and resources and leading to a struggle for survival
Interspecific competition within a shared niche will typically prompt one of two responses
Competitive exclusion
One species uses the resources more efficiently, driving the other species to local extinction
Resource partitioning
Both species can alter their use of the habitat to divide resources between them (niche separation)
Examples
Spacial
Might occupy different areas of the same habitat
Temporal
Same space at different times
Dietary
One species adapts to different types of food
Organisms that can adapt to extreme niches encounter less competition and predation
However, the competitive exclusion principle assumes that ecological conditions remain constant
Species adapt over time, there is also the possibility of resource partitioning