Biodiversity

Biodiversity: The Variety of Life

• Biodiversity explores the variety of life and its importance, as presented by Dr. Richard Cook.

Part 1: What is Biodiversity?

• Biodiversity includes the richness and abundance of genes, species, and ecosystems.
• Richness is the varying number of genes, species, and ecosystems.
• Relative abundance, also known as evenness, measures the number of individuals within each type.
• Highest diversity arises with high richness and an even distribution of all types.
• Biodiversity refers to the variety of life at all levels – including genes, species, and ecosystems – and is measured by both richness and evenness.
• Maximum diversity is achieved when there is both high richness and all types are equally abundant.
• Biodiversity increases when new genetic variations, species, or ecosystems emerge.
• Biodiversity decreases when genetic variations, species, or ecosystems are lost.
• Genetic diversity is reduced through bottlenecks.
• Species diversity declines with extinction events.
• Ecosystem diversity falls when habitats are degraded or lost.

Diversity: Definition

• Diversity definition broken down into three levels of Genetic, Species, and Ecosystem Diversity

Genetic Diversity

• Genetic Diversity occurs between all the species within an ecosystem
• Within each species is their own genetic variation
• More complex habits support greater genetic variation within a species
• Low genetic diversity ('bottleneck') can threaten the survival of a species in changing environments
• Genetic diversity within a species is the variation in genes among individuals in a population.
• Genetic diversity between species are the genetic differences among species within an ecosystem.
• A balanced ecosystem is one where no single species dominates because high species diversity supports more stable and resilient ecosystems

Species Diversity

• Species diversity measurement can be difficult
• Cryptic species are hard to measure
• It can be very difficult to access or find and count certain species
• The "Biological Species Concept" defines a species as a group of naturally interbreeding populations reproductively isolated from other groups.
• In practice, species are identified by morphology and genetics.
• Species diversity takes into account both the number of different species (richness) and how evenly the individuals are distributed among these species (evenness).

Ecosystem Diversity

• Ecosystem diversity is the variety of habitats, biological communities, and ecological processes within and between ecosystem types.
• Diverse ecosystems have a range of habitats
• A large variety of species adapt to conditions and occupying niches in dynamic equilibrium with high genetic variation
• Ecosystem diversity is the variety of habitats, communities, and ecological processes that occur both within and between ecosystems.
• Ecosystem diversity can be measured from global biomes down to microhabitats.
• More varied ecosystems create a range of niches that support different species, increasing overall biodiversity and ecosystem stability.

Ecosystem Definition

• An ecosystem is a community with an environment and the interactions between them.
• Ecosystems can be defined at various scales, including biomes at a global/regional level.
• Terrestrial ecosystems are defined by dominant vegetation
• Aquatic ecosystems are defined by physical characteristics.
• Habitats classified under the IUCN Habitats classification scheme
• Sub-habitats provide the diversity of niches organisms need to exploit
• The IUCN Habitats classification scheme organizes ecosystems into categories.
• Ecosystems are categorized as forests, savannas, shrublands, grasslands, wetlands, mountains, deserts, various marine zones, and artificial habitats.

Complex Ecosystems

• Complex ecosystems with high species and genetic diversity tend to be stable.
• Less complex ecosystems, dominated by a few species, may lead to pest emergence.
• Controlling pests in these systems necessitates more resources and energy, resulting in an unstable ecosystem.

Ecosystem Engineers

• The presence of species can create new niches or habitats for other species.
• Ecosystem engineers construct or maintain these habitats.
• Some organisms, known as ecosystem engineers or keystone species, can create or maintain habitats that support many other species.

Keystone Species

• Keystone species affect the survival/abundance of other species in a community.
• Removing keystone species results in significant shifts in the environment's composition and physical structure.
• The over-hunting of sea otters led to an urchin population explosion which destroyed kelp forests.
• The loss of a keystone species can lead to a collapse in the ecosystem, reducing genetic diversity within the remaining species.
• Sea otters help maintain kelp forests by controlling sea urchin populations.

Interconnectedness of Diversity Levels

• Genetic, species, and ecosystem diversity are interdependent, as changes in one level can directly affect the others.
• Healthy genetic diversity within species contributes to ecosystem resilience, which in turn supports a diverse array of species.
• The structure of ecosystems creates niches that promote genetic and species diversity, creating a dynamic balance vital for the sustainability of life.

Part 2: The Diversity of Life

• The diversity of life includes:
• Prokaryotes: Bacteria, Archaea, and Viruses
• Eukaryotes: Protists, Plants, Fungi, Animal Protostomes, and Animal Deuterostomes

Shared Properties of Life

• All living organisms share DNA, cell membranes, ribosomes, common metabolic pathways, and chemicals.
• All living organisms share a common ancestor (monophyletic).
• Prokaryotes include Bacteria and Archaea.
• Eukaryotes come via endosymbiosis from Archaea

Prokaryotes: Bacteria & Archaea

• Bacteria were 1st life forms c. 3.5-4 billion years ago
• For abut 2 billion years they were the only life form
• Bacteria have cell walls made of peptidoglycan, unlike Archaea.
• Gram-negative bacteria have a thin peptidoglycan layer but have an outer membrane
• Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane
• Bacteria’s peptidoglycan is targeted by many antibiotics

Bacteria Appearance and Types

• Bacteria can appear as spheres (coccus), rods (bacillus), or spirals (spirillum).
• They can be single or in chains/clusters and are medically important.
• Cyanobacteria are photosynthetic organisms
• Cyanobacteria increased oxygen levels c. 3.5 billion years causing the evolution of eukaryotes.

Eukaryotes

• Eukaryotes have a nucleus, mitochondria/chloroplasts and are membrane-bound organelles
• Eukaryotes consist of 8 major clades with "Protists" referring to eukaryotes that are not plants, animals, or fungi
• Eukaryotes include Protists, Plants, Fungi, and Animals

Eukaryotes: Protists

• Protists are critical components for ecosystems, that are primary producers, food, and pathogens
• Protists include unicellular organisms:
• Dinoflagellates are aquatic and include two flagella
• Apicomplexans are parasitic
• Ciliates use hair-like Cilia for 2 locomotion
• Diatoms are unicellular cells with no flagella
• Excavates are unicellular with flagella

Protists: Brown Algae

• Protists also include multicellular organisms, that include brown algae
• Brown algae are marine and are colored from carotenoid fucoxanthin
• Kelps and Sargassum are types of brown algae

Eukaryotes: Plants

• Plants Eukaryotes include Algae and land plants
• Land plants are embryophytes
• Plants include vascular and land plants

Plants: Bryophytes

• Bryophytes are non-vascular small plants restricted to wet habitants with no flowers or seeds
• Bryophtes include moss, sphagnum moss, and hornwort

Plants: Gymnosperms

• Gymnosperms are plants wiht 'naked' seeds with no flowers, like Coniferous Trees
• Hikck's Yew, Red Spruce, Sitka Spruce, deodar, and Eastern Hemlock are examples of Coniferous Trees

Plants: Angiosperms

• Angiosperms supply nearly all plant-based food and livestock feed.
• Angiosperms are plants with flowering seeds enclosed within fruit

Eukaryotes: Fungi

• Fungi secrete digestive enzymes to digest food outside of the body
• Fungi has cell walls made of chitin with a mass branching hyphae body (tubular filaments)

Fungi Life Strategies

• Some fungi are Parasites of plants, insects, and humans
• Saprobes: decompose plant material
• Other Fungi are Predators and trap prey
• Fungi also have lichens, which are symbatico fungus & photosynthetic
• Some fungi are free-living ('yeasts')
• Humans use Fungi for medical compounds (penicillin), food, and biological control of pests

Eukaryotes: Animals

• Animal life is broken down into non-bilaterian metazoa, Bilateria Protostomes, and Bilaterian Deuterostomes
• Most animals are bilaterally symmetrical.
• There are 4 main types of animal lifeforms
• Porifera are animals defined as sponges
• Ctenophores are marine animals, comb jellies, that feed on zooplankton
• Cnidaria are animals defined as Jellyfish, Sea anemones, Corals, Sea pens & sea fans.

Animal Types: Spiralia and Ecdysozoa

• The first animal type, Spiralia, includes Molluscs, Annelids, and Platyhelminthes
• Ecdysozoa animals a phylum incl arthropods, nematodes, and tardigrades.

Animal Types: Deuterostomes

• First opening forms anus
• Deuterostomes include Echinderms and Chordates
• Chordates animals include sub-phylum Vertebrata/ Craniata and Cephalochordates

Part 3: Benefits and Decline of Biodiversity

• Benefits of biodiversity and the effects of its decline

Benefits of Biodiversity

• Biodiversity benefits are defined across 3 main categories: Ecosystem processes, Bioresources, and Aesthetic value

Ecosystem Processes

• Ecosystem processes include oxygen production and carbon sequestration
• Nutrient cycles and water
• Natural pest and disease control
• Decomposition of organic matter and soil fertility from pollination
• Ecosystem processes includes vital ecosystem processes such as oxygen production, carbon sequestration, water and nutrient cycling, decomposition, and pollination.

Bioresources

• The category of Bioresources are food, fibers, timber
• About 50% of all medicines come from living organisms
• Improves crop qualities, include resistance to disease and increased yields
• Responsible waste management (sewage treatment and bacterial breakdown of plastics)
• Bioresources provides essential resources like food, fiber, timber, and medicines.
• Genetic diversity offers the raw material for crop improvement, such as breeding for disease resistance or drought tolerance, which is crucial for food security.

Aesthetic Value

• Aesthetic values derive from activities like keeping pets, ecotourism and other recreational activities
• Recreational Value includes keeping pets, visiting zoos and nature reserves
• Aesthetic values enriches quality of life through recreation, cultural identity, and aesthetic enjoyment.
• Natural landscapes, wildlife, and ecosystems offer recreational opportunities and have intrinsic cultural and spiritual values for many communities.

Threats to Biodiversity

• Habitat loss and fragmentation are major threats to biodiversity
• Introduced species without natural predators can disrupt ecosystems.
• Severe impacts and over-fishing severely impacts fish stocks
• Organisms are harvested at rates exceeding their reproductive capacity

Threats: Pollution

• Pollution is a threat that cause harm to Agriculture, urban development, forestry, mining
• Eutrophication, pesticides, and sewage also lead to pollution
• Atmospheric pollution, water pollution, and climate change are global and regional threats
• Habitat loss and fragmentation is caused by urban development, agriculture, forestry, mining, and pollution.

Changes to Ecosystem Stability

• Climate change will severely affect the distribution and range of species due to conditions that species cannot adapt to
• Species with poor dispersal threatened are displaced
• These threats change the ecology and impacts food productions

Useful References

• WWF (2022) Living Planet Report 2022 and IPBES (2019) The global assessment report include many threats

Threats: Global and Regional Environmental Changes

• Global and regional environmental changes include atmospheric pollution, water pollution, and climate change.
• Atmospheric pollution includes CO₂, SO₂, NOₓ, O₃.
• Water pollution includes PCBs, toxins, and plastics.

The 6th Mass Extinction

• The Current Mass Extinction:
• There have been 5 past mass extinction events (>75% species lost)
• Extinction rate now 100s or 1000s times faster than background from fossil record

• 400 vertebrate species went extinct in last 100 years

• ¼ of all species face extinction (UN report on biodiversity 2020)
• Caused by human activity
• Current extinction rates are estimated to be 100–1,000 times higher than the background rate.
• Over 400 vertebrate species have become extinct in the last century alone.
• Around a quarter of all species face extinction.
• Most of these losses are linked to habitat destruction, overexploitation, and environmental pollution, especially following the development of agriculture and industrialization.