Comprehensive Study Notes: BIO516 Conservation Biology

Introduction to Conservation Biology and Endangered Australian Taxa

This course, BIO516 Conservation Biology, is coordinated by Associate Professor Melanie Massaro at Charles Sturt University. The discipline focuses on the intersection of conservation and biodiversity to establish frameworks for intervention. Australia is currently in a crisis regarding several critically endangered species which serve as foundational case studies:

Tasmanian devil ( $Sarcophilus \, harrisii$ )
Orange-bellied parrot ( $Neophema \, chrysogaster$ )
Spider orchids (various species)
Corroboree frog ( $Pseudophryne \, corroboree$ )
Lord Howe Island phasmid ( $Dryococelus \, australis$ ), colloquially known as the "land lobster."

Historical Perspectives on Human Environmental Interaction

Human concern for the environment is intrinsic to survival and rooted in the dawn of humanity. Historically, humans relied on the environment for four essential pillars:

Food
Water
Shelter (natural resources for protection from weather and hazards)
Medicine (primary source for medicinal compounds)

A healthy environment is a prerequisite for sustaining human life, as illustrated by historical records such as John Clark Rigpath's engraving of Aboriginal Australians hunting macropods.

Global Human Migration and Demographic Trends

Modern humans ( $Homo \, sapiens$ ) originated in Africa and began global migration approximately $60,000$ years ago. Movement was dictated by:

Climate
Population pressure
Technology (e.g., the invention of boats allowing maritime crossings)

Australia was settled early, roughly $50,000$ years ago, while New Zealand was among the last major landmasses settled by Polynesians due to navigational difficulties.

Global Population Growth and Drivers

The global population is nearing $9,000,000,000$ and is projected to reach $9,400,000,000$ by $2050$ . Significant growth began after the Great Famine ( $1315-1317$ ) and the Black Death ( $1350$ ), when the population was $370,000,000$ . Peak growth occurred in the $1950$ s, $1960$ s, and $1970$ s, exceeding $1.8\%$ per annum. The historical peak was $2.2\%$ in $1963$ .

Drivers of the surge include:

Dietary Shifts: Domestication of animals (cows, sheep) provided calories for more frequent reproduction (from once every $3-4$ years to approximately every year).
Healthcare: Decreased infant mortality and increased life expectancy.

Quantifying Human Influence and Overconsumption

Impact Metrics

Human Influence Index (HII): Maps impact using data on population density, built-up areas, accessibility (roads/railroads), landscape transformation, and electric power use.
Overconsumption: Industrialized nations play a disproportionate role. The U.S. contains $5\%$ of the population but consumes $25\%$ of natural resources. An average U.S. citizen uses $23$ times more energy and $79$ times more paper than a citizen of India.

The Impact Formula

The environmental impact ( $I$ ) is calculated as: $I = P \times A \times T$ Where:

P = Population size
A = Affluence (average income)
T = Technology level

Defining Conservation Biology as a Scientific Discipline

Conservation biology is a "crisis discipline" aiming to minimize biodiversity loss by combining pure and applied science. It is distinguished from related fields:

Preservation: Protection based on cultural or religious values.
Environmentalism: Activism seeking solutions for environmental problems.
Ecology: Scientific study of organism-environment relationships.

Conservation biology often manages small, rapidly declining populations where practitioners must act before exhaustive scientific evidence is available.

Defining Biodiversity and Its Three Essential Components

Biodiversity is comprised of three distinct, interconnected levels:

Species Diversity: Encompasses all living things from bacteria to blue whales.
Ecosystem Diversity: Biological communities and their associations with the physical/chemical environment.
Genetic Diversity: Variation within species, among populations, and among individuals. This diversity acts as a safeguard against environmental disturbances (e.g., genetic resistance in some individuals during the Covid-19 outbreak).

Trophic Levels in Ecosystem Diversity

Interactions are organized into trophic levels:

Primary Producers: Photosynthetic species (algae, kelp, plants) converting solar radiation into biomass.
Primary Consumers: Herbivores (rabbits, krill).
Secondary Consumers: Predators and parasites.
Decomposers/Scavengers: Feed on dead tissues and waste.

Structural vs. Functional Biodiversity

Structural Biodiversity: The physical building blocks (species and organizational levels).
Functional Biodiversity: Ecological and evolutionary processes. Conservation typically prioritizes structural biodiversity because maintaining the structure inherently preserves the processes.

Global Patterns and Measures of Biodiversity

Biodiversity Patterns

Hotspots: Concentrated in Southeast Asia, the Amazon Basin, parts of Africa, Southwest Australia, and coastal Queensland.
Latitudinal Gradient: Brazil ( $3 \times$ more mammals than Canada) and the DR Congo (higher diversity than Argentina) illustrate that poorer tropical nations often house the most biodiversity.
Nepal Case Study: Covers $147,000\,km^2$ (smaller than the state of Victoria at $269,000\,km^2$ ) but hosts $887$ bird species ( $8.6\%$ of the global total).

Quantitative Scales of Diversity

Alpha ( $\alpha$ ): Species richness within a single area or mountain.
Gamma ( $\gamma$ ): Diversity across a whole region or continent.
Beta ( $\beta$ ): The rate of change in species composition along a gradient. High beta diversity indicates high endemism.
Shannon Diversity Index: Quantifies both richness and evenness (relative abundance).

The Taxonomic Challenge and Global Extinction Rates

Approximately $1,800,000$ species have been described, including $3,186$ viruses. Most groups (nematodes, crustaceans, fungi) remain largely undescribed. If extinction rates hit $5\%$ per decade, all species might vanish by the year $2100$ before they can be formally described.

The Australian Extinction Wave

Since $1788$ , over $10\%$ of Australia’s $320$ mammal species have gone extinct, including:

Tasmanian thylacine
Desert batong
Capricorn rabbit rat
Percy Island flying fox Introduced feral cats and foxes are the primary drivers of these losses.

The IUCN Framework and Assessment Criteria

The International Union for Conservation of Nature (IUCN) provides standardized threat levels:

Categories: Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), and Data Deficient (DD).

Threatened status is assigned based on five criteria (A-E):

A: Population reduction of $80\%$ or more over $10$ years/ $3$ generations.
B: Restricted geographical range ( $< 100\,km^2$ ) plus habitat loss.
C: Population $< 250$ mature individuals or declining by $25\%$ within $3$ years.
D: Total population $< 50$ mature individuals.
E: Extinction probability $> 50\%$ within $10$ years.

Amphibians are currently facing the most severe crisis, with $41\%$ of species threatened.

Evolutionary Theory and Mechanisms of Speciation

Darwin and Wallace

Charles Darwin ( $1809-1882$ ): Observed variation in finches during his HMS Beagle voyage ( $1831-1836$ ). He published "Origin of Species" in $1859$ .
Alfred Russel Wallace: Identified the "Wallace Line" in the Malay Archipelago and is the father of biogeography.

Speciation Processes

Division typically occurs via geographical isolation (mountain ranges, rivers, sea-level rise), restricting gene flow.

Sympatric: Species in the same geographic area.
Allopatric: Species in different, non-overlapping areas.
Adaptive Radiation: Rapid diversification into niche forms (e.g., Hawaiian honeycreepers; Cichlid fish in Lake Victoria).

Species Concepts

Biological (BSC): Focuses on interbreeding groups.
Morphological: Focuses on distinct physical/biochemical traits.
Phylogenetic (PSC): Focuses on unique genetic similarities and common ancestors.

Genetic Diversity: Mechanisms and Diminishing Processes

Mechanisms of Variation

Sex Determination in Birds: Males are homomorphic ( $ZZ$ ); females are heteromorphic ( $ZW$ ). In Gouldian finches, red heads are dominant over sex-linked recessive black heads.
Meiosis: Genetic variety arises through independent orientation ( $2^n$ combinations), random fertilization ( $64,000,000,000,000$ combinations in humans), crossing over, and mutations.

Measuring Genetic Diversity

Allelic Diversity ( $A$ ): Average alleles per locus.
Proportion of Loci Polymorphic ( $P$ ): Presence of two/more alleles at a locus.
Heterozygosity ( $H$ ): Proportion of genes where an individual is heterozygous.
Total Genetic Diversity ( $H_T$ ): Calculated as $H_T = H_S + D_{ST}$ (within-population + across-population diversity).

Processes Diminishing Diversity

Population Bottlenecks: Dramatic declines followed by recovery. Genetic diversity often fails to recover as fast as census numbers.
Inbreeding: Increases homozygous genotypes and expresses recessive deleterious alleles (e.g., stillbirths in adders).
Genetic Drift: Random extinction of alleles in small populations.
Natural Selection: Favors specific alleles over others.

The Small Population Paradigm and Extinction Vortex

Small populations face unique stochastic risks:

Environmental Stochasticity: Random disasters (wildfires, cyclones) that can wipe out range-restricted species.
Demographic Stochasticity: Random variation in birth/death rates and sex ratios. In a population of $5$ , variance increases $100$ -fold compared to population of $500$ .
Extinction Vortex: A downward spiral where smallness leads to inbreeding/drift, reduced fitness (inbreeding depression), further size reduction, and eventual extinction.

History of Mass Extinctions

Ordovician ( $5.00 \times 10^8$ years ago): Lost $50\%$ animal families.
Devonian ( $3.45 \times 10^8$ years ago): Lost $30\%$ families; impacted Agnathans/Placoderms.
Permian-Triassic ( $2.519 \times 10^8$ years ago): "The Great Dying." Lost $90\%$ marine and $75-80\%$ terrestrial species due to volcanism and ocean acidification.
Triassic-Jurassic ( $2.014 \times 10^8$ years ago): Lost $35\%$ of organisms.
Cretaceous ( $6.5 \times 10^7$ years ago): Meteorite impact at Chicxulub crater; extinction of non-avian dinosaurs and Pterosaurs.
Anthropocene (Current): Human-induced; current bird/mammal extinction rate is $100-1,000$ times the background rate.

Overexploitation and Management Models

Case Studies

Megafauna: Human arrival in North America $11,000$ years ago resulted in the loss of $34$ genera of mammals within $1,000$ years.
Whaling: Targeted large species (blue) then progressively smaller ones (fin, sei, minke). IWC moratorium enacted in $1982$ .
Atlantic Cod: Collapse of Grand Banks stocks due to technological shifts (sonar, purse seine, bottom trawling).

Maximum Sustainable Yield (MSY)

Theory assuming populations follow a logistic S-curve and can be harvested at peak growth ( $\frac{K}{2}$ , half the carrying capacity). Flaws: Simplistic; ignores age/size structure; neglects ecosystem damage and bycatch.

Harvest-Induced Selection

Trophy hunting and size-selective fishing favor individuals that grow slowly and mature early. This can lead to age-truncated, juvenescent populations with genetically fixed slow growth (e.g., Western Rock Lobster size reduction at maturity).

Habitat Loss, Fragmentation, and Ecosystem Degradation

Island Biogeography Theory

Species number reached at equilibrium where immigration equals extinction.

Area: Large islands have lower extinction rates.
Distance: Near islands have higher colonization rates.
Rule of thumb: $50\%$ habitat loss leads to $10\%$ species loss; $90\%$ loss leads to $50\%$ species loss.

NSW Forest Loss Examples

Native forest in NSW decreased from $55,000,000$ hectares in $1788$ to $25,000,000$ in $2021$ . Eucalypt woodlands are particularly degraded ( $72\%$ for Casuarina forests).

Degradation Mechanisms

Contamination: Acid rain (nitric/sulfuric acids), pesticide drift, and plastic pollution (ingestion by seabirds due to DMS infochemical attraction).
Infrastructure: Roads (roadkill), fencing (entanglement), and utility structures.
Invasive Ungulates: Hard hooves destroy soil crusts and prevent perennial grass recovery post-fire (Limmen National Park study).

Invasive Species: Terminology and Mechanisms

Definitions

Feral: Domestic animals escaped to the wild.
Pest: Species with adverse impacts on humans, environment, or agriculture.
Invasive: Translocated outside natural range; established and spreading.

Invasion Success Factors

Transport: Deliberate (acclimatization societies, biocontrol) or accidental (ballast water, luggage stowaways).
Establishment: Requires sufficient propagule pressure and environment suitability.
Spread: Facilitated by traits like "spatial sorting" (e.g., front-line cane toads evolve longer legs and higher endurance).

Management and Evolution

Evolutionary Shifts: Native snakes (Red-bellied black) developed smaller heads in toad-infested areas to prevent ingestion of lethal doses.
Control: Inoculation (toad sausages), pheromone traps, and manual removal.

Climate Change: Mechanisms and Biological Impacts

Historical Drivers

Milankovitch Cycles: Eccentricity ( $26,000$ year cycle), Obliquity ( $41,000$ year cycle), and Precession ( $100,000-400,000$ year cycle).
Geological: Volcanism and plate tectonics.

Contemporary Drivers

Industrial Revolution ( $1700$ s onwards) led to greenhouse gas accumulation ( $CO_2$ , $CH_4$ , $N_2O$ , CFCs, Water Vapor).

Impacts on Biodiversity

Marine: Ocean acidification ( $CO_2 + H_2O \rightarrow H_2CO_3$ ) dissolves calcium carbonate skeletons; coral bleaching occurs when zooxanthellae are ejected.
Terrestrial: Shifting climate envelopes and thermal tolerance breaths ( $CT_{min}$ and $CT_{max}$ ).
Direct Extinction: Bramble Cay Melomys is the first mammal extinct due strictly to climate-induced sea-level rise.

Protecting and Sustaining Ecosystems

Ecosystem Services

Provisioning: Food, water, medicines (e.g., Ozempic from healer monster venom).
Supporting: Nutrient cycling, soil formation.
Regulating: Climate, water purification, pollination.
Cultural: Aesthetic, spiritual, recreational value.

Restoration and Maintenance

Targeted restoration: Creating artificial rocks for broad-headed snakes.
Pollution reduction: Controlling PFAS ("forever chemicals"), reducing waste ( $75.8\,megatons$ in Australia in $2023$ ), and transition to renewables.

Direct Manipulations and Hands-On Strategies

Translocations

Introductions: Moving species to new sites (e.g., Northern Quolls to islands to avoid Cane Toads).
Reintroductions: Returning species to former ranges (e.g., Yellowstone wolves; Greater Bilbies to fenced sanctuaries).
Augmentation: Supplementing existing small populations.

Artificial Breeding

Double Clutching/Cross-Fostering: Pioneered by Don Merton with the Black Robin using tom tits as foster parents.
Head Starting: Raising Kiwi chicks until they reach $1,200\,g$ to survive stoats.
Artificial Insemination: Used for Kakapo to overcome low fertility and abnormal sperm.

Global Initiatives and Sustainability Frameworks

Key International Agreements

SDGs: $17$ Sustainable Development Goals.
Paris Agreement: Legal treaty aiming to limit warming to $< 2^{\circ}C$ by $2050$ .
Global Biodiversity Framework: Vision for harmony with nature by $2050$ .

National Legislation (Australia)

EPBC Act (Federal): Environment Protection and Biodiversity Conservation Act.
TSC Act (NSW State): Threatened Species Conservation Act.
Common Assessment Method: Streamlines assessment across agencies using IUCN criteria.

Institutional Leadership

Charles Sturt University (CSU) is Australia's first certified carbon-neutral university, guided by the Wiradjuri ethos of Yinyumarawin Hunga (the wisdom of respectfully knowing how to live well in a world worth living in).