UQ BIOL1030 Midsem

s1 2025

Intrinsic Value

The idea that each species has an inherent worth and right to exist

Why does modern western philosophy value biodiversity?

For its intrinsic value

Why do we describe biodiversity in different ways?

It enables different groups of society to directly compare biodiversity with their other priorities

The value of biodiversity through heritage and identity

Many cultures are closely connected to biodiversity through the expression of identity, through spirituality, and other aesthetic appreciation

The utility of biodiversity

Biodiversity provides humans with raw materials for consumption and production, also providing livelihoods for millions of people

Ecosystem services and functions

Biodiversity provides functions in ecosystems that help sustain life through a supply of clean air, water, pest control and water treatment

Ecosystem Services

The supply of services that are directly beneficial to humans

Ecosystem Functions

The control of energy and nutrient flow

Provisioning

Products obtained from ecosystems that humans use

Regulating

The biodiversity that lessens/mitigates environmental change

The biodiversity of environments that is part of provisioning or regulating is NOT…

Exclusive to one category

Provisioning services are…

Often traded in markets or depended on directly for livelihoods or food in rural areas

Geological Time

A system of chronological dating that relates geological strata (stratigraphy) to time, used by scientists to describe the timing and relationships of events that have occurred during Earth’s history

The first life on earth appeared around…

3.77 billion years ago, as microorganisms in hydrothermal vents

To characterise past life we are reliant on…

Fossils, trace fossils, and the fossil record

What does the fossil record do for scientists?

The fossil record documents and reveals changes in history throughout the course of life on earth

Radiometric Dating

Uses radioactive isotopes and their decay from “parent” to “daughter” isotopes to measure time - not affected by temperature, pressure, or other environmental variables

Isotopes - what are their half-lives?

Carbon-14

Uranium-238

5730 years

4.5 billion years

Measurements of time from big to small

Eons, eras, periods, epochs

Eras to know

• Paleozoic - (542 - 251 mya)

• Mesozoic - (251 - 65.5 mya)

• Cainozoic - (65.5 mya - present)

The evolution of predator-prey relationships

Prior to the Cambrian Explosion, all large animals were soft bodied, but over a period of around 10 million years, predators over 1 metre emerged with claws and other mechanisms while prey evolved spines and heavy body armor

Theories for the Cambrian Explosion

A (potentially temporary) increase in environmental oxygen, increased nutrients in the water from glacier movement, an “evolutionary arms race,” or changes in the food web

Evidence that hydrothermal vents existed 4.2 bya indicate that…

Life began around 3.6 bya

Since life began…

Enormous environmental changes have occurred, land masses have moved and major changes in climate have happened (both warmer and colder than present day)

With the environmental changes since life began…

Extensive evolution of life forms has occurred, with many species both appearing and disappearing

What is the earliest evidence of life dating?

3.5 billion years ago from fossilized stromalites

Stromalites

Think layered rocks that form when certain prokaryotes bind thin films of sediment together

Prokaryote

A unicellular organism that lacks a membrane bound nucleus, mitochondria, or other membrane-bound organelle

Eukaryote

An organism made up of multiple cells that posses a membrane-bound nucleus that holds genetic material as well as membrane-bound organelles

Heterotroph

An organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter

Anaerobe

An organism that does not require oxygen for growth - may react negatively and die if oxygen is present

Oxygen Revolution (2.7-2.4 bya)

Cyanobacteria photosynthesizing increased ocean and atmospheric oxygen so much that most prokaryotes were not able to survive and a mass extinction event was triggered

Ozone layer formation

All of the new oxygen in the atmosphere after the Oxygen Revolution allowed for the ozone layer to form in the upper stratosphere, protecting earth from most UV rays

Overexposure to UV radiation may result in…

Mutagenesis of DNA, indirect or direct DNA damage

Direct DNA Damage

Occurs when DNA directly absorbs a UVB photon, causing a lesion in the strand, showing as a sunburn (can also trigger the development of more melanin)

Indirect DNA Damage

Occurs when a UV-photon is absorbed by a chromopore, bimolecular reactions produce free radicals, and with nowhere to go they travel through the body and affect other areas

Endosymbiont Theory

The theory that eukaryotes evolved from prokaryotes and part of the evolutionary process was a prokaryotic cell engulfing a smaller cell that would form a symbiotic relationship with the host cell and later become a mitochondrion

Endosymbiont

A cell that lives within another cell

Host Cell

The cell that does the engulfing of the endosymbiont

When did multicellular organisms evolve?

Around 1.2 billion years ago

Key challenges to living on land

Desiccation, UV radiation, gravity, and thermal fluctuations

How unique was the evolution of multicellularity?

Multicellularity evolved independently several times in eukaryotes

Did prokaryotes ever live on land?

Yes, fossil evidence shows that cyanobacteria and other photosynthesizing prokaryotes lived on damp terrestrial surfaces, dating back to over 1 billion years ago

When did larger life forms (plants, animals, fungi) move onto land?

Less than 500 million years ago

When did vertebrates first appear and what were their characteristics?

Early vertebrates appeared around 530 million years ago and were fish-like in skeletal structure, but were jawless filter feeders

When did limbs evolve?

Around 365 million years ago

What are the three main groups of limbed vertebrates today?

Amphibians, reptiles (including birds), and mammals

How many species of vertebrates exist today?

Over 57,000 species

How did animals adapt to be suited for land?

• evolved lighter bodies with slim, long legs to fight gravity

• hard exoskeletons to protect against weather and desiccation

• Lungs from gills for effective atmospheric oxygen uptake

How did plants adapt to be suited for land?

• Gained the ability to stand upright and transport nutrients against gravity

• A waxy outer coating to prevent desiccation and conserve water

• Stomata to facilitate gas exchange

How did fungi adapt to be suited for land?

• diversified their nutrient obtaining strategies

• parasitism

• gaprobism (degradation of organic matter)

• development of mutualistic relationships

Biodiversity

Biological + diversity = the variety of all living things, from ecosystem diversity to species diversity to genetic diversity

How many species are there and out of those, how many face extinction? What types?

Of around 8 million described species, 1 million face extinction

• 500,000 plants and vertebrates

• 500,000 invertebrates

How much faster are our current extinction rates than natural evolutionary processes?

100x faster

What percent of each type of vertebrates are threatened with extinction?

• 15% of birds

• 30% of frogs

• 32% of pelagic sharks and rays

• 25% of mammals

• 50% of primates

Why do vertebrates feature predominantly in highlighting the biodiversity crisis?

• They are iconic and charismatic

• They are larger and more visible

• They are more easily counted and assessed

Vertebrates can also be good indicators of the health of an ecosystem and its biodiversity because…

They have higher trophic positions, making them more affected by ecosystem disturbance

Vertebrates can also be relevant to humans in the biodiversity crisis because…

• they can be major beneficials or pests

• they can also be resources that give food, fur, etc. to humans

• they have evolutionary closer ties to us

• they have cultural and symbolic value as well as aesthetic value

Keystone Species

An organism that helps define an entire ecosystem - the removal of it from an environment will result in a trophic cascade and the dramatic altering of its environment after its removal

Steller’s Sea Cow (1741)

Extinct within 27 years of western discovery, believed to be because of the removal of the keystone species (otters) in its ecosystems

Amphibians and Extinction

Out of 6400 described species, 30% are facing extinction, with 2500 on the decline and 435 in rapid decline since the 1980s

Insects and Extinction

Over 900,000 described species with inadequate data to gauge biodiversity, but a German study suggests a 76% decline over 26 years

Amphibian and Insect Extinction Drivers

• Habitat loss, degradation and fragmentation

• Pollution and other harmful substances

• The spread of invasive species

• Climate change

• Over-exploitation and co-extinction with other species

Consequences of Amphibian and Insect Extinctions

• Loss of abundance of biomass and diversity

• Loss of unique ecological functions

• Collapse of extensive ecological networks

What is a relatively unique extinction driver for amphibians?

The overexposure to UV rays

Amphibians in Australia

Out of 223 species, 59 are threatened, 12 critically endangered, and 4 extinct

Global Threats to Diversity

• Habitat loss, change and fragmentation

• Exploitation of species and resources

• Pollution

• Invasive/exotic species

• Emerging and novel diseases

• Environmental change

What makes some species more susceptible to extinction?

• how adapted a species is to a specific environment and what dispersal abilities it has

• feeding mechanisms or trophic positions may expose some species more to certain threats

• some species are already threatened due to genetic bottlenecks and past climate change

Our 6th Mass Extinction

• created by only one species modifying the environment

• happening in a very short time period

• rate of species lost is very high, but so far whole families have not been lost

Species Diversity

the variety of species in an ecosystem, throughout the biosphere, throughout a country, or throughout at other defined region

Species diversity is counting…

The number and richness of species

‘Richness’ is a measure of…

The number of unique species

Ecology

The study of the interactions between organisms and their environment

Many different biotic and abiotic factors can determine…

The distribution and abundance of different ecosystems and the species that occur within them

Primary Production

The rate of organic biomass growth or accumulation by plants

Terrestrial Net Primary Production (NPP) is limited by…

Solar radiation, water balance, and temperature

Terrestrial Biomes

Major life zones characterised by vegetation type

Endemism

The proportion of species that are endemic

Endemic Species

Often restricted to particular geographic regions

“Native” Species

Their presence in a geographic region is natural and not due to human interactions

Australia has a very high number of endemic species because of its…

Relative isolation and deep Gondwanan heritage

Megadiverse

An area with high levels of species diversity - Australia is one of 17 countries with this label!

Biodiversity Hotspot

A biogeographic region with significant biodiversity and high endemism, which is under threat

The requirements to be considered a biodiversity hotspot

1. Must contain at least 1500 species of vascular plants

2. Must have lost at least 70% of its habitat extent

“Exotic” species - introduced, feral, exotic, etc.

• their presence is usually due to human actions

• some dispersal events can happen naturally

• can cause major ecosystem disruption because natural regulators are missing in their new environment

• considered endemic in australia only if they were here prior to European colonisation

Genetic Diversity

The genetic variation within a population and between populations

How does genetic diversity make evolution possible?

It provides the raw material for evolutionary change by adaptation through natural selection

Species with less genetic variation are at a ______ risk of extinction.

greater

Extinction vortex

Small populations are vulnerable to inbreeding and genetic drift, the lack of genetic variation limits how well a population can respond to environmental change, this results in smaller populations, and the population spirals into extinction

Caveats to the extinction vortex

Not all small populations are doomed to low genetic diversity, and not all low genetic diversity leads to small populations

Biotic Factors in Ecosystem Diversity

plants, animals, microbes

Abiotic Factors in Ecosystem Diversity

light, geology, atmosphere, weather

Evolution (abstract)

The theory in western science that is typically used to explain patterns of units and diversity among living organisms

Key Components of Evolutionary Theory

• Similar traits among organisms are explained by descent from a common ancestor

• Differences among organisms are explained by the accumulation of heritable changes

• Natural selection is the overriding mechanism/process

Species

A group of organisms where ‘like mates with like’, but organisms vary in their traits

Differences among organisms are explained by…

The accumulation of heritable traits

Natural Selection

The overriding mechanism/process behind the persistence of advantageous traits

Adaptation refers to…

Inherited characteristics (traits) of organisms that enhance their survival and reproductive success in specific environments and has arisen as a result of natural selection

Natural selection is the mechanism behind…

Darwin’s ‘descent with modification’

How natural selection works

Individuals that are best suited to their environment are more likely to survive and reproduce - thus, evolution comes about due to the unequal reproductive success of individuals with advantageous traits