1. Theory and Evidence of Evolution

Success Criteria

Your learning has been successful if you can do the following:

I can define 'evolution'.
I can describe New Zealand's biogeography.
I can describe the scientific evidence for evolution - biogeography, fossil record, and comparing anatomical structures, DNA and proteins.
I can interpret a cladogram or phylogenetic tree.

Vocabulary

Learn these so you can communicate this concept well.

Analogous structures: Features with different evolutionary origins but have similar functions (evolved in similar environments).
Biogeography: The study of the geographical distribution of species.
Evolution: Cumulative change in alleles within a gene pool over time.
Fossils: Remains of long-dead organisms that have been preserved and after many years, become part of the Earth's crust.
Glacial period: Period of time in which large parts of Earth's surface is covered in ice and snow; also know as an Ice Age.
Homologous structures: Features similar in structure (common ancestor) and origin but have different functions (evolved in different environments).
Interglacial period: Period of time between glacial periods, where the climate is warmer and ice sheets and glaciers retreat.
Mitochondrial DNA (mtDNA): Genetic material that is only inherited from the mother, so is relatively unchanging over generations. s to create different sounds when we speak.

Lesson 1: Hei Mahi (Do Now)

Do Now in your OneNote/Notebook:

Write everything you already know about 'evolution'.

Lesson 1: Exit Task

In your Learning Journal:

Re-write this interpreting question so it is asking about the NZ's Biogeography:

How did it happen?

Then, write an answer for it.

Theories of Evolution

Early Ideas About the Origins of Life

All human cultures, from early times, tried to explain the origin of human beings and other living things on Earth. Each culture has a different story or creation myth. These stories generally share the view that species were created as they are now.

However, a number of early scientists found evidence that did not support this idea. Georges-Louis de Buffon, Jean Baptiste Lamarck, Charles Darwin and Alfred Wallace all generally share the view that all species have evolved from a common ancestor gradually.

Māori

Maori have the story of Earth goddess, papa and the sky god Rangi, who were joined so closely together that no light could come into the world and their children could not escape between them. One of their children, Tane managed to separate them.

Video: MAORI CREATION MYTH

Old Testament

The Christian story, of God making the world in six days and resting on the seventh, comes from the Old Testament. It was written down from the creation story passed down by word of mouth by Hebrew tribes.

Video: OLD TESTAMENT CREATION MYTH

Georges-Louis de Buffon

In 1760's Georges-Louis de Buffon proposed that all mammals must have come from a common ancestor after investigating the similarities in their limb bones.

Jean Baptiste Lamarck

In 1809 Jean Baptiste Lamarck put forward a theory to explain how changes in species could have come about.

He suggested that changes acquired during an organism's lifetime could be passed on to their offspring, causing a gradual change in the species (this gradual change is termed evolution).

In general, Lamarck's theory of evolution has not been supported by evidence except in the rather special case of some bacteria.

Charles Darwin & Alfred Wallace

Charles Darwin and Alfred Wallace both proposed a theory of evolution according to which species gradually change through a process called natural selection, where the individuals most fitted to their environment survive to pass on their characteristics to their offspring.

Darwin collected evidence over 20 years and published his work only when Wallace proposed a similar theory.

Darwin did not know about the role of genes and DNA played in inheritance, nor about the role of mutations in producing the variations upon which his theory depends.

What is Evolution?

In biology, the word 'EVOLUTION' refers to cumulative change in alleles within a gene pool over time. Although we will never now every detail of Earth's history, evidence points towards two absolute certainties:

The Earth is very old; about 4.6 billion years.
Living things change over time. We know that whole groups of animals and plants have become extinct, new species have appeared, and that the genetic make-up of species can, in some cases, change within a few generations.

The idea of evolution goes back more than 2,000 years. In 1859, Charles Darwin assembled many facts supporting the idea, and much more evidence for evolution has been discovered since then.

Watch from 0:00 to 4:14

Darwin's Theory of Evolution

Darwin's theory of evolution by natural selection can be summarised as follows:

Present-day species have evolved from ancestral forms.
Organisms produce more offspring than survive. The offspring compete for food and other essentials in a struggle for survival.
Offspring produced by sexual reproduction will show variation; some will have characteristics that are more suited to the environment than others.
Those individuals of a species with favourable characteristics will survive longer and produce more offspring and so pass their favourable characteristics on. Those with unfavourable characteristics will not survive as long or reproduce as frequently. This is called the 'survival of the fittest'.
Successive generations will become modified over time, particularly if their environment is changing. Gradually, the species will change sufficiently to be recognised as a new species.

Modern Developments of Darwin's Theory - It's in our DNA

The modern definition of evolution involves changes in the gene pool of a population that over the generations lead to new types of organisms. The gene pool is the collection of all the genes of all members of a population.

Darwin believed that variations in parents were blended in offspring. This was a major flaw in his theory as it would reduce variation in a population. We now know this does not happen, as variations are coded for by genes, which are discrete (non-blending) units of inheritance.

We also know that variation is caused by:

Meiosis and sexual reproduction, which reshuffle chromosomes into new combinations.
Crossing over during meiosis, where pieces of homologous chromosomes swap segments containing the same genes but often with different alleles. This results in new combinations of alleles at different loci.
Mutations, which are changes in the DNA of genes. Mutations are the raw material that evolution works on. Only mutation can alter actual genes and produce evolutionary novelties. Most mutations are harmful and selected against immediately, some are neutral in their effect, and a few might confer a selective advantage on the organism. Some mutations occur spontaneously, wile others are induced by mutagens such as radiation (X-rays, UV rays), chemicals (benzene, nitrites, nitrosamines) and viruses. Some viruses may insert their DNA into the host DNA, resulting in mutations.

An adaptation is any inherited variation (structural, physiological or behavioural) that improves an organism's chances of passing on its genes to the next generation.

Genetic adaptations are different from physiological adaptations that individual organisms make during their lifetime in response to environmental changes - although the ability to make these changes may be inherited.

Evidence of Evolution

There are four types of evidence that we will explore:

Biogeography
Fossils
Comparing anatomy
Comparing DNA and protein

Biogeography

From Zealandia's separation from Gondwanaland 65 Mya, to the effects of the Ice Age and glacial periods on the sea level, to the effects of plate tectonics on New Zealand's landscape - the constant change in New Zealand's geography is key to shaping the range and diversity of species we see today.

BIOGEOGRAPHY is the study of the geographical distribution of species. Go through these slides and the 3 infographics below for more information on New Zealand's biogeography.

Importantly, there was a bottleneck event in the Oligocene, and species moved to fill vacant niches due to the lowering of the sea level as the climate began to cool and water was being stored in the polar caps and glaciers. New land was exposed and new niches became available. Different populations would have spread out and formed a cline where neighbouring populations were exposed to slightly different conditions and had slightly different selection pressures such as food sources.

NZ Geography

Infographic: The rise and fall of New Zealand (Biozone)

Infographic: Warm INTERGLACIAL PERIODS (Biozone)

Infographic: GLACIAL PERIODS (Biozone)

Infographic: Which animals can colonise ocean islands? (Biozone)

Only certain groups of plants and animals tend to colonise oceanic islands.

The animals that successfully colonise oceanic islands have to be marine in habit or able to survive long periods at sea or in the air.

This is why bats and dolphis are the only native mammals in New Zealand.

Lesson 2: Hei Mahi (Do Now)

Do Now in your OneNote/Notebook:

Which is the dolphin more closely related to: cows or sharks? Justify your answer!

Lesson 2: Exit Task

In your Learning Journal:

Re-write this interpreting question so it is asking about the Anatomical Structures:

What can you infer?

Then, write an answer for it.

Fossil Record

FOSSILS are the remains of long-dead organisms that have been preserved and after many years, become part of the Earth's crust. Fossils provide a record of ancient organisms and the study of them provides evidence of lines of descent, showing us what the intermediate forms were like.

Infographic: Fossilisation - How fossils form (Biozone)

Comparing Anatomical Structures

HOMOLOGOUS STRUCTURES are features which are similar in structure and origin (as they likely evolved from a common ancestor) but have different functions (as they have evolved in different environments).

E.g. human arm and a frog arm

Whereas ANALOGOUS STRUCTURES are features with different evolutionary origins (meaning they are unrelated species with different ancestors) but have similar functions (as they have evolved in similar environments, exposed to similar selection pressures).

E.g. shark fin, penguin wing, dolphin flipper.

Infographic: Organisms with pentadactyl limbs share a common ancestor (Biozone)

Infographic: Analogous structures vs homologous structures

Comparing DNA Sequences

Comparing DNA sequence similarity between species can be used to measure relatedness. Studies comparing DNA sequences from different species (using techniques such as DNA sequencing or DNA hybridisation) has shown that even widely dissimilar species such as yeast and humans share most of the basic genes for biochemical processes, while more closely related species such as humans and chimpanzees have almost identical DNA. This indicates that all species currently living on Earth once had a common ancestor.

Mitochondrial DNA (mtDNA) found in the mitochondria can also be analysed to determine relatedness and when species diverged. Mitochondrial DNA:

Never undergoes crossing over
Is passed down the female/maternal lineage
Acquires mutations at a constant rate, so the presence of mutations in mtDNA can be compared to determine when species diverged.

Infographic: How is DNA used to compare similarities in sequence? Using DNA Hybridisation Technique.

Infographic: Similarity of human DNA to DNA of other primates

Comparing Protein Sequences

A protein has a specific number of amino acids arranged in a specific order. Any differences in the protein sequence reflect changes in the DNA sequence. Commonly studied proteins include blood proteins, such as haemoglobin, and the respiratory protein cytochrome C.

For example, there are no amino acid differences between the haemoglobin of humans and chimpanzees, indicating they recently shared a common ancestor. Whereas humans and frogs have 67 amino acid differences, indicating they had a common ancestor a very long time ago.

Infographic: Haemoglobin homology between humans and other animals

Full Summary of Scientific Evidence for Evolution

Tasks & Homework

Task: Continental Drift and Evolution

L3E-132-Continental-Drift-and-Evolution-Q2-Q3-Q6.pdf

Optional Task: Videos

VIDEOBiogeography of the Ice Age - Really interesting to learn about how the abiotic factors during this glacial period impacted the biotic factors and ecosystems.

Back to the Basics

VIDEO: What are DNA and Genes? (Learn.Genetics)
VIDEO: What is Inheritance (Learn.Genetics)
INTERACTIVE: Geologic Time (Learn.Genetics) - This link will help you gain an appreciation for just how immense geologic time is, and how recent animals have been.