Doggy documentary
The standard goes through all the different processes that could lead to a new species forming and probably most importantly covers how New Zealand provided the conditions and selection pressures to allow some pretty crazy organisms to form such as that flightless bird and the massive carrot eating weta you see on the front page. Just remember this is not the Animal and plant topic! you need to be thinking of why and how the species has formed from an evolution population standpoint and not only the individual behaviours and responses of an organism. Before you start this topic it will be a good thing to recap your Year 12 Biology course in the areas of species/ mutations and gene pools.
The story Ranginui and papatuanuku....
observable evolution today:
This is a little concerning. Evolution is a very slow process. However, due to the impact of human activity we now have examples of evolution happening in front of our noses. What are the biological processes that allow the following to occur?
-DDT resistant insects.
-Antibiotic resistant bacteria
-new starins of HIV
-DDT resistant insects.
-Antibiotic resistant bacteria
-new starins of HIV
Researchers at the University of Buffalo have
re-sensitized MRSA and other antibiotic-resistant bacteria by using a
protein-lipid complex found in human breast milk. Not only would this allow
doctors to treat these superbugs with a more standard treatment, but might also
help to slow resistance in other strains.
introduction to evolution & natural selection
Mr Darwin and his theory
The Definition:
Biological evolution, simply put, is descent with modification. This definition encompasses small-scale (micro) evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations or macro evolution). Evolution helps us to understand the history of life.
The Explanation:
Biological evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, you grow hair in funny places, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.
The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.
Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. Evolution means that we're all distant cousins: humans and kiwis, wetas and sheep.
Key ideas
•The change in the gene pool of a population from generation to generation.
•It is important to remember that individuals do not evolve, populations evolve.
•All the genes in a population are called the gene pool.
•The ratio of different alleles in that population can change over time.
•As the ratio changes, so evolution occurs.
Biological evolution, simply put, is descent with modification. This definition encompasses small-scale (micro) evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations or macro evolution). Evolution helps us to understand the history of life.
The Explanation:
Biological evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, you grow hair in funny places, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.
The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.
Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. Evolution means that we're all distant cousins: humans and kiwis, wetas and sheep.
Key ideas
•The change in the gene pool of a population from generation to generation.
•It is important to remember that individuals do not evolve, populations evolve.
•All the genes in a population are called the gene pool.
•The ratio of different alleles in that population can change over time.
•As the ratio changes, so evolution occurs.
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New Zealand Examples
Darwin coined ‘natural selection’; selection referring to this being an active process.
Types of selection: Stabilising
This type of selection will occur when an environment is relatively stable and, on average, a species is particularly well adapted for this environment. It may also result from instances where the synchronicity of timing in certain events is particularly important for fitness, such as in breeding or flowering. In cross-pollinating plants for example, there is clear benefits in terms of reproductive success if a plant flowers at the time when most other individuals are flowering, as its chances of fertilisation are much greater. Individuals that flower much earlier or later than the majority will be selected against.
Types of selection: Stabilising
This type of selection will occur when an environment is relatively stable and, on average, a species is particularly well adapted for this environment. It may also result from instances where the synchronicity of timing in certain events is particularly important for fitness, such as in breeding or flowering. In cross-pollinating plants for example, there is clear benefits in terms of reproductive success if a plant flowers at the time when most other individuals are flowering, as its chances of fertilisation are much greater. Individuals that flower much earlier or later than the majority will be selected against.
Directional selection can result from a changing environment, driving selection for just one end of the spectrum of variation within a species.
A great example of directional selection can actually be seen in bones of the heavy-footed moa (Pachyornis elephantopus).
Within a species, such as the heavy-footed moa, there is natural variation in body size. Larger individuals have a smaller surface area: volume ratio, and thus are able to retain heat more efficiently, and as a result have increased fitness in cold climates. Alternatively, the higher surface area: volume ratio of small individuals means they are able to lose heat more efficiently in warm climates. This relationship between body size and climate is known as ‘Bergmann’s rule”, and is an example of directional selection.
If we look at body masses of the heavy-footed moa that lived during the ice age (when temperatures were much cooler in New Zealand) we see they were on average much larger than individuals from the last 10,000 years (when New Zealand climate was relatively warmer).
A great example of directional selection can actually be seen in bones of the heavy-footed moa (Pachyornis elephantopus).
Within a species, such as the heavy-footed moa, there is natural variation in body size. Larger individuals have a smaller surface area: volume ratio, and thus are able to retain heat more efficiently, and as a result have increased fitness in cold climates. Alternatively, the higher surface area: volume ratio of small individuals means they are able to lose heat more efficiently in warm climates. This relationship between body size and climate is known as ‘Bergmann’s rule”, and is an example of directional selection.
If we look at body masses of the heavy-footed moa that lived during the ice age (when temperatures were much cooler in New Zealand) we see they were on average much larger than individuals from the last 10,000 years (when New Zealand climate was relatively warmer).
Disruptive selection occurs when the environment favours the two extremes of variation within a species. Imagine that a palm tree seed drifts to an island and begins to grow. As the population of palms grows we begin to see some natural variation in the optimal soil pH conditions for individuals. However, the island has only two types of soil, one is high pH and the other is low pH. Each will drive selection at one of the extremes on variation, which may ultimately result in sympatric speciation (discussed later).
Survival of the Fittest: Stickleback Fish & pocket mice
mutations
One of the key things required for Natural selection though is variation, or genetic diversity, upon which it can act. Genetic diversity within a population is generated via mutations.
DNA, the code of life, is made up of long sequences comprised of just four different nucleotides (or bases): Thymine (T), Adenine (A) ,Cytosine (C) and Guanine (G). A group of three of these nucleotides is known as a ‘codon’, and the sequence of each codon codes for a particular amino acid, which in turn make proteins and ultimately the entire organism. For example, we may have a DNA sequence that codes for amino acids to that forms part of a colour allele giving us a particular colour of organism.
When we talk about a mutation, we mean a change to a single one of these nucleotides. If our mutation happens to be a deletion or insertion of a nucleotide this can shift the whole codon reading frame, and hence result in a cascade of different amino acids being produced. This will greatly alter the resulting protein produced by the gene and may result in the death of the organism.
DNA, the code of life, is made up of long sequences comprised of just four different nucleotides (or bases): Thymine (T), Adenine (A) ,Cytosine (C) and Guanine (G). A group of three of these nucleotides is known as a ‘codon’, and the sequence of each codon codes for a particular amino acid, which in turn make proteins and ultimately the entire organism. For example, we may have a DNA sequence that codes for amino acids to that forms part of a colour allele giving us a particular colour of organism.
When we talk about a mutation, we mean a change to a single one of these nucleotides. If our mutation happens to be a deletion or insertion of a nucleotide this can shift the whole codon reading frame, and hence result in a cascade of different amino acids being produced. This will greatly alter the resulting protein produced by the gene and may result in the death of the organism.
At the opposite end of the spectrum, many mutations have no affect on phenotype, due to redundancy in the amino acid codons. For example, both TTT and TTC code for the amino acid Phenalalanine (Phe).
Other mutations however can alter phenotypes in a non-fatal way, and introduced variability into a species (e.g. a new colour of plumage) on which the environment can act to drive the natural selection process.
Other mutations however can alter phenotypes in a non-fatal way, and introduced variability into a species (e.g. a new colour of plumage) on which the environment can act to drive the natural selection process.
Apart from creating genetic diversity within a species upon which natural selection can act, mutations can also have a number of practical applications for researching the past movements of a species.
Imagine a species of beetle that lived in Southland 10,000 years ago. About 8,000 years ago some individuals move to Otago and a random mutation becomes present in one of these individuals and is passed to their offspring and eventually every member of that population ends up with it. The same pattern is then repeated into Canterbury 6000 years ago, but in addition to having the mutation shared with Otago, the Canterbury population develops their own specific mutation. By detecting these mutations in populations of beetles still living in these regions today it would be possible to recreate these ancient movements of the species.
Imagine a species of beetle that lived in Southland 10,000 years ago. About 8,000 years ago some individuals move to Otago and a random mutation becomes present in one of these individuals and is passed to their offspring and eventually every member of that population ends up with it. The same pattern is then repeated into Canterbury 6000 years ago, but in addition to having the mutation shared with Otago, the Canterbury population develops their own specific mutation. By detecting these mutations in populations of beetles still living in these regions today it would be possible to recreate these ancient movements of the species.
Genetic drift and founder effect are particularly important issues in the management of endangered species, where maintaining genetic or allelic diversity is important. In small populations genetic drift may ultimately lead to certain alleles being lost from the population. However, small numbers of endangered birds are frequently translocated to new predator-free islands, and so the founder-effect is also an issue within such populations.
Another key issue affecting small populations is the deleterious effect of inbreeding, which I won’t deal with here. Together, inbreeding, founder-effect and genetic drift in small populations are topics dealt with in the field of research known as ‘Conservation genetics’
Another key issue affecting small populations is the deleterious effect of inbreeding, which I won’t deal with here. Together, inbreeding, founder-effect and genetic drift in small populations are topics dealt with in the field of research known as ‘Conservation genetics’
what is a species?
why don't different species interbreed?
TASK- For each of the cartoons above identify the Isolating mechanism that it might be depicting. Explain how this isolating mechanism prevents interbreeding between species.
REPRODUCTIVE ISOLATING MECHANISMS:
Whats an isolating mechanism?
A reproductive isolating mechanism is a barrier that prevents two organisms from differing species from mating and producing fertile offspring / prevents successful interbreeding / prevents gene flow
This works to preserve the uniqueness of gene pools, prevent hybridisation thus reinforcing separateness of species.
Because species are finely tuned to their niche adding genes from another species suited to another niche will cause a reduction in fitness.
REPRODUCTIVE ISOLATING MECHANISMS:
Whats an isolating mechanism?
A reproductive isolating mechanism is a barrier that prevents two organisms from differing species from mating and producing fertile offspring / prevents successful interbreeding / prevents gene flow
This works to preserve the uniqueness of gene pools, prevent hybridisation thus reinforcing separateness of species.
Because species are finely tuned to their niche adding genes from another species suited to another niche will cause a reduction in fitness.
nz Examples
An example of behavioural isolation mechanisms may include particular courting dances or next construction (e.g. different colour objects in bowerbirds). Another example is breeding calls and vocalisations. These are widely used by birds to find and attract potential mates, and can be quite species-specific. For example, two closely related birds (within the same genus) that commonly breed on the same islands are the mottled and Cooks petrels. Their calls are quite different as you can hear here.
An example of temporal separation of breeding can be seen in the Snares Crested Penguin. Penguins on the main Snares Islands will lay eggs in mid-Sep to mid-Oct, while those that breed on the western chain of islands don’t lay eggs until 6 weeks later, in November. Nobody is sure what the reason for this is, and although the birds on the two island chains are still regarded the same species this is an example of how such isolation may eventually lead to segregation of the populations and eventually could result in speciation.
HELP BLACK STILTS ARE ON THE CRITICAL LIST
Hybridisation in the New Zealand Black Stilt, kaki.The total population currently numbers 100 birds, including captive birds that are intensively managed. Really interesting report HERE ideal for scholarship kids.
This is a radio broadcast about the NZ Wren,the Rifleman. It lasts 12 minutes but does have some info about how or why the species may have diverged. Maybe you could have it playing in the background while you are doing other work on the internet so you can listen while you work.
How do species arise?
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Allopatric speciation
UNderstanding NZ unique Geological history-LINK
In the last 1.8 million years huge changes have created NZ's landscape today. This has created unique condition, selection pressures and the evolution of many NZ plant and animal species. It is critical you understand the geological history of NZ and understand the influence it has had on the evolution of plants and animals.
Check a great link to become a little more familiar HERE
HERE is a10 minute video "ghosts of Gondwana".
Check a great link to become a little more familiar HERE
HERE is a10 minute video "ghosts of Gondwana".
allopatric speciation in Nz.
The kakapo, kaka and kea.
Zealandia 80 MYA
It took over 20 million years to separate with the Tasman Sea reaching its present width of 2,000 km around 60 MYA. NZ has undergone a number of geological events and today only 10% of the Zealandia continent sits above sea level.
The NZ animal and plant life are unique in a number of ways:
Longevity- Compared with animals from other temperate land masses, many native New Zealand animals live for a long time. For example, the kākāpō bird may live up to the age of 70, stitchbirds for 34 years, and kiwi for at least 30 years.
Slow breeders-Many native animals are also comparatively slow breeders. New Zealand pigeons, which lay only one egg at a time and extreme examples were the moa species, which took up to 10 years to reach maturity.
Radiation: diverse habitats are occupied. There are more than 100 wētā species in varied settings, from forests to caves, and even under rocks on Central Otago mountains where there are sub-zero temperatures.
Flightlessness: In the absence of predatory land mammals, many kinds of birds became flightless.
Giants: Many are now extinct but living giants include the flightless kākāpō, which is the world’s biggest parrot, the weka and the 3-kilogram takahē. Among other big New Zealand animals are giant weevils, land snails, centipedes, earthworms, flatworms and wētā.
The explanation for these oddities lies in the geographical history of NZ.
THREE key factors have been responsible for the creation of geographical barriers between populations:
- isolation for 60 MY- Why did NZ populations take a unique evolutionary path compared with their Aussie ancestors?
-mountain building- So why and how would the movement of tectonic plates which created the southern alps promote speciation?
-climate change- How did climate change cause populations to become isolated and therefore promote speciation in NZ?
Zealandia 80 MYA
It took over 20 million years to separate with the Tasman Sea reaching its present width of 2,000 km around 60 MYA. NZ has undergone a number of geological events and today only 10% of the Zealandia continent sits above sea level.
The NZ animal and plant life are unique in a number of ways:
Longevity- Compared with animals from other temperate land masses, many native New Zealand animals live for a long time. For example, the kākāpō bird may live up to the age of 70, stitchbirds for 34 years, and kiwi for at least 30 years.
Slow breeders-Many native animals are also comparatively slow breeders. New Zealand pigeons, which lay only one egg at a time and extreme examples were the moa species, which took up to 10 years to reach maturity.
Radiation: diverse habitats are occupied. There are more than 100 wētā species in varied settings, from forests to caves, and even under rocks on Central Otago mountains where there are sub-zero temperatures.
Flightlessness: In the absence of predatory land mammals, many kinds of birds became flightless.
Giants: Many are now extinct but living giants include the flightless kākāpō, which is the world’s biggest parrot, the weka and the 3-kilogram takahē. Among other big New Zealand animals are giant weevils, land snails, centipedes, earthworms, flatworms and wētā.
The explanation for these oddities lies in the geographical history of NZ.
THREE key factors have been responsible for the creation of geographical barriers between populations:
- isolation for 60 MY- Why did NZ populations take a unique evolutionary path compared with their Aussie ancestors?
-mountain building- So why and how would the movement of tectonic plates which created the southern alps promote speciation?
-climate change- How did climate change cause populations to become isolated and therefore promote speciation in NZ?
Selection ultimately drives adaptation to the environment, and over a sufficiently long period of time can result in speciation.
There are several different ways in which species can be created, but the two main forms of speciation that we can refer to are allopatric or sympatric.
Allopatric speciation occurs principally as a result of geographical or physical reproductive isolation, i.e. between two populations that are physically separated. Often the best examples of this can be found on islands, where individuals of different species have arrived by chance events such as drifting on currents or weather systems, and then evolve in isolation, separated from the main population by vast areas of ocean. Take for example the swamphens of the Pacific. The Australian purple swamphen (also a recent arrival in New Zealand, known locally as pukeko) may seem to spend most of its time on the ground, but they are in fact actually quite strong fliers and in the past individuals have arrived on a range of different islands in the Pacific. On each of these islands allopatric speciation processes have then taken place and the resulting swampens become quite different to the Australian form. On some islands the arrivals have been more recent (e.g. New Zealand, Vanuatu) and there has not been sufficient time for speciation to have occurred (i.e. these are still considered to the purple swamphens)
There are several different ways in which species can be created, but the two main forms of speciation that we can refer to are allopatric or sympatric.
Allopatric speciation occurs principally as a result of geographical or physical reproductive isolation, i.e. between two populations that are physically separated. Often the best examples of this can be found on islands, where individuals of different species have arrived by chance events such as drifting on currents or weather systems, and then evolve in isolation, separated from the main population by vast areas of ocean. Take for example the swamphens of the Pacific. The Australian purple swamphen (also a recent arrival in New Zealand, known locally as pukeko) may seem to spend most of its time on the ground, but they are in fact actually quite strong fliers and in the past individuals have arrived on a range of different islands in the Pacific. On each of these islands allopatric speciation processes have then taken place and the resulting swampens become quite different to the Australian form. On some islands the arrivals have been more recent (e.g. New Zealand, Vanuatu) and there has not been sufficient time for speciation to have occurred (i.e. these are still considered to the purple swamphens)
The following documentary is well worth a watch, trust me it will help. Ghosts of Gondwana Evolution of plants and animals in NZ, a long read but good. Link to Te Awa
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So up until about 2 million years ago it seems that moa were only found on the South Island. This is because, some 25 million years ago, large parts of New Zealand were underwater, in what is known as the Oligocene drowning (this was due to the stretching of the crust as NZ separated from Australia causing it to sink beneath the ocean). The only part of the North Island that would have been above water was a small area of Northland. Over the next 23 million years more of the North Island rose out of the sea in a southward progression. By 2 million years ago the islands were still separated by what is known as the Manawatu Strait and we had about 4 different moa species in the South Island.
Sometime between 1 and 2 million years ago the 2 main islands of New Zealand became joined and moa were able to move into the North Island for the first time.
Over the next 2 million years sea level fulctuated, being lower in ice ages and higher during interglacial warm periods, and the landmasses became cut off from each other. Now geographically isolated, moa in the North Island began to undergo allopatric speciation. For the next 500,000 years the sea levels would fluctuate with sea level change but it seems that the two islands would never again be joined together allowing gene-flow between these species.
However a diversity of moa species appeared even within each of these islands, for example in the South Island we had eastern moa (Emeus crassus), stout-legged moa (Euryapteryx gravis) and heavy-footed moa (Pachyornis elephantopus) living in the low altitude eastern parts of the islands.
So how might this sympatric speciation have been brought about?
One possibility is that due to glaciation (along the southern alps) or changing sea levels cutting off small offshore islands, different populations of moa became partly isolated from each other for long periods of time. During this time genetic drift may have operated and when these two populations came back together after the barrier was removed there was some degree of reproductive isolation between then, whether habitat or behavioural driven.
Some evidence for this can be seen in upland moa. Although still regarded as a single species, there is actually different recognisable genetic groups in different parts of the South Island, suggesting that there may have been little gene flow between them. Clades A and B are separated by high mountains that would have been heavily glaciated during the ice age, as are clades C and D. Clades C and B are also separated by a heavily glaciated area, and A and D are separated by a broad flat area of large braided rivers that may have acted as a geographic barrier as the ice cap melted at the end of the last ice age.
Given enough time, this could have perhaps resulted in speciation.
So how might this sympatric speciation have been brought about?
One possibility is that due to glaciation (along the southern alps) or changing sea levels cutting off small offshore islands, different populations of moa became partly isolated from each other for long periods of time. During this time genetic drift may have operated and when these two populations came back together after the barrier was removed there was some degree of reproductive isolation between then, whether habitat or behavioural driven.
Some evidence for this can be seen in upland moa. Although still regarded as a single species, there is actually different recognisable genetic groups in different parts of the South Island, suggesting that there may have been little gene flow between them. Clades A and B are separated by high mountains that would have been heavily glaciated during the ice age, as are clades C and D. Clades C and B are also separated by a heavily glaciated area, and A and D are separated by a broad flat area of large braided rivers that may have acted as a geographic barrier as the ice cap melted at the end of the last ice age.
Given enough time, this could have perhaps resulted in speciation.
Another possibility is that it might have been driven by selection pressures, due to ecological factors during the Pleistocene ice ages.
Some evidence that habitat, diet and feeding variation existed between the different moa species comes from 2 forms of analysis. First, morphology shows that moa species had quite different beaks to each other. As bird beaks are tightly linked to feeding ecology, this suggests that they were eating different things.
Some evidence that habitat, diet and feeding variation existed between the different moa species comes from 2 forms of analysis. First, morphology shows that moa species had quite different beaks to each other. As bird beaks are tightly linked to feeding ecology, this suggests that they were eating different things.
Sympatric speciation
Polypliody is a very interesting process. See this nifty ANIMATION and these very nifty NOTES which will help you to understand.
Example of what you will usually have to cover in a polyploidy question:
· describes polyploidy as a doubling / multiple of chromosome sets
· describes effect of polyploidy on phenotype, e.g. hybrid vigour
· explain why species must be closely related
· explains why hybrids are often infertile
· explains the role of meiotic error/ double chrom #/ non-disjunction/ amphiploidy in polyploidy
· explains the role of self fertilisation in polyploidy
· links the changes in genotype to the changes in phenotype in modern wheat development
· explains instant speciation or sympatric in terms of reproductive isolation
Example of what you will usually have to cover in a polyploidy question:
· describes polyploidy as a doubling / multiple of chromosome sets
· describes effect of polyploidy on phenotype, e.g. hybrid vigour
· explain why species must be closely related
· explains why hybrids are often infertile
· explains the role of meiotic error/ double chrom #/ non-disjunction/ amphiploidy in polyploidy
· explains the role of self fertilisation in polyploidy
· links the changes in genotype to the changes in phenotype in modern wheat development
· explains instant speciation or sympatric in terms of reproductive isolation
Understanding phylogenies
Understanding a phylogeny is a lot like reading a family tree. The root of the tree represents the ancestral lineage, and the tips of the branches represent the descendants of that ancestor. As you move from the root to the tips, you are moving forward in time. When a lineage splits (speciation), it is represented as branching on a phylogeny. When a speciation event occurs, a single ancestral lineage gives rise to two or more daughter lineages. Phylogenies trace patterns of shared ancestry between lineages. Each lineage has a part of its history that is unique to it alone and parts that are shared with other lineages. Similarly, each lineage has ancestors that are unique to that lineage and ancestors that are shared with other lineages common ancestors. |
The field of phylogenetics involves the use of biological data matrices to construct trees and understand evolutionary relationships between organisms. To a large extent the term ‘phylogenetics’ is now interchangable with ‘cladistics’, although the latter refers specifically to a method within phylogenetics. The biological data used can either be morphological (usually presented as scored traits)…
or molecular (aligned DNA sequences), or a combination of these. From a matrix we can then compare each species to each other, measuring the number of differences between them. These measurements can be used to create a distance matrix…
We can use such calibrated phylogenies to help interpret what past geological or climatic events may have resulted in speciation. For example, recent work has produced a calibrated phylogeny for the New Zealand parrots. This shows that the kea and kakas diverged approximately 5 million years ago, which geologists believe is the time at which mountain uplift in New Zealand created an ‘alpine zone’. Therefore, it can be surmised that ecological isolation between populations of the ancestral form that inhabited the alpine zone and those that inhabited lowland forests gave rise to the kea and kaka lineages respectively.
Later, the extinct Chatham Island parrot diverged from its nearest living relative, the New Zealand kaka, approximately 1.7 million years ago. This indicates that the species originated from birds that flew to the Chatham Islands from New Zealand soon after the Chatham Islands emerged above sea level (approximately 2 million years ago) and evolved in geographic isolation thereafter.
evidence for evolution-
Biogeography
Biogeography is a branch of geography that studies the past and present distribution of the world's many species. It is usually considered to be a part of physical geography as it often relates to the examination of the physical environment and how it affects species and shaped their distribution across space. As such it studies the world's biomes and taxonomy - the naming of species. In addition, biogeography has strong ties to biology, ecology, evolution studies, climatology, and soil science. HERE is a link that shows the break-up of Gondwana land. |
Fossil evidence
Fossils are important for estimating when various lineages developed in geologic time. As fossilization is an uncommon occurrence, usually requiring hard body parts and death near a site where sediments are being deposited, the fossil record only provides sparse and intermittent information about the evolution of life. Scientific evidence of organisms prior to the development of hard body parts such as shells, bones and teeth is especially scarce, but exists in the form of ancient microfossils, as well as impressions of various soft-bodied organisms.
New Zealand Evolutionary Fossil Evidence can be found here: http://sci.waikato.ac.nz/evolution/FossilEvidence.shtml
New Zealand Evolutionary Fossil Evidence can be found here: http://sci.waikato.ac.nz/evolution/FossilEvidence.shtml
Archaepteryx- the 150 million year old"missing link".The awesome fossil was found in Southern Germany....what is it's significance?
Comparative Anatomy
Why the internal structure of a bat resemble that of a whale more closely than that of a bird? Why then should the anatomy of a whale differ from that of a fish far more than it differs from that of a sheep?
The comparative study of the anatomy of groups of animals shows structural features that are fundamentally similar or homologous, demonstrating phylogenetic and ancestral relationships with other organisms, most especially when compared with fossils of ancient extinct organisms. Vestigial structures and comparisons in embryonic development are largely a contributing factor in anatomical resemblance in concordance with common descent. BASICALLY this is evidence of organisms have not been designed from scratch, BUT are the result of modifications of pre-existing structures over much time.....due to differing niche demands and selection pressures.
Why the internal structure of a bat resemble that of a whale more closely than that of a bird? Why then should the anatomy of a whale differ from that of a fish far more than it differs from that of a sheep?
The comparative study of the anatomy of groups of animals shows structural features that are fundamentally similar or homologous, demonstrating phylogenetic and ancestral relationships with other organisms, most especially when compared with fossils of ancient extinct organisms. Vestigial structures and comparisons in embryonic development are largely a contributing factor in anatomical resemblance in concordance with common descent. BASICALLY this is evidence of organisms have not been designed from scratch, BUT are the result of modifications of pre-existing structures over much time.....due to differing niche demands and selection pressures.
Embryology
Some of the most persuasive evidence for evolution comes from the study of early development of vertebrates. Although adult birds, mammals and amphibians are very different their embryos are remarkably similar. Vertebrate embryos, even those of humans are segmented, just as adult fish are. In adult amphibians, reptiles, birds and mammals this segmentation is lost early in development.
Not Gill slits which exist in early development BUT in land vertebrates they disappear....WOW WHAT DO YOU THINK>>>>
Biochemistry Analysis
Once it became possible to determine the amino acid sequence of proteins and DNA, biologists were able to compare molecules. Biochemistry also reveals similarities between organisms of different species. For example, the metabolism of vastly different organisms is based on the same complex biochemical compounds. The protein cytochrome c, essential for aerobic respiration, is one such universal compound. The universality of cytochrome c is evidence that all aerobic organisms probably descended from a common ancestor that used this compound for respiration. Certain blood proteins found in almost all organisms give additional evidence that these organisms descended form a common ancestor. Such biochemical compounds, including cytochrome c and blood proteins, are so complex it is unlikely that almost identical compounds would have evolved independently in widely different organisms. Further studies of cytochrome c in different species reveal variations in the amino acid sequence of this molecule. For example, the cytochrome c of monkeys and cows is more similar than the cytochrome c of monkeys and fish. Such similarities and differences suggest that monkeys and cows ate more closely related than are monkeys and fish. Scientists have similarly compared the biochemistry of universal blood proteins. Their studies reveal evidence of degrees of relatedness between different species. This evidence implies that some species share a more recent common ancestor than other species do. From such evidence scientists have inferred the evolutionary relationships between different species of organisms.
DNA Evidence
DNA is a test of the difference between one species and another – and thus how closely or distantly related they are.
While the genetic difference between individual humans today is minuscule – about 0.1%, on average – study of the same aspects of the chimpanzee genome indicates a difference of about 1.2%. The bonobo (Pan paniscus), which is the close cousin of chimpanzees (Pan troglodytes), differs from humans to the same degree. The DNA difference with gorillas, another of the African apes, is about 1.6%. Most importantly, chimpanzees, bonobos, andhumans all show this same amount of difference from gorillas. A difference of 3.1% distinguishes us and the African apes from the Asian great ape, the orangutan. How do the monkeys stack up? All of the great apes and humans differ from rhesus monkeys, for example, by about 7% in their DNA.
Geneticists have come up with a variety of ways of calculating the percentages, which give different impressions about how similar chimpanzees and humans are. The 1.2% chimp-human distinction, for example, involves a measurement of only substitutions in the base building blocks of those genes that chimpanzees and humans share. A comparison of the entire genome, however, indicates that segments of DNA have also been deleted, duplicated over and over, or inserted from one part of the genome into another. When these differences are counted, there is an additional 4 to 5% distinction between the human and chimpanzee genomes.
No matter how the calculation is done, the big point still holds: humans, chimpanzees, and bonobos are more closely related to one another than either is to gorillas or any other primate. From the perspective of this powerful test of biological kinship, humans are not only related to the great apes – we are one
Mitochondrial DNA Evidence
mtDNA analysis provides evidence for how closely related the organisms / groups are and their times of divergence mtDNA is found only in the mitochondria of cells (and not the nucleus of cells). Therefore, it is not subject to the processes of meiosis and crossing over.
Mitochondria remain in the cytoplasm of egg cells so are passed on when the egg is fertilized. They are therefore passed down the female / maternal lineage from generation to generation.
Changes in mtDNA result from mutation only and these are not subject to natural selection. Mutations in mtDNA typically occur at a steady rate and this typically is more rapid than in nuclear DNA, this allows scientists to use mtDNA as a molecular clock.
Therefore, by comparing presence of mutations in mtDNA from different individuals / groups, scientists can determine not only how closely related they are but the likely times of divergence of individuals / groups. These comparisons are now the main source of evidence used by scientists to produce phylogenetic trees.
patterns of evolution
Co-evolution- species evolving in response to each other.
As the slowest penguins are predated on, the more agile penguins pass on their alleles, so penguins become more agile overall. As a result, the most successful seals will be the ones that can catch these more agile penguins, and so the more successful seals will pass on their alleles, so both species become more agile.
From the 2014 Exam
The evolutionary relationship between the monarch butterfly and the milkweed plant is an example of co-evolution, where the species have exerted selection pressures on each other over time. The monarch butterfly is adapted to survive the toxicity of the milkweed, which normally poisons most other animal species. The milkweed is adapting to the damage caused by the monarch caterpillar feeding on its leaves by undergoing rapid regrowth of damaged tissue.
A co-evolution relationship develops where over time two species develop specific adaptations to enable their existence in the presence of the other organism. This might be, for example, predator-prey, parasitic, mutualistic or herbivory relationships, so that both are able to survive the impact of one upon the other.
In the case of the monarch butterfly and the milkweed plant, the monarch caterpillar has developed immunity to the milkweed’s poisonous alkaloids. This gives the monarch a virtual monopoly over milkweed both as a food supply for its larvae and a safe place for laying its eggs, as the poisonous nature of the plant keeps other animals from eating it. Potential predators of the monarch butterfly when they, in turn, become poisonous to many animals, will be reduced. The milkweed, in response to the caterpillar herbivory, have developed the ability to rapidly regenerate and replace damaged tissues. There would be pressure for this to happen where monarch caterpillar populations are high and the resulting damage to milkweed plants due to caterpillar feeding is also high. The high levels of herbivory could threaten the co-evolutionary relationship if plants became too heavily grazed and the monarchs lost their food and egg-laying preference and the protection it offers.
As the slowest penguins are predated on, the more agile penguins pass on their alleles, so penguins become more agile overall. As a result, the most successful seals will be the ones that can catch these more agile penguins, and so the more successful seals will pass on their alleles, so both species become more agile.
From the 2014 Exam
The evolutionary relationship between the monarch butterfly and the milkweed plant is an example of co-evolution, where the species have exerted selection pressures on each other over time. The monarch butterfly is adapted to survive the toxicity of the milkweed, which normally poisons most other animal species. The milkweed is adapting to the damage caused by the monarch caterpillar feeding on its leaves by undergoing rapid regrowth of damaged tissue.
A co-evolution relationship develops where over time two species develop specific adaptations to enable their existence in the presence of the other organism. This might be, for example, predator-prey, parasitic, mutualistic or herbivory relationships, so that both are able to survive the impact of one upon the other.
In the case of the monarch butterfly and the milkweed plant, the monarch caterpillar has developed immunity to the milkweed’s poisonous alkaloids. This gives the monarch a virtual monopoly over milkweed both as a food supply for its larvae and a safe place for laying its eggs, as the poisonous nature of the plant keeps other animals from eating it. Potential predators of the monarch butterfly when they, in turn, become poisonous to many animals, will be reduced. The milkweed, in response to the caterpillar herbivory, have developed the ability to rapidly regenerate and replace damaged tissues. There would be pressure for this to happen where monarch caterpillar populations are high and the resulting damage to milkweed plants due to caterpillar feeding is also high. The high levels of herbivory could threaten the co-evolutionary relationship if plants became too heavily grazed and the monarchs lost their food and egg-laying preference and the protection it offers.
- When does speciation occur? gradualism vs punctuated evolution
Gradualism, the idea that change is constantly happening, was favoured by early scientists such as Darwin, and can perhaps best be represented in a tree like this.
A more recent alternative hypothesis is known as ‘puntuated equilibrium’, whereby species arise through a process of ‘cladogenesis’, that is the near-instant splitting of one species into two. Therefore, in this model, species arise almost instantaneously, and remain stable for long periods of time. This hypothesis was proposed by paleontologists, who, upon examining the fossil record, found that it best reflected this model of speciation.
In reality speciation is likely a mix of these two models (which are in fact slight variations on the same principle). Genetic change is a constant process, but speciation depends on changing environments to drive selection, and the frequency and speed of these changes may ultimately dictate the pattern of speciation.
A more recent alternative hypothesis is known as ‘puntuated equilibrium’, whereby species arise through a process of ‘cladogenesis’, that is the near-instant splitting of one species into two. Therefore, in this model, species arise almost instantaneously, and remain stable for long periods of time. This hypothesis was proposed by paleontologists, who, upon examining the fossil record, found that it best reflected this model of speciation.
In reality speciation is likely a mix of these two models (which are in fact slight variations on the same principle). Genetic change is a constant process, but speciation depends on changing environments to drive selection, and the frequency and speed of these changes may ultimately dictate the pattern of speciation.
ME and MY BUDDIES Case study:
It is super important that you know and use NZ examples: http://sci.waikato.ac.nz/evolution/NZevidence.shtml#Geckos
It is super important that you know and use NZ examples: http://sci.waikato.ac.nz/evolution/NZevidence.shtml#Geckos