Observed Evolutionary Events

The purpose of this page is to illustrate the following: it is a scientific fact that new species can form, mutations can add genetic material to the genome of an organism, mutations can change the phenotype of an organism, and mutations can create advanced new features.

Contents

1. Observed instances of new species forming
2. Observed instances of new genetic material / information arising
3. Observed instances of beneficial mutations
4. Observed instances of large morphological changes
5. Observed evolution of novel organs and features
6. Observed evolution of a multicellular organism
7. Observed endosymbiosis
8. Mutation rates
9. Human evolution


1. Observed instances of new species forming


Observed beneficial mutations and macro evolutionary change in Anolis lizards

An excellent example of evolution in action is a 14-year experiment done with Anolis lizards.(Losos et al, 1997) A single species of Anolis lizards was spread across 14 Caribbean islands none of which had any previous lizard populations. Over the time of the experiment, the lizards each adapted to their respective environments. Several new species of lizards evolved. The lizards each changed body shape in response to the flora in their environment. In fact, scientists were able to predict exactly how each lizard population would evolve before seeing the results. Scientists estimate that this change was on the order of 200 darwins, which are measured units of evolutionary change. In comparison, the average rate observed in the fossil record is only 0.6 darwins.(Gingerich, 1983) (Image Source 1)

Speciation of the Faeroe Island house mouse

Irish monks originally brought the house mouse to the Faeroe Islands, where it has quickly diverged in different species, or possibly sub-species, in less than 250 years. (Stanley,1979) (Image Source 2)



Evolution of five new species of cichlid fishes in Lake Nagubago.

Less than 5,000 years ago, a sandbar formed and cut off Lake Nagubago from the larger Lake Victoria. Since then, at least 5 new species of cichlid fish have evolved in Lake Nagubago, and these species are found nowhere else in the entire world.(Mayr, 1970)

 

Speciation in action among Larus seagulls.

Gulls of the genus Larus form an evolutionary ring around the North Pole, which acts as a geographic barrier for their population. Although some have argued that this is technically not an example of a ring species(Liebers et al., 2004), it is certainly an example of speciation in action.

In the image above, one can see the "ring" the sub-species of gulls make around the pole. The herring gull can interbreed with its neighbor, the American herring gull, which can interbreed with its neighbor, the Vega gull, which can interbreed with its neighbor, Birula's gull, which can interbreed with its neighbor, Heruglin's gull, which can interbreed with its neighbor, the Siberian black-backed gull, which can finally interbreed with its neighbor, the lesser black-backed gull. (Image Source 4)

However, the populations of the herring gulls and the lesser black-backed gulls are genetically different enough so that, even though they now live in relatively the same area, they cannot reproduce together. Thus, they can not truly be the same species. As you move west around the pole, the genetic difference in each population becomes slightly greater and greater until the two ends meet, at which we have two separate species.

Examples such as the Larus gulls essentially show all the steps of speciation laid out in a ring. Each population is slightly different from the last, until the two ends meet and these populations are completely different species that will now continue to grow more and more genetically different. To the left you can see the two distinct species of gulls, the herring gull and the lesser black-backed gull. (Image Source 5)

A new species of Evening Primrose named Oenothera gigas

The early geneticist Hugo de Vries observed an act of speciation while studying the evening primrose plant. The original species, Oenothera lamarckiana, had 14 chromosomes, while the new species had 28. The new species was unable to breed with Oenothera lamarckiana, and thus he named it Oenothera gigas.(De Vires, 1905) (Image Source 6)




Evolution of a new multicellular species from unicellular Chlorella

When a predator was introduced to the environment of the unicellular Chlorella algae in a lab test, scientists observed the algae cells bond together in colonies, and eventually became an entirely new multicellular species. One could even argue that this change extends past the species level. In the image to the left, FC is the unicellular chlorella algae, Oc is the predator introduced to the environment, and CC is the new multicellular algae.

This is not simply a "cell colony", but a new multicellular organism. The multicellularity was achieved by a mutation that fused the cell wall of the mother cell and its daughter cell together. Because these cells are thus dependent upon each other for survival, the new organism is multicellular and not a simple bacterial colony.(Boraas et al., 1998) (Note: The image is also from this source.)

A new species of mosquito in London


The new species of mosquito Culex pipiens molestus recently formed in, and is endemic to, the London Underground rapid transit system. It most likely speciated from the surface population Culex pipiens, although it is now genetically dissimilar enough to be considered another. (Byrne et al., 1999)

Finch speciation in the Galapagos

The finch populations of the Galapagos islands have been famous ever since they were included as elegant examples of natural selection in Darwin's On the Origin of Species. In recent times, scientists have successfully observed a new species of finch develop after an extreme bottleneck in the finch population on the island Daphne Major, caused by a drought. This new species refuses to mate with its sister-species, and thus is reproductively isolated. Over time, it will genetically diverge; this is evolution in action just as Darwin predicted, in the very place where the formation of his ideas have their roots(Peter Grant and Rosemary Grant 2009).


Even more examples can be found at:
More Observed Speciation events
Even More Observed Speciation events
Macroevolution Examples


2. Observed instances of new genetic material(information) arising

The following examples are scientific studies in which mutations or other natural genetic processes were observed to add new genetic information(found via talkOrigins):

  • increased genetic variety in a population (Lenski 1995; Lenski et al. 1991)
  • increased genetic material (Alves et al. 2001; Brown et al. 1998; Hughes and Friedman 2003; Lynch and Conery 2000; Ohta 2003)
  • novel genetic material (Knox et al. 1996; Park et al. 1996)
  • novel genetically-regulated abilities (Prijambada et al. 1995)

Another specific way in which information in a genome increases is by gene duplication followed by a point mutation, changing the duplicated genes. Scientists have found strong evidence that this mechanism has added to the genome of organisms in the past (Ossad and Innan 2008). A diagram of gene duplication and divergence is below.

Specific, observed examples of this occurring are explained below.

"RNASE1, a gene for a pancreatic enzyme, was duplicated, and in langur monkeys one of the copies mutated into RNASE1B, which works better in the more acidic small intestine of the langur." (Zhang et al. 2002)





"Yeast was put in a medium with very little sugar. After 450 generations, hexose transport genes had duplicated several times, and some of the duplicated versions had mutated further." (Brown et al. 1998)

(quotes above are from TalkOrigins)






Additional examples of an observed increase in information throughout the genome or chemical structure of an organism:

Chromosome duplication in Evening Primrose

As discussed above, this species was created when the number of chromosomes in an individual doubled. Thus, genetic information was increased. (De Vires, 1905)

Retrovirus protection in Old World Monkeys

Some old world monkeys developed a mutation in the protein TRIM5 that created a new protein called TRIM5-CrypA. This novel protein helped protect cells from HIV and other retroviruses. (Newman, 2008)

Observed Chromosomal fusion and the creation of a new sex chromosome

A chromosome fusion event in stickleback fish of the Japan Sea resulted in the formation of a new species.(Gilbert, 2009)

Evolution of novel genes in Fruit Flies

Begun et al., 2007 and Levine et al., 2006 observed the formation of de novo genes arise from mutations in noncoding DNA in a population of Drosophila.

A new, protein-coding gene in Yeast

Cai et al. 2008 found that a new, functional gene in a specific yeast species had evolved from a previously non-coding region.

Evolution of novel genes and function in HIV

The HIV virus has recently undergone rapid evolution which has resulted in the emergence of new genetic information; specifically, the Vpu gene. For more, see blogger Abbie Smith's post here.

A new gene arises by Gene duplication in Zebrafish

Most Zebrafish have two copies of the FGFR1 gene, involved in embryonic development. The second copy is generally functionally redundant. However, researchers recently found that in some zebrafish the second copy has since mutated and attained a new function involved in scale production(Rohner et al. 2009).

Formation of a novel X-Chromosome in Stickleback fish

While studying two extremely closely related populations of stickleback fish, scientists found a novel X-chromosome in one of the two which is unobserved in other fish populations. To the left, one can see the chromosomes of an individual male specimen with the neo-x chromosome. The new X-chromosome is marked with a green tint. The scientists then concluded that this new chromosome had been slowly driving the two populations apart into two distinct species (Kitano et al. 2009). (Image modified from source)






3. Observed instances of beneficial mutations

Note: Because this category includes most of the case examples that are in other categories, we have not duplicated most of the other examples in this section.

Beneficial mutations of yeast in a low phosphate environment

In an experiment on evolutionary change, yeast was placed in a low phosphate environment and scientists observed three beneficial mutations that helped the yeast adapt. The yeast was derived from an clonal line, which is a group of individual organisms with identical genomes. The first mutation observed affected the permease molecule, and allowed the yeast to absorb more phosphate, and thus it caused a boom in the population density. The second mutation changed the yeast's phosphatase, which became more active. Finally, the thread mutation allowed the yeast to clump together, and thus the population density grew further. (Francis & Hansche, 1972/1973) (Image Source 7)

Yeast adapts to a glucose limited environment via gene duplications and natural selection

As discussed above, in this experiment the hexose transport genes of the yeast duplicated and the duplicated versions mutated, which is an obvious addition of new material to the genome of the yeast. These new genes allowed the yeast to more efficiently process glucose and thus be more likely to survive.(Brown et al., 1998)




Chlamydomonas adapts to grow in the dark

Chlamydomonas is an algae that uses photosynthesis as its food source. Thus, it is ill adapted to grow in the dark. However, in an experiment conducted by Graham Bell, the organisms were selected in preference of those which grow in the dark, and after several generations, chlamydomonas developed an ability to use acetate as a carbon source so effectively that the final strain was very adept at growth in the dark. (Bell)



Bacteria evolve to eat nylon

Researchers found a strain of Flavobacterium in pools containing waste water from a nylon factory. The strain had evolved to digest nylon, which is a recent modern man-made product.

The enzymes that allowed the bacteria to do so were novel and unlike any of those found in other strains of the same bacteria, and they do not aid the bacteria in digestion of any known materials besides nylon. Although the exact type of mutation is under debate, a large portion of the scientific community accepts the hypothesis that the mutation was caused by a gene duplication combined with a frameshift mutation.(Ohno, 1984) If this is so, this would also be an example of a mutation increasing genetic information in the genome. Gene duplication and frameshift mutations work like this example:

The genetic sequence may start as: THE CAT. The genetic sequence is duplication by a gene duplication mutation: "THE CAT" and "THE CAT". The duplicate is further transformed by a frameshift mutation: "THE CAT" and "HEC ATK", where 'K' is a shifted base pair from a adjacent gene sequence. Thus, information has been added. The genome has the new sequence "HEC ATK", which it had nothing like before.

Inaccurate creationist claims about this are dealt with here.

Resistance to atherosclerosis

Resistance to atherosclerosis was documented in small population in Italy. The resistance was caused by a mutation in the angiotensin-converting enzyme gene, which affects the plasma levels in an individual.(Margaglione, et al., 1998)

E. coli evolves to hydrolyze galactosylarabinose

Scientists observed two mutations arise in a population of E. coli which allowed the bacteria to hydrolyze galactosylarabinose. (Hall and Zuzel 1980)


E. coli evolves to metabolize propanediol

In normal circumstances, E. coli digest L-fucose and convert it into dihydroxyacetone phosphate and lactaldehyde, the latter of which is a waste product. Then, this waste product is converted into propanediol, which is then excreted from the cell. However, in a laboratory environment rich with propanediol, scientists observed a mutation in E. coli that allowed it to digest the previous waste material and effectively use it as an energy source. (Lin and Wu 1984)

E. coli evolves to digest citrate

In a long term experiment on evolution with E. coli, scientists observed a mutation create a complex, new feature which allowed the E. coli to absorb citrate through its membrane. Because E. coli is usually distinguished as a species which cannot digest citrate, this could also be considered a speciation event. To the left is an image of the flasks containing the E. coli mutant from the experiment. (Lenski et al., 2008) (Image Source 8) (The response from the creationist organization Conservapedia to this study is dealt with here.)

Klebsiella bacteria develop a new metabolic pathway to metabolize 5-carbon sugars

Several mutations that occurred in the bacteria Klebsiella created an entirely new metabolic pathway in order to help metabolize exotic five-caborn sugars such as D-arabinose and xylitol. (Hartley, 1984)

Fruit fly adaptations to low oxygen environments

In a controlled laboratory experiment, fruit flies were slowly exposed to lower oxygen levels. A number of mutations helped many of the test populations beneficially adapt to survive in extremely low oxygen environments. (Zhou et al. 2008)


Blowfly Insecticide Resistance

A simple mutation was observed to give insecticide resistance to blowflies. (Newcomb, et al., 1997)

Fungi evolves to harness high radiation levels in Chernobyl, Russia

Researchers found an interesting new type of fungi directly inside the Chernobyl reactor core. As most know, Chernobyl, Russia was the site of an infamous nuclear disaster over 20 years ago. The specific fungus appears to not only thrive in the dangerously radioactive environment, but the fungus actually harnesses the radioactive energy to survive. Evidence indicates that this new fungus evolved from the local fungi in the surrounding area.(Monaghan, 2008)

Chlorella algae evolves multicellularity in response to a predator

As discussed above, the introduction of a predator to the controlled environment of a Chlorella population selected a beneficial mutation in daughter-cell replication which effectively created a new multicellular strain of Chlorella. (Boraas et al., 1998)

For more examples of beneficial mutations, check out the below suggestions.
A. Most of the examples in the other sections include beneficial mutations.
B. http://www.gate.net/~rwms/EvoMutations.html
C. http://www.gate.net/~rwms/EvoHumBenMutations.html


4. Observed instances of large morphological changes


Croatian Lizards change body shape to adapt to a new environment

Lizards of the species Podarcis sicula from a nearby island were introduced by scientists to a new island previously uninhabited by scientists in 1971. Since then, several evolutionary changes have occurred. The lizards now have larger heads and stronger bites. In addition, the population has evolved cecal valves, entirely new organs.(see below) (Herral, A. et al. 2008) (Image Source 9)


Anolis Lizards change body shape to adapt to new island environments

An excellent example of evolution in action is a 14-year experiment done with Anolis lizards.(Losos et al, 1997) A single species of Anolis lizards was spread across 14 Caribbean islands none of which had any previous lizard populations. Over the time of the experiment, the lizards each adapted to their respective environments. Several new species of lizards evolved. The lizards each changed body shape in response to the flora in their environment. In fact, scientists were able to predict exactly how each lizard population would evolve before seeing the results. Scientists estimate that this change was on the order of 200 darwins, which are measured units of evolutionary change. In comparison, the average rate observed in the fossil record is only 0.6 darwins.(Gingerich, 1983)

Galapagos Finches morphologically change in response to seed sizes

This is one of the most famous examples of evolution in history. In fact, during Darwin's visit to the Galapagos, the unique variation he observed among the finch beaks influenced his ideas on natural selection. Since then, scientific observation has confirmed that Darwin's initial hypothesis was correct; the finches do evolve in response to the size of available seeds. A large study found that over the years, the size of beaks in the population Geospiza fortis fluctuated in response to the size of the available seeds.(Grant 2002) (Image Source 10)

Autralian snakes adapt to introduction of poisonous toads

The species of toad Bufo marinus was introduced to Australia in 1935. As invasive species, they have quickly spread and today are quite numerous. This is especially due to their toxic flesh, which kills any predator attempting to grab one to eat. Since then, at least two species of snakes have evolved smaller heads, and thus smaller bites, in response to the toads. Snakes with smaller heads could not eat the large toads, and thus did not die from the poisonous flesh, and were capable of eating other smaller, harmless species. (Phillips et al., 2004)

Change in size of the bony armor of Stickleback fish

Researchers isolated specific genetic mutations in a population of stickleback fish that change the size of the fish's bony armor enormously. The photo to the left shows a stickleback with minor bony armor (bottom), and one with an enlarged plate (top).(Kingsley 2004 and 2005) (Image from source)



Some more examples of large morphological changes:
Genetic and developmental basis of evolutionary pelvic reduction in threespine sticklebacks
Limb alterations in brachypodism mice due to mutations in a new member of the TGF|[beta]|-superfamily

5. Observed evolution of novel organs and features

Croatian Lizards develop Cecal Valves

Lizards of the species Podarcis sicula from a nearby island were introduced by scientists to a new island previously uninhabited by scientists in 1971. Since then, several evolutionary changes have occurred. This included the formation of completely new organs in the lizards known as cecal valves, which helped the lizards digest their new strictly plant diet. To the left is a photograph of the cecal valve in a male specimen. (Herral A., et al., 2008) (Photo from article)



A simple mutation in Ciona intestinalis transforms its single heart into a functional multichambered organ

The sea squirt species Ciona intestinalis is a well-studied and documented organism, and its entire genome has been sequenced. Scientists recently found that a relatively simple mutation changed its simple single chambered heart into a more complex multichambered one, like those of most vertebrates. As the article concludes: "This expansion produces an unexpected phenotype: transformation of a single-compartment heart into a functional multicompartment organ."(Davidson et al. 2006) (Image Source 11)


Bacteria evolve a new pathway for the formation of protein disulfide bonds

In an experiment, scientists removed the ability of a population of bacteria to form protein disulfide bonds, which effectively stops the bacteria from operating their flagellum. The bacteria were then placed in a dish. If the bacteria couldn't move before the nearby food supply ran out, they would die from starvation. However, a completely new pathway for the formation of protein disulfide bonds formed in one of the bacteria, which allowed it to move and thus successfully reproduce. (Masip et al., 2004)

Antarctica fish develop a natural antifreeze protein

Although not directly observed, Chen, DeVries, and Cheng 1997 found strong evidence which indicated that the natural antifreeze protein used by various Antarctic fish was created by a mutation duplicating and changing a previous pancreatic protein. This is an example of modification of a duplicated gene to create a new gene/protein and feature.

A new metabolic pathway in Mustard species

Scientists recently found strong evidence that a new metabolic path involved in pollen development formed in species of mustard plants. This occurred with a combination of retroposition, gene duplication, and new mutations changing the duplication. This new feature is an excellent example of how modified gene duplication can result in neofunctionalization(Matsuno et al. 2009).

6. Observed evolution of a multicellular organismAS

Evolution of a new multicellular species from unicellular Chlorella

When a predator was introduced to the environment of the unicellular Chlorella algae in a lab test, scientists observed the algae cells bond together in colonies, and eventually became an entirely new multicellular species. One could even argue that this change extends past the species level. In the image to the left, FC is the unicellular chlorella algae, Oc is the predator introduced to the environment, and CC is the new multicellular algae.

This is not simply a "cell colony", but a new multicellular organism. The multicellularity was achieved by a mutation that fused the cell wall of the mother cell and its daughter cell together. Because these cells are thus dependent upon each other for survival, the new organism is multicellular and not a simple bacterial colony.(Boraas et al., 1998) (Note: The Image is also from this source.)

7. Observed endosymbiosis

Endosymbiosis is the evolutionary theory that the organelles in eukaryotes were once separate prokaryotic organisms which were taken in by another prokaryote. This effectively explains the evolution of eukaryotes. This old theory has recently been shown possible by an observed case of endosymbiosis in the laboratory. In this specific case, the unicellular predator Hatena absorbed the algae producer Nephroselmis. Instead of digesting Nephroselmis, the algae grows inside Hatena, and begins to produce food for both of the organisms. Hatena no longer needs a mouth, and thus this feature completely disappears. Effectively these two prokaryotes form a new eukaryotic cell. On the left is a picture of Hatena with Nephroselmis and without (Okamoto, 2005). (Note: The image is also from this source)

Microbiologist K.W. Jeon has done extensive research documenting an example of observed endosymbiosis in the laboratory. His experiment consisted of infecting a population of amoebae with a bacterial strain. While the majority of the amoebae died from the infection, some of the bacterial cells remained within the amoebae cells. Over time, Jeon proved that the amoebae eventually grew dependent on these bacterial cells, effectively creating a newly endosymbiotic eukaryote (K.W. Jeon 1972, 1977, 1987, 1995).

8. Mutation rates

Below we have listed the results of several studies on mutation rates. These results show that mutations aren't extremely rare, and beneficial mutations aren't as uncommon as one might think. Additionally, note that although beneficial mutations are a minority, harmful mutations are selected out of a population and thus have no lasting effects.

A. Most mutations are neutral, and have no effects. Only approximately 1 in 15 mutations have any effect.(Perfeito et al. 2007)

B. 12% (3 out of 26) of random mutations in a strain of bacteria improved fitness in a particular environment.(Remold and Lenski 2001)

C. Another study found that 10% of functional mutations in E. coli were beneficial. (Perfeito et al. 2007)

D. Another study approximated that there are around 64 mutations in each human zygote.(Drake et al. 1998)

Human evolution

Obviously, the human species is still evolving, and humans have changed quite a bit since our species first arose. We already talked about the evolution of lactose tolerance in a previous post, but there is quite a bit more to cover. Thus, this blog post is all about evolution in humans from the present and recent past.

Brain Evolution

Evans et al. 2005 found that a gene named Microcephalin regulates brain size in humans. A specific variant of this gene first arose in humans about 37,000 years ago, and has since for been positively selected for in the human population. This study provides strong evidence that the human brain has been undergoing rapid evolution in the recent past.

The Evolution Of Lactose Tolerance

It may come as a surprise to many people living in the Western world that the majority of adults on Earth are to some degree lactose intolerant. After all, we take lactose tolerance largely for granted in societies dominated by Europeans; in fact, milk and milk based products are essential staples of the daily diets of these countries. From breakfast to dessert, butter, milk, and cheese come with the meal.

However, those with complete lactose tolerance are in the global minority, and are in fact mutants. A few single nucleotide( nucleotides are individual units of DNA) changes confer lactose tolerance through adulthood in European and a few African populations with the mutations seen below:

(Tishkoff et al. 2007) (Image adapted from source)

This is merely a successful example of evolution at the most basic level: a beneficial mutation arising naturally and successfully spreading throughout a population.

Sickle-cell and Malaria Resistance

Sickle-cell is a human blood disorder in which red blood cells take on a sickle shape instead of the normal round donut shape of red blood cells, and is caused by a single point mutation. While having both of the recessive sickle-cell alleles can cause several life-disrupting complications, being a genetic carrier of the recessive allele has a positive advantage in that it confers some resistance to malaria. Thus, the allele has been positively selected for in recent times throughout Africa, where malaria is extremely common and poses a significant threat. (Kwiatkowski 2005)

Resistance to Heart Disease

Several carriers of a mutant allele called Apo A-1 Milano have been found in Italy. This allele has been shown to confer resistance to Heart Disease even if cholesterol levels of a carrier are extremely high.(Long 1994; Weisgraber et al. 1983)

Resistance to HIV in Humans

Resistance to HIV has been found to be conferred by a mutation in some Caucasian individuals with a mutant form of a gene called CCR-5. (Samson et al. 1996)

Tibetan Adaptations to High Altitudes

Considered to be one of the fastest known examples of human evolution in recent times, several mutations in Tibetans have allowed them to adapt and survive at high altitudes. About 30 different genes which regulate metabolism and oxygen have specifically undergone natural selection to confer these beneficial changes. (Yi et al. 2010)

More on recent evolution in humans from TalkOrigins

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Citations for the Images which require them are below. Thanks to everyone who created one of the images we used.

1. Carolina Anole. Image Attributed to Pollinator. Under the GPL 1.2+ license. Source

2. House mouse. Image Attributed to George Shuklin. Under the CC Attribution SA license. Source.

3. Cichlid fishes. Found by LiveScience. Attributed to Martine Maan, University of Leiden. It is assumed the author retains all rights to this image. Source.

4. Larus gull ring. Accredited to: http://cairnarvon.rotahall.org/2008/09/09/on-ring-species/

5. Photo of two Larus gulls. Accredited to Tomasz Sienicki. Under the CC Attr. 2.5 license. Source.

6. Photo of Evening Primrose. Under the GFDL license version 1.2+. Source.

7. Yeast cells. Under dual, perhaps triple, licensing. Accredited to Wiki user: Masur. Source.

8. Lenski flasks of citrate mutant. Accredited to Brian Baer and Neerja Hajela. Under a CC Attributtion Share-alike 3.0 license. Source.

9. Croatian lizard, Podarcis siculus. Accredited to Hans Hillewaert. Under a CC Attribution SA license. Source.

10. Image of Geospiza fortis. Attributed to flicker user putneymark. Source.

11. Image of Ciona intestinalis. Under the GFDL license. Source.