Drivers of Past and Present Biodiversity Changes in the Peruvian Andes

The Peruvian Andes are a biodiversity hotspot with 25 000 species of plants, 700 bird species, 450 mammal species and 2000 fish species. While most of these are in the Amazonian (East) side of the Andes, the West side has its fair share of this diversity, mainly in its vast montane forests. Of these species, 122 are threatened due to land use change, deforestation, melting glaciers and drought (local climate change). When exploring the biodiversity gradient of the Andes, it is important to understand the concept of species richness which is the total number of species in a particular total area. This paper will explore the general relationship of biodiversity and elevation, how landscape changes have shaped the biodiversity of the Marañón valley and Andean ecosystems at risk.

Considering that the West Peruvian Andes are generally a desert ecosystem, many of the species that reside there have evolved adaptations for water conservancy and extreme temperatures. Temperature poses direct physiological constraints on many organisms as well as indirect constraints through food and resource availability. Many plants cannot grow in extreme aridity, however the plants that do grow, have adapted to the lack of moisture through the development of a variety of mechanisms including succulence, wide spacing (to reduce competition for moisture), allelopathy, deciduous habits, thorns, and rapid life cycles. Insect abundances are also limited by water availability, as many need small pools of water to lay eggs or for larvae to grow.

Water availability and temperature are therefore the primary influences on species richness, as the physiologies of organisms are adapted to particular ranges of conditions and their food (plants and insects) are also constrained by water and temperature. The water and temperature gradients of the West Peruvian Andes can be observed in Figure 1. Peak in water availability (precipitation), as determined by McCain (2006) is at approximately 1500 -2000m, and in many cases, species richness also peaks at this elevation. Below is an example of how bat species richness in the Andes is influenced by the temperature and water availability gradients.

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Figure 3 Distribution of Mimosa species in the Maranon valley


Species diversity in the Marañón valley contains a very high level of endemic species richness, mainly in terms of plant species. In a study conducted by Särkinen et al. (2011), it was found to harbor nine endemic Mimosa species and about three more widespread species with their distribution shown below. This valley is also home to many endemic species of Inca-finches, scaled lizards, land snails, and harlequin frogs. Distribution of these species appears to be fragmented, with species occurring in isolated patches. When observing and comparing the phylogenetic trees of Andean Mimosa, as well as Coursetia, Poissonia, and Cyathostegia, the sequence divergence patterns and the presence of monophyly (each taxa containing all descendants of a single common ancestor in the narrowly restricted) in geographically isolated species suggests that these species have been isolated for a long time, but all originated from the same area. This is referred to as geographic speciation, in which physical isolation is the key component in splitting the single ancestor into two species. In addition, Särkinen et al. (2011) observed high local endemism, as well as high elevation habitats fostering narrowly restricted species. These results suggest that the species diversification over large time scales was largely driven by landscape features isolating populations, specifically the high Andean Cordilleras.

As mentioned above, although the Peruvian Andes are home to a vast number of species, many are endangered. In Peru, ~75% of endangered species are protected by one of many national and international agreements and treaties that Peru is involved with. The Marañón valley has been deemed a biodiversity hotspot of global conservation priority because of its high number of endemic fauna and flora, but its dry forests are still largely unprotected. These species are at risk mainly because of human-induced climate change.

Climatic studies of Peru and surrounding areas, have shown that general conditions are shifting toward being warmer and drier. Shifts in precipitation patterns and type of precipitation (solid, liquid or mist) could cause increased erosion and landslides in some places, and severe drought in others. These changes will likely affect the abiotic functions of ecosystems as well as ecosystems that span the steep slopes of the montane or cloud forests. Cloud forests are particularly vulnerable, because the structure and functioning of the ecosystems are dependent on the level of cloud bases, which is predicted to shift with climate change. Rising cloud bases could lead to decreased moisture in some areas. This has severe consequences on epiphyte species that have evolved epiphytic characteristics because of abundant moisture. These effects do not occur in isolation, as collapse of the base of the food chain (plants) tends to lead to trophic cascades.

In terms of aquatic ecosystems, rising temperatures and lower precipitation levels could result in diminished wetlands and lower dissolved oxygen levels. High temperatures will reduce the capacity of water bodies to dissolve oxygen, leading to increased mortality of many organisms with narrow temperature ranges organisms. As wetlands dry up, the habitat of many species is destroyed and they could even shift from carbon sinks to become potential carbon sources, further amplifying the effects of climate change.

Changes in the physical environment could also lead to contractions or expansions in species ranges in terms of area, and disappearance or migration of species. A recent study by von May et al. (2008) showed three frog species expanded their historical ranges to higher elevations because of recent de-glaciation, while three other species migrated to other areas. Species shifting ranges and relocating themselves will have many (unknown) effects on ecosystems structure and functioning. It also leads to the creation of many no-analog ecosystems, for which there are many uncertainties about whether or not functional roles of shifting species will be replaced by new species migrating into ecosystems.

Biodiversity of the Peruvian Andes has always been and will continue to be shaped by the climatic conditions (temperature and precipitation) and landscape features. Current climate change continue to put pressure on many ecosystems, particularly ecosystems that contain organisms with narrow temperature ranges and low resilience. Further climate changes could lead to changes in the landscape features and continuity, leading to isolation or even uniting of previously isolated species, highlighting the immense dynamism of these ecosystems.


Anderson, E. P., et al. (2011). Consequences of climate change for ecosystems and ecosystem services in the tropical Andes. SK Herzog, R. Martínez, PM Jørgensen y H. Tiessen (comps.), Climate Change and Biodiversity in the Tropical Andes. São José dos Campos y París: Instituto Interamericano para la Investigación del Cambio Global y Comité Científico sobre Problemas del Medio Ambiente.

Facts about Peru’s biodiversity and environment. (2016). Retrieved 29 April 2016, from

McCain, C. M. (January 01, 2007). Could temperature and water availability drive elevational species richness patterns? A global case study for bats. Global Ecology and Biogeography, 16, 1, 1-13.

Sarkinen, T. E., Simon, M. F., Hughes, C. E., Marcelo-Pena, J. L., Daza, Y. A., & Toby, P. R. (February 01, 2011). Underestimated endemic species diversity in the dry inter-Andean valley of the Río Marañón, northern Peru:   An example from Mimosa (Leguminosae, Mimosoideae). Taxon, 60, 1, 139-150.

von May, Rudolf, et al. “Current state of conservation knowledge on threatened amphibian species in Peru.” Tropical Conservation Science 1.4 (2008).


Budget Allocations Open up Agrifood Research opportunities at McGill

Included in the most recent provincial budget announcement is a very promising opportunity for research at McGill. The Quebec government has allocated $1 million per year for the next five years to create the McGill Agrifood Innovation Network (MAIN).

This network initiative will be led by the Faculty of Agricultural and Environmental Sciences in conjunction with Conseil de la transformation alimentaire du Québec (CTAQ) and Saint-Hyacinthe Food Research and Development Centre (CRDA), as well as other universities. The McGill University Business Engagement Centre (MUBEC) also contributed to getting this network in motion, as the opportunities for growth in agribusiness in Quebec are on the rise.

McGill has been known to be a strong research university. Pairing these strengths with agribusiness policies in government and industry could lead to great advancements in agribusiness as well as increasing research opportunities at McGill.

When producing food on an industrial scale, there is a tremendous amount of transportation and storage needed to get a given product from the producer to the consumer. Adding preservatives to food products is often essential to ensure that the product will not spoil and will still be safe to eat by the time it reaches the consumer. The food must also be suitable for consumption for a reasonable amount of time afterward (shelf-life). Preservatives act to prevent or slow the growth of any microbes or mould in the food, keeping it as fresh as possible for the longest amount of time.

Most commonly, synthetic chemical preservatives are used in many products and they tend to have complicated and long names: Sodium benzoate, calcium propionate, and sodium erythorbate. These names can confuse consumers when reading the food labels if they are not familiar with chemistry nomenclature. In the recent past, certain common preservatives have been questioned regarding potential links to cancer, notably butylated hydroxyanisole (BHA). It was officially banned from being added to processed foods sold in Canada once a significant amount of evidence supporting a possible link to cancer was discovered. “More specifically, BHA is considered as an epigenetic carcinogen because it causes cell proliferation via epigenetic events” states a 2012 review article from the Obstetrics and Gynecology International Journal looking at Epigenetics and Breast Cancers.

This case and similar ones are driving consumers toward having ‘clean’ labels, meaning that the products contain natural ingredients with familiar names such as grapefruit seed and rosemary extracts.

These natural preservatives are not always as effective or efficient as the more common chemical preservatives, but still have potential for development, and this is where MAIN comes in.

The main driver for the development of MAIN is the increasing consumer demand for (artificial) preservative-free and minimally-processed foods that still have reasonably long shelf-lives. The group working in MAIN will have this goal in mind and while working with natural ingredients to produce foods that meet those criteria and are economically feasible to produce on a larger scale.

The discovery or innovation of new natural preservatives is a rigorous and long process which undoubtedly requires a tremendous amount of research. This will open up many group research projects within the Agricultural and Environmental Sciences Faculty as well as interdisciplinary research projects for graduate students.



Let’s Talk About Mass Extinctions: Permian Triassic

This is the second of a three-part series. To view the previous post of the series, go here.

The Permian Triassic extinction is the largest known extinction to date, wiping out an estimated 96% of all species. The surface of the Earth 251 million years ago looked much different than it does today. All the continents were connected, forming one large super continent, known as Pangea. Ocean circulation was set up similarly today, where upwelling of cold water to the surface would have been in the Tethys Sea. 

The cause of the Permian Triassic extinction was mostly uncertain until recently. It was known that oxygen levels in the atmosphere were lower than they are today, but the reason for this was unclear. It was thought that the intense volcanism occurring at the time drastically increased atmospheric CO2 levels, causing global warming and lower atmospheric O2 levels. This alone would not have been a sufficient cause for the massive amount of species that went extinct during this time. In particular, it especially could not explain the number of plant species that went extinct considering the fact that plants thrive in conditions of elevated CO2. The discovery of some very important marine fossils brought some light to the situation.

Marine fossils from the Permian Triassic boundary contain large amounts of photosynthetic green and purple sulfur bacteria. Today, these bacteria are found in anoxic (without oxygen) aquatic areas such as deep, stagnant lakes and the Black Sea. They need light in order to photosynthesize, meaning that they need to stay fairly close to the surface. One of their main functions is the production of H2S gas, which is very toxic to most life forms.

 Typically, these bacteria reside fairly deep down in the ocean, because the surface ocean contains a fair amount of oxygen that these bacteria don’t like. The low light at these depths slows their photosynthesis and proliferation, preventing a bloom of the toxic bacteria. The abundance of these bacteria suggests that the world’s oceans were in an anoxic state right up to the surface. The high atmospheric CO2 levels from intense volcanism was most likely the main contributor to anoxic oceans, because warmer waters have a lower ability to absorb oxygen.

The conditions of the ocean were perfect for rapid and widespread proliferation of these bacteria, and this would have led to huge bubbles of H2S gas erupting into the atmosphere. This toxic gas would have been detrimental to nearly all life forms on Earth at the time. In addition to this, elevated sulfideatmospheric CO2 and warming would have increased the lethality of H2S.

This process did not become so intense overnight, it took hundreds of thousands of years for levels of H2S in the atmosphere to reach toxic levels. Models of H2S levels line up with estimations of past ocean circulation, where highest levels were in primary areas of upwelling of deep ocean waters. It is estimated that amount of H2S entering the atmosphere from the ocean was 2000 times greater than what is released by any volcano.

More than just fossil evidence of the H2S producing bacteria is needed to confirm this explanation for the biggest known extinction. Elevated levels of toxic H2S gas in the atmosphere would have surely caused great damage/thinning to the Earth’s ozone layer, the layer of O3 gas protecting the surface from the UV radiation of the sun. Fossil spores found in Greenland show deformities that are known to be caused by high UV exposure. High UV levels would have also caused great distress to any life on land, further contributing the extinctions.

In summary, the Permian Triassic is a classic example of “priming the pump” meaning that all the conditions were lined up perfectly for everything to go wrong causing the extinction of almost all life on Earth. High volcanic activity led to high CO2 and low O2 levels in the atmosphere causing rapid global warming. This made it difficult for the oceans to absorb oxygen, leading to anoxic oceans and an ocean wide bloom of oxygen-hating-H2S-producing bacteria. Massive bubbles of H2S gas were being emitted into the atmosphere from the oceans. The amplified lethality of H2S from the warm conditions of Earth at the time was slowly killing off life on Earth and damaging the ozone layer, exposing plants and animals to dangerously high levels of UV radiation. 

The likelihood of all these events lining up so perfectly is extremely small and rare, but not impossible. Considering that mass extinctions are also rare (but very important) occurrences, it would make sense that more significant and complex events than just volcanos caused them. Next week, we will explore how we could be currently entering the 6th mass extinction.

Let’s Talk About Mass Extinctions: Uncovering Evidence of Past Extinctions

This is the first of a 3 part series that will teach you all about mass extinctions, travelling through time to share the details of the mass extinctions that have occurred in the past, all the way up to the one that is currently happening.

Extinctions are a normal part of life in fact, species of organisms are always going extinct. The background rate of extinction defines the ‘normal’ rate that extinctions occur, without human interference. This rate is has been recently estimated to be about 0.1 extinctions per million species per year (E/MSY). In addition to this, new species are always emerging in a type of punctuated equilibrium model, leading to a constantly changing amount of biodiversity on Earth through time. 

A mass extinction is defined as an event in which a least 75% of all species on Earth disappear. This must occur on a global scale, with corresponding evidence in both the geologic and biological records. For past extinctions, determining what 75% of species at that time was and what the coinciding geological markers are, are difficult and nearly impossible tasks.

There is no real way of determining with certainty how many species existed in the past and when they went extinct. The main source of evidence of past biodiversity is in the fossil record which has some major issues. A type of ‘bias’ exists in the fossil record, meaning that very specific geographic and geologic conditions need to be present for an organism to be fossilized.

Essentially, the organism needs to be in the right place at the wrong time, in other words, all the conditions for fossilization are there, but so is the thing that kills them. Ideally, that place is an anoxic environment that will slow or stall decomposition. It must also be saturated with carbonates, otherwise the soils will use the organism’s bones as a source of carbonate, dissolving them rather than preserving them. Chance is also a key element for fossilization: for fossils to be preserved for many years, it must occur in a place where sediments are deposited, lithified (compressed and built into the rock), then uplifted and preserved rather than eroded.

These very specific conditions were obviously not present everywhere, thus, only certain species over the past millions of years were fossilized. Marine animals, and some land animals and plants are the main components of the fossil record, leaving out a huge number of species of insects and bacteria that often don’t have opportunities to be fossilized. In addition to this, for these fossils to be discovered in modern times, they must be fairly abundant meaning that we are most likely only uncovering the most common species of the past. 

How different oxygen isotope ratios form depending on climatic conditions

In terms of the geologic record, it is where scientists can infer the conditions of the past depending on the thickness of layers of certain elements in the sedimentary rocks. For example, a thick iridium layer could infer a meteorite crash on Earth (however further evidence is required to confirm this) because iridium is uncommon on Earth, but very common in extra-terrestrial materials. Another example is the use of oxygen isotope ratios in sediments and ice cores as indicators of temperature (ie. markers for glaciations). Colder waters contain higher O18/O16 ratio because H2O16 is favored over H2O18 for evaporation since it is lighter. Therefore if conditions on Earth were cold, the H2O16 would be evaporated and trapped in ice and snow on land, leaving greater O18 in marine sediment records.

The main issue with the geologic record is that rocks don’t last forever. Earth’s crust is constantly being constantly renewed (sea floors spreading) and destroyed (subduction), meaning that most of the really old rocks are all gone. The oldest rocks on Earth are found in places where subduction does not occur, therefore they are fairly sporadic, making it difficult to discern past conditions.

Even today, the definitive number of species on Earth cannot be determined, but calculating extinction rates is a lot simpler, since we do not have to rely on old and sporadic fossils and sediments.

Massive spikes in extinction rates indicate a mass extinction

The periods when extinctions occurred are determined when, over a geologically “short” period of time, a significantly lower variety of fossils are discovered indicating a sharp drop in biodiversity during that time. If this drop coincides with addition markers such as an iridium spike (and many others) then this could indicate a mass extinction event.


The geologic markers and other astounding evidence found all over the world for what is believed to be the cause of the Permian-Triassic mass extinction will be discussed in next week’s post.

Yes it is Possible for Store Bought Eggs to Hatch

It is something many people have tried or thought about trying at least once in their life: getting store bought eggs to hatch. They have probably done this without thinking about what they would do with the chicken if it did hatch, but that’s another story. It is hard and a little odd to imagine that breakfast food could actually have been alive and growing before cooking it, but it is surely not an impossible occurrence. Once hens reach reproductive maturity, they begin producing eggs whether or not they have been fertilized by a rooster. Only fertilized eggs have the capacity to grow and hatch and it’s not impossible that a fertilized egg could wind up in your refrigerator.

Eggs that come from large factories, where the chickens are caged, will most likely never hatch, simply due to the fact that the hen has probably never left her cage and has therefore never encountered a rooster to fertilize her eggs.

Free-range eggs are another story. Eggs that have been marked as “free-range” mean that the hens that produced them were not caged and were allowed to roam “free” on the farm. It is possible that these hens have had interactions with roosters, as it is a quite common practice for farmers to introduce a rooster into the flock of hens to regulate their behaviour. These types of eggs are the ones that have potential to hatch.

Without a hen, hatching an egg requires quite a bit of effort. The eggs should be kept at or just above body temperature and about 50% humidity to mimic the conditions of the mother hen sitting on them. Incubators are ideal for this, which is mainly why very few people have successfully hatched a store bought egg. I don’t know many people who keep incubators in their storage closets…

Even before incubating, it’s baffling that the chicken embryo could have possibly survived the transport, refrigeration, washing, being tossed around by machines and conveyor belts, sorting, packaging, storage, more transport, and more refrigeration in the store and at home. Surprisingly, it’s survivable because of the simple mechanisms behind how eggs work. The embryo is only a small collection of cells on the egg yolk’s wall during all this and it is protected by the liquid albumen of the egg white.

The refrigeration will stop the growth of the embryo, but it will not necessarily kill it. Once in the ideal conditions of the incubator (or the mother hen’s underbody) the embryo will resume growth. And this is precisely what happened to little Albert the quail.

Although Albert is a rare occurrence, it’s not abnormal. Just keep in mind that if you ever want to hatch a store bought egg, you must remember the implications of actually having a living, breathing chick in your home afterward, (that could have been your breakfast).

Busted Myths of the Electric Car

This morning, I was sifting through The Gazette local newspaper while sipping my morning coffee and came across a particularly interesting article. It tells how Quebec has a goal of having 100 000 electric cars on the road by 2020. This goal seems rather unrealistic at this moment, but I believe that with a little more publicity and education, that goal can be achieved.

The article describes that the lack of electric cars on the road was previously argued to be a lack of supply rather than demand, however this is now proven to be untrue. There is a low demand for electric cars (despite many incentives) mainly because people don’t know much about them and what they do know, is often a series of misconceptions. I quickly realized that I too have very little knowledge of electric cars, so this article encouraged me to do some research that I will now share with all of you. 

The main concern that people have with electric cars is the convenience of charging them. The myth is that the electric car is doomed without prevalent charging stations. The fact is that the vast majority of electric car owners only ever need to charge at home, and a little bit at work, but rarely. According to The Gazette, about 90% of the charging of a personal car will typically occur at home. Quebec is busting this myth by installing more and more charging stations across the province to show civilians that they could charge their electric car (if they had one) at many locations that they go to regularly, such as local arenas and grocery stores. The goal is to give them a comforting and reassuring feeling, further encouraging the purchasing of electric cars. Quebec is also working on installing super-charging stations along highways, making road trips with an electric car just as practical as with a regular car.

Another myth that I came across is that the batteries of electric vehicles will die after only a few years of usage. It is true that areas with extremely hot or cold weather can wear the battery faster than in more mild climates, but it is also true that manufacturers are constantly learning from their mistakes and improving the technology to increase battery durability. They also have made 8-10 year warranties on the battery packs, lightening the burden of a faulty battery.

The question that I found the most concerning is regarding the driving range of an electric vehicle per charge. While researching, I found out that the driving range for one full charge is actually eight times the distance of an average trip. Some models even have options to attach extra battery packs for long-distance drives. In addition to this, the gas tank of the vehicle will kick in and recharge the battery if needed.

Lastly, there is the issue of manufacturing the vehicle itself. The workers driving to and from the factory, the machinery, the facilities and the transport and fabrication of the materials all emit carbon dioxide, meaning that the electric car does have a carbon footprint. However, it is fairly obvious that it is significantly smaller than an internally combusting car. In this video, the two men discuss how the manufacturing emissions of an internally combusting car versus an electric car is 17% and 39% of the car’s total lifetime emissions respectfully. These numbers are extremely misleading, so let me put this into perspective for you. Electric cars have 0 tailpipe emissions whereas cars that use gas emit 20 pounds (9 kg) of CO2 per gallon (about 4 L) of gasoline that it uses. Add this up over the lifetime of the car, and you’ll have a massive amount of CO2. Although the percentages are different, the CO2 emitted in manufacturing is about the same. The percentage for the electric car is only larger because there are no tailpipe emissions to add to the total emissions. It’s basic math; 17% of a massive number is still much larger than 39% of a much smaller number.

I would consider this to be quite the successful post, as I have now educated myself and (hopefully) many others! I will definitely be investing in an electric car when the time comes for me to buy my own, and I will be for sure encouraging many of the people I know to do the same.